BARCLAYS BANK PLC (SEC Filing Page | XBRL Cloud Viewer | XBRL Instance)

Line	Label	Object Class	Period Type	Balance	Report ElementName
1	000010 - Document - Document and Entity Information	Network	*	*	http://www.barclays.co.uk/role/DocumentAndEntityInformation
2	Implied Table	Table	*	*	implied:Table
3	Document And Entity Information [abstract]	Abstract			c070:DocumentAndEntityInformationAbstract
4	Document Type	Concept (Submission Type)	For Period		dei:DocumentType
5	Amendment Flag	Concept (Yes/No)	For Period		dei:AmendmentFlag
6	Document Period End Date	Concept (Date)	For Period		dei:DocumentPeriodEndDate
7	Document Fiscal Year Focus	Concept (Year)	For Period		dei:DocumentFiscalYearFocus
8	Document Fiscal Period Focus	Concept (Fiscal Period)	For Period		dei:DocumentFiscalPeriodFocus
9	Entity Registrant Name	Concept (Text/String)	For Period		dei:EntityRegistrantName
10	Entity Central Index Key	Concept (CIK Number)	For Period		dei:EntityCentralIndexKey
11	Current Fiscal Year End Date	Concept (Month/Day)	For Period		dei:CurrentFiscalYearEndDate
12	Entity Well Known Seasoned Issuer	Concept (Yes/No)	For Period		dei:EntityWellKnownSeasonedIssuer
13	Entity Current Reporting Status	Concept (Yes/No)	For Period		dei:EntityCurrentReportingStatus
14	Entity Filer Category	Concept (Filer Category)	For Period		dei:EntityFilerCategory
15	Entity Emerging Growth Company	Concept (Yes/No)	For Period		dei:EntityEmergingGrowthCompany
16	Entity Shell Company	Concept (Yes/No)	For Period		dei:EntityShellCompany
17	Entity Common Stock Shares Outstanding	Concept (Shares)	As Of		dei:EntityCommonStockSharesOutstanding
18	000100 - Statement - Consolidated Income Statement	Network	*	*	http://www.barclays.co.uk/role/ConsolidatedIncomeStatement
19	Implied Table	Table	*	*	implied:Table
20	Income statement	Abstract			ifrs-full:ProfitLossAbstract
21	Continuing operations	Abstract			c070:ContinuingOperationsAbstract
22	Interest income	Concept (Monetary)	For Period	Credit	ifrs-full:InterestRevenueCalculatedUsingEffectiveInterestMethod
23	Interest expense	Concept (Monetary)	For Period	Debit	ifrs-full:InterestExpense
24	Net interest income	Concept (Monetary)	For Period	Credit	ifrs-full:InterestRevenueExpense
25	Fee and commission income	Concept (Monetary)	For Period	Credit	ifrs-full:FeeAndCommissionIncome
26	Fee and commission expense	Concept (Monetary)	For Period	Debit	ifrs-full:FeeAndCommissionExpense
27	Net fee and commission income	Concept (Monetary)	For Period	Credit	ifrs-full:FeeAndCommissionIncomeExpense
28	Net trading income	Concept (Monetary)	For Period	Credit	ifrs-full:TradingIncomeExpense
29	Net investment income	Concept (Monetary)	For Period	Credit	c070:InvestmentIncomeExpense
30	Other income	Concept (Monetary)	For Period	Credit	ifrs-full:OtherIncome
31	Total income	Concept (Monetary)	For Period	Credit	c070:ProfitLossFromOperatingActivitiesBeforeImpairmentLossReversalOfImpairmentLossRecognisedInProfitOrLoss
32	Credit impairment charges and other provisions	Concept (Monetary)	For Period	Debit	ifrs-full:ImpairmentLossReversalOfImpairmentLossRecognisedInProfitOrLoss
33	Net operating income	Concept (Monetary)	For Period	Credit	ifrs-full:ProfitLossFromOperatingActivities
34	Staff costs	Concept (Monetary)	For Period	Debit	ifrs-full:EmployeeBenefitsExpense
35	Infrastructure costs	Concept (Monetary)	For Period	Debit	c070:InfrastructureCosts
36	Administration and general expenses	Concept (Monetary)	For Period	Debit	ifrs-full:GeneralAndAdministrativeExpense
37	Litigation and conduct	Concept (Monetary)	For Period	Debit	ifrs-full:LossesOnLitigationSettlements
38	Total operating expenses	Concept (Monetary)	For Period	Debit	ifrs-full:OperatingExpense
39	Share of profit of post-tax results of associates and joint ventures	Concept (Monetary)	For Period	Credit	ifrs-full:ShareOfProfitLossOfAssociatesAndJointVenturesAccountedForUsingEquityMethod
40	Profit/(loss) on disposal of subsidiaries, associates and joint ventures	Concept (Monetary)	For Period	Credit	ifrs-full:GainLossRecognisedOnMeasurementToFairValueLessCostsToSellOrOnDisposalOfAssetsOrDisposalGroupsConstitutingDiscontinuedOperation
41	Profit (loss) before tax	Concept (Monetary)	For Period	Credit	ifrs-full:ProfitLossBeforeTax
42	Taxation	Concept (Monetary)	For Period	Debit	ifrs-full:IncomeTaxExpenseContinuingOperations
43	Profit/(loss) after tax in respect of continuing operations	Concept (Monetary)	For Period	Credit	ifrs-full:ProfitLossFromContinuingOperations
44	(Loss)/profit after tax in respect of discontinued operations	Concept (Monetary)	For Period	Credit	ifrs-full:ProfitLossFromDiscontinuedOperations
45	Profit (loss) after tax	Concept (Monetary)	For Period	Credit	ifrs-full:ProfitLoss
46	Attributable to:	Abstract			ifrs-full:ProfitLossAttributableToAbstract
47	Ordinary equity holders	Concept (Monetary)	For Period	Credit	ifrs-full:ProfitLossAttributableToOrdinaryEquityHoldersOfParentEntity
48	Other equity instrument holders	Concept (Monetary)	For Period	Credit	c070:ProfitLossAttributableToOtherEquityHoldersOfTheParent
49	Total equity holders	Concept (Monetary)	For Period	Credit	ifrs-full:ProfitLossAttributableToOwnersOfParent
50	Non-controlling interests in respect of continuing operations	Concept (Monetary)	For Period	Credit	ifrs-full:ProfitLossFromContinuingOperationsAttributableToNoncontrollingInterests
51	Non-controlling interests in respect of discontinued operation	Concept (Monetary)	For Period	Credit	ifrs-full:ProfitLossFromDiscontinuedOperationsAttributableToNoncontrollingInterests
52	Profit (loss) after tax	Concept (Monetary)	For Period	Credit	ifrs-full:ProfitLoss
53	000200 - Statement - Consolidated statement of comprehensive income	Network	*	*	http://www.barclays.co.uk/role/ConsolidatedStatementOfComprehensiveIncome
54	Disclosure of operating segments [table]	Table	*	*	ifrs-full:DisclosureOfOperatingSegmentsTable
55	Continuing and discontinued operations [axis]	Axis			ifrs-full:ContinuingAndDiscontinuedOperationsAxis
56	Aggregate continuing and discontinued operations [member]	Member			ifrs-full:AggregateContinuingAndDiscontinuedOperationsMember
57	Continuing operations [member]	Member			ifrs-full:ContinuingOperationsMember
58	Discontinued operations [member]	Member			ifrs-full:DiscontinuedOperationsMember
59	Consolidated Entities [Axis]	Axis			srt:ConsolidatedEntitiesAxis
60	Consolidated Entities [Domain]	Member			srt:ConsolidatedEntitiesDomain
61	Barclays Bank Group [member]	Member			c070:BarclaysBankGroupMember
62	Disclosure of operating segments [line items]	LineItems			ifrs-full:DisclosureOfOperatingSegmentsLineItems
63	Profit (loss) after tax	Concept (Monetary)	For Period	Credit	ifrs-full:ProfitLoss
64	Profit/(loss) after tax in respect of continuing operations	Concept (Monetary)	For Period	Credit	ifrs-full:ProfitLossFromContinuingOperations
65	(Loss)/profit after tax in respect of discontinued operations	Concept (Monetary)	For Period	Credit	ifrs-full:ProfitLossFromDiscontinuedOperations
66	Other comprehensive income/loss that may be recycled to profit or loss from continuing operations:	Abstract			ifrs-full:ComponentsOfOtherComprehensiveIncomeThatWillBeReclassifiedToProfitOrLossNetOfTaxAbstract
67	Currency translation reserve	Abstract			ifrs-full:ExchangeDifferencesOnTranslationAbstract
68	Currency translation differences	Concept (Monetary)	For Period	Credit	ifrs-full:OtherComprehensiveIncomeNetOfTaxExchangeDifferencesOnTranslation
69	Available for sale reserve	Abstract			ifrs-full:AvailableforsaleFinancialAssetsAbstract
70	Net gains from changes in fair value	Concept (Monetary)	For Period	Credit	ifrs-full:GainsLossesOnRemeasuringAvailableforsaleFinancialAssetsBeforeTax
71	Net (gains) transferred to net profit on disposal	Concept (Monetary)	For Period	Debit	c070:ReclassificationAdjustmentsOnAvailableforsaleFinancialAssetsBeforeTaxOnDisposal
72	Net losses transferred to net profit due to impairment	Concept (Monetary)	For Period	Debit	c070:ReclassificationAdjustmentsOnAvailableForSaleFinancialAssetsBeforeTaxDueToImpairment
73	Net losses/(gains) transferred to net profit due to fair value hedging	Concept (Monetary)	For Period	Debit	c070:ReclassificationAdjustmentsOnAvailableForSaleFinancialAssetsBeforeTaxFairValueHedging
74	Changes in insurance liabilities and other movements	Concept (Monetary)	For Period	Credit	c070:GainsLossesOnRemeasuringAvailableforsaleFinancialAssetsBeforeTaxInsuranceLiabilitiesAndOtherMovements
75	Tax	Concept (Monetary)	For Period	Debit	ifrs-full:IncomeTaxRelatingToAvailableforsaleFinancialAssetsOfOtherComprehensiveIncome
76	Fair value through other comprehensive income reserve	Abstract			ifrs-full:FinancialAssetsMeasuredAtFairValueThroughOtherComprehensiveIncomeAbstract
77	Net losses from changes in fair value	Concept (Monetary)	For Period	Credit	ifrs-full:GainsLossesOnFinancialAssetsMeasuredAtFairValueThroughOtherComprehensiveIncomeBeforeTax
78	Net losses transferred to net profit on disposal	Concept (Monetary)	For Period	Debit	c070:ReclassificationAdjustmentsOnFinancialAssetsMeasuredAtFairValueThroughOtherComprehensiveIncomeBeforeTaxOnDisposal
79	Net losses transferred to net profit due to impairment	Concept (Monetary)	For Period	Debit	c070:ReclassificationAdjustmentsOnFinancialAssetsMeasuredAtFairValueThroughOtherComprehensiveIncomeBeforeTaxDueToImpairment
80	Net losses transferred to net profit due to fair value hedging	Concept (Monetary)	For Period	Debit	c070:ReclassificationAdjustmentsOnFinancialAssetsMeasuredAtFairValueThroughOtherComprehensiveIncomeBeforeTaxDueToFairValueHedging
81	Changes in insurance liabilities and other movements	Concept (Monetary)	For Period	Credit	c070:GainsLossesOnRemeasuringFinancialAssetsMeasuredAtFairValueThroughOtherComprehensiveIncomeBeforeTaxInsuranceLiabilitiesAndOtherMovements
82	Tax	Concept (Monetary)	For Period	Debit	ifrs-full:IncomeTaxRelatingToFinancialAssetsMeasuredAtFairValueThroughOtherComprehensiveIncome
83	Cash flow hedging reserve	Abstract			ifrs-full:CashFlowHedgesAbstract
84	Net (losses)/gains from changes in fair value	Concept (Monetary)	For Period	Credit	ifrs-full:GainsLossesOnCashFlowHedgesBeforeTax
85	Net gains transferred to net profit	Concept (Monetary)	For Period	Debit	ifrs-full:ReclassificationAdjustmentsOnCashFlowHedgesBeforeTax
86	Tax	Concept (Monetary)	For Period	Debit	ifrs-full:IncomeTaxRelatingToCashFlowHedgesOfOtherComprehensiveIncome
87	Other	Concept (Monetary)	For Period	Credit	ifrs-full:OtherIndividuallyImmaterialComponentsOfOtherComprehensiveIncomeNetOfTax
88	Other comprehensive income/(loss) that may be recycled to profit or loss	Concept (Monetary)	For Period	Credit	ifrs-full:OtherComprehensiveIncomeThatWillBeReclassifiedToProfitOrLossNetOfTax
89	Other comprehensive income/(loss) not recycled to profit or loss from continuing operations:	Abstract			ifrs-full:ComponentsOfOtherComprehensiveIncomeThatWillNotBeReclassifiedToProfitOrLossNetOfTaxAbstract
90	Retirement benefit remeasurements	Concept (Monetary)	For Period	Credit	ifrs-full:OtherComprehensiveIncomeBeforeTaxGainsLossesOnRemeasurementsOfDefinedBenefitPlans
91	Fair value through other comprehensive income reserve	Concept (Monetary)	For Period	Credit	ifrs-full:OtherComprehensiveIncomeBeforeTaxGainsLossesFromInvestmentsInEquityInstruments
92	Own credit	Concept (Monetary)	For Period	Credit	ifrs-full:OtherComprehensiveIncomeBeforeTaxChangeInFairValueOfFinancialLiabilityAttributableToChangeInCreditRiskOfLiability
93	Tax	Concept (Monetary)	For Period	Debit	ifrs-full:IncomeTaxRelatingToComponentsOfOtherComprehensiveIncomeThatWillNotBeReclassifiedToProfitOrLoss
94	Other comprehensive income/(loss) not recycled to profit or loss, from continuing operations	Concept (Monetary)	For Period	Credit	ifrs-full:OtherComprehensiveIncomeThatWillNotBeReclassifiedToProfitOrLossNetOfTax
95	Other comprehensive income/(loss) for the year	Concept (Monetary)	For Period	Credit	ifrs-full:OtherComprehensiveIncome
96	Total comprehensive income/(loss) for the year	Concept (Monetary)	For Period	Credit	ifrs-full:ComprehensiveIncome
97	Attributable to:	Abstract			ifrs-full:ComprehensiveIncomeAttributableToAbstract
98	Equity holders of the parent	Concept (Monetary)	For Period	Credit	ifrs-full:ComprehensiveIncomeAttributableToOwnersOfParent
99	Non-controlling interests	Concept (Monetary)	For Period	Credit	ifrs-full:ComprehensiveIncomeAttributableToNoncontrollingInterests
100	Total comprehensive income/(loss) for the year	Concept (Monetary)	For Period	Credit	ifrs-full:ComprehensiveIncome
101	000201 - Statement - Consolidated statement of comprehensive income (Parenthetical)	Network	*	*	http://www.barclays.co.uk/role/ConsolidatedStatementOfComprehensiveIncomeParenthetical
102	Condensed Statement of Comprehensive Income [Table]	Table	*	*	srt:CondensedStatementOfComprehensiveIncomeTable
103	Consolidated Entities [Axis]	Axis			srt:ConsolidatedEntitiesAxis
104	Consolidated Entities [Domain]	Member			srt:ConsolidatedEntitiesDomain
105	Barclays Bank Group [member]	Member			c070:BarclaysBankGroupMember
106	Condensed Statement of Income Captions [Line Items]	LineItems			srt:CondensedStatementOfIncomeCaptionsLineItems
107	Gain (loss) on recycling of currency translation differences	Concept (Monetary)	For Period	Debit	ifrs-full:ReclassificationAdjustmentsOnExchangeDifferencesOnTranslationNetOfTax
108	000300 - Statement - Consolidated balance sheet	Network	*	*	http://www.barclays.co.uk/role/ConsolidatedBalanceSheet
109	Condensed Balance Sheet Statement [Table]	Table	*	*	srt:CondensedBalanceSheetStatementTable
110	Consolidated Entities [Axis]	Axis			srt:ConsolidatedEntitiesAxis
111	Consolidated Entities [Domain]	Member			srt:ConsolidatedEntitiesDomain
112	Barclays Bank Group [member]	Member			c070:BarclaysBankGroupMember
113	Condensed Balance Sheet Statements, Captions [Line Items]	LineItems			srt:CondensedBalanceSheetStatementsCaptionsLineItems
114	Assets	Abstract			ifrs-full:AssetsAbstract
115	Cash and balances at central banks	Concept (Monetary)	As Of	Debit	ifrs-full:CashAndBankBalancesAtCentralBanks
116	Cash collateral and settlement balances	Concept (Monetary)	As Of	Debit	ifrs-full:BankAcceptanceAssets
117	Loans and advances at amortised cost	Concept (Monetary)	As Of	Debit	ifrs-full:LoansAndReceivables
118	Reverse repurchase agreements and other similar secured lending	Concept (Monetary)	As Of	Debit	ifrs-full:ReverseRepurchaseAgreementsAndCashCollateralOnSecuritiesBorrowed
119	Trading portfolio assets	Concept (Monetary)	As Of	Debit	ifrs-full:FinancialAssetsAtFairValueThroughProfitOrLossClassifiedAsHeldForTrading
120	Financial assets at fair value through the income statement	Concept (Monetary)	As Of	Debit	ifrs-full:FinancialAssetsAtFairValueThroughProfitOrLoss
121	Derivative financial instruments	Concept (Monetary)	As Of	Debit	ifrs-full:DerivativeFinancialAssets
122	Financial investments	Concept (Monetary)	As Of	Debit	c070:FinancialInvestments
123	Financial assets at fair value through other comprehensive income	Concept (Monetary)	As Of	Debit	ifrs-full:FinancialAssetsAtFairValueThroughOtherComprehensiveIncome
124	Investments in associates and joint ventures	Concept (Monetary)	As Of	Debit	ifrs-full:InvestmentAccountedForUsingEquityMethod
125	Goodwill and intangible assets	Concept (Monetary)	As Of	Debit	ifrs-full:IntangibleAssetsAndGoodwill
126	Property, plant and equipment	Concept (Monetary)	As Of	Debit	ifrs-full:PropertyPlantAndEquipment
127	Current tax assets	Concept (Monetary)	As Of	Debit	ifrs-full:CurrentTaxAssets
128	Deferred tax assets	Concept (Monetary)	As Of	Debit	ifrs-full:DeferredTaxAssets
129	Retirement benefit assets	Concept (Monetary)	As Of	Debit	ifrs-full:AssetsOfBenefitPlan
130	Other assets	Concept (Monetary)	As Of	Debit	ifrs-full:OtherAssets
131	Assets included in disposal groups classified as held for sale	Concept (Monetary)	As Of	Debit	ifrs-full:NoncurrentAssetsOrDisposalGroupsClassifiedAsHeldForSaleOrAsHeldForDistributionToOwners
132	Total Assets	Concept (Monetary)	As Of	Debit	ifrs-full:Assets
133	Liabilities	Abstract			ifrs-full:LiabilitiesAbstract
134	Deposits at amortised cost	Concept (Monetary)	As Of	Credit	c070:DepositsAtAmortisedCost
135	Cash collateral and settlement balances	Concept (Monetary)	As Of	Credit	ifrs-full:BankAcceptanceLiabilities
136	Repurchase agreements and other similar secured borrowing	Concept (Monetary)	As Of	Credit	ifrs-full:RepurchaseAgreementsAndCashCollateralOnSecuritiesLent
137	Debt securities in issue	Concept (Monetary)	As Of	Credit	ifrs-full:DebtSecurities
138	Subordinated liabilities	Concept (Monetary)	As Of	Credit	ifrs-full:SubordinatedLiabilities
139	Trading portfolio liabilities	Concept (Monetary)	As Of	Credit	ifrs-full:FinancialLiabilitiesAtFairValueThroughProfitOrLossClassifiedAsHeldForTrading
140	Financial liabilities designated at fair value	Concept (Monetary)	As Of	Credit	ifrs-full:FinancialLiabilitiesAtFairValueThroughProfitOrLossDesignatedAsUponInitialRecognition
141	Derivative financial instruments	Concept (Monetary)	As Of	Credit	ifrs-full:DerivativeFinancialLiabilities
142	Current tax liabilities	Concept (Monetary)	As Of	Credit	ifrs-full:CurrentTaxLiabilities
143	Retirement benefit liabilities	Concept (Monetary)	As Of	Credit	ifrs-full:LiabilitiesOtherThanActuarialPresentValueOfPromisedRetirementBenefits
144	Other liabilities	Concept (Monetary)	As Of	Credit	ifrs-full:OtherLiabilities
145	Provisions	Concept (Monetary)	As Of	Credit	ifrs-full:Provisions
146	Total liabilities	Concept (Monetary)	As Of	Credit	ifrs-full:Liabilities
147	Equity	Abstract			ifrs-full:EquityAbstract
148	Called up share capital and share premium	Concept (Monetary)	As Of	Credit	c070:CalledUpShareCapitalAndSharePremium
149	Other equity instruments	Concept (Monetary)	As Of	Credit	ifrs-full:OtherEquityInterest
150	Other reserves	Concept (Monetary)	As Of	Credit	ifrs-full:OtherReserves
151	Retained earnings	Concept (Monetary)	As Of	Credit	ifrs-full:RetainedEarnings
152	Total equity excluding non-controlling interests	Concept (Monetary)	As Of	Credit	ifrs-full:EquityAttributableToOwnersOfParent
153	Non-controlling interests	Concept (Monetary)	As Of	Credit	ifrs-full:NoncontrollingInterests
154	Total equity	Concept (Monetary)	As Of	Credit	ifrs-full:Equity
155	Total liabilities and equity	Concept (Monetary)	As Of	Credit	ifrs-full:EquityAndLiabilities
156	000400 - Statement - Consolidated statement of changes in equity	Network	*	*	http://www.barclays.co.uk/role/ConsolidatedStatementOfChangesInEquity
157	Statement of changes in equity [table]	Table	*	*	ifrs-full:StatementOfChangesInEquityTable
158	Components of equity [axis]	Axis			ifrs-full:ComponentsOfEquityAxis
159	Equity [member]	Member			ifrs-full:EquityMember
160	Called up share capital and share premium [member]	Member			c070:IssuedCapitalAndSharePremiumMember
161	Other equity instruments [member]	Member			ifrs-full:OtherEquityInterestMember
162	Available for sale reserve [member]	Member			ifrs-full:ReserveOfGainsAndLossesOnRemeasuringAvailableforsaleFinancialAssetsMember
163	Fair value through other comprehensive income reserve [member]	Member			ifrs-full:ReserveOfGainsAndLossesOnFinancialAssetsMeasuredAtFairValueThroughOtherComprehensiveIncomeMember
164	Cash flow hedging reserve [member]	Member			ifrs-full:ReserveOfCashFlowHedgesMember
165	Currency translation reserve [member]	Member			ifrs-full:ReserveOfExchangeDifferencesOnTranslationMember
166	Other reserves and other shareholders equity [member]	Member			c070:OtherReservesAndOtherShareholdersEquityMember
167	Own credit reserve [member]	Member			ifrs-full:ReserveOfChangeInFairValueOfFinancialLiabilityAttributableToChangeInCreditRiskOfLiabilityMember
168	Retained earnings [member]	Member			ifrs-full:RetainedEarningsMember
169	Total equity excluding non-controlling interests [member]	Member			ifrs-full:EquityAttributableToOwnersOfParentMember
170	Non-controlling interests [member]	Member			ifrs-full:NoncontrollingInterestsMember
171	Continuing and discontinued operations [axis]	Axis			ifrs-full:ContinuingAndDiscontinuedOperationsAxis
172	Aggregate continuing and discontinued operations [member]	Member			ifrs-full:AggregateContinuingAndDiscontinuedOperationsMember
173	Continuing operations [member]	Member			ifrs-full:ContinuingOperationsMember
174	Discontinued operations [member]	Member			ifrs-full:DiscontinuedOperationsMember
175	Statement of changes in equity [line items]	LineItems			ifrs-full:StatementOfChangesInEquityLineItems
176	Beginning Balance, equity	Concept (Monetary)	As Of	Credit	ifrs-full:Equity
177	Effects of changes in accounting policies	Concept (Monetary)	For Period		ifrs-full:AmountOfReclassificationsOrChangesInPresentation
178	Equity, adjusted balance	Concept (Monetary)	As Of	Credit	c070:EquityAdjustedBalance
179	Profit/(loss) after tax in respect of continuing operations	Concept (Monetary)	For Period	Credit	ifrs-full:ProfitLossFromContinuingOperations
180	Currency translation movements	Concept (Monetary)	For Period	Credit	ifrs-full:OtherComprehensiveIncomeNetOfTaxExchangeDifferencesOnTranslation
181	Fair value through other comprehensive income reserve	Concept (Monetary)	For Period	Credit	ifrs-full:OtherComprehensiveIncomeNetOfTaxFinancialAssetsMeasuredAtFairValueThroughOtherComprehensiveIncome
182	Available for sale investments	Concept (Monetary)	For Period	Credit	ifrs-full:OtherComprehensiveIncomeNetOfTaxAvailableforsaleFinancialAssets
183	Cash flow hedges	Concept (Monetary)	For Period	Credit	ifrs-full:OtherComprehensiveIncomeNetOfTaxCashFlowHedges
184	Retirement benefit re-measurements	Concept (Monetary)	For Period	Credit	ifrs-full:OtherComprehensiveIncomeNetOfTaxGainsLossesOnRemeasurementsOfDefinedBenefitPlans
185	Own credit reserve	Concept (Monetary)	For Period	Credit	ifrs-full:OtherComprehensiveIncomeNetOfTaxChangeInFairValueOfFinancialLiabilityAttributableToChangeInCreditRiskOfLiability
186	Other	Concept (Monetary)	For Period	Credit	ifrs-full:OtherIndividuallyImmaterialComponentsOfOtherComprehensiveIncomeNetOfTax
187	Total comprehensive income/(loss) for the year	Concept (Monetary)	For Period	Credit	ifrs-full:ComprehensiveIncome
188	Issue and exchange of other equity instruments	Concept (Monetary)	For Period	Credit	c070:IssueAndExchangeOfOtherEquityInstruments
189	Capital reorganisation	Concept (Monetary)	For Period	Credit	ifrs-full:IncreaseDecreaseThroughTransferBetweenRevaluationReserveAndRetainedEarnings
190	Other equity instruments coupons paid	Concept (Monetary)	For Period	Credit	c070:IncreaseDecreaseOtherEquityInstrumentsCouponsPaid
191	Redemption of preference shares, value	Concept (Monetary)	For Period	Credit	c070:RedemptionOfPreferenceSharesValue
192	Equity to debt reclassification	Concept (Monetary)	For Period		ifrs-full:EquityReclassifiedIntoFinancialLiabilities
193	Equity settled share schemes	Concept (Monetary)	For Period	Debit	ifrs-full:ExpenseFromSharebasedPaymentTransactionsWithEmployees
194	Vesting of Barclays PLC shares under share-based payment schemes	Concept (Monetary)	For Period	Credit	ifrs-full:IncreaseDecreaseThroughExerciseOfOptions
195	Dividends on ordinary shares	Concept (Monetary)	For Period	Debit	ifrs-full:DividendsPaidOrdinaryShares
196	Dividends on preference shares and other shareholders equity	Concept (Monetary)	For Period	Debit	ifrs-full:DividendsPaidOtherShares
197	Capital contribution from Barclays PLC	Concept (Monetary)	For Period	Credit	ifrs-full:IncreaseDecreaseThroughOtherContributionsByOwners
198	Net equity impact of intra-group transfers	Concept (Monetary)	For Period	Credit	ifrs-full:IncreaseDecreaseThroughChangeInEquityOfSubsidiaries
199	Net equity impact of partial BAGL disposal	Concept (Monetary)	For Period	Credit	ifrs-full:IncreaseDecreaseThroughDisposalOfSubsidiary
200	Other reserve movements	Concept (Monetary)	For Period	Credit	ifrs-full:IncreaseDecreaseThroughTransfersAndOtherChangesEquity
201	Ending Balance, equity	Concept (Monetary)	As Of	Credit	ifrs-full:Equity
202	000401 - Statement - Consolidated statement of changes in equity (Parenthetical)	Network	*	*	http://www.barclays.co.uk/role/ConsolidatedStatementOfChangesInEquityParenthetical
203	Statement of changes in equity [table]	Table	*	*	ifrs-full:StatementOfChangesInEquityTable
204	Initially applied IFRSs [axis]	Axis			ifrs-full:InitiallyAppliedIFRSsAxis
205	Initially applied IFRSs [member]	Member			ifrs-full:InitiallyAppliedIFRSsMember
206	IFRSs 9 [member]	Member			c070:IFRSs9Member
207	Components of equity [axis]	Axis			ifrs-full:ComponentsOfEquityAxis
208	Equity [member]	Member			ifrs-full:EquityMember
209	Other reserves [member]	Member			ifrs-full:OtherReservesMember
210	Fair value through other comprehensive income reserve [member]	Member			ifrs-full:ReserveOfGainsAndLossesOnFinancialAssetsMeasuredAtFairValueThroughOtherComprehensiveIncomeMember
211	Retained earnings [member]	Member			ifrs-full:RetainedEarningsMember
212	Statement of changes in equity [line items]	LineItems			ifrs-full:StatementOfChangesInEquityLineItems
213	Effects of changes in accounting policies	Concept (Monetary)	For Period		ifrs-full:AmountOfReclassificationsOrChangesInPresentation
214	IFRS 9 impairment change	Concept (Monetary)	As Of	Credit	c070:IncreaseDecreaseInEquityArisingFromChangeInMeasurementAttributeInitialApplicationOfIfrs9
215	Gain (loss) on designation of financial instrument as measured at fair value through profit or loss because credit derivative is used to manage credit risk	Concept (Monetary)	For Period	Credit	ifrs-full:GainLossOnDesignationOfFinancialInstrumentAsMeasuredAtFairValueThroughProfitOrLossBecauseCreditDerivativeIsUsedToManageCreditRisk
216	000500 - Statement - Consolidated cash flow statement	Network	*	*	http://www.barclays.co.uk/role/ConsolidatedCashFlowStatement
217	Disclosure of operating segments [table]	Table	*	*	ifrs-full:DisclosureOfOperatingSegmentsTable
218	Continuing and discontinued operations [axis]	Axis			ifrs-full:ContinuingAndDiscontinuedOperationsAxis
219	Aggregate continuing and discontinued operations [member]	Member			ifrs-full:AggregateContinuingAndDiscontinuedOperationsMember
220	Continuing operations [member]	Member			ifrs-full:ContinuingOperationsMember
221	Discontinued operations [member]	Member			ifrs-full:DiscontinuedOperationsMember
222	Disclosure of operating segments [line items]	LineItems			ifrs-full:DisclosureOfOperatingSegmentsLineItems
223	Reconciliation of profit before tax to net cash flows from operating activities:	Abstract			ifrs-full:AdjustmentsForReconcileProfitLossAbstract
224	Profit (loss) before tax	Concept (Monetary)	For Period	Credit	ifrs-full:ProfitLossBeforeTax
225	Adjustment for non-cash items [abstract]	Abstract			c070:AdjustmentsForNonCashItemsAbstract
226	Allowance for impairment	Concept (Monetary)	For Period	Debit	ifrs-full:AdjustmentsForImpairmentLossReversalOfImpairmentLossRecognisedInProfitOrLoss
227	Depreciation, amortisation and impairment of property, plant, equipment and intangibles	Concept (Monetary)	For Period	Debit	ifrs-full:AdjustmentsForDepreciationAndAmortisationExpenseAndImpairmentLossReversalOfImpairmentLossRecognisedInProfitOrLoss
228	Other provisions, including pensions	Concept (Monetary)	For Period	Debit	ifrs-full:AdjustmentsForProvisions
229	Net profit/(loss) on disposal of investments and property, plant and equipment	Concept (Monetary)	For Period	Debit	ifrs-full:AdjustmentsForLossesGainsOnDisposalOfNoncurrentAssets
230	Other non-cash movements including exchange rate movements	Concept (Monetary)	For Period	Debit	ifrs-full:OtherAdjustmentsForNoncashItems
231	Changes in operating assets and liabilities [abstract]	Abstract			c070:ChangesInOperatingAssetsAndLiabilitiesAbstract
232	Net decrease/(increase) in cash collateral and settlement balances	Concept (Monetary)	For Period	Debit	ifrs-full:AdjustmentsForDecreaseIncreaseInTradeAccountReceivable
233	Net decrease/(increase) in loans and advances	Concept (Monetary)	For Period	Debit	c070:AdjustmentsForDecreaseIncreaseInLoansAndAdvances
234	Net (increase)/decrease in reverse repurchase agreements and other similar lending	Concept (Monetary)	For Period	Debit	ifrs-full:AdjustmentsForDecreaseIncreaseInReverseRepurchaseAgreementsAndCashCollateralOnSecuritiesBorrowed
235	Net (decrease)/increase in deposits and debt securities in issue	Concept (Monetary)	For Period	Debit	ifrs-full:AdjustmentsForIncreaseDecreaseInDepositsFromCustomers
236	Net increase/(decrease) in repurchase agreements and other similar borrowing	Concept (Monetary)	For Period	Debit	ifrs-full:AdjustmentsForIncreaseDecreaseInRepurchaseAgreementsAndCashCollateralOnSecuritiesLent
237	Net decrease/(increase) in derivative financial instruments	Concept (Monetary)	For Period	Credit	ifrs-full:AdjustmentsForGainsLossesOnChangeInFairValueOfDerivatives
238	Net (increase)/decrease in trading assets	Concept (Monetary)	For Period	Debit	ifrs-full:AdjustmentsForDecreaseIncreaseInFinancialAssetsHeldForTrading
239	Net increase/(decrease) in trading liabilities	Concept (Monetary)	For Period	Debit	ifrs-full:AdjustmentsForIncreaseDecreaseInFinancialLiabilitiesHeldForTrading
240	Net decrease/(increase) in financial assets and liabilities at fair value through income statement	Concept (Monetary)	For Period	Debit	ifrs-full:IncreaseDecreaseInFinancialAssets
241	Net decrease/(increase) in other assets	Concept (Monetary)	For Period	Debit	ifrs-full:AdjustmentsForDecreaseIncreaseInOtherAssets
242	Net increase/(decrease) in other liabilities	Concept (Monetary)	For Period	Debit	ifrs-full:AdjustmentsForIncreaseDecreaseInOtherLiabilities
243	Corporate income tax paid	Concept (Monetary)	For Period	Credit	ifrs-full:IncomeTaxesPaidClassifiedAsOperatingActivities
244	Net cash from operating activities	Concept (Monetary)	For Period		ifrs-full:CashFlowsFromUsedInOperatingActivities
245	Cash flows from (used in) investing activities [abstract]	Abstract			ifrs-full:CashFlowsFromUsedInInvestingActivitiesAbstract
246	Net cash disposed of due to the disposal of the UK banking business	Concept (Monetary)	For Period	Debit	ifrs-full:CashAndCashEquivalentsInSubsidiaryOrBusinessesAcquiredOrDisposed2013
247	Purchase of available for sale investments	Concept (Monetary)	For Period	Credit	ifrs-full:PurchaseOfAvailableforsaleFinancialAssets
248	Purchase of financial assets at fair value through other comprehensive income	Concept (Monetary)	For Period	Credit	ifrs-full:PurchaseOfFinancialInstrumentsClassifiedAsInvestingActivities
249	Proceeds from sale or redemption of available for sale investments	Concept (Monetary)	For Period	Debit	ifrs-full:ProceedsFromDisposalOrMaturityOfAvailableforsaleFinancialAssets
250	Proceeds from sale or redemption of financial assets at fair value through other comprehensive income	Concept (Monetary)	For Period	Debit	ifrs-full:ProceedsFromSalesOrMaturityOfFinancialInstrumentsClassifiedAsInvestingActivities
251	Purchase of property, plant and equipment and intangibles	Concept (Monetary)	For Period	Credit	ifrs-full:PurchaseOfPropertyPlantAndEquipmentIntangibleAssetsOtherThanGoodwillInvestmentPropertyAndOtherNoncurrentAssets
252	Proceeds from sale of property, plant and equipment and intangibles	Concept (Monetary)	For Period	Debit	ifrs-full:ProceedsFromDisposalsOfPropertyPlantAndEquipmentIntangibleAssetsOtherThanGoodwillInvestmentPropertyAndOtherNoncurrentAssets
253	Disposal of discontinued operation, net of cash disposed	Concept (Monetary)	For Period	Debit	ifrs-full:ProceedsFromDisposalOfNoncurrentAssetsOrDisposalGroupsClassifiedAsHeldForSaleAndDiscontinuedOperations
254	Disposal of subsidiaries, net of cash disposed	Concept (Monetary)	For Period	Debit	ifrs-full:CashFlowsFromLosingControlOfSubsidiariesOrOtherBusinessesClassifiedAsInvestingActivities
255	Net (increase)/decrease in investment in subsidiaries	Concept (Monetary)	For Period	Debit	c070:NetIncreaseDecreaseInInvestmentInSubsidiaries
256	Other cash flows associated with investing activities	Concept (Monetary)	For Period	Debit	ifrs-full:OtherInflowsOutflowsOfCashClassifiedAsInvestingActivities
257	Net cash from investing activities	Concept (Monetary)	For Period	Debit	ifrs-full:CashFlowsFromUsedInInvestingActivities
258	Cash flows from (used in) financing activities [abstract]	Abstract			ifrs-full:CashFlowsFromUsedInFinancingActivitiesAbstract
259	Dividends paid	Concept (Monetary)	For Period	Credit	ifrs-full:DividendsPaidClassifiedAsFinancingActivities
260	Issuance of subordinated debt	Concept (Monetary)	For Period	Debit	ifrs-full:ProceedsFromIssueOfSubordinatedLiabilities
261	Redemption of subordinated debt	Concept (Monetary)	For Period	Credit	ifrs-full:RepaymentsOfSubordinatedLiabilities
262	Net issue of shares and other equity instruments	Concept (Monetary)	For Period	Debit	c070:ProceedsFromIssuingSharesAndOtherEquityInstruments
263	Redemption of shares and other equity instruments	Concept (Monetary)	For Period	Credit	ifrs-full:PaymentsToAcquireOrRedeemEntitysShares
264	Capital contribution from Barclays PLC	Concept (Monetary)	For Period	Debit	ifrs-full:ProceedsFromContributionsOfNoncontrollingInterests
265	Vesting of shares under employee share schemes	Concept (Monetary)	For Period	Credit	c070:PaymentsForVestingOfSharesUnderEmployeeShareSchemes
266	Net cash from financing activities	Concept (Monetary)	For Period	Debit	ifrs-full:CashFlowsFromUsedInFinancingActivities
267	Effect of exchange rates on cash and cash equivalents	Concept (Monetary)	For Period	Debit	ifrs-full:EffectOfExchangeRateChangesOnCashAndCashEquivalents
268	Net increase/(decrease) in cash and cash equivalents	Concept (Monetary)	For Period	Debit	ifrs-full:IncreaseDecreaseInCashAndCashEquivalents
269	Cash and cash equivalents at beginning of the year	Concept (Monetary)	As Of	Debit	ifrs-full:CashAndCashEquivalents
270	Cash and cash equivalents at end of the year	Concept (Monetary)	As Of	Debit	ifrs-full:CashAndCashEquivalents
271	Cash and cash equivalents comprise [abstract]	Abstract			c070:CashAndCashEquivalentsCompriseAbstract
272	Cash and balances at central banks	Concept (Monetary)	As Of	Debit	ifrs-full:CashAndBankBalancesAtCentralBanks
273	Loans and advances to banks with original maturity less than three months	Concept (Monetary)	As Of	Debit	ifrs-full:ShorttermDepositsClassifiedAsCashEquivalents
274	Cash collateral and settlement balances with banks with original maturity less than three months	Concept (Monetary)	As Of	Debit	c070:BankAcceptanceAssetsClassifiedAsCashEquivalents
275	Available for sale treasury and other eligible bills with original maturity less than three months	Concept (Monetary)	As Of	Debit	ifrs-full:ShorttermInvestmentsClassifiedAsCashEquivalents
276	Trading portfolio assets with original maturity less than three months	Concept (Monetary)	As Of	Debit	ifrs-full:OtherCashAndCashEquivalents
277	Cash and cash equivalents held for sale	Concept (Monetary)	As Of	Debit	ifrs-full:CashAndCashEquivalentsClassifiedAsPartOfDisposalGroupHeldForSale
278	Cash and cash equivalents	Concept (Monetary)	As Of	Debit	ifrs-full:CashAndCashEquivalents
279	010002 - Statement - Financial statements of Barclays Bank PLC - Balance sheet	Network	*	*	http://www.barclays.co.uk/role/FinancialStatementsOfBarclaysBankPLCBalanceSheet
280	Condensed Balance Sheet Statement [Table]	Table	*	*	srt:CondensedBalanceSheetStatementTable
281	Consolidated Entities [Axis]	Axis			srt:ConsolidatedEntitiesAxis
282	Consolidated Entities [Domain]	Member			srt:ConsolidatedEntitiesDomain
283	Barclays Bank PLC [member]	Member			c070:BarclaysBankPlcMember
284	Condensed Balance Sheet Statements, Captions [Line Items]	LineItems			srt:CondensedBalanceSheetStatementsCaptionsLineItems
285	Assets	Abstract			ifrs-full:AssetsAbstract
286	Cash and balances at central banks	Concept (Monetary)	As Of	Debit	ifrs-full:CashAndBankBalancesAtCentralBanks
287	Cash collateral and settlement balances	Concept (Monetary)	As Of	Debit	ifrs-full:BankAcceptanceAssets
288	Loans and advances at amortised cost	Concept (Monetary)	As Of	Debit	ifrs-full:LoansAndReceivables
289	Reverse repurchase agreements and other similar secured lending	Concept (Monetary)	As Of	Debit	ifrs-full:ReverseRepurchaseAgreementsAndCashCollateralOnSecuritiesBorrowed
290	Trading portfolio assets	Concept (Monetary)	As Of	Debit	ifrs-full:FinancialAssetsAtFairValueThroughProfitOrLossClassifiedAsHeldForTrading
291	Financial assets at fair value through the income statement	Concept (Monetary)	As Of	Debit	ifrs-full:FinancialAssetsAtFairValueThroughProfitOrLoss
292	Derivative financial instruments	Concept (Monetary)	As Of	Debit	ifrs-full:DerivativeFinancialAssets
293	Financial investments	Concept (Monetary)	As Of	Debit	c070:FinancialInvestments
294	Financial assets at fair value through other comprehensive income	Concept (Monetary)	As Of	Debit	ifrs-full:FinancialAssetsAtFairValueThroughOtherComprehensiveIncome
295	Investments in associates and joint ventures	Concept (Monetary)	As Of	Debit	ifrs-full:InvestmentAccountedForUsingEquityMethod
296	Investments in subsidiaries	Concept (Monetary)	As Of	Debit	ifrs-full:InvestmentsInSubsidiaries
297	Goodwill and intangible assets	Concept (Monetary)	As Of	Debit	ifrs-full:IntangibleAssetsAndGoodwill
298	Property, plant and equipment	Concept (Monetary)	As Of	Debit	ifrs-full:PropertyPlantAndEquipment
299	Current tax assets	Concept (Monetary)	As Of	Debit	ifrs-full:CurrentTaxAssets
300	Deferred tax assets	Concept (Monetary)	As Of	Debit	ifrs-full:DeferredTaxAssets
301	Retirement benefit assets	Concept (Monetary)	As Of	Debit	ifrs-full:AssetsOfBenefitPlan
302	Other assets	Concept (Monetary)	As Of	Debit	ifrs-full:OtherAssets
303	Total assets	Concept (Monetary)	As Of	Debit	ifrs-full:Assets
304	Liabilities	Abstract			ifrs-full:LiabilitiesAbstract
305	Deposits at amortised cost	Concept (Monetary)	As Of	Credit	c070:DepositsAtAmortisedCost
306	Cash collateral and settlement balances	Concept (Monetary)	As Of	Credit	ifrs-full:BankAcceptanceLiabilities
307	Repurchase agreements and other similar secured borrowing	Concept (Monetary)	As Of	Credit	ifrs-full:RepurchaseAgreementsAndCashCollateralOnSecuritiesLent
308	Debt securities in issue	Concept (Monetary)	As Of	Credit	ifrs-full:DebtSecurities
309	Subordinated liabilities	Concept (Monetary)	As Of	Credit	ifrs-full:SubordinatedLiabilities
310	Trading portfolio liabilities	Concept (Monetary)	As Of	Credit	ifrs-full:FinancialLiabilitiesAtFairValueThroughProfitOrLossClassifiedAsHeldForTrading
311	Financial liabilities designated at fair value	Concept (Monetary)	As Of	Credit	ifrs-full:FinancialLiabilitiesAtFairValueThroughProfitOrLossDesignatedAsUponInitialRecognition
312	Derivative financial instruments	Concept (Monetary)	As Of	Credit	ifrs-full:DerivativeFinancialLiabilities
313	Current tax liabilities	Concept (Monetary)	As Of	Credit	ifrs-full:CurrentTaxLiabilities
314	Deferred tax liabilities	Concept (Monetary)	As Of	Credit	ifrs-full:DeferredTaxLiabilities
315	Retirement benefit liabilities	Concept (Monetary)	As Of	Credit	ifrs-full:LiabilitiesOtherThanActuarialPresentValueOfPromisedRetirementBenefits
316	Other liabilities	Concept (Monetary)	As Of	Credit	ifrs-full:OtherLiabilities
317	Provisions	Concept (Monetary)	As Of	Credit	ifrs-full:Provisions
318	Total liabilities	Concept (Monetary)	As Of	Credit	ifrs-full:Liabilities
319	Equity	Abstract			ifrs-full:EquityAbstract
320	Called up share capital and share premium	Concept (Monetary)	As Of	Credit	c070:CalledUpShareCapitalAndSharePremium
321	Other equity instruments	Concept (Monetary)	As Of	Credit	ifrs-full:OtherEquityInterest
322	Other reserves	Concept (Monetary)	As Of	Credit	ifrs-full:OtherReserves
323	Retained earnings	Concept (Monetary)	As Of	Credit	ifrs-full:RetainedEarnings
324	Total equity	Concept (Monetary)	As Of	Credit	ifrs-full:Equity
325	Total liabilities and equity	Concept (Monetary)	As Of	Credit	ifrs-full:EquityAndLiabilities
326	010003 - Statement - Financial statements of Barclays Bank PLC - Balance sheet (Parenthetical)	Network	*	*	http://www.barclays.co.uk/role/FinancialStatementsOfBarclaysBankPLCBalanceSheetParenthetical
327	Condensed Balance Sheet Statement [Table]	Table	*	*	srt:CondensedBalanceSheetStatementTable
328	Consolidated Entities [Axis]	Axis			srt:ConsolidatedEntitiesAxis
329	Consolidated Entities [Domain]	Member			srt:ConsolidatedEntitiesDomain
330	Barclays Bank PLC [member]	Member			c070:BarclaysBankPlcMember
331	Condensed Balance Sheet Statements, Captions [Line Items]	LineItems			srt:CondensedBalanceSheetStatementsCaptionsLineItems
332	Profit (loss) after tax	Concept (Monetary)	For Period	Credit	ifrs-full:ProfitLoss
333	010006 - Statement - Financial statements of Barclays Bank PLC - Statement of changes in equity	Network	*	*	http://www.barclays.co.uk/role/FinancialStatementsOfBarclaysBankPLCStatementOfChangesInEquity
334	Statement of changes in equity [table]	Table	*	*	ifrs-full:StatementOfChangesInEquityTable
335	Components of equity [axis]	Axis			ifrs-full:ComponentsOfEquityAxis
336	Equity [member]	Member			ifrs-full:EquityMember
337	Called up share capital and share premium [member]	Member			c070:IssuedCapitalAndSharePremiumMember
338	Other equity instruments [member]	Member			ifrs-full:OtherEquityInterestMember
339	Available for sale reserve [member]	Member			ifrs-full:ReserveOfGainsAndLossesOnRemeasuringAvailableforsaleFinancialAssetsMember
340	Fair value through other comprehensive income reserve [member]	Member			ifrs-full:ReserveOfGainsAndLossesOnFinancialAssetsMeasuredAtFairValueThroughOtherComprehensiveIncomeMember
341	Cash flow hedging reserve [member]	Member			ifrs-full:ReserveOfCashFlowHedgesMember
342	Currency translation reserve [member]	Member			ifrs-full:ReserveOfExchangeDifferencesOnTranslationMember
343	Other reserves and other shareholders equity [member]	Member			c070:OtherReservesAndOtherShareholdersEquityMember
344	Own credit reserve [member]	Member			ifrs-full:ReserveOfChangeInFairValueOfFinancialLiabilityAttributableToChangeInCreditRiskOfLiabilityMember
345	Retained earnings [member]	Member			ifrs-full:RetainedEarningsMember
346	Total equity excluding non-controlling interests [member]	Member			ifrs-full:EquityAttributableToOwnersOfParentMember
347	Non-controlling interests [member]	Member			ifrs-full:NoncontrollingInterestsMember
348	Consolidated Entities [Axis]	Axis			srt:ConsolidatedEntitiesAxis
349	Consolidated Entities [Domain]	Member			srt:ConsolidatedEntitiesDomain
350	Barclays Bank PLC [member]	Member			c070:BarclaysBankPlcMember
351	Continuing and discontinued operations [axis]	Axis			ifrs-full:ContinuingAndDiscontinuedOperationsAxis
352	Aggregate continuing and discontinued operations [member]	Member			ifrs-full:AggregateContinuingAndDiscontinuedOperationsMember
353	Continuing operations [member]	Member			ifrs-full:ContinuingOperationsMember
354	Discontinued operations [member]	Member			ifrs-full:DiscontinuedOperationsMember
355	Statement of changes in equity [line items]	LineItems			ifrs-full:StatementOfChangesInEquityLineItems
356	Beginning Balance, equity	Concept (Monetary)	As Of	Credit	ifrs-full:Equity
357	Effects of changes in accounting policies	Concept (Monetary)	For Period		ifrs-full:AmountOfReclassificationsOrChangesInPresentation
358	Equity, adjusted balance	Concept (Monetary)	As Of	Credit	c070:EquityAdjustedBalance
359	Profit/(loss) after tax in respect of continuing operations	Concept (Monetary)	For Period	Credit	ifrs-full:ProfitLossFromContinuingOperations
360	Currency translation movements	Concept (Monetary)	For Period	Credit	ifrs-full:OtherComprehensiveIncomeNetOfTaxExchangeDifferencesOnTranslation
361	Fair value through other comprehensive income reserve	Concept (Monetary)	For Period	Credit	ifrs-full:OtherComprehensiveIncomeNetOfTaxFinancialAssetsMeasuredAtFairValueThroughOtherComprehensiveIncome
362	Available for sale investments	Concept (Monetary)	For Period	Credit	ifrs-full:OtherComprehensiveIncomeNetOfTaxAvailableforsaleFinancialAssets
363	Cash flow hedges	Concept (Monetary)	For Period	Credit	ifrs-full:OtherComprehensiveIncomeNetOfTaxCashFlowHedges
364	Retirement benefit re-measurements	Concept (Monetary)	For Period	Credit	ifrs-full:OtherComprehensiveIncomeNetOfTaxGainsLossesOnRemeasurementsOfDefinedBenefitPlans
365	Own credit reserve	Concept (Monetary)	For Period	Credit	ifrs-full:OtherComprehensiveIncomeNetOfTaxChangeInFairValueOfFinancialLiabilityAttributableToChangeInCreditRiskOfLiability
366	Other	Concept (Monetary)	For Period	Credit	ifrs-full:OtherIndividuallyImmaterialComponentsOfOtherComprehensiveIncomeNetOfTax
367	Total comprehensive income/(loss) for the year	Concept (Monetary)	For Period	Credit	ifrs-full:ComprehensiveIncome
368	Issue and exchange of other equity instruments	Concept (Monetary)	For Period	Credit	c070:IssueAndExchangeOfOtherEquityInstruments
369	Capital reorganisation	Concept (Monetary)	For Period	Credit	ifrs-full:IncreaseDecreaseThroughTransferBetweenRevaluationReserveAndRetainedEarnings
370	Other equity instruments coupons paid	Concept (Monetary)	For Period	Credit	c070:IncreaseDecreaseOtherEquityInstrumentsCouponsPaid
371	Redemption of preference shares, value	Concept (Monetary)	For Period	Credit	c070:RedemptionOfPreferenceSharesValue
372	Equity to debt reclassification	Concept (Monetary)	For Period		ifrs-full:EquityReclassifiedIntoFinancialLiabilities
373	Equity settled share schemes	Concept (Monetary)	For Period	Debit	ifrs-full:ExpenseFromSharebasedPaymentTransactionsWithEmployees
374	Vesting of Barclays PLC shares under share-based payment schemes	Concept (Monetary)	For Period	Credit	ifrs-full:IncreaseDecreaseThroughExerciseOfOptions
375	Dividends on ordinary shares	Concept (Monetary)	For Period	Debit	ifrs-full:DividendsPaidOrdinaryShares
376	Dividends on preference shares and other shareholders equity	Concept (Monetary)	For Period	Debit	ifrs-full:DividendsPaidOtherShares
377	Capital contribution from Barclays PLC	Concept (Monetary)	For Period	Credit	ifrs-full:IncreaseDecreaseThroughOtherContributionsByOwners
378	Net equity impact of intra-group transfers	Concept (Monetary)	For Period	Credit	ifrs-full:IncreaseDecreaseThroughChangeInEquityOfSubsidiaries
379	Net equity impact of partial BAGL disposal	Concept (Monetary)	For Period	Credit	ifrs-full:IncreaseDecreaseThroughDisposalOfSubsidiary
380	Other reserve movements	Concept (Monetary)	For Period	Credit	ifrs-full:IncreaseDecreaseThroughTransfersAndOtherChangesEquity
381	Ending Balance, equity	Concept (Monetary)	As Of	Credit	ifrs-full:Equity
382	010007 - Statement - Financial statements of Barclays Bank PLC - Statement of changes in equity (Parenthetical)	Network	*	*	http://www.barclays.co.uk/role/FinancialStatementsOfBarclaysBankPLCStatementOfChangesInEquityParenthetical
383	Statement of changes in equity [table]	Table	*	*	ifrs-full:StatementOfChangesInEquityTable
384	Initially applied IFRSs [axis]	Axis			ifrs-full:InitiallyAppliedIFRSsAxis
385	Initially applied IFRSs [member]	Member			ifrs-full:InitiallyAppliedIFRSsMember
386	IFRS 9 - Financial instruments [member]	Member			c070:IFRSs9Member
387	Components of equity [axis]	Axis			ifrs-full:ComponentsOfEquityAxis
388	Equity [member]	Member			ifrs-full:EquityMember
389	Other equity interest [member]	Member			ifrs-full:OtherEquityInterestMember
390	AT1 Securities [member]	Member			c070:AdditionalTierOneSecuritiesMember
391	Retained earnings [member]	Member			ifrs-full:RetainedEarningsMember
392	Other reserves [member]	Member			ifrs-full:OtherReservesMember
393	Fair value through other comprehensive income reserve [member]	Member			ifrs-full:ReserveOfGainsAndLossesOnFinancialAssetsMeasuredAtFairValueThroughOtherComprehensiveIncomeMember
394	Own credit reserve [member]	Member			ifrs-full:ReserveOfChangeInFairValueOfFinancialLiabilityAttributableToChangeInCreditRiskOfLiabilityMember
395	Carrying amount, accumulated depreciation, amortisation and impairment and gross carrying amount [axis]	Axis			ifrs-full:CarryingAmountAccumulatedDepreciationAmortisationAndImpairmentAndGrossCarryingAmountAxis
396	Carrying amount [member]	Member			ifrs-full:CarryingAmountMember
397	Impairment charge [member]	Member			ifrs-full:AccumulatedImpairmentMember
398	Consolidated Entities [Axis]	Axis			srt:ConsolidatedEntitiesAxis
399	Consolidated Entities [Domain]	Member			srt:ConsolidatedEntitiesDomain
400	Barclays Bank PLC [member]	Member			c070:BarclaysBankPlcMember
401	Statement of changes in equity [line items]	LineItems			ifrs-full:StatementOfChangesInEquityLineItems
402	Effects of changes in accounting policies	Concept (Monetary)	For Period		ifrs-full:AmountOfReclassificationsOrChangesInPresentation
403	IFRS 9 impairment change	Concept (Monetary)	As Of	Credit	c070:IncreaseDecreaseInEquityArisingFromChangeInMeasurementAttributeInitialApplicationOfIfrs9
404	Gain (loss) on own credit booked in the reserve	Concept (Monetary)	For Period	Credit	ifrs-full:GainLossOnDesignationOfFinancialInstrumentAsMeasuredAtFairValueThroughProfitOrLossBecauseCreditDerivativeIsUsedToManageCreditRisk
405	010008 - Statement - Financial statements of Barclays Bank PLC - Cash flow statement	Network	*	*	http://www.barclays.co.uk/role/FinancialStatementsOfBarclaysBankPLCCashFlowStatement
406	Disclosure of operating segments [table]	Table	*	*	ifrs-full:DisclosureOfOperatingSegmentsTable
407	Continuing and discontinued operations [axis]	Axis			ifrs-full:ContinuingAndDiscontinuedOperationsAxis
408	Aggregate continuing and discontinued operations [member]	Member			ifrs-full:AggregateContinuingAndDiscontinuedOperationsMember
409	Continuing operations [member]	Member			ifrs-full:ContinuingOperationsMember
410	Discontinued operations [member]	Member			ifrs-full:DiscontinuedOperationsMember
411	Consolidated Entities [Axis]	Axis			srt:ConsolidatedEntitiesAxis
412	Consolidated Entities [Domain]	Member			srt:ConsolidatedEntitiesDomain
413	Barclays Bank PLC [member]	Member			c070:BarclaysBankPlcMember
414	Disclosure of operating segments [line items]	LineItems			ifrs-full:DisclosureOfOperatingSegmentsLineItems
415	Reconciliation of profit before tax to net cash flows from operating activities:	Abstract			ifrs-full:AdjustmentsForReconcileProfitLossAbstract
416	Profit (loss) before tax	Concept (Monetary)	For Period	Credit	ifrs-full:ProfitLossBeforeTax
417	Adjustment for non-cash items [abstract]	Abstract			c070:AdjustmentsForNonCashItemsAbstract
418	Allowance for impairment	Concept (Monetary)	For Period	Debit	ifrs-full:AdjustmentsForImpairmentLossReversalOfImpairmentLossRecognisedInProfitOrLoss
419	Depreciation, amortisation and impairment of property, plant, equipment and intangibles	Concept (Monetary)	For Period	Debit	ifrs-full:AdjustmentsForDepreciationAndAmortisationExpenseAndImpairmentLossReversalOfImpairmentLossRecognisedInProfitOrLoss
420	Other provisions, including pensions	Concept (Monetary)	For Period	Debit	ifrs-full:AdjustmentsForProvisions
421	Net profit/(loss) on disposal of investments and property, plant and equipment	Concept (Monetary)	For Period	Debit	ifrs-full:AdjustmentsForLossesGainsOnDisposalOfNoncurrentAssets
422	Other non-cash movements including exchange rate movements	Concept (Monetary)	For Period	Debit	ifrs-full:OtherAdjustmentsForNoncashItems
423	Changes in operating assets and liabilities [abstract]	Abstract			c070:ChangesInOperatingAssetsAndLiabilitiesAbstract
424	Net decrease/(increase) in cash collateral and settlement balances	Concept (Monetary)	For Period	Debit	ifrs-full:AdjustmentsForDecreaseIncreaseInTradeAccountReceivable
425	Net decrease/(increase) in loans and advances	Concept (Monetary)	For Period	Debit	c070:AdjustmentsForDecreaseIncreaseInLoansAndAdvances
426	Net decrease in reverse repurchase agreements and other similar lending	Concept (Monetary)	For Period	Debit	ifrs-full:AdjustmentsForDecreaseIncreaseInReverseRepurchaseAgreementsAndCashCollateralOnSecuritiesBorrowed
427	Net (decrease)/increase in deposits and debt securities in issue	Concept (Monetary)	For Period	Debit	ifrs-full:AdjustmentsForIncreaseDecreaseInDepositsFromCustomers
428	Net increase/(decrease) in repurchase agreements and other similar borrowing	Concept (Monetary)	For Period	Debit	ifrs-full:AdjustmentsForIncreaseDecreaseInRepurchaseAgreementsAndCashCollateralOnSecuritiesLent
429	Net decrease/(increase) in derivative financial instruments	Concept (Monetary)	For Period	Credit	ifrs-full:AdjustmentsForGainsLossesOnChangeInFairValueOfDerivatives
430	Net (increase) in trading assets	Concept (Monetary)	For Period	Debit	ifrs-full:AdjustmentsForDecreaseIncreaseInFinancialAssetsHeldForTrading
431	Net increase/(decrease) in trading liabilities	Concept (Monetary)	For Period	Debit	ifrs-full:AdjustmentsForIncreaseDecreaseInFinancialLiabilitiesHeldForTrading
432	Net decrease/(increase) in financial assets and liabilities at fair value through income statement	Concept (Monetary)	For Period	Debit	ifrs-full:IncreaseDecreaseInFinancialAssets
433	Net decrease/(increase) in other assets	Concept (Monetary)	For Period	Debit	ifrs-full:AdjustmentsForDecreaseIncreaseInOtherAssets
434	Net (decrease) in other liabilities	Concept (Monetary)	For Period	Debit	ifrs-full:AdjustmentsForIncreaseDecreaseInOtherLiabilities
435	Corporate income tax paid	Concept (Monetary)	For Period	Credit	ifrs-full:IncomeTaxesPaidClassifiedAsOperatingActivities
436	Net cash from operating activities	Concept (Monetary)	For Period		ifrs-full:CashFlowsFromUsedInOperatingActivities
437	Cash flows from (used in) investing activities [abstract]	Abstract			ifrs-full:CashFlowsFromUsedInInvestingActivitiesAbstract
438	Net cash disposed of due to the disposal of the UK banking business	Concept (Monetary)	For Period	Debit	ifrs-full:CashAndCashEquivalentsInSubsidiaryOrBusinessesAcquiredOrDisposed2013
439	Purchase of available for sale investments	Concept (Monetary)	For Period	Credit	ifrs-full:PurchaseOfAvailableforsaleFinancialAssets
440	Purchase of financial assets at fair value through other comprehensive income	Concept (Monetary)	For Period	Credit	ifrs-full:PurchaseOfFinancialInstrumentsClassifiedAsInvestingActivities
441	Proceeds from sale or redemption of available for sale investments	Concept (Monetary)	For Period	Debit	ifrs-full:ProceedsFromDisposalOrMaturityOfAvailableforsaleFinancialAssets
442	Proceeds from sale or redemption of financial assets at fair value through other comprehensive income	Concept (Monetary)	For Period	Debit	ifrs-full:ProceedsFromSalesOrMaturityOfFinancialInstrumentsClassifiedAsInvestingActivities
443	Purchase of property, plant and equipment and intangibles	Concept (Monetary)	For Period	Credit	ifrs-full:PurchaseOfPropertyPlantAndEquipmentIntangibleAssetsOtherThanGoodwillInvestmentPropertyAndOtherNoncurrentAssets
444	Proceeds from sale of property, plant and equipment and intangibles	Concept (Monetary)	For Period	Debit	ifrs-full:ProceedsFromDisposalsOfPropertyPlantAndEquipmentIntangibleAssetsOtherThanGoodwillInvestmentPropertyAndOtherNoncurrentAssets
445	Disposal of subsidiaries, net of cash disposed	Concept (Monetary)	For Period	Debit	ifrs-full:CashFlowsFromLosingControlOfSubsidiariesOrOtherBusinessesClassifiedAsInvestingActivities
446	Net (increase)/decrease in investment in subsidiaries	Concept (Monetary)	For Period	Debit	c070:NetIncreaseDecreaseInInvestmentInSubsidiaries
447	Other cash flows associated with investing activities	Concept (Monetary)	For Period	Debit	ifrs-full:OtherInflowsOutflowsOfCashClassifiedAsInvestingActivities
448	Net cash from investing activities	Concept (Monetary)	For Period	Debit	ifrs-full:CashFlowsFromUsedInInvestingActivities
449	Cash flows from (used in) financing activities [abstract]	Abstract			ifrs-full:CashFlowsFromUsedInFinancingActivitiesAbstract
450	Dividends paid	Concept (Monetary)	For Period	Credit	ifrs-full:DividendsPaidClassifiedAsFinancingActivities
451	Issuance of subordinated debt	Concept (Monetary)	For Period	Debit	ifrs-full:ProceedsFromIssueOfSubordinatedLiabilities
452	Redemption of subordinated debt	Concept (Monetary)	For Period	Credit	ifrs-full:RepaymentsOfSubordinatedLiabilities
453	Net issue of shares and other equity instruments	Concept (Monetary)	For Period	Debit	c070:ProceedsFromIssuingSharesAndOtherEquityInstruments
454	Redemption of shares and other equity instruments	Concept (Monetary)	For Period	Credit	ifrs-full:PaymentsToAcquireOrRedeemEntitysShares
455	Capital contribution from Barclays PLC	Concept (Monetary)	For Period	Debit	ifrs-full:ProceedsFromContributionsOfNoncontrollingInterests
456	Vesting of shares under employee share schemes	Concept (Monetary)	For Period	Credit	c070:PaymentsForVestingOfSharesUnderEmployeeShareSchemes
457	Net cash from financing activities	Concept (Monetary)	For Period	Debit	ifrs-full:CashFlowsFromUsedInFinancingActivities
458	Effect of exchange rates on cash and cash equivalents	Concept (Monetary)	For Period	Debit	ifrs-full:EffectOfExchangeRateChangesOnCashAndCashEquivalents
459	Net increase in cash and cash equivalents	Concept (Monetary)	For Period	Debit	ifrs-full:IncreaseDecreaseInCashAndCashEquivalents
460	Cash and cash equivalents at beginning of the year	Concept (Monetary)	As Of	Debit	ifrs-full:CashAndCashEquivalents
461	Cash and cash equivalents at end of the year	Concept (Monetary)	As Of	Debit	ifrs-full:CashAndCashEquivalents
462	Cash and cash equivalents comprise [abstract]	Abstract			c070:CashAndCashEquivalentsCompriseAbstract
463	Cash and balances at central banks	Concept (Monetary)	As Of	Debit	ifrs-full:CashAndBankBalancesAtCentralBanks
464	Loans and advances to banks with original maturity less than three months	Concept (Monetary)	As Of	Debit	ifrs-full:ShorttermDepositsClassifiedAsCashEquivalents
465	Cash collateral and settlement balances with banks with original maturity less than three months	Concept (Monetary)	As Of	Debit	c070:BankAcceptanceAssetsClassifiedAsCashEquivalents
466	Available for sale treasury and other eligible bills with original maturity less than three months	Concept (Monetary)	As Of	Debit	ifrs-full:ShorttermInvestmentsClassifiedAsCashEquivalents
467	Trading portfolio assets with original maturity less than three months	Concept (Monetary)	As Of	Debit	ifrs-full:OtherCashAndCashEquivalents
468	Cash and cash equivalents held for sale	Concept (Monetary)	As Of	Debit	ifrs-full:CashAndCashEquivalentsClassifiedAsPartOfDisposalGroupHeldForSale
469	Cash and cash equivalents	Concept (Monetary)	As Of	Debit	ifrs-full:CashAndCashEquivalents
470	010010 - Disclosure - Consolidated balance sheet (Narrative)	Network	*	*	http://www.barclays.co.uk/role/ConsolidatedBalanceSheetNarrative
471	Implied Table	Table	*	*	implied:Table
472	Balance sheet	Abstract			ifrs-full:StatementOfFinancialPositionAbstract
473	Disclosure of authorisation of financial statements	Concept (Text Block (HTML))	For Period		ifrs-full:DisclosureOfAuthorisationOfFinancialStatementsExplanatory
474	010015 - Disclosure - Consolidated cash flow statement (Narrative)	Network	*	*	http://www.barclays.co.uk/role/ConsolidatedCashFlowStatementNarrative
475	Implied Table	Table	*	*	implied:Table
476	Statement of cash flows	Abstract			ifrs-full:StatementOfCashFlowsAbstract
477	Disclosure of additional information about understanding financial position and liquidity of entity	Concept (Text Block (HTML))	For Period		ifrs-full:DisclosureOfAdditionalInformationAboutUnderstandingFinancialPositionsAndLiquidityOfEntityExplanatory
478	010020 - Disclosure - Financial statements of Barclays Bank PLC - Cash flow statement (narrative)	Network	*	*	http://www.barclays.co.uk/role/FinancialStatementsOfBarclaysBankPLCCashFlowStatementnarrative
479	Condensed Cash Flow Statement [Table]	Table	*	*	srt:CondensedCashFlowStatementTable
480	Consolidated Entities [Axis]	Axis			srt:ConsolidatedEntitiesAxis
481	Consolidated Entities [Domain]	Member			srt:ConsolidatedEntitiesDomain
482	Barclays Bank PLC [member]	Member			c070:BarclaysBankPlcMember
483	Condensed Cash Flow Statements, Captions [Line Items]	LineItems			srt:CondensedCashFlowStatementsCaptionsLineItems
484	Disclosure of additional information about understanding financial position and liquidity of entity	Concept (Text Block (HTML))	For Period		ifrs-full:DisclosureOfAdditionalInformationAboutUnderstandingFinancialPositionsAndLiquidityOfEntityExplanatory
485	010101 - Disclosure - Significant accounting policies	Network	*	*	http://www.barclays.co.uk/role/SignificantAccountingPolicies
486	Implied Table	Table	*	*	implied:Table
487	Significant accounting policies	Abstract			c070:DisclosureOfSignificantAccountingPoliciesAbstract
488	Significant accounting policies	Concept (Text Block (HTML))	For Period		ifrs-full:DisclosureOfSummaryOfSignificantAccountingPoliciesExplanatory
489	010201 - Disclosure - Disposal of business and transfer of ownership of subsidiary	Network	*	*	http://www.barclays.co.uk/role/DisposalOfBusinessAndTransferOfOwnershipOfSubsidiary
490	Implied Table	Table	*	*	implied:Table
491	Disposal of business and transfer of ownership of subsidiary	Abstract			c070:DisposalOfBusinessAndTransferOfOwnershipOfSubsidiaryAbstract
492	Disposal of business and transfer of ownership of subsidiary	Concept (Text Block (HTML))	For Period		c070:DisclosureOfDisposalOfBusinessAndTransferOfOwnershipOfSubsidiary
493	010301 - Disclosure - Discontinued operations and assets included in disposal groups classified as held for sale and associated liabilities	Network	*	*	http://www.barclays.co.uk/role/DiscontinuedOperationsAndAssetsIncludedInDisposalGroupsClassifiedAsHeldForSaleAndAssociatedLiabilities
494	Implied Table	Table	*	*	implied:Table
495	Discontinued operations and assets included in disposal groups classified as held for sale and associated liabilities	Abstract			ifrs-full:NoncurrentAssetsOrDisposalGroupsClassifiedAsHeldForSaleOrAsHeldForDistributionToOwnersAbstract
496	Discontinued oeprations and held for sale assets	Concept (Text Block (HTML))	For Period		ifrs-full:DisclosureOfDiscontinuedOperationsExplanatory
497	010401 - Disclosure - Segmental reporting	Network	*	*	http://www.barclays.co.uk/role/SegmentalReporting
498	Implied Table	Table	*	*	implied:Table
499	Disclosure of operating segments [abstract]	Abstract			ifrs-full:DisclosureOfOperatingSegmentsAbstract
500	Segmental Reporting	Concept (Text Block (HTML))	For Period		ifrs-full:DisclosureOfEntitysReportableSegmentsExplanatory
501	010501 - Disclosure - Net interest income	Network	*	*	http://www.barclays.co.uk/role/NetInterestIncome
502	Implied Table	Table	*	*	implied:Table
503	Net interest income	Abstract			ifrs-full:AnalysisOfIncomeAndExpenseAbstract
504	Net interest income	Concept (Text Block (HTML))	For Period		ifrs-full:DisclosureOfInterestIncomeExpenseExplanatory
505	010601 - Disclosure - Net fee and commission income	Network	*	*	http://www.barclays.co.uk/role/NetFeeAndCommissionIncome
506	Implied Table	Table	*	*	implied:Table
507	Net Fee and commission income	Abstract			ifrs-full:FeeAndCommissionIncomeExpenseAbstract
508	Net fee and commission income	Concept (Text Block (HTML))	For Period		ifrs-full:DisclosureOfFeeAndCommissionIncomeExpenseExplanatory
509	010701 - Disclosure - Net trading income	Network	*	*	http://www.barclays.co.uk/role/NetTradingIncome
510	Implied Table	Table	*	*	implied:Table
511	Net trading income	Abstract			ifrs-full:TradingIncomeExpenseAbstract
512	Net trading income	Concept (Text Block (HTML))	For Period		ifrs-full:DisclosureOfTradingIncomeExpenseExplanatory
513	010801 - Disclosure - Net investment income	Network	*	*	http://www.barclays.co.uk/role/NetInvestmentIncome
514	Implied Table	Table	*	*	implied:Table
515	Net investment income [abstract	Abstract			ifrs-full:MaterialIncomeAndExpenseAbstract
516	Net investment income	Concept (Text Block (HTML))	For Period		ifrs-full:DisclosureOfFinanceIncomeExpenseExplanatory
517	010901 - Disclosure - Credit impairment charges and other provisions	Network	*	*	http://www.barclays.co.uk/role/CreditImpairmentChargesAndOtherProvisions
518	Implied Table	Table	*	*	implied:Table
519	Credit impairment charges and other provisions	Abstract			ifrs-full:DisclosureOfImpairmentLossAndReversalOfImpairmentLossAbstract
520	Credit impairment charges and other provisions	Concept (Text Block (HTML))	For Period		ifrs-full:DisclosureOfImpairmentOfAssetsExplanatory
521	011001 - Disclosure - Operating expenses	Network	*	*	http://www.barclays.co.uk/role/OperatingExpenses
522	Implied Table	Table	*	*	implied:Table
523	Operating expenses	Abstract			ifrs-full:ExpenseByNatureAbstract
524	Operating expenses	Concept (Text Block (HTML))	For Period		ifrs-full:DisclosureOfExpensesExplanatory
525	011101 - Disclosure - Profit/(loss) on disposal of subsidiaries, associates and joint ventures	Network	*	*	http://www.barclays.co.uk/role/ProfitlossOnDisposalOfSubsidiariesAssociatesAndJointVentures
526	Implied Table	Table	*	*	implied:Table
527	Profit/(loss) on disposal of subsidiaries, associates and joint ventures	Abstract			ifrs-full:GainsLossesOnDisposalsOfInvestmentsAbstract
528	Profit/(loss) on disposal of subsidiaries, associates and joint ventures	Concept (Text Block (HTML))	For Period		ifrs-full:DisclosureOfNoncurrentAssetsHeldForSaleAndDiscontinuedOperationsExplanatory
529	011201 - Disclosure - Tax	Network	*	*	http://www.barclays.co.uk/role/Tax
530	Implied Table	Table	*	*	implied:Table
531	Tax	Abstract			ifrs-full:MajorComponentsOfTaxExpenseIncomeAbstract
532	Tax	Concept (Text Block (HTML))	For Period		ifrs-full:DisclosureOfIncomeTaxExplanatory
533	011301 - Disclosure - Dividends on ordinary shares	Network	*	*	http://www.barclays.co.uk/role/DividendsOnOrdinaryShares
534	Implied Table	Table	*	*	implied:Table
535	Dividends on ordinary shares	Abstract			c070:DisclosureOfDividendsOnOrdinarySharesAbstract
536	Dividends on ordinary shares	Concept (Text Block (HTML))	For Period		ifrs-full:DisclosureOfDividendsExplanatory
537	011401 - Disclosure - Trading portfolio	Network	*	*	http://www.barclays.co.uk/role/TradingPortfolio
538	Implied Table	Table	*	*	implied:Table
539	Trading Portfolio	Abstract			ifrs-full:NetAssetsLiabilitiesAbstract
540	Trading portfolio	Concept (Text Block (HTML))	For Period		ifrs-full:DisclosureOfFinancialInstrumentsHeldForTradingExplanatory
541	011501 - Disclosure - Financial assets at fair value through the income statement	Network	*	*	http://www.barclays.co.uk/role/FinancialAssetsAtFairValueThroughTheIncomeStatement
542	Implied Table	Table	*	*	implied:Table
543	Financial assets at fair value through the income statement [abstract]	Abstract			ifrs-full:FinancialAssetsDesignatedAsMeasuredAtFairValueAbstract
544	Financial assets at fair value through the income statement	Concept (Text Block (HTML))	For Period		ifrs-full:DisclosureOfFinancialAssetsExplanatory
545	011601 - Disclosure - Derivative financial instruments	Network	*	*	http://www.barclays.co.uk/role/DerivativeFinancialInstruments
546	Implied Table	Table	*	*	implied:Table
547	Derivative financial instruments	Abstract			ifrs-full:DisclosureOfNatureAndExtentOfRisksArisingFromFinancialInstrumentsAbstract
548	Derivative financial instruments	Concept (Text Block (HTML))	For Period		ifrs-full:DisclosureOfDerivativeFinancialInstrumentsExplanatory
549	011701 - Disclosure - Financial assets at fair value through other comprehensive income and Financial Investments	Network	*	*	http://www.barclays.co.uk/role/FinancialAssetsAtFairValueThroughOtherComprehensiveIncomeAndFinancialInvestments
550	Implied Table	Table	*	*	implied:Table
551	Financial assets at fair value through other comprehensive income [abstract]	Abstract			ifrs-full:FinancialAssetsAtFairValueThroughOtherComprehensiveIncomeAbstract
552	Financial assets at fair value through other comprehensive income	Concept (Text Block (HTML))	For Period		ifrs-full:DisclosureOfFinancialInstrumentsExplanatory
553	011801 - Disclosure - Financial liabilities designated at fair value	Network	*	*	http://www.barclays.co.uk/role/FinancialLiabilitiesDesignatedAtFairValue
554	Implied Table	Table	*	*	implied:Table
555	Financial liabilities designated at fair value	Abstract			ifrs-full:DesignatedFinancialLiabilitiesAtFairValueThroughProfitOrLossAbstract
556	Financial liabilities designated at fair value	Concept (Text Block (HTML))	For Period		ifrs-full:DisclosureOfFinancialLiabilitiesExplanatory
557	011901 - Disclosure - Fair value of financial instruments	Network	*	*	http://www.barclays.co.uk/role/FairValueOfFinancialInstruments
558	Implied Table	Table	*	*	implied:Table
559	Fair value of financial instruments	Abstract			c070:DisclosureOfFairValueMeasurementOfAssetsAndLiabilitiesAbstract
560	Fair value of financial instruments	Concept (Text Block (HTML))	For Period		ifrs-full:DisclosureOfFairValueOfFinancialInstrumentsExplanatory
561	012001 - Disclosure - Offsetting financial assets and financial liabilities	Network	*	*	http://www.barclays.co.uk/role/OffsettingFinancialAssetsAndFinancialLiabilities
562	Implied Table	Table	*	*	implied:Table
563	Offsetting financial assets and financial liabilities	Abstract			c070:DisclosureOfOffsettingOfFinancialAssetsAndFinancialLiabilitiesAbstract
564	Disclosure of offsetting of financial assets and financial liabilities [text block]	Concept (Text Block (HTML))	For Period		ifrs-full:DisclosureOfOffsettingOfFinancialAssetsAndFinancialLiabilitiesExplanatory
565	012101 - Disclosure - Loans and advances and deposits at amortised cost	Network	*	*	http://www.barclays.co.uk/role/LoansAndAdvancesAndDepositsAtAmortisedCost
566	Implied Table	Table	*	*	implied:Table
567	Loans and advances and deposits at amortised cost	Abstract			c070:LoansAndAdvancesAndDepositsAtAmortisedCostAbstract
568	Loans and advances and deposits at amortised cost	Concept (Text Block (HTML))	For Period		c070:DisclosureOfLoansAndAdvancesAndDepositsAtAmortisedCost
569	012201 - Disclosure - Finance leases	Network	*	*	http://www.barclays.co.uk/role/FinanceLeases
570	Implied Table	Table	*	*	implied:Table
571	Finance leases	Abstract			c070:DisclosureOfFinanceLeasesAbstract
572	Finance leases	Concept (Text Block (HTML))	For Period		c070:DisclosureOfFinanceLeasesExplanatory
573	012301 - Disclosure - Property, plant and equipment	Network	*	*	http://www.barclays.co.uk/role/PropertyPlantAndEquipment
574	Implied Table	Table	*	*	implied:Table
575	Property, plant and equipment [abstract]	Abstract			ifrs-full:DisclosureOfPropertyPlantAndEquipmentAbstract
576	Property, plant and equipment	Concept (Text Block (HTML))	For Period		ifrs-full:DisclosureOfPropertyPlantAndEquipmentExplanatory
577	012401 - Disclosure - Goodwill and intangible assets	Network	*	*	http://www.barclays.co.uk/role/GoodwillAndIntangibleAssets
578	Implied Table	Table	*	*	implied:Table
579	Goodwill and intangible assets	Abstract			ifrs-full:IntangibleAssetsAndGoodwillAbstract
580	Disclosure of intangible assets and goodwill [text block]	Concept (Text Block (HTML))	For Period		ifrs-full:DisclosureOfIntangibleAssetsAndGoodwillExplanatory
581	012501 - Disclosure - Operating leases	Network	*	*	http://www.barclays.co.uk/role/OperatingLeases
582	Implied Table	Table	*	*	implied:Table
583	Disclosure of operating leases [abstract]	Abstract			c070:DisclosureOfOperatingLeasesAbstract
584	Operating leases	Concept (Text Block (HTML))	For Period		c070:DisclosureOfOperatingLeasesExplanatory
585	012601 - Disclosure - Other liabilities	Network	*	*	http://www.barclays.co.uk/role/OtherLiabilities
586	Implied Table	Table	*	*	implied:Table
587	Other liabilities [abstract]	Abstract			ifrs-full:AccrualsAndDeferredIncomeAbstract
588	Accruals, deferred income and other liabilities	Concept (Text Block (HTML))	For Period		ifrs-full:DisclosureOfAccruedExpensesAndOtherLiabilitiesExplanatory
589	012701 - Disclosure - Provisions	Network	*	*	http://www.barclays.co.uk/role/Provisions
590	Implied Table	Table	*	*	implied:Table
591	Provisions [abstract]	Abstract			ifrs-full:ProvisionsAbstract
592	Provisions	Concept (Text Block (HTML))	For Period		ifrs-full:DisclosureOfProvisionsExplanatory
593	012801 - Disclosure - Contingent liabilities and commitments	Network	*	*	http://www.barclays.co.uk/role/ContingentLiabilitiesAndCommitments
594	Implied Table	Table	*	*	implied:Table
595	Contingent liabilities and commitments [abstract]	Abstract			ifrs-full:DisclosureOfContingentLiabilitiesAbstract
596	Contingent liabilities and commitments	Concept (Text Block (HTML))	For Period		ifrs-full:DisclosureOfCommitmentsAndContingentLiabilitiesExplanatory
597	012901 - Disclosure - Legal, competition and regulatory matters	Network	*	*	http://www.barclays.co.uk/role/LegalCompetitionAndRegulatoryMatters
598	Implied Table	Table	*	*	implied:Table
599	Legal, competition and regulatory matters	Abstract			c070:DisclosureOfLegalCompetitionAndRegulatoryMattersAbstract
600	Legal, competition and regulatory matters	Concept (Text Block (HTML))	For Period		c070:DisclosureOfLegalCompetitionAndRegulatoryMattersExplanatory
601	013001 - Disclosure - Subordinated Liabilities	Network	*	*	http://www.barclays.co.uk/role/SubordinatedLiabilities
602	Implied Table	Table	*	*	implied:Table
603	Subordinated liabilities [abstract]	Abstract			ifrs-full:SubordinatedLiabilitiesAbstract
604	Subordinated Liabilities	Concept (Text Block (HTML))	For Period		ifrs-full:DisclosureOfSubordinatedLiabilitiesExplanatory
605	013101 - Disclosure - Ordinary shares, share premium, and other equity	Network	*	*	http://www.barclays.co.uk/role/OrdinarySharesSharePremiumAndOtherEquity
606	Implied Table	Table	*	*	implied:Table
607	Equity [abstract]	Abstract			ifrs-full:EquityAbstract
608	Called up share capital	Concept (Text Block (HTML))	For Period		ifrs-full:DisclosureOfIssuedCapitalExplanatory
609	013201 - Disclosure - Reserves	Network	*	*	http://www.barclays.co.uk/role/Reserves
610	Implied Table	Table	*	*	implied:Table
611	Reserves	Abstract			ifrs-full:DisclosureOfReservesWithinEquityAbstract
612	Reserves	Concept (Text Block (HTML))	For Period		ifrs-full:DisclosureOfReservesAndOtherEquityInterestExplanatory
613	013301 - Disclosure - Non-controlling interests	Network	*	*	http://www.barclays.co.uk/role/NoncontrollingInterests
614	Implied Table	Table	*	*	implied:Table
615	Non-controlling interests [abstract]	Abstract			c070:NoncontrollingInterestsAbstract
616	Non-controlling interests	Concept (Text Block (HTML))	For Period		ifrs-full:DisclosureOfNoncontrollingInterestsExplanatory
617	013401 - Disclosure - Staff costs	Network	*	*	http://www.barclays.co.uk/role/StaffCosts
618	Implied Table	Table	*	*	implied:Table
619	Staff costs	Abstract			ifrs-full:ClassesOfEmployeeBenefitsExpenseAbstract
620	Staff costs	Concept (Text Block (HTML))	For Period		c070:DisclosureOfShorttermEmployeeBenefitsExplanatoryTextBlock
621	013501 - Disclosure - Share-based payments	Network	*	*	http://www.barclays.co.uk/role/SharebasedPayments
622	Implied Table	Table	*	*	implied:Table
623	Disclosure of terms and conditions of share-based payment arrangement [abstract]	Abstract			ifrs-full:DisclosureOfTermsAndConditionsOfSharebasedPaymentArrangementAbstract
624	Share-based payments	Concept (Text Block (HTML))	For Period		ifrs-full:DisclosureOfSharebasedPaymentArrangementsExplanatory
625	013601 - Disclosure - Pension and post-retirement benefits	Network	*	*	http://www.barclays.co.uk/role/PensionAndPostretirementBenefits
626	Implied Table	Table	*	*	implied:Table
627	Pension and post-retirement benefits	Abstract			ifrs-full:DisclosureOfDefinedBenefitPlansAbstract
628	Pension and post-retirement benefits	Concept (Text Block (HTML))	For Period		ifrs-full:DisclosureOfEmployeeBenefitsExplanatory
629	013701 - Disclosure - Principal subsidiaries	Network	*	*	http://www.barclays.co.uk/role/PrincipalSubsidiaries
630	Implied Table	Table	*	*	implied:Table
631	Principal Subsidiaries	Abstract			ifrs-full:DisclosureOfSignificantInvestmentsInSubsidiariesAbstract
632	Principal subsidiaries	Concept (Text Block (HTML))	For Period		ifrs-full:DisclosureOfSignificantInvestmentsInSubsidiariesExplanatory
633	013801 - Disclosure - Structured entities	Network	*	*	http://www.barclays.co.uk/role/StructuredEntities
634	Implied Table	Table	*	*	implied:Table
635	Disclosure of information about consolidated structured entities [abstract]	Abstract			ifrs-full:DisclosureOfInformationAboutConsolidatedStructuredEntitiesAbstract
636	Structured entities	Concept (Text Block (HTML))	For Period		ifrs-full:DisclosureOfInformationAboutInterestsInStructuredEntityExplanatory
637	013901 - Disclosure - Investments in associates and joint ventures	Network	*	*	http://www.barclays.co.uk/role/InvestmentsInAssociatesAndJointVentures
638	Implied Table	Table	*	*	implied:Table
639	Investments in joint ventures and associates [abstract]	Abstract			c070:InvestmentsInJointVenturesAndAssociatesAbstract
640	Investments in associates and joint ventures	Concept (Text Block (HTML))	For Period		c070:DisclosureOfInvestmentsInAsssociatesAndJointVenturesTextBlock
641	014001 - Disclosure - Securitisations	Network	*	*	http://www.barclays.co.uk/role/Securitisations
642	Implied Table	Table	*	*	implied:Table
643	Secutritisations	Abstract			ifrs-full:DisclosureOfFinancialAssetsTransferredDuringPeriodWhichDoNotQualifyForDerecognitionAbstract
644	Securitisations	Concept (Text Block (HTML))	For Period		ifrs-full:DisclosureOfTransfersOfFinancialAssetsExplanatory
645	014101 - Disclosure - Assets pledged	Network	*	*	http://www.barclays.co.uk/role/AssetsPledged
646	Implied Table	Table	*	*	implied:Table
647	Assets pledged	Abstract			c070:AssetsPledgedAbstract
648	Assets pledged	Concept (Text Block (HTML))	For Period		ifrs-full:DisclosureOfCollateralExplanatory
649	014201 - Disclosure - Related party transactions and Directors' remuneration	Network	*	*	http://www.barclays.co.uk/role/RelatedPartyTransactionsAndDirectorsRemuneration
650	Implied Table	Table	*	*	implied:Table
651	Related party transactions and Directors' remuneration [abstract]	Abstract			ifrs-full:DisclosureOfTransactionsBetweenRelatedPartiesAbstract
652	Related party transactions	Concept (Text Block (HTML))	For Period		ifrs-full:DisclosureOfRelatedPartyExplanatory
653	014302 - Disclosure - Auditors' remuneration	Network	*	*	http://www.barclays.co.uk/role/AuditorsRemuneration
654	Implied Table	Table	*	*	implied:Table
655	Auditors' remuneration [abstract]	Abstract			ifrs-full:AuditorsRemunerationAbstract
656	Auditors' remuneration	Concept (Text Block (HTML))	For Period		ifrs-full:DisclosureOfAuditorsRemunerationExplanatory
657	014401 - Disclosure - Transition disclosures	Network	*	*	http://www.barclays.co.uk/role/TransitionDisclosures
658	Implied Table	Table	*	*	implied:Table
659	Transition disclosures	Abstract			ifrs-full:DisclosureOfReclassificationsOrChangesInPresentationAbstract
660	Transition disclosures	Concept (Text Block (HTML))	For Period		ifrs-full:DisclosureOfChangesInAccountingPoliciesAccountingEstimatesAndErrorsExplanatory
661	014701 - Disclosure - Other disclosures - Risk Management and Principal Risks (audited)	Network	*	*	http://www.barclays.co.uk/role/OtherDisclosuresRiskManagementAndPrincipalRisksaudited
662	Implied Table	Table	*	*	implied:Table
663	Other disclosures - Risk Management and Principal Risks	Abstract			ifrs-full:DisclosureOfCreditRiskExposureAbstract
664	Other disclosures - Risk Management and Principal Risks (audited)	Concept (Text Block (HTML))	For Period		ifrs-full:DisclosureOfObjectivesPoliciesAndProcessesForManagingCapitalExplanatory
665	020101 - Disclosure - Significant accounting policies (Policy)	Network	*	*	http://www.barclays.co.uk/role/SignificantAccountingPoliciesPolicy
666	Disclosure of detailed information about financial instruments [table]	Table	*	*	ifrs-full:DisclosureOfFinancialInstrumentsTable
667	Categories of financial assets [axis]	Axis			ifrs-full:CategoriesOfFinancialAssetsAxis
668	Financial assets, category [member]	Member			ifrs-full:FinancialAssetsCategoryMember
669	Financial assets designated at fair value [member]	Member			ifrs-full:FinancialAssetsAtFairValueThroughProfitOrLossDesignatedUponInitialRecognitionCategoryMember
670	Financial assets mandatory at fair value [member]	Member			ifrs-full:FinancialAssetsAtFairValueThroughProfitOrLossMandatorilyMeasuredAtFairValueCategoryMember
671	Financial instruments at fair value through OCI [member]	Member			ifrs-full:FinancialAssetsMeasuredAtFairValueThroughOtherComprehensiveIncomeCategoryMember
672	Financial Investments [member]	Member			c070:FinancialInvestmentsMember
673	Financial assets at amortised cost [member]	Member			ifrs-full:FinancialAssetsAtAmortisedCostCategoryMember
674	Categories of financial liabilities [axis]	Axis			ifrs-full:CategoriesOfFinancialLiabilitiesAxis
675	Financial liabilities, category [member]	Member			ifrs-full:FinancialLiabilitiesCategoryMember
676	Deposits at amortised cost [member]	Member			c070:DepositsAtAmortisedCostMember
677	Disclosure of detailed information about financial instruments [line items]	LineItems			ifrs-full:DisclosureOfFinancialInstrumentsLineItems
678	Accounting for financial assets at fair value	Concept (Text Block (HTML))	For Period		ifrs-full:DescriptionOfAccountingPolicyForFinancialAssetsExplanatory
679	Accounting for loans and advances and deposits held at amortised cost	Concept (Text Block (HTML))	For Period		ifrs-full:DescriptionOfAccountingPolicyForFinancialInstrumentsExplanatory
680	030201 - Disclosure - Disposal of business and transfer of ownership of subsidiary (Tables)	Network	*	*	http://www.barclays.co.uk/role/DisposalOfBusinessAndTransferOfOwnershipOfSubsidiaryTables
681	Implied Table	Table	*	*	implied:Table
682	Disposal of business and transfer of ownership of subsidiary	Abstract			c070:DisposalOfBusinessAndTransferOfOwnershipOfSubsidiaryAbstract
683	The impact on the individual balance sheet line item as a result of the transfer of the ownership of subsidiary	Concept (Text Block (HTML))	For Period		c070:AssetsLiabilitiesIncludedInDisposalGroupAndTransferOfOwnershipOfSubsidiaryTableTextBlock
684	030301 - Disclosure - Discontinued operations and assets included in disposal groups classified as held for sale and associated liabilities (Tables)	Network	*	*	http://www.barclays.co.uk/role/DiscontinuedOperationsAndAssetsIncludedInDisposalGroupsClassifiedAsHeldForSaleAndAssociatedLiabilitiesTables
685	Disclosure of subsidiaries [table]	Table	*	*	ifrs-full:DisclosureOfSignificantInvestmentsInSubsidiariesTable
686	Continuing and discontinued operations [axis]	Axis			ifrs-full:ContinuingAndDiscontinuedOperationsAxis
687	Aggregate continuing and discontinued operations [member]	Member			ifrs-full:AggregateContinuingAndDiscontinuedOperationsMember
688	Discontinued operations [member]	Member			ifrs-full:DiscontinuedOperationsMember
689	UK Banking Business [member]	Member			c070:BarclaysUkMember
690	Barclay's Africa Banking Group Limited (BAGL) [member]	Member			c070:BarclaysAfricaBankingGroupLimitedMember
691	Assets and liabilities classified as held for sale [axis]	Axis			ifrs-full:AssetsAndLiabilitiesClassifiedAsHeldForSaleAxis
692	Assets and liabilities not classified as held for sale [member]	Member			ifrs-full:AssetsAndLiabilitiesNotClassifiedAsHeldForSaleMember
693	Held for sale [member]	Member			ifrs-full:DisposalGroupsClassifiedAsHeldForSaleMember
694	Categories of related parties [axis]	Axis			ifrs-full:CategoriesOfRelatedPartiesAxis
695	Entity's total for related parties [member]	Member			ifrs-full:EntitysTotalForRelatedPartiesMember
696	Barclays Bank UK PLC [member]	Member			c070:BarclaysBankUkPlcMember
697	Disclosure of subsidiaries [line items]	LineItems			ifrs-full:DisclosureOfSignificantInvestmentsInSubsidiariesLineItems
698	Assets included in disposal groups classified as held for sale	Concept (Text Block (HTML))	For Period		srt:ScheduleOfCondensedBalanceSheetTableTextBlock
699	Disposal group income statement	Concept (Text Block (HTML))	For Period		srt:ScheduleOfCondensedIncomeStatementTableTextBlock
700	Other comprehensive income	Concept (Text Block (HTML))	For Period		srt:CondensedStatementOfComprehensiveIncomeTableTextBlock
701	Cash flows	Concept (Text Block (HTML))	For Period		srt:ScheduleOfCondensedCashFlowStatementTableTextBlock
702	Reconciliation of consolidated income statement to prior period	Concept (Text Block (HTML))	For Period		c070:DisclosureOfReconciliaitonOfContinuingOperationsIncomeStatement
703	030401 - Disclosure - Segmental reporting (Tables)	Network	*	*	http://www.barclays.co.uk/role/SegmentalReportingTables
704	Implied Table	Table	*	*	implied:Table
705	Disclosure of operating segments [abstract]	Abstract			ifrs-full:DisclosureOfOperatingSegmentsAbstract
706	Analysis of results by business	Concept (Text Block (HTML))	For Period		ifrs-full:DisclosureOfOperatingSegmentsExplanatory
707	Income by geographic region (audited)	Concept (Text Block (HTML))	For Period		ifrs-full:DisclosureOfGeographicalAreasExplanatory
708	030501 - Disclosure - Net interest income (Tables)	Network	*	*	http://www.barclays.co.uk/role/NetInterestIncomeTables
709	Implied Table	Table	*	*	implied:Table
710	Net interest income	Abstract			ifrs-full:AnalysisOfIncomeAndExpenseAbstract
711	Consolidated and separate financial statements [line items]	LineItems			c070:ConsolidatedAndSeparateFinancialStatementsLineItems
712	Net interest income	Concept (Text Block (HTML))	For Period		c070:DisclosureOfNetInterestIncomeTableTextBlock
713	030701 - Disclosure - Net fee and commission income (Tables)	Network	*	*	http://www.barclays.co.uk/role/NetFeeAndCommissionIncomeTables
714	Implied Table	Table	*	*	implied:Table
715	Net Fee and commission income	Abstract			ifrs-full:FeeAndCommissionIncomeExpenseAbstract
716	Total fees in scope of IFRS 15 Revenues from Contracts with Customers	Concept (Text Block (HTML))	For Period		ifrs-full:DisclosureOfDisaggregationOfRevenueFromContractsWithCustomersExplanatory
717	030801 - Disclosure - Net trading income (Tables)	Network	*	*	http://www.barclays.co.uk/role/NetTradingIncomeTables
718	Implied Table	Table	*	*	implied:Table
719	Net trading income	Abstract			ifrs-full:TradingIncomeExpenseAbstract
720	Net trading income	Concept (Text Block (HTML))	For Period		c070:DisclosureOfNetTradingIncomeTableTextBlock
721	030901 - Disclosure - Net investment income (Tables)	Network	*	*	http://www.barclays.co.uk/role/NetInvestmentIncomeTables
722	Implied Table	Table	*	*	implied:Table
723	Net investment income [abstract	Abstract			ifrs-full:MaterialIncomeAndExpenseAbstract
724	Net investment income	Concept (Text Block (HTML))	For Period		c070:DisclosureOfNetInvestmentIncomeTableTextBlock
725	031001 - Disclosure - Credit impairment charges and other provisions (Tables)	Network	*	*	http://www.barclays.co.uk/role/CreditImpairmentChargesAndOtherProvisionsTables
726	Implied Table	Table	*	*	implied:Table
727	Credit impairment charges and other provisions	Abstract			ifrs-full:DisclosureOfImpairmentLossAndReversalOfImpairmentLossAbstract
728	Credit impairment charges and other provisions	Concept (Text Block (HTML))	For Period		ifrs-full:DisclosureOfImpairmentLossAndReversalOfImpairmentLossExplanatory
729	Movements in allowance for impairment by asset class (audited)	Concept (Text Block (HTML))	For Period		ifrs-full:DisclosureOfAllowanceForCreditLossesExplanatory
730	031101 - Disclosure - Operating expenses (Tables)	Network	*	*	http://www.barclays.co.uk/role/OperatingExpensesTables
731	Implied Table	Table	*	*	implied:Table
732	Operating expenses	Abstract			ifrs-full:ExpenseByNatureAbstract
733	Operating expenses	Concept (Text Block (HTML))	For Period		ifrs-full:DisclosureOfExpensesByNatureExplanatory
734	031201 - Disclosure - Tax (Tables)	Network	*	*	http://www.barclays.co.uk/role/TaxTables
735	Implied Table	Table	*	*	implied:Table
736	Tax	Abstract			ifrs-full:MajorComponentsOfTaxExpenseIncomeAbstract
737	Tax charge	Concept (Text Block (HTML))	For Period		c070:DisclosureOfComponentsOfIncomeTaxTableTextBlock
738	Reconciliation between the actual tax charge and the corporate tax rate	Concept (Text Block (HTML))	For Period		c070:DisclosureOfReconciliationOfActualTaxRateToCorporateTaxRateTableTextBlock
739	Current tax assets and liabilities	Concept (Text Block (HTML))	For Period		c070:DisclosureOfCurrentTaxesTableTextBlock
740	Deferred tax assets and liabilities	Concept (Text Block (HTML))	For Period		ifrs-full:DisclosureOfDeferredTaxesExplanatory
741	Movements on deferred tax assets and liabilities during the year before offsetting	Concept (Text Block (HTML))	For Period		ifrs-full:DisclosureOfTemporaryDifferenceUnusedTaxLossesAndUnusedTaxCreditsExplanatory
742	031401 - Disclosure - Trading portfolio (Tables)	Network	*	*	http://www.barclays.co.uk/role/TradingPortfolioTables
743	Implied Table	Table	*	*	implied:Table
744	Trading Portfolio	Abstract			ifrs-full:NetAssetsLiabilitiesAbstract
745	Trading portfolio	Concept (Text Block (HTML))	For Period		c070:DisclosureOfFinancialAssetsAndLiabilitiesHeldForTradingTableTextBlock
746	031501 - Disclosure - Financial assets at fair value through the income statement (Tables)	Network	*	*	http://www.barclays.co.uk/role/FinancialAssetsAtFairValueThroughTheIncomeStatementTables
747	Disclosure of financial assets [table]	Table	*	*	ifrs-full:DisclosureOfFinancialAssetsTable
748	Categories of financial assets [axis]	Axis			ifrs-full:CategoriesOfFinancialAssetsAxis
749	Financial assets, category [member]	Member			ifrs-full:FinancialAssetsCategoryMember
750	Financial assets at fair value through the income statement [member]	Member			ifrs-full:FinancialAssetsAtFairValueThroughProfitOrLossCategoryMember
751	Disclosure of financial assets [line items]	LineItems			ifrs-full:DisclosureOfFinancialAssetsLineItems
752	Financial assets designated at fair value	Concept (Text Block (HTML))	For Period		ifrs-full:DisclosureOfFinancialInstrumentsDesignatedAtFairValueThroughProfitOrLossExplanatory
753	Credit risk of loans and advances designated at fair value and related credit derivatives	Concept (Text Block (HTML))	For Period		ifrs-full:DisclosureOfCreditRiskExposureExplanatory
754	031601 - Disclosure - Derivative financial instruments (Tables)	Network	*	*	http://www.barclays.co.uk/role/DerivativeFinancialInstrumentsTables
755	Implied Table	Table	*	*	implied:Table
756	Derivative financial instruments	Abstract			ifrs-full:DisclosureOfNatureAndExtentOfRisksArisingFromFinancialInstrumentsAbstract
757	Total derivatives	Concept (Text Block (HTML))	For Period		c070:DisclosureOnSummaryOfDerivativeAssetsAndLiabilitiesTableTextBlock
758	Derivatives held for trading	Concept (Text Block (HTML))	For Period		c070:DisclosureOfDerivativesHeldForTradingTableTextBlock
759	Derivatives held for risk management	Concept (Text Block (HTML))	For Period		ifrs-full:DisclosureOfRiskManagementStrategyRelatedToHedgeAccountingExplanatory
760	Hedged forecast cash flows	Concept (Text Block (HTML))	For Period		ifrs-full:DisclosureOfSignificantUnobservableInputsUsedInFairValueMeasurementOfAssetsExplanatory
761	Amounts recognised in net interest income	Concept (Text Block (HTML))	For Period		ifrs-full:DisclosureOfHedgeAccountingExplanatory
762	Hedging instruments which are carried on the Barclays Bank Group's balance sheet	Concept (Text Block (HTML))	For Period		ifrs-full:DisclosureOfDetailedInformationAboutHedgingInstrumentsExplanatory
763	The Expected notional values of current hedging instruments in future years	Concept (Text Block (HTML))	For Period		ifrs-full:DisclosureOfInformationAboutTermsAndConditionsOfHedgingInstrumentsAndHowTheyAffectFutureCashFlowsExplanatory
764	Hedged items hedge accounting relationships including the ineffectiveness recognised in the income statement	Concept (Text Block (HTML))	For Period		ifrs-full:DisclosureOfDetailedInformationAboutHedgedItemsExplanatory
765	Impact on the income statement and OCI of recycling amounts in respect of Cash flow hedges and Net investment hedges of foreign operations	Concept (Text Block (HTML))	For Period		ifrs-full:DisclosureOfInformationAboutAmountsThatAffectedStatementOfComprehensiveIncomeAsResultOfHedgeAccountingExplanatory
766	Reconciliation of the movements of the cash flow hedge reserve and the currency translation reserve	Concept (Text Block (HTML))	For Period		ifrs-full:DisclosureOfDetailedInformationAboutHedgesExplanatory
767	031701 - Disclosure - Financial assets at fair value through other comprehensive income and Financial Investments (Tables)	Network	*	*	http://www.barclays.co.uk/role/FinancialAssetsAtFairValueThroughOtherComprehensiveIncomeAndFinancialInvestmentsTables
768	Implied Table	Table	*	*	implied:Table
769	Financial assets at fair value through other comprehensive income [abstract]	Abstract			ifrs-full:FinancialAssetsAtFairValueThroughOtherComprehensiveIncomeAbstract
770	Financial assets at fair value through other comprehensive income/Financial investments	Concept (Text Block (HTML))	For Period		ifrs-full:DisclosureOfDetailedInformationAboutFinancialInstrumentsExplanatory
771	031801 - Disclosure - Financial liabilities designated at fair value (Tables)	Network	*	*	http://www.barclays.co.uk/role/FinancialLiabilitiesDesignatedAtFairValueTables
772	Disclosure of financial liabilities [table]	Table	*	*	ifrs-full:DisclosureOfFinancialLiabilitiesTable
773	Categories of financial liabilities [axis]	Axis			ifrs-full:CategoriesOfFinancialLiabilitiesAxis
774	Financial liabilities, category [member]	Member			ifrs-full:FinancialLiabilitiesCategoryMember
775	Financial liabilities designated at fair value [member]	Member			ifrs-full:FinancialLiabilitiesAtFairValueThroughProfitOrLossDesignatedUponInitialRecognitionCategoryMember
776	Disclosure of financial liabilities [line items]	LineItems			ifrs-full:DisclosureOfFinancialLiabilitiesLineItems
777	Financial liabilities designated at fair value	Concept (Text Block (HTML))	For Period		ifrs-full:DisclosureOfFinancialInstrumentsDesignatedAtFairValueThroughProfitOrLossExplanatory
778	031901 - Disclosure - Fair value of financial instruments (Tables)	Network	*	*	http://www.barclays.co.uk/role/FairValueOfFinancialInstrumentsTables
779	Disclosure of products and services [table]	Table	*	*	ifrs-full:DisclosureOfProductsAndServicesTable
780	Products and services [axis]	Axis			ifrs-full:ProductsAndServicesAxis
781	Products and services [member]	Member			ifrs-full:ProductsAndServicesMember
782	By Product type [Member]	Member			c070:ByProductTypeMember
783	Disclosure of products and services [line items]	LineItems			ifrs-full:DisclosureOfProductsAndServicesLineItems
784	Assets and liabilities held at fair value	Concept (Text Block (HTML))	For Period		c070:DisclosureOfFairValueMeasurementOfAssetsAndLiabilitiesTableTextBlock
785	032001 - Disclosure - Offsetting financial assets and financial liabilities (Tables)	Network	*	*	http://www.barclays.co.uk/role/OffsettingFinancialAssetsAndFinancialLiabilitiesTables
786	Implied Table	Table	*	*	implied:Table
787	Offsetting financial assets and financial liabilities	Abstract			c070:DisclosureOfOffsettingOfFinancialAssetsAndFinancialLiabilitiesAbstract
788	Disclosure of Offsetting of financial assets and financial liabilities [table text block]	Concept (Text Block (HTML))	For Period		c070:DisclosureOfOffsettingOfFinancialAssetsAndFinancialLiabilitiesTableTextBlock
789	032101 - Disclosure - Loans and advances at amortised cost (Tables)	Network	*	*	http://www.barclays.co.uk/role/LoansAndAdvancesAtAmortisedCostTables
790	Implied Table	Table	*	*	implied:Table
791	Loans and advances and deposits at amortised cost	Abstract			c070:LoansAndAdvancesAndDepositsAtAmortisedCostAbstract
792	Loans and advances and deposits at amortised cost	Concept (Text Block (HTML))	For Period		c070:DisclosureOfLoansAndAdvancesAtAmortisedCostTableTextBlock
793	032201 - Disclosure - Finance leases (Tables)	Network	*	*	http://www.barclays.co.uk/role/FinanceLeasesTables
794	Implied Table	Table	*	*	implied:Table
795	Finance leases	Abstract			c070:DisclosureOfFinanceLeasesAbstract
796	Finance leases	Concept (Text Block (HTML))	For Period		c070:DisclosureOfRecognisedFinanceLeaseAsAssetsByLesseeAndLessorTableTextBlock
797	032301 - Disclosure - Property, plant and equipment (Tables)	Network	*	*	http://www.barclays.co.uk/role/PropertyPlantAndEquipmentTables
798	Implied Table	Table	*	*	implied:Table
799	Property, plant and equipment [abstract]	Abstract			ifrs-full:DisclosureOfPropertyPlantAndEquipmentAbstract
800	Property, plant and equipment	Concept (Text Block (HTML))	For Period		ifrs-full:DisclosureOfDetailedInformationAboutPropertyPlantAndEquipmentExplanatory
801	032401 - Disclosure - Goodwill and intangible assets (Tables)	Network	*	*	http://www.barclays.co.uk/role/GoodwillAndIntangibleAssetsTables
802	Implied Table	Table	*	*	implied:Table
803	Goodwill and intangible assets	Abstract			ifrs-full:IntangibleAssetsAndGoodwillAbstract
804	Intangible assets	Concept (Text Block (HTML))	For Period		ifrs-full:DisclosureOfIntangibleAssetsExplanatory
805	Goodwill	Concept (Text Block (HTML))	For Period		ifrs-full:DisclosureOfGoodwillExplanatory
806	032501 - Disclosure - Operating leases (Tables)	Network	*	*	http://www.barclays.co.uk/role/OperatingLeasesTables
807	Implied Table	Table	*	*	implied:Table
808	Disclosure of operating leases [abstract]	Abstract			c070:DisclosureOfOperatingLeasesAbstract
809	Future minimum lease payments by the Group under non-cancellable operating leases	Concept (Text Block (HTML))	For Period		c070:DiclosureOfOperatingLeaseByLesseeTableTextBlock
810	032601 - Disclosure - Other liabilities (Tables)	Network	*	*	http://www.barclays.co.uk/role/OtherLiabilitiesTables
811	Implied Table	Table	*	*	implied:Table
812	Other liabilities [abstract]	Abstract			ifrs-full:AccrualsAndDeferredIncomeAbstract
813	Other liabilities	Concept (Text Block (HTML))	For Period		ifrs-full:DisclosureOfOtherLiabilitiesExplanatory
814	032701 - Disclosure - Provisions (Tables)	Network	*	*	http://www.barclays.co.uk/role/ProvisionsTables
815	Implied Table	Table	*	*	implied:Table
816	Provisions [abstract]	Abstract			ifrs-full:ProvisionsAbstract
817	Provisions	Concept (Text Block (HTML))	For Period		ifrs-full:DisclosureOfOtherProvisionsExplanatory
818	032801 - Disclosure - Contingent liabilities and commitments (Tables)	Network	*	*	http://www.barclays.co.uk/role/ContingentLiabilitiesAndCommitmentsTables
819	Implied Table	Table	*	*	implied:Table
820	Contingent liabilities and commitments [abstract]	Abstract			ifrs-full:DisclosureOfContingentLiabilitiesAbstract
821	Contingent liabilities and commitments	Concept (Text Block (HTML))	For Period		c070:DisclosureOfCommitmentsAndContingentLiabilitiesTableTextBlock
822	033001 - Disclosure - Subordinated Liabilities (Tables)	Network	*	*	http://www.barclays.co.uk/role/SubordinatedLiabilitiesTables
823	Disclosure of detailed information about borrowings [table]	Table	*	*	ifrs-full:DisclosureOfDetailedInformationAboutBorrowingsTable
824	Classes of liabilities [axis]	Axis			ifrs-full:ClassesOfLiabilitiesAxis
825	Liabilities [member]	Member			ifrs-full:LiabilitiesMember
826	Undated Subordinated liabilities [member]	Member			c070:UndatedSubordinatedLiabilitiesMember
827	Dated subordinated liabilities [member]	Member			c070:DatedSubordinatedLiabilitiesMember
828	Disclosure of detailed information about borrowings [line items]	LineItems			ifrs-full:DisclosureOfDetailedInformationAboutBorrowingsLineItems
829	Subordinated liabilities	Concept (Text Block (HTML))	For Period		ifrs-full:DisclosureOfBorrowingsExplanatory
830	Detailed information about Subordinated liabilities	Concept (Text Block (HTML))	For Period		ifrs-full:DisclosureOfDetailedInformationAboutBorrowingsExplanatory
831	033101 - Disclosure - Ordinary shares, share premium, and other equity (Tables)	Network	*	*	http://www.barclays.co.uk/role/OrdinarySharesSharePremiumAndOtherEquityTables
832	Implied Table	Table	*	*	implied:Table
833	Equity [abstract]	Abstract			ifrs-full:EquityAbstract
834	Called up share capital	Concept (Text Block (HTML))	For Period		ifrs-full:DisclosureOfClassesOfShareCapitalExplanatory
835	AT1 equity instruments	Concept (Text Block (HTML))	For Period		ifrs-full:DisclosureOfShareCapitalReservesAndOtherEquityInterestExplanatory
836	033201 - Disclosure - Reserves (Tables)	Network	*	*	http://www.barclays.co.uk/role/ReservesTables
837	Implied Table	Table	*	*	implied:Table
838	Reserves	Abstract			ifrs-full:DisclosureOfReservesWithinEquityAbstract
839	Other reserves	Concept (Text Block (HTML))	For Period		c070:DisclosureOfReservesAndOtherEquityInterestTableTextBlock
840	033301 - Disclosure - Non-controlling interests (Tables)	Network	*	*	http://www.barclays.co.uk/role/NoncontrollingInterestsTables
841	Implied Table	Table	*	*	implied:Table
842	Non-controlling interests [abstract]	Abstract			c070:NoncontrollingInterestsAbstract
843	Detailed information of non controlling interest by group	Concept (Text Block (HTML))	For Period		c070:DetailedInformationOfNoncontrollingInterestByGroupTableTextBlock
844	Detailed information of non-controlling interest by instruments	Concept (Text Block (HTML))	For Period		c070:DetailedInformationOfNoncontrollingInterestByInstrumentsTableTextBlock
845	033401 - Disclosure - Staff costs (Tables)	Network	*	*	http://www.barclays.co.uk/role/StaffCostsTables
846	Implied Table	Table	*	*	implied:Table
847	Staff costs	Abstract			ifrs-full:ClassesOfEmployeeBenefitsExpenseAbstract
848	Staff costs	Concept (Text Block (HTML))	For Period		c070:ScheduleOfShorttermEmployeeBenefitsExplanatoryTableTextBlock
849	033501 - Disclosure - Share-based payments (Tables)	Network	*	*	http://www.barclays.co.uk/role/SharebasedPaymentsTables
850	Implied Table	Table	*	*	implied:Table
851	Disclosure of terms and conditions of share-based payment arrangement [abstract]	Abstract			ifrs-full:DisclosureOfTermsAndConditionsOfSharebasedPaymentArrangementAbstract
852	Share-based payment schemes	Concept (Text Block (HTML))	For Period		ifrs-full:DisclosureOfTermsAndConditionsOfSharebasedPaymentArrangementExplanatory
853	Share option and award plans	Concept (Text Block (HTML))	For Period		c070:DisclosureOfStockOptionsAndAwardPlansOfSharebasedPaymentArrangementExplanatory
854	Movements in options and awards	Concept (Text Block (HTML))	For Period		ifrs-full:DisclosureOfNumberAndWeightedAverageExercisePricesOfShareOptionsExplanatory
855	033601 - Disclosure - Pension and post-retirement benefits (Tables)	Network	*	*	http://www.barclays.co.uk/role/PensionAndPostretirementBenefitsTables
856	Disclosure of sensitivity analysis for actuarial assumptions [table]	Table	*	*	ifrs-full:DisclosureOfSensitivityAnalysisForActuarialAssumptionsTable
857	Actuarial assumptions [axis]	Axis			ifrs-full:ActuarialAssumptionsAxis
858	Actuarial assumptions [member]	Member			ifrs-full:ActuarialAssumptionsMember
859	Key UKRF financial assumptions [member]	Member			c070:ActuarialAssumptionOfKeyFinancialAssumptionsMember
860	Assumed life expectancy [member]	Member			ifrs-full:ActuarialAssumptionOfLifeExpectancyAfterRetirementMember
861	Change in key assumptions [member]	Member			c070:ActuarialAssumptionChangeInKeyAssumptionsMember
862	Disclosure of sensitivity analysis for actuarial assumptions [line items]	LineItems			ifrs-full:DisclosureOfSensitivityAnalysisForActuarialAssumptionsLineItems
863	Income statement charge	Concept (Text Block (HTML))	For Period		c070:DisclosureOfNetPensionCostTableTextBlock
864	Balance sheet reconciliation	Concept (Text Block (HTML))	For Period		ifrs-full:DisclosureOfNetDefinedBenefitLiabilityAssetExplanatory
865	Analysis of scheme assets	Concept (Text Block (HTML))	For Period		ifrs-full:DisclosureOfFairValueOfPlanAssetsExplanatory
866	Actuarial valuation of the schemes' obligation based on assumptions	Concept (Text Block (HTML))	For Period		ifrs-full:DisclosureOfSensitivityAnalysisForActuarialAssumptionsExplanatory
867	Deficit reduction contributions	Concept (Text Block (HTML))	For Period		c070:DisclosureOfDeficitReductionContributionsTableTextBlock
868	Defined benefit contributions paid	Concept (Text Block (HTML))	For Period		c070:DisclosureOfDefinedBenefitContributionsPaidExplanatoryTableTextBlock
869	033701 - Disclosure - Principal subsidiaries (Tables)	Network	*	*	http://www.barclays.co.uk/role/PrincipalSubsidiariesTables
870	Implied Table	Table	*	*	implied:Table
871	Principal Subsidiaries	Abstract			ifrs-full:DisclosureOfSignificantInvestmentsInSubsidiariesAbstract
872	Principal subsidiaries details	Concept (Text Block (HTML))	For Period		ifrs-full:DisclosureOfInformationAboutConsolidatedStructuredEntitiesExplanatory
873	Entities excluded from consolidation	Concept (Text Block (HTML))	For Period		ifrs-full:DisclosureOfInterestsInUnconsolidatedStructuredEntitiesExplanatory
874	033801 - Disclosure - Structured entities (Tables)	Network	*	*	http://www.barclays.co.uk/role/StructuredEntitiesTables
875	Implied Table	Table	*	*	implied:Table
876	Disclosure of information about consolidated structured entities [abstract]	Abstract			ifrs-full:DisclosureOfInformationAboutConsolidatedStructuredEntitiesAbstract
877	Summary of interests in unconsolidated structured entities	Concept (Text Block (HTML))	For Period		ifrs-full:DisclosureOfUnconsolidatedStructuredEntitiesExplanatory
878	033901 - Disclosure - Investments in associates and joint ventures (Tables)	Network	*	*	http://www.barclays.co.uk/role/InvestmentsInAssociatesAndJointVenturesTables
879	Implied Table	Table	*	*	implied:Table
880	Investments in joint ventures and associates [abstract]	Abstract			c070:InvestmentsInJointVenturesAndAssociatesAbstract
881	Detailed information about investments in associates and joint ventures	Concept (Text Block (HTML))	For Period		c070:DisclosureOfDetailedInformationAboutInvestmentsInAssociatesAndJointVenturesTableTextBlock
882	Summarised financial information associates and joint ventures	Concept (Text Block (HTML))	For Period		c070:DisclosureOfReconciliationOfSummarisedFinancialInformationOfAssociatesAndJointVenturesTableTextBlock
883	034001 - Disclosure - Securitisations (Tables)	Network	*	*	http://www.barclays.co.uk/role/SecuritisationsTables
884	Implied Table	Table	*	*	implied:Table
885	Secutritisations	Abstract			ifrs-full:DisclosureOfFinancialAssetsTransferredDuringPeriodWhichDoNotQualifyForDerecognitionAbstract
886	Transfers of financial assets that do not result in derecognition	Concept (Text Block (HTML))	For Period		ifrs-full:DisclosureOfFinancialAssetsTransferredDuringPeriodWhichDoNotQualifyForDerecognitionExplanatory
887	Continuing involvement in financial assets that have been derecognised	Concept (Text Block (HTML))	For Period		ifrs-full:DisclosureOfContinuingInvolvementInDerecognisedFinancialAssetsExplanatory
888	034101 - Disclosure - Assets pledged (Tables)	Network	*	*	http://www.barclays.co.uk/role/AssetsPledgedTables
889	Implied Table	Table	*	*	implied:Table
890	Assets pledged	Abstract			c070:AssetsPledgedAbstract
891	Carrying amount of the assets pledged as security against liabilities	Concept (Text Block (HTML))	For Period		c070:DisclosureOfCarryingAmountOfTheAssetsPledgedAsSecurityAgainstLiabilitiesTableTextBlock
892	Collateral held as security for assets	Concept (Text Block (HTML))	For Period		ifrs-full:InformationAboutCollateralHeldAsSecurityAndOtherCreditEnhancementsForCreditimpairedFinancialAssetsExplanatory
893	034201 - Disclosure - Related party transactions and Directors remuneration (Tables)	Network	*	*	http://www.barclays.co.uk/role/RelatedPartyTransactionsAndDirectorsRemunerationTables
894	Disclosure of transactions between related parties [table]	Table	*	*	ifrs-full:DisclosureOfTransactionsBetweenRelatedPartiesTable
895	Categories of related parties [axis]	Axis			ifrs-full:CategoriesOfRelatedPartiesAxis
896	Entity's total for related parties [member]	Member			ifrs-full:EntitysTotalForRelatedPartiesMember
897	Related parties [member]	Member			ifrs-full:RelatedPartiesMember
898	Classes of financial assets [axis]	Axis			ifrs-full:ClassesOfFinancialAssetsAxis
899	Financial assets, class [member]	Member			ifrs-full:FinancialAssetsMember
900	Loans [member]	Member			c070:OustandingLoansMember
901	Deposits [member]	Member			c070:OutstandingDepositsMember
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903	Related party transactions Loans and deposits outstanding	Concept (Text Block (HTML))	For Period		ifrs-full:DisclosureOfTransactionsBetweenRelatedPartiesExplanatory
904	034301 - Disclosure - Auditors' remuneration (Tables)	Network	*	*	http://www.barclays.co.uk/role/AuditorsRemunerationTables
905	Implied Table	Table	*	*	implied:Table
906	Auditors' remuneration [abstract]	Abstract			ifrs-full:AuditorsRemunerationAbstract
907	Auditors' remuneration	Concept (Text Block (HTML))	For Period		c070:DisclosureOfDetailedInformationAboutAuditorsRemunerationTableTextBlock
908	034401 - Disclosure - Transition disclosures (Tables)	Network	*	*	http://www.barclays.co.uk/role/TransitionDisclosuresTables
909	Implied Table	Table	*	*	implied:Table
910	Transition disclosures	Abstract			ifrs-full:DisclosureOfReclassificationsOrChangesInPresentationAbstract
911	Reconciliation of impairment allowance and provisions	Concept (Text Block (HTML))	For Period		ifrs-full:DisclosureOfReconciliationOfChangesInLossAllowanceAndExplanationOfChangesInGrossCarryingAmountForFinancialInstrumentsExplanatory
912	Balance sheet movement - impact of transition to IFRS 9 and IFRS 15	Concept (Text Block (HTML))	For Period		ifrs-full:DisclosureOfReclassificationsOrChangesInPresentationExplanatory
913	Classification and measurement detail	Concept (Text Block (HTML))	For Period		ifrs-full:DisclosureOfReclassificationOfFinancialAssetsExplanatory
914	The effects of the reclassification of financial assets from IAS 39 categories into the amortised cost category under IFRS 9	Concept (Text Block (HTML))	For Period		ifrs-full:DisclosureOfFinancialAssetsAtDateOfInitialApplicationOfIFRS9Explanatory
915	034701 - Disclosure - Other disclosures - Risk Management and Principal Risks (audited) (Tables)	Network	*	*	http://www.barclays.co.uk/role/OtherDisclosuresRiskManagementAndPrincipalRisksauditedTables
916	Implied Table	Table	*	*	implied:Table
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918	Maximum exposure and effects of collateral and other credit enhancements (audited)	Concept (Text Block (HTML))	For Period		ifrs-full:SummaryQuantitativeDataAboutEntitysExposureToRisk
919	Loans and advances at amortised cost by product (audited)	Concept (Text Block (HTML))	For Period		ifrs-full:DisclosureOfProvisionMatrixExplanatory
920	Movement in gross exposures and impairment allowance (audited)	Concept (Text Block (HTML))	For Period		ifrs-full:DisclosureOfCreditRiskExplanatory
921	Management adjustments to models for impairment (audited)	Concept (Text Block (HTML))	For Period		ifrs-full:DisclosureOfAdditionalInformationExplanatory
922	Core macroeconomic variables for each scenario and the respective scenario weights	Concept (Text Block (HTML))	For Period		ifrs-full:AnalysisOfCreditExposuresUsingExternalCreditGradingSystemExplanatory
923	ECL under 100% weighted scenarios for key principal portfolios	Concept (Text Block (HTML))	For Period		ifrs-full:ExplanationOfInputsAssumptionsAndEstimationTechniquesUsedToApplyImpairmentRequirementsExplanatory
924	Concentrations of Credit Risk by geography and industry (audited)	Concept (Text Block (HTML))	For Period		ifrs-full:ExplanationOfCreditRiskManagementPracticesAndHowTheyRelateToRecognitionAndMeasurementOfExpectedCreditLossesExplanatory
925	Balance Sheet credit quality (audited)	Concept (Text Block (HTML))	For Period		ifrs-full:DisclosureOfInternalCreditExposuresExplanatory
926	Credit risk profile by internal PD band for loans and advances at amortised cost, contingent liabilities and loan commitments (audited)	Concept (Text Block (HTML))	For Period		ifrs-full:AnalysisOfCreditExposuresUsingInternalCreditGradingSystemExplanatory
927	Management Value at Risk (audited)	Concept (Text Block (HTML))	For Period		c070:ManagementValueAtRiskTableTextBlock
928	Contractual maturity of financial assets and liabilities (audited)	Concept (Text Block (HTML))	For Period		ifrs-full:DisclosureOfMaturityAnalysisForFinancialAssetsHeldForManagingLiquidityRiskExplanatory
929	Contractual maturity of financial liabilities - undiscounted (audited)	Concept (Text Block (HTML))	For Period		ifrs-full:MaturityAnalysisForNonderivativeFinancialLiabilities
930	Maturity analysis of off-balance sheet commitments received (audited)	Concept (Text Block (HTML))	For Period		c070:MaturityAnalysisOfOffBalanceSheetCommitmentsReceivedTableTextBlock
931	Maturity analysis of off-balance sheet commitments given (audited)	Concept (Text Block (HTML))	For Period		c070:MaturityAnalysisOfOffBalanceSheetCommitmentsGivenTableTextBlock
932	Captial resources (audited)	Concept (Text Block (HTML))	For Period		ifrs-full:DisclosureOfFinancialRiskManagementExplanatory
933	Functional currency of the operation (audited)	Concept (Text Block (HTML))	For Period		ifrs-full:DisclosureOfEffectOfChangesInForeignExchangeRatesExplanatory
934	Analysis of equity sensivity (audited)	Concept (Text Block (HTML))	For Period		ifrs-full:DisclosureOfSensitivityAnalysisToChangesInRiskExposuresThatAriseFromContractsWithinScopeOfIFRS17Explanatory
935	040020 - Disclosure - Consolidated cash flow statement (Narrative) (Details)	Network	*	*	http://www.barclays.co.uk/role/ConsolidatedCashFlowStatementNarrativeDetails
936	Implied Table	Table	*	*	implied:Table
937	Statement of cash flows	Abstract			ifrs-full:StatementOfCashFlowsAbstract
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939	Interest paid, classified as operating activities	Concept (Monetary)	For Period	Credit	ifrs-full:InterestPaidClassifiedAsOperatingActivities
940	Balances with banks and other regulatory authorities	Concept (Monetary)	As Of	Debit	ifrs-full:MandatoryReserveDepositsAtCentralBanks
941	040025 - Disclosure - Financial statements of Barclays Bank PLC - Cash flow statement (Narrative) (Details)	Network	*	*	http://www.barclays.co.uk/role/FinancialStatementsOfBarclaysBankPLCCashFlowStatementNarrativeDetails
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948	Interest paid, classified as operating activities	Concept (Monetary)	For Period	Credit	ifrs-full:InterestPaidClassifiedAsOperatingActivities
949	Balances with banks and other regulatory authorities	Concept (Monetary)	As Of	Debit	ifrs-full:MandatoryReserveDepositsAtCentralBanks
950	040101 - Disclosure - Significant accounting policies (Details)	Network	*	*	http://www.barclays.co.uk/role/SignificantAccountingPoliciesDetails
951	Disclosure of expected impact of initial application of new standards or interpretations [table]	Table	*	*	ifrs-full:DescriptionOfExpectedImpactOfInitialApplicationOfNewStandardsOrInterpretationsTable
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955	IFRS 15 - Revenue from Contracts with Customers [member]	Member			c070:IFRSs15Member
956	Amendments to IFRS 2 Share-based Payment	Member			c070:IFRS2Member
957	IFRS 16 - Leases [member]	Member			c070:IFRSs16Member
958	IFRS 17 - Insurance contracts [member]	Member			c070:IFRSs17Member
959	IFRIC Interpretation 23 [member]	Member			c070:IFRSsInterpretation23Member
960	IAS 12 [member]	Member			c070:Ias12Member
961	IAS 19 Employee Benefits - Amendments to IAS 19	Member			c070:Ias19Member
962	Disclosure of expected impact of initial application of new standards or interpretations [line items]	LineItems			ifrs-full:DescriptionOfExpectedImpactOfInitialApplicationOfNewStandardsOrInterpretationsLineItems
963	New and amended standards and interpretations	Concept (Text/String)	For Period		ifrs-full:DiscussionOfImpactThatInitialApplicationOfIFRSIsExpectedToHaveOnFinancialStatements
964	040201 - Disclosure - Disposal of business and transfer of ownership of subsidiary (Details)	Network	*	*	http://www.barclays.co.uk/role/DisposalOfBusinessAndTransferOfOwnershipOfSubsidiaryDetails
965	Disclosure of operating segments [table]	Table	*	*	ifrs-full:DisclosureOfOperatingSegmentsTable
966	Continuing and discontinued operations [axis]	Axis			ifrs-full:ContinuingAndDiscontinuedOperationsAxis
967	Aggregate continuing and discontinued operations [member]	Member			ifrs-full:AggregateContinuingAndDiscontinuedOperationsMember
968	Discontinued operations [member]	Member			ifrs-full:DiscontinuedOperationsMember
969	Disposal of major subsidiary [member]	Member			ifrs-full:DisposalOfMajorSubsidiaryMember
970	UK Banking Business [member]	Member			c070:BarclaysUkMember
971	Other disposals [member]	Member			ifrs-full:OtherDisposalsOfAssetsMember
972	Categories of related parties [axis]	Axis			ifrs-full:CategoriesOfRelatedPartiesAxis
973	Entity's total for related parties [member]	Member			ifrs-full:EntitysTotalForRelatedPartiesMember
974	Barclays Bank UK PLC [member]	Member			c070:BarclaysBankUkPlcMember
975	Consolidated Entities [Axis]	Axis			srt:ConsolidatedEntitiesAxis
976	Consolidated Entities [Domain]	Member			srt:ConsolidatedEntitiesDomain
977	Barclays Bank PLC [member]	Member			c070:BarclaysBankPlcMember
978	Classes of assets [axis]	Axis			ifrs-full:ClassesOfAssetsAxis
979	Assets [member]	Member			ifrs-full:ClassesOfAssetsMember
980	Cash and balances at central banks [member]	Member			c070:CashAndBankBalancesAtCentralBanksMember
981	Cash collateral and settlement balances [member]	Member			ifrs-full:TradeReceivablesMember
982	Reverse repurchase agreements and other similar secured lending [member]	Member			c070:ReverseRepurchaseAgreementsAndOtherSimilarSecuredLendingMember
983	Derivative financial instruments [member]	Member			ifrs-full:DerivativesMember
984	Investments in subsidiaries [member]	Member			c070:InvestmentsInSubsidiariesMember
985	Goodwill and intangible assets [member]	Member			ifrs-full:IntangibleAssetsAndGoodwillMember
986	Property, plant and equipment [member]	Member			ifrs-full:PropertyPlantAndEquipmentMember
987	Current tax assets [member]	Member			c070:CurrentTaxAssetsMember
988	Deferred tax assets [member]	Member			c070:DeferredTaxAssetsMember
989	Other assets [member]	Member			ifrs-full:OtherAssetsMember
990	Categories of financial assets [axis]	Axis			ifrs-full:CategoriesOfFinancialAssetsAxis
991	Financial assets, category [member]	Member			ifrs-full:FinancialAssetsCategoryMember
992	Loans and advances [member]	Member			ifrs-full:LoansAndReceivablesCategoryMember
993	Financial assets at fair value through the income statement [member]	Member			ifrs-full:FinancialAssetsAtFairValueThroughProfitOrLossCategoryMember
994	Financial assets at fair value through other comprehensive income [member]	Member			ifrs-full:FinancialAssetsAtFairValueThroughOtherComprehensiveIncomeCategoryMember
995	Classes of financial assets [axis]	Axis			ifrs-full:ClassesOfFinancialAssetsAxis
996	Financial assets, class [member]	Member			ifrs-full:FinancialAssetsMember
997	Financial assets at amortised cost [member]	Member			ifrs-full:FinancialAssetsAtAmortisedCostMember
998	Classes of liabilities [axis]	Axis			ifrs-full:ClassesOfLiabilitiesAxis
999	Liabilities [member]	Member			ifrs-full:LiabilitiesMember
1000	Deposits at amortised cost [member]	Member			c070:DepositsAtAmortisedCostMember
1001	Repurchase agreements and other similar secured borrowing [member]	Member			c070:RepurchaseAgreementsAndOtherSimilarSecuredBorrowingMember
1002	Debt securities in issue [member]	Member			ifrs-full:DebtSecuritiesMember
1003	Subordinated liabilities [member]	Member			c070:SubordinatedLiabilitiesMember
1004	Derivative financial instruments [member]	Member			ifrs-full:DerivativesMember
1005	Current tax liabilities [member]	Member			c070:CurrentTaxLiabilitiesMember
1006	Retirement benefit liabilities [member]	Member			c070:RetirementBenefitLiabilitiesMember
1007	Other liabilities [member]	Member			c070:OtherLiabilitiesMember
1008	Provisions [member]	Member			ifrs-full:OtherProvisionsMember
1009	Categories of financial liabilities [axis]	Axis			ifrs-full:CategoriesOfFinancialLiabilitiesAxis
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1011	Trading portfolio liabilities [member]	Member			ifrs-full:FinancialLiabilitiesAtFairValueThroughProfitOrLossThatMeetDefinitionOfHeldForTradingCategoryMember
1012	Financial liabilities designated at fair value [member]	Member			ifrs-full:FinancialLiabilitiesAtFairValueThroughProfitOrLossDesignatedUponInitialRecognitionCategoryMember
1013	Classes of financial liabilities [axis]	Axis			ifrs-full:ClassesOfFinancialLiabilitiesAxis
1014	Financial liabilities, class [member]	Member			ifrs-full:FinancialLiabilitiesMember
1015	Financial liabilities at amortised cost [member]	Member			ifrs-full:FinancialLiabilitiesAtAmortisedCostMember
1016	Disclosure of operating segments [line items]	LineItems			ifrs-full:DisclosureOfOperatingSegmentsLineItems
1017	Disposal of business, assets	Concept (Monetary)	For Period	Debit	ifrs-full:AssetsOtherThanCashOrCashEquivalentsInSubsidiaryOrBusinessesAcquiredOrDisposed2013
1018	Disposal of business, liabilities	Concept (Monetary)	For Period	Credit	ifrs-full:LiabilitiesInSubsidiaryOrBusinessesAcquiredOrDisposed2013
1019	040202 - Disclosure - Disposal of business and transfer of ownership of subsidiary (Narrative) (Details)	Network	*	*	http://www.barclays.co.uk/role/DisposalOfBusinessAndTransferOfOwnershipOfSubsidiaryNarrativeDetails
1020	Disclosure of operating segments [table]	Table	*	*	ifrs-full:DisclosureOfOperatingSegmentsTable
1021	Continuing and discontinued operations [axis]	Axis			ifrs-full:ContinuingAndDiscontinuedOperationsAxis
1022	Aggregate continuing and discontinued operations [member]	Member			ifrs-full:AggregateContinuingAndDiscontinuedOperationsMember
1023	Discontinued operations [member]	Member			ifrs-full:DiscontinuedOperationsMember
1024	Disposal of major subsidiary [member]	Member			ifrs-full:DisposalOfMajorSubsidiaryMember
1025	UK Banking Business [member]	Member			c070:BarclaysUkMember
1026	Other disposals [member]	Member			ifrs-full:OtherDisposalsOfAssetsMember
1027	Barclay's Africa Banking Group Limited [member]	Member			c070:BarclaysAfricaBankingGroupLimitedMember
1028	Barclays Bank Ireland PLC [member]	Member			c070:BarclaysBankIrelandPlcMember
1029	Categories of related parties [axis]	Axis			ifrs-full:CategoriesOfRelatedPartiesAxis
1030	Entity's total for related parties [member]	Member			ifrs-full:EntitysTotalForRelatedPartiesMember
1031	Barclays Bank UK PLC [member]	Member			c070:BarclaysBankUkPlcMember
1032	Barclays PLC [member]	Member			ifrs-full:ParentMember
1033	Consolidated Entities [Axis]	Axis			srt:ConsolidatedEntitiesAxis
1034	Consolidated Entities [Domain]	Member			srt:ConsolidatedEntitiesDomain
1035	Barclays Bank PLC [member]	Member			c070:BarclaysBankPlcMember
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1038	Consolidation, Eliminations [member]	Member			srt:ConsolidationEliminationsMember
1039	Legal Entity [Axis]	Axis			dei:LegalEntityAxis
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1042	Barclays Bank UK PLC [member]	Member			c070:BarclaysBankUkPlcMember
1043	Barclays Bank Ireland PLC [member]	Member			c070:BarclaysBankIrelandPlcMember
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1046	Barclays Bank UK PLC [member]	Member			c070:BarclaysBankUkPlcMember
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1049	in exchange for ordinary share [member]	Member			c070:BusinessDisposalInExchangeForOrdinaryShareMember
1050	Classes of share capital [axis]	Axis			ifrs-full:ClassesOfShareCapitalAxis
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1053	Measurement [axis]	Axis			ifrs-full:MeasurementAxis
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1055	At cost [member]	Member			ifrs-full:AtCostMember
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1059	Accumulated depreciation, amortisation and impairment [member]	Member			ifrs-full:AccumulatedDepreciationAmortisationAndImpairmentMember
1060	Components of equity [axis]	Axis			ifrs-full:ComponentsOfEquityAxis
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1062	Other equity instruments [member]	Member			ifrs-full:OtherEquityInterestMember
1063	AT1 Securities [member]	Member			c070:AdditionalTierOneSecuritiesMember
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1065	Retained earnings [member]	Member			ifrs-full:RetainedEarningsMember
1066	Classes of assets [axis]	Axis			ifrs-full:ClassesOfAssetsAxis
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1071	Licences and other [member]	Member			c070:LicencesAndOtherMember
1072	Property, plant and equipment [member]	Member			ifrs-full:PropertyPlantAndEquipmentMember
1073	Deferred tax assets [member]	Member			c070:DeferredTaxAssetsMember
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1075	Classes of financial liabilities [axis]	Axis			ifrs-full:ClassesOfFinancialLiabilitiesAxis
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1077	Financial liabilities at amortised cost [member]	Member			ifrs-full:FinancialLiabilitiesAtAmortisedCostMember
1078	Classes of liabilities [axis]	Axis			ifrs-full:ClassesOfLiabilitiesAxis
1079	Liabilities [member]	Member			ifrs-full:LiabilitiesMember
1080	Deposits at amortised cost [member]	Member			c070:DepositsAtAmortisedCostMember
1081	Debt securities in issue [member]	Member			ifrs-full:DebtSecuritiesMember
1082	Derivative financial instruments [member]	Member			ifrs-full:DerivativesMember
1083	Current tax liabilities [member]	Member			c070:CurrentTaxLiabilitiesMember
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1090	Financial assets at fair value through the income statement [member]	Member			ifrs-full:FinancialAssetsAtFairValueThroughProfitOrLossCategoryMember
1091	Loans and advances [member]	Member			ifrs-full:LoansAndReceivablesCategoryMember
1092	Home loans [member]	Member			ifrs-full:MortgagesMember
1093	Credit cards, unsecured and other retail lending [member]	Member			c070:CreditCardsUnsecuredAndOtherRetailLendingMember
1094	Corporate loans [member]	Member			ifrs-full:CorporateLoansMember
1095	Continuing involvement in derecognised financial assets by type of transfer [axis]	Axis			ifrs-full:ContinuingInvolvementInDerecognisedFinancialAssetsByTypeOfTransferAxis
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1098	Disclosure of operating segments [line items]	LineItems			ifrs-full:DisclosureOfOperatingSegmentsLineItems
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1100	Number of shares issued as consideration	Concept (Decimal)	As Of		ifrs-full:NumberOfInstrumentsOrInterestsIssuedOrIssuable
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1103	Disposal of business, assets	Concept (Monetary)	For Period	Debit	ifrs-full:AssetsOtherThanCashOrCashEquivalentsInSubsidiaryOrBusinessesAcquiredOrDisposed2013
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1109	Loans and advances	Concept (Monetary)	As Of	Debit	ifrs-full:LoansAndReceivables
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1113	Goodwill	Concept (Monetary)	As Of	Debit	ifrs-full:Goodwill
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1115	Property, plant and equipment	Concept (Monetary)	As Of	Debit	ifrs-full:PropertyPlantAndEquipment
1116	Prepayments	Concept (Monetary)	As Of	Debit	ifrs-full:Prepayments
1117	Items in course of collection from other banks	Concept (Monetary)	As Of	Debit	ifrs-full:ItemsInCourseOfCollectionFromOtherBanks
1118	Sundry receivables	Concept (Monetary)	As Of	Debit	ifrs-full:OtherReceivables
1119	Accrued income	Concept (Monetary)	As Of	Debit	ifrs-full:AccruedIncome
1120	Bonds	Concept (Monetary)	As Of	Credit	ifrs-full:BondsIssued
1121	Other debt securities	Concept (Monetary)	As Of	Credit	ifrs-full:OtherBorrowings
1122	Accruals and deferred income	Concept (Monetary)	As Of	Credit	ifrs-full:AccrualsAndDeferredIncome
1123	Sundry creditors	Concept (Monetary)	As Of	Credit	ifrs-full:OtherPayables
1124	040300 - Disclosure - Discontinued operations and assets included in disposal groups classified as held for sale and associated liabilities - Assets included in disposal groups classified as held for sale (Details)	Network	*	*	http://www.barclays.co.uk/role/DiscontinuedOperationsAndAssetsIncludedInDisposalGroupsClassifiedAsHeldForSaleAndAssociatedLiabilitiesAssetsIncludedInDisposalGroupsClassifiedAsHeldForSaleDetails
1125	Condensed Balance Sheet Statement [Table]	Table	*	*	srt:CondensedBalanceSheetStatementTable
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1128	Held for sale [member]	Member			ifrs-full:DisposalGroupsClassifiedAsHeldForSaleMember
1129	Consolidated Entities [Axis]	Axis			srt:ConsolidatedEntitiesAxis
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1133	Assets	Abstract			ifrs-full:AssetsAbstract
1134	Financial assets at fair value through the income statement	Concept (Monetary)	As Of	Debit	ifrs-full:FinancialAssetsAtFairValueThroughProfitOrLoss
1135	Loans and advances at amortised cost	Concept (Monetary)	As Of	Debit	ifrs-full:LoansAndReceivables
1136	Property, plant and equipment	Concept (Monetary)	As Of	Debit	ifrs-full:PropertyPlantAndEquipment
1137	Total assets classified as held for sale	Concept (Monetary)	As Of	Debit	ifrs-full:NoncurrentAssetsOrDisposalGroupsClassifiedAsHeldForSaleOrAsHeldForDistributionToOwners
1138	040301 - Disclosure - Discontinued operations and assets included in disposal groups classified as held for sale and associated liabilities - UK banking business disposal group income statement (Details)	Network	*	*	http://www.barclays.co.uk/role/DiscontinuedOperationsAndAssetsIncludedInDisposalGroupsClassifiedAsHeldForSaleAndAssociatedLiabilitiesUKBankingBusinessDisposalGroupIncomeStatementDetails
1139	Condensed Income Statement [Table]	Table	*	*	srt:CondensedIncomeStatementTable
1140	Continuing and discontinued operations [axis]	Axis			ifrs-full:ContinuingAndDiscontinuedOperationsAxis
1141	Aggregate continuing and discontinued operations [member]	Member			ifrs-full:AggregateContinuingAndDiscontinuedOperationsMember
1142	Discontinued operations [member]	Member			ifrs-full:DiscontinuedOperationsMember
1143	Disposal of major subsidiary [member]	Member			ifrs-full:DisposalOfMajorSubsidiaryMember
1144	UK Banking Business [member]	Member			c070:BarclaysUkMember
1145	Categories of related parties [axis]	Axis			ifrs-full:CategoriesOfRelatedPartiesAxis
1146	Entity's total for related parties [member]	Member			ifrs-full:EntitysTotalForRelatedPartiesMember
1147	Barclays Bank UK PLC [member]	Member			c070:BarclaysBankUkPlcMember
1148	Condensed Income Statements, Captions [Line Items]	LineItems			srt:CondensedIncomeStatementsCaptionsLineItems
1149	Income statement	Abstract			ifrs-full:ProfitLossAbstract
1150	Net interest income	Concept (Monetary)	For Period	Credit	ifrs-full:InterestRevenueExpense
1151	Net fee and commission income	Concept (Monetary)	For Period	Credit	ifrs-full:FeeAndCommissionIncomeExpense
1152	Net trading income	Concept (Monetary)	For Period	Credit	ifrs-full:TradingIncomeExpense
1153	Net investment income	Concept (Monetary)	For Period	Credit	c070:InvestmentIncomeExpense
1154	Other income	Concept (Monetary)	For Period	Credit	ifrs-full:OtherOperatingIncomeExpense
1155	Total income	Concept (Monetary)	For Period	Credit	c070:ProfitLossFromOperatingActivitiesBeforeImpairmentLossReversalOfImpairmentLossRecognisedInProfitOrLoss
1156	Credit impairment (charges)/releases and other provisions	Concept (Monetary)	For Period	Debit	ifrs-full:ImpairmentLossReversalOfImpairmentLossRecognisedInProfitOrLoss
1157	Net operating income	Concept (Monetary)	For Period	Credit	ifrs-full:ProfitLossFromOperatingActivities
1158	Staff costs	Concept (Monetary)	For Period	Debit	ifrs-full:EmployeeBenefitsExpense
1159	Administration and general expenses	Concept (Monetary)	For Period	Debit	ifrs-full:GeneralAndAdministrativeExpense
1160	Operating expenses	Concept (Monetary)	For Period	Debit	ifrs-full:OperatingExpense
1161	Share of profit of post-tax results of associates and joint ventures	Concept (Monetary)	For Period	Credit	ifrs-full:ShareOfProfitLossOfAssociatesAndJointVenturesAccountedForUsingEquityMethod
1162	Profit (loss) before tax	Concept (Monetary)	For Period	Credit	ifrs-full:ProfitLossBeforeTax
1163	Taxation	Concept (Monetary)	For Period	Debit	ifrs-full:IncomeTaxExpenseContinuingOperations
1164	Profit (loss) after tax	Concept (Monetary)	For Period	Credit	ifrs-full:ProfitLoss
1165	Attributable to:	Abstract			ifrs-full:ProfitLossAttributableToAbstract
1166	Equity holders of the parent	Concept (Monetary)	For Period	Credit	ifrs-full:ProfitLossAttributableToOwnersOfParent
1167	Non-controlling interests	Concept (Monetary)	For Period	Credit	ifrs-full:ProfitLossAttributableToNoncontrollingInterests
1168	Profit (loss) after tax	Concept (Monetary)	For Period	Credit	ifrs-full:ProfitLoss
1169	040303 - Disclosure - Discontinued operations and assets included in disposal groups classified as held for sale and associated liabilities - Other comprehensive income relating to UK banking business discontinued operations (Details)	Network	*	*	http://www.barclays.co.uk/role/DiscontinuedOperationsAndAssetsIncludedInDisposalGroupsClassifiedAsHeldForSaleAndAssociatedLiabilitiesOtherComprehensiveIncomeRelatingToUKBankingBusinessDiscontinuedOperationsDetails
1170	Condensed Statement of Comprehensive Income [Table]	Table	*	*	srt:CondensedStatementOfComprehensiveIncomeTable
1171	Continuing and discontinued operations [axis]	Axis			ifrs-full:ContinuingAndDiscontinuedOperationsAxis
1172	Aggregate continuing and discontinued operations [member]	Member			ifrs-full:AggregateContinuingAndDiscontinuedOperationsMember
1173	Discontinued operations [member]	Member			ifrs-full:DiscontinuedOperationsMember
1174	Disposal of major subsidiary [member]	Member			ifrs-full:DisposalOfMajorSubsidiaryMember
1175	UK Banking Business [member]	Member			c070:BarclaysUkMember
1176	Categories of related parties [axis]	Axis			ifrs-full:CategoriesOfRelatedPartiesAxis
1177	Entity's total for related parties [member]	Member			ifrs-full:EntitysTotalForRelatedPartiesMember
1178	Barclays Bank UK PLC [member]	Member			c070:BarclaysBankUkPlcMember
1179	Condensed Statement of Income Captions [Line Items]	LineItems			srt:CondensedStatementOfIncomeCaptionsLineItems
1180	Statement of comprehensive income	Abstract			ifrs-full:StatementOfComprehensiveIncomeAbstract
1181	Available for sale assets	Concept (Monetary)	For Period	Credit	ifrs-full:OtherComprehensiveIncomeNetOfTaxAvailableforsaleFinancialAssets
1182	Currency translation reserves	Concept (Monetary)	For Period	Credit	ifrs-full:OtherComprehensiveIncomeNetOfTaxExchangeDifferencesOnTranslation
1183	Cash flow hedge reserves	Concept (Monetary)	For Period	Credit	ifrs-full:OtherComprehensiveIncomeNetOfTaxCashFlowHedges
1184	Other comprehensive (loss)/income, net of tax from discontinued operations	Concept (Monetary)	For Period	Credit	ifrs-full:OtherComprehensiveIncome
1185	040304 - Disclosure - Discontinued operations and assets included in disposal groups classified as held for sale and associated liabilities - Cash flows attributed to UK banking business discontinued operations (Details)	Network	*	*	http://www.barclays.co.uk/role/DiscontinuedOperationsAndAssetsIncludedInDisposalGroupsClassifiedAsHeldForSaleAndAssociatedLiabilitiesCashFlowsAttributedToUKBankingBusinessDiscontinuedOperationsDetails
1186	Condensed Cash Flow Statement [Table]	Table	*	*	srt:CondensedCashFlowStatementTable
1187	Continuing and discontinued operations [axis]	Axis			ifrs-full:ContinuingAndDiscontinuedOperationsAxis
1188	Aggregate continuing and discontinued operations [member]	Member			ifrs-full:AggregateContinuingAndDiscontinuedOperationsMember
1189	Discontinued operations [member]	Member			ifrs-full:DiscontinuedOperationsMember
1190	Disposal of major subsidiary [member]	Member			ifrs-full:DisposalOfMajorSubsidiaryMember
1191	UK Banking Business [member]	Member			c070:BarclaysUkMember
1192	Categories of related parties [axis]	Axis			ifrs-full:CategoriesOfRelatedPartiesAxis
1193	Entity's total for related parties [member]	Member			ifrs-full:EntitysTotalForRelatedPartiesMember
1194	Barclays Bank UK PLC [member]	Member			c070:BarclaysBankUkPlcMember
1195	Condensed Cash Flow Statements, Captions [Line Items]	LineItems			srt:CondensedCashFlowStatementsCaptionsLineItems
1196	Cash flows from continuing and discontinued operations [abstract]	Abstract			ifrs-full:CashFlowsFromContinuingAndDiscontinuedOperationsAbstract
1197	Net cash from operating activities	Concept (Monetary)	For Period		ifrs-full:CashFlowsFromUsedInOperatingActivities
1198	Net cash from investing activities	Concept (Monetary)	For Period	Debit	ifrs-full:CashFlowsFromUsedInInvestingActivities
1199	Net cash from financing activities	Concept (Monetary)	For Period	Debit	ifrs-full:CashFlowsFromUsedInFinancingActivities
1200	Effect of exchange rates on cash and cash equivalents	Concept (Monetary)	For Period	Debit	ifrs-full:EffectOfExchangeRateChangesOnCashAndCashEquivalents
1201	Net increase in cash and cash equivalents	Concept (Monetary)	For Period	Debit	ifrs-full:IncreaseDecreaseInCashAndCashEquivalents
1202	040305 - Disclosure - Discontinued operations and assets included in disposal groups classified as held for sale and associated liabilities - Reconciliation of consolidated income statement to prior period (Details)	Network	*	*	http://www.barclays.co.uk/role/DiscontinuedOperationsAndAssetsIncludedInDisposalGroupsClassifiedAsHeldForSaleAndAssociatedLiabilitiesReconciliationOfConsolidatedIncomeStatementToPriorPeriodDetails
1203	Condensed Income Statement [Table]	Table	*	*	srt:CondensedIncomeStatementTable
1204	Continuing and discontinued operations [axis]	Axis			ifrs-full:ContinuingAndDiscontinuedOperationsAxis
1205	Aggregate continuing and discontinued operations [member]	Member			ifrs-full:AggregateContinuingAndDiscontinuedOperationsMember
1206	Continuing operations [member]	Member			ifrs-full:ContinuingOperationsMember
1207	Discontinued operations [member]	Member			ifrs-full:DiscontinuedOperationsMember
1208	Disposal of major subsidiary [member]	Member			ifrs-full:DisposalOfMajorSubsidiaryMember
1209	UK Banking Business [member]	Member			c070:BarclaysUkMember
1210	Categories of related parties [axis]	Axis			ifrs-full:CategoriesOfRelatedPartiesAxis
1211	Entity's total for related parties [member]	Member			ifrs-full:EntitysTotalForRelatedPartiesMember
1212	Barclays Bank UK PLC [member]	Member			c070:BarclaysBankUkPlcMember
1213	Retrospective application and retrospective restatement [axis]	Axis			ifrs-full:RetrospectiveApplicationAndRetrospectiveRestatementAxis
1214	Currently stated [member]	Member			ifrs-full:RestatedMember
1215	Previously stated [member]	Member			ifrs-full:PreviouslyStatedMember
1216	Condensed Income Statements, Captions [Line Items]	LineItems			srt:CondensedIncomeStatementsCaptionsLineItems
1217	Income statement	Abstract			ifrs-full:ProfitLossAbstract
1218	Interest income	Concept (Monetary)	For Period	Credit	ifrs-full:InterestRevenueCalculatedUsingEffectiveInterestMethod
1219	Interest expense	Concept (Monetary)	For Period	Debit	ifrs-full:InterestExpense
1220	Net interest income	Concept (Monetary)	For Period	Credit	ifrs-full:InterestRevenueExpense
1221	Fee and commission income	Concept (Monetary)	For Period	Credit	ifrs-full:FeeAndCommissionIncome
1222	Fee and commission expense	Concept (Monetary)	For Period	Debit	ifrs-full:FeeAndCommissionExpense
1223	Net fee and commission income	Concept (Monetary)	For Period	Credit	ifrs-full:FeeAndCommissionIncomeExpense
1224	Net trading income	Concept (Monetary)	For Period	Credit	ifrs-full:TradingIncomeExpense
1225	Net investment income	Concept (Monetary)	For Period	Credit	c070:InvestmentIncomeExpense
1226	Other income	Concept (Monetary)	For Period	Credit	ifrs-full:OtherOperatingIncomeExpense
1227	Total income	Concept (Monetary)	For Period	Credit	c070:ProfitLossFromOperatingActivitiesBeforeImpairmentLossReversalOfImpairmentLossRecognisedInProfitOrLoss
1228	Credit impairment charges and other provisions	Concept (Monetary)	For Period	Debit	ifrs-full:ImpairmentLossReversalOfImpairmentLossRecognisedInProfitOrLoss
1229	Net operating income	Concept (Monetary)	For Period	Credit	ifrs-full:ProfitLossFromOperatingActivities
1230	Staff costs	Concept (Monetary)	For Period	Debit	ifrs-full:EmployeeBenefitsExpense
1231	Infrastructure costs	Concept (Monetary)	For Period	Debit	c070:InfrastructureCosts
1232	Administration and general expenses	Concept (Monetary)	For Period	Debit	c070:GeneralAndAdministrativeExpenseExcludingLitigationAndConductExpense
1233	Litigation and conduct	Concept (Monetary)	For Period	Debit	ifrs-full:LossesOnLitigationSettlements
1234	Operating expenses	Concept (Monetary)	For Period	Debit	ifrs-full:OperatingExpense
1235	Share of profit of post-tax results of associates and joint ventures	Concept (Monetary)	For Period	Credit	ifrs-full:ShareOfProfitLossOfAssociatesAndJointVenturesAccountedForUsingEquityMethod
1236	Profit/(loss) on disposal of subsidiaries, associates and joint ventures	Concept (Monetary)	For Period	Credit	ifrs-full:GainLossRecognisedOnMeasurementToFairValueLessCostsToSellOrOnDisposalOfAssetsOrDisposalGroupsConstitutingDiscontinuedOperation
1237	Profit (loss) before tax	Concept (Monetary)	For Period	Credit	ifrs-full:ProfitLossBeforeTax
1238	Tax charge	Concept (Monetary)	For Period	Debit	ifrs-full:IncomeTaxExpenseContinuingOperations
1239	Profit (loss) from continuing operations	Concept (Monetary)	For Period	Credit	ifrs-full:ProfitLossFromContinuingOperations
1240	040306 - Disclosure - Discontinued operations and assets included in disposal groups classified as held for sale and associated liabilities - Barclays Africa disposal group income statement (Details)	Network	*	*	http://www.barclays.co.uk/role/DiscontinuedOperationsAndAssetsIncludedInDisposalGroupsClassifiedAsHeldForSaleAndAssociatedLiabilitiesBarclaysAfricaDisposalGroupIncomeStatementDetails
1241	Condensed Income Statement [Table]	Table	*	*	srt:CondensedIncomeStatementTable
1242	Continuing and discontinued operations [axis]	Axis			ifrs-full:ContinuingAndDiscontinuedOperationsAxis
1243	Aggregate continuing and discontinued operations [member]	Member			ifrs-full:AggregateContinuingAndDiscontinuedOperationsMember
1244	Discontinued operations [member]	Member			ifrs-full:DiscontinuedOperationsMember
1245	Barclay's Africa Banking Group Limited (BAGL) [member]	Member			c070:BarclaysAfricaBankingGroupLimitedMember
1246	Condensed Income Statements, Captions [Line Items]	LineItems			srt:CondensedIncomeStatementsCaptionsLineItems
1247	Income statement	Abstract			ifrs-full:ProfitLossAbstract
1248	Net interest income	Concept (Monetary)	For Period	Credit	ifrs-full:InterestRevenueExpense
1249	Net fee and commission income	Concept (Monetary)	For Period	Credit	ifrs-full:FeeAndCommissionIncomeExpense
1250	Net trading income	Concept (Monetary)	For Period	Credit	ifrs-full:TradingIncomeExpense
1251	Net investment income	Concept (Monetary)	For Period	Credit	c070:InvestmentIncomeExpense
1252	Net premiums from insurance contracts	Concept (Monetary)	For Period	Credit	ifrs-full:NetEarnedPremium
1253	Other income	Concept (Monetary)	For Period	Credit	ifrs-full:OtherOperatingIncomeExpense
1254	Total income	Concept (Monetary)	For Period	Credit	c070:ProfitLossFromOperatingActivitiesBeforeInsuranceClaimsImpairmentLossReversalOfImpairmentLossRecognisedInProfitOrLoss
1255	Net claims and benefits incurred on insurance contracts	Concept (Monetary)	For Period	Debit	c070:NetClaimsAndBenefitsIncurredOnInsuranceContracts
1256	Total income	Concept (Monetary)	For Period	Credit	c070:ProfitLossFromOperatingActivitiesBeforeImpairmentLossReversalOfImpairmentLossRecognisedInProfitOrLoss
1257	Credit impairment (charges)/releases and other provisions	Concept (Monetary)	For Period	Debit	ifrs-full:ImpairmentLossReversalOfImpairmentLossRecognisedInProfitOrLoss
1258	Net operating income	Concept (Monetary)	For Period	Credit	ifrs-full:ProfitLossFromOperatingActivities
1259	Staff costs	Concept (Monetary)	For Period	Debit	ifrs-full:EmployeeBenefitsExpense
1260	Administration and general expenses	Concept (Monetary)	For Period	Debit	ifrs-full:GeneralAndAdministrativeExpense
1261	Operating expenses	Concept (Monetary)	For Period	Debit	ifrs-full:OperatingExpense
1262	Share of profit of post-tax results of associates and joint ventures	Concept (Monetary)	For Period	Credit	ifrs-full:ShareOfProfitLossOfAssociatesAndJointVenturesAccountedForUsingEquityMethod
1263	Profit (loss) before tax	Concept (Monetary)	For Period	Credit	ifrs-full:ProfitLossBeforeTax
1264	Taxation	Concept (Monetary)	For Period	Debit	ifrs-full:IncomeTaxExpenseContinuingOperations
1265	Profit (loss) after tax	Concept (Monetary)	For Period	Credit	ifrs-full:ProfitLoss
1266	Attributable to:	Abstract			ifrs-full:ProfitLossAttributableToAbstract
1267	Equity holders of the parent	Concept (Monetary)	For Period	Credit	ifrs-full:ProfitLossAttributableToOwnersOfParent
1268	Non-controlling interests	Concept (Monetary)	For Period	Credit	ifrs-full:ProfitLossAttributableToNoncontrollingInterests
1269	Profit (loss) after tax	Concept (Monetary)	For Period	Credit	ifrs-full:ProfitLoss
1270	040309 - Disclosure - Discontinued operations and assets included in disposal groups classified as held for sale and associated liabilities - Barclays Africa disposal group income statement (Narrative) (Details)	Network	*	*	http://www.barclays.co.uk/role/DiscontinuedOperationsAndAssetsIncludedInDisposalGroupsClassifiedAsHeldForSaleAndAssociatedLiabilitiesBarclaysAfricaDisposalGroupIncomeStatementNarrativeDetails
1271	Condensed Income Statement [Table]	Table	*	*	srt:CondensedIncomeStatementTable
1272	Continuing and discontinued operations [axis]	Axis			ifrs-full:ContinuingAndDiscontinuedOperationsAxis
1273	Aggregate continuing and discontinued operations [member]	Member			ifrs-full:AggregateContinuingAndDiscontinuedOperationsMember
1274	Discontinued operations [member]	Member			ifrs-full:DiscontinuedOperationsMember
1275	Barclay's Africa Banking Group Limited (BAGL) [member]	Member			c070:BarclaysAfricaBankingGroupLimitedMember
1276	Carrying amount, accumulated depreciation, amortisation and impairment and gross carrying amount [axis]	Axis			ifrs-full:CarryingAmountAccumulatedDepreciationAmortisationAndImpairmentAndGrossCarryingAmountAxis
1277	Carrying amount [member]	Member			ifrs-full:CarryingAmountMember
1278	Impairment charge [member]	Member			ifrs-full:AccumulatedImpairmentMember
1279	Condensed Income Statements, Captions [Line Items]	LineItems			srt:CondensedIncomeStatementsCaptionsLineItems
1280	Administration and general expenses	Concept (Monetary)	For Period	Debit	ifrs-full:GeneralAndAdministrativeExpense
1281	Total loss in respect of the discontinued operation	Concept (Monetary)	For Period	Credit	ifrs-full:ProfitLossFromDiscontinuedOperations
1282	Disposal of discontinued operation, net of cash disposed	Concept (Monetary)	For Period	Debit	ifrs-full:ProceedsFromDisposalOfNoncurrentAssetsOrDisposalGroupsClassifiedAsHeldForSaleAndDiscontinuedOperations
1283	Other comprehensive income that may be recycled to profit or loss	Concept (Monetary)	For Period	Credit	ifrs-full:OtherComprehensiveIncomeThatWillBeReclassifiedToProfitOrLossNetOfTax
1284	040310 - Disclosure - Discontinued operations and assets included in disposal groups classified as held for sale and associated liabilities - Other comprehensive income relating to Barclays Africa discontinued operations (Details)	Network	*	*	http://www.barclays.co.uk/role/DiscontinuedOperationsAndAssetsIncludedInDisposalGroupsClassifiedAsHeldForSaleAndAssociatedLiabilitiesOtherComprehensiveIncomeRelatingToBarclaysAfricaDiscontinuedOperationsDetails
1285	Condensed Statement of Comprehensive Income [Table]	Table	*	*	srt:CondensedStatementOfComprehensiveIncomeTable
1286	Continuing and discontinued operations [axis]	Axis			ifrs-full:ContinuingAndDiscontinuedOperationsAxis
1287	Aggregate continuing and discontinued operations [member]	Member			ifrs-full:AggregateContinuingAndDiscontinuedOperationsMember
1288	Discontinued operations [member]	Member			ifrs-full:DiscontinuedOperationsMember
1289	Barclay's Africa Banking Group Limited (BAGL) [member]	Member			c070:BarclaysAfricaBankingGroupLimitedMember
1290	Condensed Statement of Income Captions [Line Items]	LineItems			srt:CondensedStatementOfIncomeCaptionsLineItems
1291	Statement of comprehensive income	Abstract			ifrs-full:StatementOfComprehensiveIncomeAbstract
1292	Available for sale assets	Concept (Monetary)	For Period	Credit	ifrs-full:OtherComprehensiveIncomeNetOfTaxAvailableforsaleFinancialAssets
1293	Currency translation reserves	Concept (Monetary)	For Period	Credit	ifrs-full:OtherComprehensiveIncomeNetOfTaxExchangeDifferencesOnTranslation
1294	Cash flow hedge reserves	Concept (Monetary)	For Period	Credit	ifrs-full:OtherComprehensiveIncomeNetOfTaxCashFlowHedges
1295	Other comprehensive (loss)/income, net of tax from discontinued operations	Concept (Monetary)	For Period	Credit	ifrs-full:OtherComprehensiveIncome
1296	040312 - Disclosure - Discontinued operations and assets included in disposal groups classified as held for sale and associated liabilities - Cash flows attributed to Barclays Africa discontinued operations (Details)	Network	*	*	http://www.barclays.co.uk/role/DiscontinuedOperationsAndAssetsIncludedInDisposalGroupsClassifiedAsHeldForSaleAndAssociatedLiabilitiesCashFlowsAttributedToBarclaysAfricaDiscontinuedOperationsDetails
1297	Condensed Cash Flow Statement [Table]	Table	*	*	srt:CondensedCashFlowStatementTable
1298	Continuing and discontinued operations [axis]	Axis			ifrs-full:ContinuingAndDiscontinuedOperationsAxis
1299	Aggregate continuing and discontinued operations [member]	Member			ifrs-full:AggregateContinuingAndDiscontinuedOperationsMember
1300	Discontinued operations [member]	Member			ifrs-full:DiscontinuedOperationsMember
1301	Barclay's Africa Banking Group Limited (BAGL) [member]	Member			c070:BarclaysAfricaBankingGroupLimitedMember
1302	Condensed Cash Flow Statements, Captions [Line Items]	LineItems			srt:CondensedCashFlowStatementsCaptionsLineItems
1303	Cash flows from continuing and discontinued operations [abstract]	Abstract			ifrs-full:CashFlowsFromContinuingAndDiscontinuedOperationsAbstract
1304	Net cash from operating activities	Concept (Monetary)	For Period		ifrs-full:CashFlowsFromUsedInOperatingActivities
1305	Net cash from investing activities	Concept (Monetary)	For Period	Debit	ifrs-full:CashFlowsFromUsedInInvestingActivities
1306	Net cash from financing activities	Concept (Monetary)	For Period	Debit	ifrs-full:CashFlowsFromUsedInFinancingActivities
1307	Effect of exchange rates on cash and cash equivalents	Concept (Monetary)	For Period	Debit	ifrs-full:EffectOfExchangeRateChangesOnCashAndCashEquivalents
1308	Net increase in cash and cash equivalents	Concept (Monetary)	For Period	Debit	ifrs-full:IncreaseDecreaseInCashAndCashEquivalents
1309	040315 - Disclosure - Discontinued operations and assets included in disposal groups classified as held for sale and associated liabilities (Narrative) (Details)	Network	*	*	http://www.barclays.co.uk/role/DiscontinuedOperationsAndAssetsIncludedInDisposalGroupsClassifiedAsHeldForSaleAndAssociatedLiabilitiesNarrativeDetails
1310	Disclosure of subsidiaries [table]	Table	*	*	ifrs-full:DisclosureOfSignificantInvestmentsInSubsidiariesTable
1311	Assets and liabilities classified as held for sale [axis]	Axis			ifrs-full:AssetsAndLiabilitiesClassifiedAsHeldForSaleAxis
1312	Assets and liabilities not classified as held for sale [member]	Member			ifrs-full:AssetsAndLiabilitiesNotClassifiedAsHeldForSaleMember
1313	Assets and liabilities classified as held for sale [member]	Member			ifrs-full:AssetsAndLiabilitiesClassifiedAsHeldForSaleMember
1314	Other disposals of assets [member]	Member			ifrs-full:OtherDisposalsOfAssetsMember
1315	Barclaycard US Receivables [member]	Member			c070:BarclaycardUsReceivablesMember
1316	Continuing and discontinued operations [axis]	Axis			ifrs-full:ContinuingAndDiscontinuedOperationsAxis
1317	Aggregate continuing and discontinued operations [member]	Member			ifrs-full:AggregateContinuingAndDiscontinuedOperationsMember
1318	Discontinued operations [member]	Member			ifrs-full:DiscontinuedOperationsMember
1319	Disposal of major subsidiary [member]	Member			ifrs-full:DisposalOfMajorSubsidiaryMember
1320	UK Banking Business [member]	Member			c070:BarclaysUkMember
1321	Barclay's Africa Banking Group Limited [member]	Member			c070:BarclaysAfricaBankingGroupLimitedMember
1322	Categories of related parties [axis]	Axis			ifrs-full:CategoriesOfRelatedPartiesAxis
1323	Entity's total for related parties [member]	Member			ifrs-full:EntitysTotalForRelatedPartiesMember
1324	Barclays Bank UK PLC [member]	Member			c070:BarclaysBankUkPlcMember
1325	Disclosure of subsidiaries [line items]	LineItems			ifrs-full:DisclosureOfSignificantInvestmentsInSubsidiariesLineItems
1326	Profit (loss) from discontinued operations	Concept (Monetary)	For Period	Credit	ifrs-full:ProfitLossFromDiscontinuedOperations
1327	Non-current assets or disposal groups classified as held for sale	Concept (Monetary)	As Of	Debit	ifrs-full:NoncurrentAssetsOrDisposalGroupsClassifiedAsHeldForSale
1328	040401 - Disclosure - Segmental reporting - Analysis of results by business (Details)	Network	*	*	http://www.barclays.co.uk/role/SegmentalReportingAnalysisOfResultsByBusinessDetails
1329	Disclosure of operating segments [table]	Table	*	*	ifrs-full:DisclosureOfOperatingSegmentsTable
1330	Segment consolidation items [axis]	Axis			ifrs-full:SegmentConsolidationItemsAxis
1331	Entity's total for segment consolidation items [member]	Member			ifrs-full:EntitysTotalForSegmentConsolidationItemsMember
1332	Operating segments [member]	Member			ifrs-full:OperatingSegmentsMember
1333	Head Office [member]	Member			ifrs-full:EliminationOfIntersegmentAmountsMember
1334	Segments [axis]	Axis			ifrs-full:SegmentsAxis
1335	Segments [member]	Member			ifrs-full:SegmentsMember
1336	Reportable segments [member]	Member			ifrs-full:ReportableSegmentsMember
1337	Corporate and investment bank [member]	Member			c070:CorporateAndInvestmentBankMember
1338	Consumer, cards and payments [member]	Member			c070:ConsumerCardsAndPaymentsMember
1339	Barclays Non-core [member]	Member			c070:BarclaysNonCoreMember
1340	Consolidated Entities [Axis]	Axis			srt:ConsolidatedEntitiesAxis
1341	Consolidated Entities [Domain]	Member			srt:ConsolidatedEntitiesDomain
1342	Barclays Bank Group [member]	Member			c070:BarclaysBankGroupMember
1343	Continuing and discontinued operations [axis]	Axis			ifrs-full:ContinuingAndDiscontinuedOperationsAxis
1344	Aggregate continuing and discontinued operations [member]	Member			ifrs-full:AggregateContinuingAndDiscontinuedOperationsMember
1345	Continuing operations [member]	Member			ifrs-full:ContinuingOperationsMember
1346	Disclosure of operating segments [line items]	LineItems			ifrs-full:DisclosureOfOperatingSegmentsLineItems
1347	Total income	Concept (Monetary)	For Period	Credit	c070:ProfitLossFromOperatingActivitiesBeforeImpairmentLossReversalOfImpairmentLossRecognisedInProfitOrLoss
1348	Credit impairment (charges)/releases and other provisions	Concept (Monetary)	For Period	Debit	ifrs-full:ImpairmentLossReversalOfImpairmentLossRecognisedInProfitOrLoss
1349	Net operating income/(expenses)	Concept (Monetary)	For Period	Credit	ifrs-full:ProfitLossFromOperatingActivities
1350	Operating expenses	Concept (Monetary)	For Period	Debit	c070:OperatingExpensesExcludingUkBankLevyGuaranteedMinimumPensionsChargeAndLitigationAndConduct
1351	GMP Charge	Concept (Monetary)	For Period	Debit	c070:GuaranteedMinimumPensionsCharge
1352	Litigation and conduct	Concept (Monetary)	For Period	Debit	c070:LitigationAndConductExpense
1353	Total operating expenses	Concept (Monetary)	For Period	Debit	ifrs-full:OperatingExpense
1354	Other net (expenses)/income	Concept (Monetary)	For Period	Credit	ifrs-full:OtherGainsLosses
1355	Profit (loss) before tax	Concept (Monetary)	For Period	Credit	ifrs-full:ProfitLossBeforeTax
1356	Total assets	Concept (Monetary)	As Of	Debit	ifrs-full:Assets
1357	Number of employees (full time equivalent)	Concept (Integer)	As Of		c070:NumberOfEmployeesExpressedAsInteger
1358	040402 - Disclosure - Segmental reporting - Analysis of results by business (Narrative) (Details)	Network	*	*	http://www.barclays.co.uk/role/SegmentalReportingAnalysisOfResultsByBusinessNarrativeDetails
1359	Disclosure of operating segments [table]	Table	*	*	ifrs-full:DisclosureOfOperatingSegmentsTable
1360	Assets and liabilities classified as held for sale [axis]	Axis			ifrs-full:AssetsAndLiabilitiesClassifiedAsHeldForSaleAxis
1361	Assets and liabilities not classified as held for sale [member]	Member			ifrs-full:AssetsAndLiabilitiesNotClassifiedAsHeldForSaleMember
1362	Assets and liabilities classified as held for sale [member]	Member			ifrs-full:AssetsAndLiabilitiesClassifiedAsHeldForSaleMember
1363	Barclay's Africa Banking Group Limited [member]	Member			c070:BarclaysAfricaBankingGroupLimitedMember
1364	Consolidated Entities [Axis]	Axis			srt:ConsolidatedEntitiesAxis
1365	Consolidated Entities [Domain]	Member			srt:ConsolidatedEntitiesDomain
1366	Barclays Bank Group [member]	Member			c070:BarclaysBankGroupMember
1367	Segment consolidation items [axis]	Axis			ifrs-full:SegmentConsolidationItemsAxis
1368	Entity's total for segment consolidation items [member]	Member			ifrs-full:EntitysTotalForSegmentConsolidationItemsMember
1369	Head Office [member]	Member			ifrs-full:EliminationOfIntersegmentAmountsMember
1370	Disclosure of operating segments [line items]	LineItems			ifrs-full:DisclosureOfOperatingSegmentsLineItems
1371	Certain legacy capital instrument funding costs	Concept (Monetary)	For Period	Debit	c070:CertainLegacyCapitalInstrumentFundingCosts
1372	Number of employees (full time equivalent)	Concept (Integer)	As Of		c070:NumberOfEmployeesExpressedAsInteger
1373	040404 - Disclosure - Segmental reporting - Income by geographic region (Details)	Network	*	*	http://www.barclays.co.uk/role/SegmentalReportingIncomeByGeographicRegionDetails
1374	Disclosure of operating segments [table]	Table	*	*	ifrs-full:DisclosureOfOperatingSegmentsTable
1375	Geographical areas [axis]	Axis			ifrs-full:GeographicalAreasAxis
1376	Geographical areas [member]	Member			ifrs-full:GeographicalAreasMember
1377	United Kingdom [member]	Member			ifrs-full:CountryOfDomicileMember
1378	Europe [member]	Member			srt:EuropeMember
1379	Americas [member]	Member			srt:AmericasMember
1380	Africa and middle east [member]	Member			c070:AfricaAndMiddleEastMember
1381	Asia [member]	Member			srt:AsiaMember
1382	United States [member]	Member			country:US
1383	Counterparties [axis]	Axis			ifrs-full:CounterpartiesAxis
1384	Counterparties [member]	Member			ifrs-full:CounterpartiesMember
1385	Income from individual countries which represent more than 5% of total income [member]	Member			c070:MoreThanFivePercentOfTotalIncomeMember
1386	Continuing and discontinued operations [axis]	Axis			ifrs-full:ContinuingAndDiscontinuedOperationsAxis
1387	Aggregate continuing and discontinued operations [member]	Member			ifrs-full:AggregateContinuingAndDiscontinuedOperationsMember
1388	Continuing operations [member]	Member			ifrs-full:ContinuingOperationsMember
1389	Disclosure of operating segments [line items]	LineItems			ifrs-full:DisclosureOfOperatingSegmentsLineItems
1390	Total income	Concept (Monetary)	For Period	Credit	c070:ProfitLossFromOperatingActivitiesBeforeImpairmentLossReversalOfImpairmentLossRecognisedInProfitOrLoss
1391	040405 - Disclosure - Segmental reporting - Income by geographic region (Narrative) (Details)	Network	*	*	http://www.barclays.co.uk/role/SegmentalReportingIncomeByGeographicRegionNarrativeDetails
1392	Disclosure of major customers [table]	Table	*	*	ifrs-full:DisclosureOfMajorCustomersTable
1393	Major customers [axis]	Axis			ifrs-full:MajorCustomersAxis
1394	Customers [member]	Member			ifrs-full:MajorCustomersMember
1395	Each single external customer [member]	Member			c070:EachSingleExternalCustomerMember
1396	Range [axis]	Axis			ifrs-full:RangeAxis
1397	Ranges [member]	Member			ifrs-full:RangesMember
1398	Max [member]	Member			ifrs-full:TopOfRangeMember
1399	Continuing and discontinued operations [axis]	Axis			ifrs-full:ContinuingAndDiscontinuedOperationsAxis
1400	Aggregate continuing and discontinued operations [member]	Member			ifrs-full:AggregateContinuingAndDiscontinuedOperationsMember
1401	Continuing operations [member]	Member			ifrs-full:ContinuingOperationsMember
1402	Disclosure of operating segments [line items]	LineItems			ifrs-full:DisclosureOfOperatingSegmentsLineItems
1403	Percentage of entity's revenue	Concept (Percent)	For Period		ifrs-full:PercentageOfEntitysRevenue
1404	040501 - Disclosure - Net interest income (Details)	Network	*	*	http://www.barclays.co.uk/role/NetInterestIncomeDetails
1405	Implied Table	Table	*	*	implied:Table
1406	Net interest income	Abstract			ifrs-full:AnalysisOfIncomeAndExpenseAbstract
1407	Condensed Income Statements, Captions [Line Items]	LineItems			srt:CondensedIncomeStatementsCaptionsLineItems
1408	Cash and balances with central banks	Concept (Monetary)	For Period	Credit	ifrs-full:InterestIncomeOnCashAndBankBalancesAtCentralBanks
1409	Financial investments	Concept (Monetary)	For Period	Credit	c070:InterestIncomeOnAvailableForSaleFinancialAssetsAndHeldToMaturityInvestments
1410	Fair value through other comprehensive income	Concept (Monetary)	For Period	Credit	ifrs-full:InterestRevenueForFinancialAssetsMeasuredAtFairValueThroughOtherComprehensiveIncome
1411	Loans and advances at amortised cost	Concept (Monetary)	For Period	Credit	ifrs-full:InterestIncomeForFinancialAssetsMeasuredAtAmortisedCost
1412	Other	Concept (Monetary)	For Period	Credit	ifrs-full:InterestIncomeOnOtherFinancialAssets
1413	Interest income	Concept (Monetary)	For Period	Credit	ifrs-full:InterestRevenueCalculatedUsingEffectiveInterestMethod
1414	Deposits at amortised cost	Concept (Monetary)	For Period	Debit	c070:InterestExpenseOnDepositsAtAmortisedCost
1415	Debt securities in issue	Concept (Monetary)	For Period	Debit	ifrs-full:InterestExpenseOnDebtInstrumentsIssued
1416	Subordinated liabilities	Concept (Monetary)	For Period	Debit	ifrs-full:InterestExpenseOnBorrowings
1417	Other	Concept (Monetary)	For Period	Debit	ifrs-full:InterestExpenseOnOtherFinancialLiabilities
1418	Interest expense	Concept (Monetary)	For Period	Debit	ifrs-full:InterestExpense
1419	Net interest income	Concept (Monetary)	For Period	Credit	ifrs-full:InterestRevenueExpense
1420	040502 - Disclosure - Net interest income (Narrative) (Details)	Network	*	*	http://www.barclays.co.uk/role/NetInterestIncomeNarrativeDetails
1421	Condensed Income Statement [Table]	Table	*	*	srt:CondensedIncomeStatementTable
1422	Consolidated Entities [Axis]	Axis			srt:ConsolidatedEntitiesAxis
1423	Consolidated Entities [Domain]	Member			srt:ConsolidatedEntitiesDomain
1424	Barclays Bank Group [member]	Member			c070:BarclaysBankGroupMember
1425	Condensed Income Statements, Captions [Line Items]	LineItems			srt:CondensedIncomeStatementsCaptionsLineItems
1426	Costs to originate credit card balances	Concept (Monetary)	For Period	Debit	c070:CostsToOrginateCreditCardBalances
1427	Interest income on impaired financial assets accrued	Concept (Monetary)	For Period	Credit	ifrs-full:InterestIncomeOnImpairedFinancialAssetsAccrued
1428	Gain (loss) on hedge ineffectiveness recognised in net interest income	Concept (Monetary)	For Period	Credit	ifrs-full:GainLossOnHedgeIneffectivenessRecognisedInProfitOrLoss
1429	040601 - Disclosure - Net fee and commission income (Details)	Network	*	*	http://www.barclays.co.uk/role/NetFeeAndCommissionIncomeDetails
1430	Disclosure of disaggregation of revenue from contracts with customers [table]	Table	*	*	ifrs-full:DisclosureOfDisaggregationOfRevenueFromContractsWithCustomersTable
1431	Segment consolidation items [axis]	Axis			ifrs-full:SegmentConsolidationItemsAxis
1432	Entity's total for segment consolidation items [member]	Member			ifrs-full:EntitysTotalForSegmentConsolidationItemsMember
1433	Operating segments [member]	Member			ifrs-full:OperatingSegmentsMember
1434	Head Office [member]	Member			ifrs-full:EliminationOfIntersegmentAmountsMember
1435	Segments [axis]	Axis			ifrs-full:SegmentsAxis
1436	Segments [member]	Member			ifrs-full:SegmentsMember
1437	Reportable segments [member]	Member			ifrs-full:ReportableSegmentsMember
1438	Corporate and investment bank [member]	Member			c070:CorporateAndInvestmentBankMember
1439	Consumer, cards and payments [member]	Member			c070:ConsumerCardsAndPaymentsMember
1440	Products and services [axis]	Axis			ifrs-full:ProductsAndServicesAxis
1441	Products and services [member]	Member			ifrs-full:ProductsAndServicesMember
1442	Transactional [member]	Member			c070:TransactionalBankingServicesMember
1443	Advisory [member]	Member			c070:ManagementAndAdvisorySevicesMember
1444	Brokerage and execution [member]	Member			c070:BrokerageCommissionsAndClientExecutionFeesMember
1445	Underwriting and syndication [member]	Member			c070:UnderwritingSyndicationAndCommitmentFeesMember
1446	Other [member]	Member			c070:OtherFeesMember
1447	Banking, investment management and credit related fees and commissions [member]	Member			c070:BankingInvestmentManagementAndCreditRelatedFeesAndCommissionsMember
1448	Foreign exchange commission [member]	Member			c070:ForeignExchangeCommissionMember
1449	Disclosure of disaggregation of revenue from contracts with customers [line items]	LineItems			ifrs-full:DisclosureOfDisaggregationOfRevenueFromContractsWithCustomersLineItems
1450	Fee and commission income [abstract]	Abstract			ifrs-full:FeeAndCommissionIncomeAbstract
1451	Revenue from contracts with customers	Concept (Monetary)	For Period	Credit	ifrs-full:RevenueFromContractsWithCustomers
1452	Other non-contract fee income	Concept (Monetary)	For Period	Credit	ifrs-full:OtherFeeAndCommissionIncome
1453	Fee and commission income	Concept (Monetary)	For Period	Credit	ifrs-full:FeeAndCommissionIncome
1454	Fee and commission expense	Concept (Monetary)	For Period	Debit	ifrs-full:FeeAndCommissionExpense
1455	Net fee and commission income	Concept (Monetary)	For Period	Credit	ifrs-full:FeeAndCommissionIncomeExpense
1456	040602 - Disclosure - Net fee and commission income (Narrative) (Details)	Network	*	*	http://www.barclays.co.uk/role/NetFeeAndCommissionIncomeNarrativeDetails
1457	Disclosure of detailed information about intangible assets [table]	Table	*	*	ifrs-full:DisclosureOfIntangibleAssetsTable
1458	Products and services [axis]	Axis			ifrs-full:ProductsAndServicesAxis
1459	Products and services [member]	Member			ifrs-full:ProductsAndServicesMember
1460	Transactional [member]	Member			c070:TransactionalBankingServicesMember
1461	Advisory [member]	Member			c070:ManagementAndAdvisorySevicesMember
1462	Brokerage and execution [member]	Member			c070:BrokerageCommissionsAndClientExecutionFeesMember
1463	Underwriting and syndication [member]	Member			c070:UnderwritingSyndicationAndCommitmentFeesMember
1464	Disclosure of detailed information about intangible assets [line items]	LineItems			ifrs-full:DisclosureOfIntangibleAssetsLineItems
1465	Description of methods used to recognise revenue from contracts with customers	Concept (Text/String)	For Period		ifrs-full:DescriptionOfMethodsUsedToRecogniseRevenueFromContractsWithCustomers
1466	Explanation of whether practical expedient is applied for disclosure of transaction price allocated to remaining performance obligations	Concept (Text/String)	For Period		ifrs-full:ExplanationOfWhetherPracticalExpedientIsAppliedForDisclosureOfTransactionPriceAllocatedToRemainingPerformanceObligations
1467	Fee and commission expense	Concept (Monetary)	For Period	Debit	ifrs-full:FeeAndCommissionExpense
1468	Capitalised contract costs	Concept (Monetary)	As Of	Debit	ifrs-full:AssetsRecognisedFromCostsToObtainOrFulfilContractsWithCustomers
1469	Amortisation, assets recognised from costs incurred to obtain or fulfil contracts with customers	Concept (Monetary)	For Period	Debit	ifrs-full:AmortisationAssetsRecognisedFromCostsIncurredToObtainOrFulfilContractsWithCustomers
1470	Impairment loss, assets recognised from costs incurred to obtain or fulfil contracts with customers	Concept (Monetary)	For Period	Debit	ifrs-full:ImpairmentLossAssetsRecognisedFromCostsIncurredToObtainOrFulfilContractsWithCustomers
1471	Description of method used to determine amortisation of assets recognised from costs to obtain or fulfil contracts with customers	Concept (Text/String)	For Period		ifrs-full:DescriptionOfMethodUsedToDetermineAmortisationOfAssetsRecognisedFromCostsToObtainOrFulfilContractsWithCustomers
1472	040701 - Disclosure - Net trading income (Details)	Network	*	*	http://www.barclays.co.uk/role/NetTradingIncomeDetails
1473	Disclosure of detailed information about financial instruments [table]	Table	*	*	ifrs-full:DisclosureOfFinancialInstrumentsTable
1474	Categories of financial assets [axis]	Axis			ifrs-full:CategoriesOfFinancialAssetsAxis
1475	Financial assets, category [member]	Member			ifrs-full:FinancialAssetsCategoryMember
1476	Assets held for trading [member]	Member			ifrs-full:FinancialAssetsAtFairValueThroughProfitOrLossClassifiedAsHeldForTradingCategoryMember
1477	Financial assets designated at fair value [member]	Member			ifrs-full:FinancialAssetsAtFairValueThroughProfitOrLossDesignatedUponInitialRecognitionCategoryMember
1478	Financial assets mandatory at fair value [member]	Member			ifrs-full:FinancialAssetsAtFairValueThroughProfitOrLossMandatorilyMeasuredAtFairValueCategoryMember
1479	Categories of financial liabilities [axis]	Axis			ifrs-full:CategoriesOfFinancialLiabilitiesAxis
1480	Financial liabilities, category [member]	Member			ifrs-full:FinancialLiabilitiesCategoryMember
1481	Liabilities held for trading [member]	Member			ifrs-full:FinancialLiabilitiesAtFairValueThroughProfitOrLossThatMeetDefinitionOfHeldForTradingCategoryMember
1482	Financial liabilities designated at fair value [member]	Member			ifrs-full:FinancialLiabilitiesAtFairValueThroughProfitOrLossDesignatedUponInitialRecognitionCategoryMember
1483	Consolidated Entities [Axis]	Axis			srt:ConsolidatedEntitiesAxis
1484	Consolidated Entities [Domain]	Member			srt:ConsolidatedEntitiesDomain
1485	Barclays Bank Group [member]	Member			c070:BarclaysBankGroupMember
1486	Classes of financial instruments [axis]	Axis			ifrs-full:ClassesOfFinancialInstrumentsAxis
1487	Financial instruments, class [member]	Member			ifrs-full:ClassesOfFinancialInstrumentsMember
1488	own credit losses [member]	Member			ifrs-full:FinancialInstrumentsMeasuredAtFairValueThroughProfitOrLossBecauseCreditDerivativeIsUsedToManageCreditRiskMember
1489	Disclosure of detailed information about financial instruments [line items]	LineItems			ifrs-full:DisclosureOfFinancialInstrumentsLineItems
1490	Net trading income	Concept (Monetary)	For Period	Credit	ifrs-full:TradingIncomeExpense
1491	040801 - Disclosure - Net investment income (Details)	Network	*	*	http://www.barclays.co.uk/role/NetInvestmentIncomeDetails
1492	Condensed Income Statement [Table]	Table	*	*	srt:CondensedIncomeStatementTable
1493	Consolidated Entities [Axis]	Axis			srt:ConsolidatedEntitiesAxis
1494	Consolidated Entities [Domain]	Member			srt:ConsolidatedEntitiesDomain
1495	Barclays Bank Group [member]	Member			c070:BarclaysBankGroupMember
1496	Condensed Income Statements, Captions [Line Items]	LineItems			srt:CondensedIncomeStatementsCaptionsLineItems
1497	Net gain from disposal of available for sale investments	Concept (Monetary)	For Period	Credit	ifrs-full:GainsLossesOnDisposalsOfInvestments
1498	Net gain on disposal of FVOCI investments	Concept (Monetary)	For Period	Credit	c070:GainLossOnDisposalOfInvestmentsInDebtInstrumentsDesignatedAtFairValueThroughOtherComprehensiveIncome
1499	Dividend income	Concept (Monetary)	For Period	Credit	ifrs-full:RevenueFromDividends
1500	Net gain from financial instruments designated at fair value	Concept (Monetary)	For Period	Credit	ifrs-full:GainsLossesOnFinancialAssetsAtFairValueThroughProfitOrLossDesignatedAsUponInitialRecognition
1501	Net gain from financial instruments mandatorily at fair value	Concept (Monetary)	For Period	Credit	ifrs-full:GainsLossesOnFinancialAssetsAtFairValueThroughProfitOrLossMandatorilyMeasuredAtFairValue
1502	Other investment income	Concept (Monetary)	For Period	Credit	c070:OtherInvestmentIncome
1503	Net investment income	Concept (Monetary)	For Period	Credit	c070:InvestmentIncomeExpense
1504	040901 - Disclosure - Credit impairment charges and other provisions (Details)	Network	*	*	http://www.barclays.co.uk/role/CreditImpairmentChargesAndOtherProvisionsDetails
1505	Disclosure of impairment loss recognised or reversed for cash-generating unit [table]	Table	*	*	ifrs-full:DisclosureOfImpairmentLossRecognisedOrReversedTable
1506	Categories of financial assets [axis]	Axis			ifrs-full:CategoriesOfFinancialAssetsAxis
1507	Financial assets, category [member]	Member			ifrs-full:FinancialAssetsCategoryMember
1508	Financial Investments [member]	Member			c070:FinancialInvestmentsMember
1509	Financial instruments at fair value through OCI [member]	Member			ifrs-full:FinancialAssetsMeasuredAtFairValueThroughOtherComprehensiveIncomeCategoryMember
1510	Classes of assets [axis]	Axis			ifrs-full:ClassesOfAssetsAxis
1511	Assets [member]	Member			ifrs-full:ClassesOfAssetsMember
1512	Cash collateral and settlement balances [member]	Member			ifrs-full:TradeReceivablesMember
1513	Consolidated Entities [Axis]	Axis			srt:ConsolidatedEntitiesAxis
1514	Consolidated Entities [Domain]	Member			srt:ConsolidatedEntitiesDomain
1515	Barclays Bank Group [member]	Member			c070:BarclaysBankGroupMember
1516	Disclosure of impairment loss and reversal of impairment loss [line items]	LineItems			ifrs-full:DisclosureOfImpairmentLossAndReversalOfImpairmentLossLineItems
1517	Impairment loss (reversal of impairment loss) recognised in profit or loss, loans and advances [abstract]	Abstract			ifrs-full:ImpairmentLossReversalOfImpairmentLossRecognisedInProfitOrLossLoansAndAdvancesAbstract
1518	Loans and advances, impairment charges	Concept (Monetary)	For Period		ifrs-full:ImpairmentLossRecognisedInProfitOrLossLoansAndAdvances
1519	Loans and advances, recoveries	Concept (Monetary)	For Period		ifrs-full:ReversalOfImpairmentLossRecognisedInProfitOrLossLoansAndAdvances
1520	Loan lmpairment, impairment	Concept (Monetary)	For Period	Debit	ifrs-full:ImpairmentLossReversalOfImpairmentLossRecognisedInProfitOrLossLoansAndAdvances
1521	Provision for undrawn contractually committed facilities and guarantees provided	Abstract			ifrs-full:IncreaseDecreaseInExposureToCreditRiskOnLoanCommitmentsAndFinancialGuaranteeContractsAbstract
1522	Provision for undrawn contractually committed facilities and guarantees provided	Concept (Monetary)	For Period	Credit	ifrs-full:IncreaseDecreaseInExposureToCreditRiskOnLoanCommitmentsAndFinancialGuaranteeContracts
1523	Provision for undrawn contractually committed facilities and guarantees provided, recoveries	Concept (Monetary)	For Period	Debit	ifrs-full:DecreaseThroughDerecognitionExposureToCreditRiskOnLoanCommitmentsAndFinancialGuaranteeContracts
1524	Impairment charges	Concept (Monetary)	For Period	Debit	ifrs-full:ImpairmentLossRecognisedInProfitOrLoss
1525	Recoveries	Concept (Monetary)	For Period	Credit	ifrs-full:ReversalOfImpairmentLossRecognisedInProfitOrLoss
1526	Credit impairment charges and other provisions	Concept (Monetary)	For Period	Debit	ifrs-full:ImpairmentLossReversalOfImpairmentLossRecognisedInProfitOrLoss
1527	040905 - Disclosure - Credit impairment charges and other provisions - Movements in allowance for impairment by asset class (audited) (Details)	Network	*	*	http://www.barclays.co.uk/role/CreditImpairmentChargesAndOtherProvisionsMovementsInAllowanceForImpairmentByAssetClassauditedDetails
1528	Disclosure of impairment loss recognised or reversed for cash-generating unit [table]	Table	*	*	ifrs-full:DisclosureOfImpairmentLossRecognisedOrReversedTable
1529	Categories of financial assets [axis]	Axis			ifrs-full:CategoriesOfFinancialAssetsAxis
1530	Financial assets, category [member]	Member			ifrs-full:FinancialAssetsCategoryMember
1531	Loans and advances [member]	Member			ifrs-full:LoansAndReceivablesCategoryMember
1532	Home loans [member]	Member			ifrs-full:MortgagesMember
1533	Credit cards, unsecured and other retail lending [member]	Member			c070:CreditCardsUnsecuredAndOtherRetailLendingMember
1534	Corporate loans [member]	Member			ifrs-full:CorporateLoansMember
1535	Disclosure of impairment loss and reversal of impairment loss [line items]	LineItems			ifrs-full:DisclosureOfImpairmentLossAndReversalOfImpairmentLossLineItems
1536	Opening/Beginning balance	Concept (Monetary)	As Of	Credit	ifrs-full:AllowanceAccountForCreditLossesOfFinancialAssets
1537	Acquisitions and disposals	Concept (Monetary)	For Period	Credit	c070:IncreaseDecreaseThroughAcquisitionsAndDisposalsAllowanceForCreditLossesOfFinancialAssets
1538	Unwind of discount	Concept (Monetary)	For Period	Credit	ifrs-full:IncreaseDecreaseThroughAdjustmentsArisingFromPassageOfTimeAllowanceAccountForCreditLossesOfFinancialAssets
1539	Exchange and other adjustments	Concept (Monetary)	For Period	Credit	ifrs-full:IncreaseDecreaseThroughNetExchangeDifferencesAllowanceAccountForCreditLossesOfFinancialAssets
1540	Amounts written off	Concept (Monetary)	For Period	Debit	ifrs-full:UtilisationAllowanceAccountForCreditLossesOfFinancialAssets
1541	Recoveries	Concept (Monetary)	For Period		ifrs-full:ReversalAllowanceAccountForCreditLossesOfFinancialAssets
1542	Amounts charged to income statement	Concept (Monetary)	For Period		ifrs-full:AdditionalAllowanceRecognisedInProfitOrLossAllowanceAccountForCreditLossesOfFinancialAssets
1543	Closing/Ending balance	Concept (Monetary)	As Of	Credit	ifrs-full:AllowanceAccountForCreditLossesOfFinancialAssets
1544	040915 - Disclosure - Credit impairment charges and other provisions (Narrative) (Details)	Network	*	*	http://www.barclays.co.uk/role/CreditImpairmentChargesAndOtherProvisionsNarrativeDetails
1545	Disclosure of impairment loss and reversal of impairment loss [table]	Table	*	*	ifrs-full:DisclosureOfImpairmentLossAndReversalOfImpairmentLossTable
1546	Continuing and discontinued operations [axis]	Axis			ifrs-full:ContinuingAndDiscontinuedOperationsAxis
1547	Aggregate continuing and discontinued operations [member]	Member			ifrs-full:AggregateContinuingAndDiscontinuedOperationsMember
1548	Discontinued operations [member]	Member			ifrs-full:DiscontinuedOperationsMember
1549	UK Banking Business [member]	Member			c070:BarclaysUkMember
1550	Categories of related parties [axis]	Axis			ifrs-full:CategoriesOfRelatedPartiesAxis
1551	Entity's total for related parties [member]	Member			ifrs-full:EntitysTotalForRelatedPartiesMember
1552	Barclays Bank UK PLC [member]	Member			c070:BarclaysBankUkPlcMember
1553	Consolidated Entities [Axis]	Axis			srt:ConsolidatedEntitiesAxis
1554	Consolidated Entities [Domain]	Member			srt:ConsolidatedEntitiesDomain
1555	Barclays Bank Group [member]	Member			c070:BarclaysBankGroupMember
1556	Disclosure of impairment loss and reversal of impairment loss [line items]	LineItems			ifrs-full:DisclosureOfImpairmentLossAndReversalOfImpairmentLossLineItems
1557	Impairment charges	Concept (Monetary)	For Period	Debit	ifrs-full:ImpairmentLossOnFinancialAssets
1558	Recoveries	Concept (Monetary)	For Period		ifrs-full:ReversalAllowanceAccountForCreditLossesOfFinancialAssets
1559	Financial assets written off during reporting period and still subject to enforcement activity, contractual amount outstanding	Concept (Monetary)	As Of	Debit	ifrs-full:FinancialAssetsWrittenOffDuringReportingPeriodAndStillSubjectToEnforcementActivityContractualAmountOutstanding
1560	041001 - Disclosure - Operating expenses (Details)	Network	*	*	http://www.barclays.co.uk/role/OperatingExpensesDetails
1561	Condensed Income Statement [Table]	Table	*	*	srt:CondensedIncomeStatementTable
1562	Consolidated Entities [Axis]	Axis			srt:ConsolidatedEntitiesAxis
1563	Consolidated Entities [Domain]	Member			srt:ConsolidatedEntitiesDomain
1564	Barclays Bank Group [member]	Member			c070:BarclaysBankGroupMember
1565	Condensed Income Statements, Captions [Line Items]	LineItems			srt:CondensedIncomeStatementsCaptionsLineItems
1566	Infrastructure costs	Abstract			ifrs-full:ChangesInPropertyPlantAndEquipmentAbstract
1567	Property and equipment	Concept (Monetary)	For Period	Debit	ifrs-full:ChangesInPropertyPlantAndEquipment
1568	Depreciation of property, plant and equipment	Concept (Monetary)	For Period		ifrs-full:DepreciationPropertyPlantAndEquipment
1569	Operating lease rentals	Concept (Monetary)	For Period	Debit	ifrs-full:RentalExpense
1570	Amortisation of intangible assets	Concept (Monetary)	For Period	Debit	ifrs-full:AmortisationExpense
1571	Impairment of property, equipment and intangible assets	Concept (Monetary)	For Period		ifrs-full:ImpairmentLossRecognisedInProfitOrLossPropertyPlantAndEquipment
1572	Gain on property disposals	Concept (Monetary)	For Period	Credit	ifrs-full:GainsLossesOnDisposalsOfPropertyPlantAndEquipment
1573	Total Infrastructure costs	Concept (Monetary)	For Period	Debit	c070:InfrastructureCosts
1574	Administration and general costs	Abstract			c070:SellingGeneralAndAdministrativeAbstract
1575	Consultancy, legal and professional fees	Concept (Monetary)	For Period	Debit	ifrs-full:ProfessionalFeesExpense
1576	Subscriptions, publications, stationery and communications	Concept (Monetary)	For Period	Debit	ifrs-full:CommunicationExpense
1577	Marketing, advertising and sponsorship	Concept (Monetary)	For Period	Debit	ifrs-full:SalesAndMarketingExpense
1578	Travel and accommodation	Concept (Monetary)	For Period	Debit	ifrs-full:TravelExpense
1579	UK Bank levy	Concept (Monetary)	For Period	Debit	ifrs-full:BankAndSimilarCharges
1580	Other administration and general expenses	Concept (Monetary)	For Period	Debit	ifrs-full:MiscellaneousOtherOperatingExpense
1581	Total administration and general expenses	Concept (Monetary)	For Period	Debit	ifrs-full:GeneralAndAdministrativeExpense
1582	Staff costs	Concept (Monetary)	For Period	Debit	ifrs-full:EmployeeBenefitsExpense
1583	Litigation and conduct	Concept (Monetary)	For Period	Debit	ifrs-full:LossesOnLitigationSettlements
1584	Operating expenses	Concept (Monetary)	For Period	Debit	ifrs-full:OperatingExpense
1585	041101 - Disclosure - Profit/(loss) on disposal of subsidiaries, associates and joint ventures (Narrative) (Details)	Network	*	*	http://www.barclays.co.uk/role/ProfitlossOnDisposalOfSubsidiariesAssociatesAndJointVenturesNarrativeDetails
1586	Condensed Income Statement [Table]	Table	*	*	srt:CondensedIncomeStatementTable
1587	Consolidated Entities [Axis]	Axis			srt:ConsolidatedEntitiesAxis
1588	Consolidated Entities [Domain]	Member			srt:ConsolidatedEntitiesDomain
1589	Barclays Bank Group [member]	Member			c070:BarclaysBankGroupMember
1590	Condensed Income Statements, Captions [Line Items]	LineItems			srt:CondensedIncomeStatementsCaptionsLineItems
1591	Gain (loss) on the sale of assets of disposal group	Concept (Monetary)	For Period	Credit	ifrs-full:GainLossRecognisedOnMeasurementToFairValueLessCostsToSellOrOnDisposalOfAssetsOrDisposalGroupsConstitutingDiscontinuedOperation
1592	041201 - Disclosure - Tax - Tax Charge (Details)	Network	*	*	http://www.barclays.co.uk/role/TaxTaxChargeDetails
1593	Condensed Income Statement [Table]	Table	*	*	srt:CondensedIncomeStatementTable
1594	Consolidated Entities [Axis]	Axis			srt:ConsolidatedEntitiesAxis
1595	Consolidated Entities [Domain]	Member			srt:ConsolidatedEntitiesDomain
1596	Barclays Bank Group [member]	Member			c070:BarclaysBankGroupMember
1597	Condensed Income Statements, Captions [Line Items]	LineItems			srt:CondensedIncomeStatementsCaptionsLineItems
1598	Current tax charge/(credit)	Abstract			ifrs-full:CurrentTaxExpenseIncomeAndAdjustmentsForCurrentTaxOfPriorPeriodsAbstract
1599	Current year	Concept (Monetary)	For Period	Debit	ifrs-full:CurrentTaxExpenseIncome
1600	Adjustments in respect of prior years	Concept (Monetary)	For Period	Debit	ifrs-full:AdjustmentsForCurrentTaxOfPriorPeriod
1601	Total	Concept (Monetary)	For Period	Debit	ifrs-full:CurrentTaxExpenseIncomeAndAdjustmentsForCurrentTaxOfPriorPeriods
1602	Deferred tax charge/(credit)	Abstract			ifrs-full:DeferredTaxExpenseIncomeAbstract
1603	Current year	Concept (Monetary)	For Period	Debit	ifrs-full:DeferredTaxExpenseIncome
1604	Adjustments in respect of prior years	Concept (Monetary)	For Period	Debit	ifrs-full:AdjustmentsForDeferredTaxOfPriorPeriods
1605	Total	Concept (Monetary)	For Period		ifrs-full:DeferredTaxExpenseIncomeRecognisedInProfitOrLoss
1606	Tax charge	Concept (Monetary)	For Period	Debit	ifrs-full:IncomeTaxExpenseContinuingOperations
1607	041202 - Disclosure - Tax - Reconciliation between the actual tax charge and the corporate tax rate (Details)	Network	*	*	http://www.barclays.co.uk/role/TaxReconciliationBetweenTheActualTaxChargeAndTheCorporateTaxRateDetails
1608	Condensed Income Statement [Table]	Table	*	*	srt:CondensedIncomeStatementTable
1609	Consolidated Entities [Axis]	Axis			srt:ConsolidatedEntitiesAxis
1610	Consolidated Entities [Domain]	Member			srt:ConsolidatedEntitiesDomain
1611	Barclays Bank Group [member]	Member			c070:BarclaysBankGroupMember
1612	Condensed Income Statements, Captions [Line Items]	LineItems			srt:CondensedIncomeStatementsCaptionsLineItems
1613	Profit before tax from continuing operations	Concept (Monetary)	For Period	Credit	ifrs-full:AccountingProfit
1614	Tax charge based on the standard UK corporation tax rate of 19% (2017: 19.25%, 2016: 20.0%)	Concept (Monetary)	For Period	Debit	ifrs-full:TaxExpenseIncomeAtApplicableTaxRate
1615	Impact of profits/losses earned in territories with different statutory rates to the UK (weighted average tax rate is 27.1% (2017: 38.2%, 2016: 41.9%))	Concept (Monetary)	For Period	Debit	ifrs-full:TaxEffectOfForeignTaxRates
1616	Tax, percentage [abstract]	Abstract			c070:TaxPercentageAbstract
1617	Tax charge based on the standard UK corporation tax rate of 19% (2017: 19.25%, 2016: 20.0%)	Concept (Percent)	For Period		ifrs-full:ApplicableTaxRate
1618	Impact of profits/losses earned in territories with different statutory rates to the UK (weighted average tax rate is 27.1% (2017: 38.2%, 2016: 41.9%))	Concept (Percent)	For Period		ifrs-full:TaxRateEffectOfForeignTaxRates
1619	Recurring items [abstract]	Abstract			c070:RecurringItemsAbstract
1620	Non-creditable taxes including withholding taxes	Concept (Monetary)	For Period	Debit	c070:TaxEffectOfNonCreditableTaxesIncludingWitholdingTaxes
1621	Non-deductible expenses	Concept (Monetary)	For Period	Debit	ifrs-full:TaxEffectOfExpenseNotDeductibleInDeterminingTaxableProfitTaxLoss
1622	Impact of UK bank levy being non-deductible	Concept (Monetary)	For Period	Debit	c070:TaxEffectOfUkBankLevyBeingNonDeductible
1623	Tax adjustments in respect of share-based payments	Concept (Monetary)	For Period	Debit	c070:TaxAdjustmentsForSharebasedPayments
1624	Non-taxable gains and income	Concept (Monetary)	For Period	Credit	ifrs-full:TaxEffectOfRevenuesExemptFromTaxation2011
1625	Changes in recognition of deferred tax and effect of unrecognised tax losses	Concept (Monetary)	For Period	Credit	c070:TaxEffectOfChangesInRecognitionOfDeferredTaxAndEffectOfUnrecognisedTax
1626	Impact of Barclays Bank PLC's overseas branches being taxed both locally and in the UK	Concept (Monetary)	For Period	Credit	c070:TaxEffectOfOverseasBranchesBeingTaxedBothLocallyAndIUk
1627	Adjustments in respect of prior years	Concept (Monetary)	For Period	Debit	c070:AdjustmentsInRespectOfPriorYears
1628	Banking surcharge and other items	Concept (Monetary)	For Period	Debit	ifrs-full:OtherTaxEffectsForReconciliationBetweenAccountingProfitAndTaxExpenseIncome
1629	Recurring items, percentages [abstract]	Abstract			c070:RecurringItemsPercentagesAbstract
1630	Non-creditable taxes including withholding taxes, percentage	Concept (Percent)	For Period		c070:TaxRateEffectOfNonCreditableTaxesIncludingWitholdingTaxes
1631	Non-deductible expenses, percentage	Concept (Percent)	For Period		ifrs-full:TaxRateEffectOfExpenseNotDeductibleInDeterminingTaxableProfitTaxLoss
1632	Impact of UK bank levy being non-deductible, percentage	Concept (Percent)	For Period		c070:TaxRateEffectOfUkBankLevyBeingNonDeductible
1633	Tax adjustments in respect of share-based payments, percentage	Concept (Percent)	For Period		c070:TaxRateEffectOfAdjustmentsForSharebasedPayments
1634	Non-taxable gains and income, percentage	Concept (Percent)	For Period		ifrs-full:TaxRateEffectOfRevenuesExemptFromTaxation
1635	Changes in recognition of deferred tax and effect of unrecognised tax losses, percentage	Concept (Percent)	For Period		c070:TaxRateEffectOfChangesInRecognitionOfDeferredTaxAndEffectOfUnrecognisedTax
1636	Impact of Barclays Bank PLC's overseas branches being taxed both locally and in the UK, percentage	Concept (Percent)	For Period		c070:TaxRateEffectOfOverseasBranchesBeingTaxedBothLocallyAndUk
1637	Adjustments in respect of prior years, percentage	Concept (Percent)	For Period		c070:AdjustmentsInRespectOfPriorYearsPercentage
1638	Banking surcharge and other items, percentage	Concept (Percent)	For Period		ifrs-full:OtherTaxRateEffectsForReconciliationBetweenAccountingProfitAndTaxExpenseIncome
1639	Non-recurring items [abstract]	Abstract			c070:NonrecurringItemsAbstract
1640	One off re-measurement of US deferred tax assets	Concept (Monetary)	For Period	Debit	c070:RemeasurementOfUnitedStatesDeferredTaxAssets
1641	Impact of the UK branch exemption election on US branch deferred tax assets	Concept (Monetary)	For Period	Credit	c070:ImpactOfTheUnitedKingdomBranchExemptionOnDeferredTaxAssets
1642	Non-deductible provisions for UK customer redress	Concept (Monetary)	For Period	Debit	c070:TaxEffectNonDeductibleProvisionsForUkCustomerRedress
1643	Non-deductible provisions for investigations and litigation	Concept (Monetary)	For Period	Debit	c070:TaxEffectNondeductibleProvisionsForInvestigationsAndLitigation
1644	Non-taxable gains and income on divestments	Concept (Monetary)	For Period	Credit	c070:TaxEffectNontaxableGainsAndIncomeOnDivestments
1645	Non-deductible impairments and losses on divestments	Concept (Monetary)	For Period	Debit	c070:TaxEffectNondeductibleImpairmentsAndLossesOnDivestments
1646	Non-recurring items, percentages [abstract]	Abstract			c070:NonRecurringItemsPercentagesAbstract
1647	One off re-measurement of US deferred tax assets, percentage	Concept (Percent)	For Period		c070:TaxRateEffectRemeasurementOfUnitedStatesDeferredTaxAssetsPercentage
1648	Impact of the United Kingdom branch exemption election on US branch deferred tax assets, percentage	Concept (Percent)	For Period		c070:ImpactOfTheUnitedKingdomBranchExemptionOnDeferredTaxAssetsPercentage
1649	Non-deductible provisions for UK customer redress, percentage	Concept (Percent)	For Period		c070:TaxRateEffectNonDeductibleProvisionsForUkCustomerRedress
1650	Non-deductible provisions for investigations and litigation , percentage	Concept (Percent)	For Period		c070:TaxRateEffectNondeductibleProvisionsForInvestigationsAndLitigation
1651	Non-taxable gains and income on divestments, percentage	Concept (Percent)	For Period		c070:TaxRateEffectNontaxableGainsAndIncomeOnDivestments
1652	Non-deductible impairments and losses on divestments, percentage	Concept (Percent)	For Period		c070:TaxRateEffectNondeductibleImpairmentsAndLossesOnDivestments
1653	Tax charge	Concept (Monetary)	For Period	Debit	ifrs-full:IncomeTaxExpenseContinuingOperations
1654	Total tax charge, percentage	Concept (Percent)	For Period		ifrs-full:AverageEffectiveTaxRate
1655	041203 - Disclosure - Tax - Reconciliation between the actual tax charge and the corporate tax rate (Parenthetical) (Details)	Network	*	*	http://www.barclays.co.uk/role/TaxReconciliationBetweenTheActualTaxChargeAndTheCorporateTaxRateParentheticalDetails
1656	Condensed Income Statement [Table]	Table	*	*	srt:CondensedIncomeStatementTable
1657	Range [axis]	Axis			ifrs-full:RangeAxis
1658	Ranges [member]	Member			ifrs-full:RangesMember
1659	Weighted average [member]	Member			ifrs-full:WeightedAverageMember
1660	Consolidated Entities [Axis]	Axis			srt:ConsolidatedEntitiesAxis
1661	Consolidated Entities [Domain]	Member			srt:ConsolidatedEntitiesDomain
1662	Barclays Bank Group [member]	Member			c070:BarclaysBankGroupMember
1663	Condensed Income Statements, Captions [Line Items]	LineItems			srt:CondensedIncomeStatementsCaptionsLineItems
1664	Tax charge based on the standard UK corporation tax rate	Concept (Percent)	For Period		ifrs-full:ApplicableTaxRate
1665	Weighted average tax rate, territories with different statutory rates to the UK	Concept (Percent)	For Period		ifrs-full:TaxRateEffectOfForeignTaxRates
1666	041204 - Disclosure - Tax - Current tax assets and liabilities (Details)	Network	*	*	http://www.barclays.co.uk/role/TaxCurrentTaxAssetsAndLiabilitiesDetails
1667	Condensed Balance Sheet Statement [Table]	Table	*	*	srt:CondensedBalanceSheetStatementTable
1668	Consolidated Entities [Axis]	Axis			srt:ConsolidatedEntitiesAxis
1669	Consolidated Entities [Domain]	Member			srt:ConsolidatedEntitiesDomain
1670	Barclays Bank Group [member]	Member			c070:BarclaysBankGroupMember
1671	Barclays Bank PLC [member]	Member			c070:BarclaysBankPlcMember
1672	Condensed Balance Sheet Statements, Captions [Line Items]	LineItems			srt:CondensedBalanceSheetStatementsCaptionsLineItems
1673	Assets	Concept (Monetary)	As Of	Debit	ifrs-full:CurrentTaxAssets
1674	Liabilities	Concept (Monetary)	As Of	Credit	ifrs-full:CurrentTaxLiabilities
1675	Net current tax assets (liabilities)	Concept (Monetary)	As Of	Credit	c070:NetCurrentTaxAssetsLiabilities
1676	As at 1 January	Concept (Monetary)	As Of	Credit	c070:NetCurrentTaxAssetsLiabilities
1677	Income statement from continuing operations	Concept (Monetary)	For Period	Debit	ifrs-full:CurrentTaxExpenseIncomeAndAdjustmentsForCurrentTaxOfPriorPeriods
1678	Income statement from discontinued UK banking business	Concept (Monetary)	For Period	Debit	ifrs-full:TaxExpenseRelatingToGainLossOnDiscontinuance
1679	Other comprehensive income	Concept (Monetary)	For Period		c070:IncomeTaxRelatingToComponentsOfOtherComprehensiveIncomeCurrentTaxAssetLiability
1680	Corporate income tax paid from continuing operations	Concept (Monetary)	For Period	Credit	ifrs-full:IncomeTaxesPaidRefund
1681	Corporate income tax paid from discontinued UK banking business	Concept (Monetary)	For Period	Credit	c070:IncomeTaxesPaidRefundDiscontinuedOperations
1682	Transfer to Barclays Bank UK PLC	Concept (Monetary)	For Period	Credit	c070:IncreaseDecreaseThroughLossOfControlOfSubsidiaryCurrentTaxLiabilityAsset
1683	Other movements	Concept (Monetary)	For Period	Credit	c070:CurrentTaxOtherMovements
1684	As at 31 December	Concept (Monetary)	As Of	Credit	c070:NetCurrentTaxAssetsLiabilities
1685	Assets	Concept (Monetary)	As Of	Debit	ifrs-full:CurrentTaxAssets
1686	Liabilities	Concept (Monetary)	As Of	Credit	ifrs-full:CurrentTaxLiabilities
1687	Net current tax assets (liabilities)	Concept (Monetary)	As Of	Credit	c070:NetCurrentTaxAssetsLiabilities
1688	041205 - Disclosure - Tax - Deferred tax assets and liabilities (Details)	Network	*	*	http://www.barclays.co.uk/role/TaxDeferredTaxAssetsAndLiabilitiesDetails
1689	Disclosure of temporary difference, unused tax losses and unused tax credits [table]	Table	*	*	ifrs-full:DisclosureOfTemporaryDifferenceUnusedTaxLossesAndUnusedTaxCreditsTable
1690	Consolidated Entities [Axis]	Axis			srt:ConsolidatedEntitiesAxis
1691	Consolidated Entities [Domain]	Member			srt:ConsolidatedEntitiesDomain
1692	Barclays Bank Group [member]	Member			c070:BarclaysBankGroupMember
1693	Barclays Bank PLC [member]	Member			c070:BarclaysBankPlcMember
1694	Categories of related parties [axis]	Axis			ifrs-full:CategoriesOfRelatedPartiesAxis
1695	Entity's total for related parties [member]	Member			ifrs-full:EntitysTotalForRelatedPartiesMember
1696	Intermediate Holding Company - IHC Tax Group [member]	Member			c070:IntermediateHoldingCompanyMember
1697	US Branch Tax group [member]	Member			c070:UnitedStatesBranchTaxGroupMember
1698	UK Tax group [member]	Member			srt:ParentCompanyMember
1699	Other [member]	Member			c070:OtherSubsidiariesMember
1700	Disclosure of temporary difference, unused tax losses and unused tax credits [line items]	LineItems			ifrs-full:DisclosureOfTemporaryDifferenceUnusedTaxLossesAndUnusedTaxCreditsLineItems
1701	Deferred tax asset	Concept (Monetary)	As Of	Debit	ifrs-full:DeferredTaxAssets
1702	Deferred tax liability	Concept (Monetary)	As Of	Credit	ifrs-full:DeferredTaxLiabilities
1703	Net deferred tax	Concept (Monetary)	As Of	Credit	ifrs-full:DeferredTaxLiabilityAsset
1704	041206 - Disclosure - Tax - Movements on deferred tax assets and liabilities during the year before offsetting (Details)	Network	*	*	http://www.barclays.co.uk/role/TaxMovementsOnDeferredTaxAssetsAndLiabilitiesDuringTheYearBeforeOffsettingDetails
1705	Disclosure of temporary difference, unused tax losses and unused tax credits [table]	Table	*	*	ifrs-full:DisclosureOfTemporaryDifferenceUnusedTaxLossesAndUnusedTaxCreditsTable
1706	Temporary difference, unused tax losses and unused tax credits [axis]	Axis			ifrs-full:TemporaryDifferenceUnusedTaxLossesAndUnusedTaxCreditsAxis
1707	Temporary difference, unused tax losses and unused tax credits [member]	Member			ifrs-full:TemporaryDifferenceUnusedTaxLossesAndUnusedTaxCreditsMember
1708	Fixed asset timing differences [member]	Member			c070:FixedAssetTimingDifferencesMember
1709	Loan impairment allowance [member]	Member			ifrs-full:AllowanceForCreditLossesMember
1710	Tax losses carried forward [member]	Member			ifrs-full:UnusedTaxLossesMember
1711	Other [member]	Member			ifrs-full:OtherTemporaryDifferencesMember
1712	Categories of financial assets [axis]	Axis			ifrs-full:CategoriesOfFinancialAssetsAxis
1713	Financial assets, category [member]	Member			ifrs-full:FinancialAssetsCategoryMember
1714	Available for sale investments [member]	Member			ifrs-full:FinancialAssetsAvailableforsaleCategoryMember
1715	Types of hedges [axis]	Axis			ifrs-full:TypesOfHedgesAxis
1716	Hedges [member]	Member			ifrs-full:TypesOfHedgesMember
1717	Cash flow hedges [member]	Member			ifrs-full:CashFlowHedgesMember
1718	Net defined benefit liability (asset) [axis]	Axis			ifrs-full:NetDefinedBenefitLiabilityAssetAxis
1719	Net defined benefit liability (asset) [member]	Member			ifrs-full:NetDefinedBenefitLiabilityAssetMember
1720	Retirement benefit obligation [member]	Member			ifrs-full:PresentValueOfDefinedBenefitObligationMember
1721	Classes of other provisions [axis]	Axis			ifrs-full:ClassesOfProvisionsAxis
1722	Other provisions [member]	Member			ifrs-full:OtherProvisionsMember
1723	Other provisions [member]	Member			ifrs-full:MiscellaneousOtherProvisionsMember
1724	Types of share-based payment arrangements [axis]	Axis			ifrs-full:TypesOfSharebasedPaymentArrangementsAxis
1725	Share-based payment arrangements [member]	Member			ifrs-full:SharebasedPaymentArrangementsMember
1726	Share-based compensation and deferred compensation [member]	Member			c070:SharebasedCompensationAndDeferredCompensationMember
1727	Consolidated Entities [Axis]	Axis			srt:ConsolidatedEntitiesAxis
1728	Consolidated Entities [Domain]	Member			srt:ConsolidatedEntitiesDomain
1729	Barclays Bank Group [member]	Member			c070:BarclaysBankGroupMember
1730	Disclosure of temporary difference, unused tax losses and unused tax credits [line items]	LineItems			ifrs-full:DisclosureOfTemporaryDifferenceUnusedTaxLossesAndUnusedTaxCreditsLineItems
1731	Deferred tax asset, before offsetting	Concept (Monetary)	As Of	Debit	c070:DeferredTaxAssetsBeforeOffsetting
1732	Deferred tax liability, before offsetting	Concept (Monetary)	As Of	Credit	c070:DeferredTaxLiabilitiesBeforeOffsetting
1733	Net deferred tax (liability) asset	Concept (Monetary)	As Of	Credit	c070:DeferredTaxLiabilityAssetBeforeOffsetting
1734	Net deferred tax (liability) asset	Concept (Monetary)	As Of	Credit	c070:DeferredTaxLiabilityAssetBeforeOffsetting
1735	Income statement from continuing operations	Concept (Monetary)	For Period		ifrs-full:DeferredTaxExpenseIncomeRecognisedInProfitOrLoss
1736	Income statement from discontinued UK banking business	Concept (Monetary)	For Period	Debit	c070:TaxExpenseRelatingToGainLossOnDiscontinuanceDeferredTaxLiabilityAsset
1737	Other comprehensive income	Concept (Monetary)	For Period		c070:IncomeTaxRelatingToComponentsOfOtherComprehensiveIncomeDeferredTaxAssetLiability
1738	Transfer to Barclays Bank UK PLC	Concept (Monetary)	For Period	Credit	ifrs-full:IncreaseDecreaseThroughLossOfControlOfSubsidiaryDeferredTaxLiabilityAsset
1739	Other movements	Concept (Monetary)	For Period	Credit	ifrs-full:IncreaseDecreaseThroughNetExchangeDifferencesDeferredTaxLiabilityAsset
1740	Deferred tax liability (asset), before offsetting	Concept (Monetary)	As Of	Credit	c070:DeferredTaxLiabilityAssetBeforeOffsetting
1741	Deferred tax asset, before offsetting	Concept (Monetary)	As Of	Debit	c070:DeferredTaxAssetsBeforeOffsetting
1742	Deferred tax liability, before offsetting	Concept (Monetary)	As Of	Credit	c070:DeferredTaxLiabilitiesBeforeOffsetting
1743	Net deferred tax (liability) asset	Concept (Monetary)	As Of	Credit	c070:DeferredTaxLiabilityAssetBeforeOffsetting
1744	041207 - Disclosure - Tax - Movements on deferred tax assets and liabilities during the year before offsetting (Narrative) (Details)	Network	*	*	http://www.barclays.co.uk/role/TaxMovementsOnDeferredTaxAssetsAndLiabilitiesDuringTheYearBeforeOffsettingNarrativeDetails
1745	Disclosure of temporary difference, unused tax losses and unused tax credits [table]	Table	*	*	ifrs-full:DisclosureOfTemporaryDifferenceUnusedTaxLossesAndUnusedTaxCreditsTable
1746	Consolidated Entities [Axis]	Axis			srt:ConsolidatedEntitiesAxis
1747	Consolidated Entities [Domain]	Member			srt:ConsolidatedEntitiesDomain
1748	Barclays Bank Group [member]	Member			c070:BarclaysBankGroupMember
1749	Classes of assets [axis]	Axis			ifrs-full:ClassesOfAssetsAxis
1750	Assets [member]	Member			ifrs-full:ClassesOfAssetsMember
1751	Deferred tax assets [member]	Member			c070:DeferredTaxAssetsMember
1752	Disclosure of temporary difference, unused tax losses and unused tax credits [line items]	LineItems			ifrs-full:DisclosureOfTemporaryDifferenceUnusedTaxLossesAndUnusedTaxCreditsLineItems
1753	IFRS 9 Impairment change	Concept (Monetary)	As Of	Debit	ifrs-full:IncreaseDecreaseInFinancialAssetsArisingFromChangeInMeasurementAttributeFirstApplicationOfIFRS9
1754	041210 - Disclosure - Tax (Narrative) (Details)	Network	*	*	http://www.barclays.co.uk/role/TaxNarrativeDetails
1755	Disclosure of temporary difference, unused tax losses and unused tax credits [table]	Table	*	*	ifrs-full:DisclosureOfTemporaryDifferenceUnusedTaxLossesAndUnusedTaxCreditsTable
1756	Temporary difference, unused tax losses and unused tax credits [axis]	Axis			ifrs-full:TemporaryDifferenceUnusedTaxLossesAndUnusedTaxCreditsAxis
1757	Temporary difference, unused tax losses and unused tax credits [member]	Member			ifrs-full:TemporaryDifferenceUnusedTaxLossesAndUnusedTaxCreditsMember
1758	Temporary differences [member]	Member			ifrs-full:TemporaryDifferenceMember
1759	Unused tax losses [member]	Member			ifrs-full:UnusedTaxLossesMember
1760	Unused tax credits [member]	Member			ifrs-full:UnusedTaxCreditsMember
1761	Capital losses [member]	Member			c070:CapitalLossMember
1762	Loss in current or prior year [member]	Member			c070:LossInCurrentOrPriorYearMember
1763	Range [axis]	Axis			ifrs-full:RangeAxis
1764	Ranges [member]	Member			ifrs-full:RangesMember
1765	Weighted average [member]	Member			ifrs-full:WeightedAverageMember
1766	Continuing and discontinued operations [axis]	Axis			ifrs-full:ContinuingAndDiscontinuedOperationsAxis
1767	Aggregate continuing and discontinued operations [member]	Member			ifrs-full:AggregateContinuingAndDiscontinuedOperationsMember
1768	Discontinued operations [member]	Member			ifrs-full:DiscontinuedOperationsMember
1769	Barclay's Africa Banking Group Limited (BAGL) [member]	Member			c070:BarclaysAfricaBankingGroupLimitedMember
1770	Maturity [axis]	Axis			ifrs-full:MaturityAxis
1771	Aggregated time bands [member]	Member			ifrs-full:AggregatedTimeBandsMember
1772	After more than 12 months [member]	Member			ifrs-full:LaterThanOneYearMember
1773	Within five years [member]	Member			c070:WithinFiveYearsMember
1774	Within six to ten years [member]	Member			c070:WithinSixToTenYearsMember
1775	Within eleven to twenty years [member]	Member			c070:WithinElevenToTwentyYearsMember
1776	Indefinitely [member]	Member			c070:IndefinitelyMember
1777	Categories of related parties [axis]	Axis			ifrs-full:CategoriesOfRelatedPartiesAxis
1778	Entity's total for related parties [member]	Member			ifrs-full:EntitysTotalForRelatedPartiesMember
1779	Intermediate Holding Company - IHC Tax Group [member]	Member			c070:IntermediateHoldingCompanyMember
1780	US Branch Tax group [member]	Member			c070:UnitedStatesBranchTaxGroupMember
1781	UK Tax group [member]	Member			srt:ParentCompanyMember
1782	Other [member]	Member			c070:OtherSubsidiariesMember
1783	Related parties [member]	Member			ifrs-full:RelatedPartiesMember
1784	Geographical areas [axis]	Axis			ifrs-full:GeographicalAreasAxis
1785	Geographical areas [member]	Member			ifrs-full:GeographicalAreasMember
1786	UK Legislation enacted [member]	Member			country:GB
1787	Consolidated Entities [Axis]	Axis			srt:ConsolidatedEntitiesAxis
1788	Consolidated Entities [Domain]	Member			srt:ConsolidatedEntitiesDomain
1789	Barclays Bank Group [member]	Member			c070:BarclaysBankGroupMember
1790	Non-adjusting events after reporting period [axis]	Axis			ifrs-full:NonadjustingEventsAfterReportingPeriodAxis
1791	Non-adjusting events after reporting period [member]	Member			ifrs-full:NonadjustingEventsMember
1792	Changes in tax rates or tax laws enacted or announced [member]	Member			ifrs-full:ChangesInTaxRatesOrTaxLawsEnactedOrAnnouncedMember
1793	New IFRSs [axis]	Axis			ifrs-full:NewIFRSsAxis
1794	New IFRSs [member]	Member			ifrs-full:NewIFRSsMember
1795	IAS 12 [member]	Member			c070:Ias12Member
1796	Components of equity [axis]	Axis			ifrs-full:ComponentsOfEquityAxis
1797	Equity [member]	Member			ifrs-full:EquityMember
1798	Other equity instruments [member]	Member			ifrs-full:OtherEquityInterestMember
1799	Additional Tier 1 securities [member]	Member			c070:AdditionalTierOneSecuritiesMember
1800	Disclosure of temporary difference, unused tax losses and unused tax credits [line items]	LineItems			ifrs-full:DisclosureOfTemporaryDifferenceUnusedTaxLossesAndUnusedTaxCreditsLineItems
1801	Average effective tax rate	Concept (Percent)	For Period		ifrs-full:AverageEffectiveTaxRate
1802	Applicable tax rate	Concept (Percent)	For Period		ifrs-full:ApplicableTaxRate
1803	New and amended standards and interpretations	Concept (Text/String)	For Period		ifrs-full:DiscussionOfImpactThatInitialApplicationOfIFRSIsExpectedToHaveOnFinancialStatements
1804	Tax effect from change in tax rate	Concept (Monetary)	For Period	Debit	ifrs-full:TaxEffectFromChangeInTaxRate
1805	Other	Concept (Monetary)	For Period	Credit	ifrs-full:OtherIndividuallyImmaterialComponentsOfOtherComprehensiveIncomeNetOfTax
1806	Tax expense relating to profit (loss) from ordinary activities of discontinued operations	Concept (Monetary)	For Period	Debit	ifrs-full:TaxExpenseRelatingToProfitLossFromOrdinaryActivitiesOfDiscontinuedOperations
1807	Deferred tax assets	Concept (Monetary)	As Of	Debit	ifrs-full:DeferredTaxAssets
1808	Deferred tax liabilities	Concept (Monetary)	As Of	Credit	ifrs-full:DeferredTaxLiabilities
1809	Deductible temporary differences for which no deferred tax asset is recognised	Concept (Monetary)	As Of		ifrs-full:DeductibleTemporaryDifferencesForWhichNoDeferredTaxAssetIsRecognised
1810	Unused tax losses for which no deferred tax asset recognised	Concept (Monetary)	As Of		ifrs-full:UnusedTaxLossesForWhichNoDeferredTaxAssetRecognised
1811	Unused tax credits for which no deferred tax asset recognised	Concept (Monetary)	As Of		ifrs-full:UnusedTaxCreditsForWhichNoDeferredTaxAssetRecognised
1812	Temporary differences associated with investments in subsidiaries, branches and associates and interests in joint arrangements for which deferred tax liabilities have not been recognised	Concept (Monetary)	As Of		ifrs-full:TemporaryDifferencesAssociatedWithInvestmentsInSubsidiariesBranchesAndAssociatesAndInterestsInJointVentures
1813	Tax benefit arising from previously unrecognised tax loss, tax credit or temporary difference of prior period used to reduce current tax expense	Concept (Monetary)	For Period	Credit	ifrs-full:TaxBenefitArisingFromPreviouslyUnrecognisedTaxLossTaxCreditOrTemporaryDifferenceOfPriorPeriodUsedToReduceCurrentTaxExpense
1814	041301 - Disclosure - Dividends on ordinary shares (Narrative) (Details)	Network	*	*	http://www.barclays.co.uk/role/DividendsOnOrdinarySharesNarrativeDetails
1815	Statement of changes in equity [table]	Table	*	*	ifrs-full:StatementOfChangesInEquityTable
1816	Classes of share capital [axis]	Axis			ifrs-full:ClassesOfShareCapitalAxis
1817	Share capital [member]	Member			ifrs-full:ClassesOfShareCapitalMember
1818	Ordinary shares [member]	Member			ifrs-full:OrdinarySharesMember
1819	Preference shares [member]	Member			ifrs-full:PreferenceSharesMember
1820	4.75% Euro Preference Shares [member]	Member			c070:FourPointSevenFivePercentEuroOneHundredParValueMember
1821	6.278% USD 100 [member]	Member			c070:SixPointTwoSevenEightPercentUsdOneHundredParValueMember
1822	8.125% USD 0.25 [member]	Member			c070:EightPointOneTwoFivePercentUsdTwentyFiveCentsParValueMember
1823	Categories of related parties [axis]	Axis			ifrs-full:CategoriesOfRelatedPartiesAxis
1824	Entity's total for related parties [member]	Member			ifrs-full:EntitysTotalForRelatedPartiesMember
1825	Barclays PLC [member]	Member			srt:ParentCompanyMember
1826	Barclays Bank UK PLC [member]	Member			c070:BarclaysBankUkPlcMember
1827	Components of equity [axis]	Axis			ifrs-full:ComponentsOfEquityAxis
1828	Equity [member]	Member			ifrs-full:EquityMember
1829	Total equity excluding non-controlling interests [member]	Member			ifrs-full:EquityAttributableToOwnersOfParentMember
1830	Other equity instruments [member]	Member			ifrs-full:OtherEquityInterestMember
1831	Statement of changes in equity [line items]	LineItems			ifrs-full:StatementOfChangesInEquityLineItems
1832	Dividends paid, ordinary shares	Concept (Monetary)	For Period	Debit	ifrs-full:DividendsPaidOrdinaryShares
1833	Dividends declared	Concept (Monetary)	For Period		ifrs-full:DividendsProposedOrDeclaredBeforeFinancialStatementsAuthorisedForIssueButNotRecognisedAsDistributionToOwners
1834	Interim dividends	Concept (Monetary)	As Of	Credit	ifrs-full:DividendsPayable
1835	Dividends paid	Concept (Monetary)	For Period	Debit	ifrs-full:DividendsRecognisedAsDistributionsToOwnersOfParent
1836	Dividends paid, ordinary shares per share	Concept (Share)	For Period		ifrs-full:DividendsPaidOrdinarySharesPerShare
1837	Dividends paid, other shares per share	Concept (Share)	For Period		ifrs-full:DividendsPaidOtherSharesPerShare
1838	Par value per share	Concept (Share)	As Of		ifrs-full:ParValuePerShare
1839	Dividends on preference shares and other shareholders equity	Concept (Monetary)	For Period	Debit	ifrs-full:DividendsPaidOtherShares
1840	Other equity instrument holders	Concept (Monetary)	For Period	Credit	c070:ProfitLossAttributableToOtherEquityHoldersOfTheParent
1841	041401 - Disclosure - Trading portfolio (Details)	Network	*	*	http://www.barclays.co.uk/role/TradingPortfolioDetails
1842	Disclosure of detailed information about financial instruments [table]	Table	*	*	ifrs-full:DisclosureOfFinancialInstrumentsTable
1843	Classes of financial instruments [axis]	Axis			ifrs-full:ClassesOfFinancialInstrumentsAxis
1844	Financial instruments, class [member]	Member			ifrs-full:ClassesOfFinancialInstrumentsMember
1845	Debt securities and other eligible bills [member]	Member			ifrs-full:DebtSecuritiesMember
1846	Equity securities [member]	Member			ifrs-full:TradingEquitySecuritiesMember
1847	Traded loans [member]	Member			c070:TradedLoansMember
1848	Commodities [member]	Member			c070:CommoditiesMember
1849	Consolidated Entities [Axis]	Axis			srt:ConsolidatedEntitiesAxis
1850	Consolidated Entities [Domain]	Member			srt:ConsolidatedEntitiesDomain
1851	Barclays Bank Group [member]	Member			c070:BarclaysBankGroupMember
1852	Disclosure of detailed information about financial instruments [line items]	LineItems			ifrs-full:DisclosureOfFinancialInstrumentsLineItems
1853	Trading portfolio assets	Concept (Monetary)	As Of	Debit	ifrs-full:FinancialAssetsAtFairValueThroughProfitOrLossClassifiedAsHeldForTrading
1854	Trading portfolio liabilities	Concept (Monetary)	As Of	Credit	ifrs-full:FinancialLiabilitiesAtFairValueThroughProfitOrLossClassifiedAsHeldForTrading
1855	041501 - Disclosure - Financial assets at fair value through the income statement (Details)	Network	*	*	http://www.barclays.co.uk/role/FinancialAssetsAtFairValueThroughTheIncomeStatementDetails
1856	Disclosure of financial assets [table]	Table	*	*	ifrs-full:DisclosureOfFinancialAssetsTable
1857	Consolidated Entities [Axis]	Axis			srt:ConsolidatedEntitiesAxis
1858	Consolidated Entities [Domain]	Member			srt:ConsolidatedEntitiesDomain
1859	Barclays Bank Group [member]	Member			c070:BarclaysBankGroupMember
1860	Categories of financial assets [axis]	Axis			ifrs-full:CategoriesOfFinancialAssetsAxis
1861	Financial assets, category [member]	Member			ifrs-full:FinancialAssetsCategoryMember
1862	Financial assets designated at fair value [member]	Member			ifrs-full:FinancialAssetsAtFairValueThroughProfitOrLossDesignatedUponInitialRecognitionCategoryMember
1863	Financial assets mandatory at fair value [member]	Member			ifrs-full:FinancialAssetsAtFairValueThroughProfitOrLossMandatorilyMeasuredAtFairValueCategoryMember
1864	Disclosure of financial assets [line items]	LineItems			ifrs-full:DisclosureOfFinancialAssetsLineItems
1865	Loans and advances	Concept (Monetary)	As Of	Debit	ifrs-full:LoansAndReceivables
1866	Debt securities	Concept (Monetary)	As Of	Debit	ifrs-full:DebtInstrumentsHeld
1867	Equity securities	Concept (Monetary)	As Of	Debit	ifrs-full:EquityInstrumentsHeld
1868	Reverse repurchase agreements	Concept (Monetary)	As Of	Debit	ifrs-full:ReverseRepurchaseAgreementsAndCashCollateralOnSecuritiesBorrowed
1869	Other financial assets	Concept (Monetary)	As Of	Debit	ifrs-full:OtherFinancialAssets
1870	Financial assets at fair value through the income statement	Concept (Monetary)	As Of	Debit	ifrs-full:FinancialAssetsAtFairValueThroughProfitOrLoss
1871	041502 - Disclosure - Financial assets at fair value through the income statement - Credit risk of loans and advances designated at fair value and related credit derivatives (Details)	Network	*	*	http://www.barclays.co.uk/role/FinancialAssetsAtFairValueThroughTheIncomeStatementCreditRiskOfLoansAndAdvancesDesignatedAtFairValueAndRelatedCreditDerivativesDetails
1872	Disclosure of financial assets [table]	Table	*	*	ifrs-full:DisclosureOfFinancialAssetsTable
1873	Categories of financial assets [axis]	Axis			ifrs-full:CategoriesOfFinancialAssetsAxis
1874	Financial assets, category [member]	Member			ifrs-full:FinancialAssetsCategoryMember
1875	Loans and advances [member]	Member			ifrs-full:LoansAndReceivablesCategoryMember
1876	Types of risks [axis]	Axis			ifrs-full:TypesOfRisksAxis
1877	Risks [member]	Member			ifrs-full:TypesOfRisksMember
1878	Credit risk [member]	Member			ifrs-full:CreditRiskMember
1879	Classes of financial assets [axis]	Axis			ifrs-full:ClassesOfFinancialAssetsAxis
1880	Financial assets, class [member]	Member			ifrs-full:FinancialAssetsMember
1881	Derivatives [member]	Member			ifrs-full:DerivativesMember
1882	Consolidated Entities [Axis]	Axis			srt:ConsolidatedEntitiesAxis
1883	Consolidated Entities [Domain]	Member			srt:ConsolidatedEntitiesDomain
1884	Barclays Bank Group [member]	Member			c070:BarclaysBankGroupMember
1885	Disclosure of financial assets [line items]	LineItems			ifrs-full:DisclosureOfFinancialAssetsLineItems
1886	Loans and advances designated at fair value, attributable to credit risk	Concept (Monetary)	As Of		ifrs-full:MaximumExposureToCreditRiskOfLoansOrReceivables
1887	Value mitigated by related credit derivatives	Concept (Monetary)	As Of		ifrs-full:AmountByWhichLoansOrReceivablesRelatedCreditDerivativesOrSimilarInstrumentsMitigateMaximumExposureToCreditRisk
1888	Changes in fair value during the year ended	Concept (Monetary)	For Period	Debit	ifrs-full:ChangesInFairValueOfLoansOrReceivablesAttributableToChangesInCreditRiskOfFinancialAssets
1889	Cumulative changes in fair value from inception	Concept (Monetary)	As Of	Debit	ifrs-full:AccumulatedChangesInFairValueOfLoanOrReceivableAttributableToChangesInCreditRiskOfFinancialAssets
1890	041600 - Disclosure - Derivative financial instruments - Total Derivatives (Details)	Network	*	*	http://www.barclays.co.uk/role/DerivativeFinancialInstrumentsTotalDerivativesDetails
1891	Disclosure of detailed information about financial instruments [table]	Table	*	*	ifrs-full:DisclosureOfFinancialInstrumentsTable
1892	Classes of financial instruments [axis]	Axis			ifrs-full:ClassesOfFinancialInstrumentsAxis
1893	Financial instruments, class [member]	Member			ifrs-full:ClassesOfFinancialInstrumentsMember
1894	Held for trading [member]	Member			c070:HeldForTradingMember
1895	Hedging instruments [axis]	Axis			ifrs-full:HedgingInstrumentsAxis
1896	Hedging instruments [member]	Member			ifrs-full:HedgingInstrumentsMember
1897	Held for risk management [Member]	Member			c070:HeldForRiskManagementMember
1898	Measurement [axis]	Axis			ifrs-full:MeasurementAxis
1899	Aggregated measurement [member]	Member			ifrs-full:AggregatedMeasurementMember
1900	At fair value [member]	Member			ifrs-full:AtFairValueMember
1901	Consolidated Entities [Axis]	Axis			srt:ConsolidatedEntitiesAxis
1902	Consolidated Entities [Domain]	Member			srt:ConsolidatedEntitiesDomain
1903	Barclays Bank Group [member]	Member			c070:BarclaysBankGroupMember
1904	Classes of financial assets [axis]	Axis			ifrs-full:ClassesOfFinancialAssetsAxis
1905	Financial assets, class [member]	Member			ifrs-full:FinancialAssetsMember
1906	Derivatives [member]	Member			ifrs-full:DerivativesMember
1907	Disclosure of risk management strategy related to hedge accounting [line items]	LineItems			ifrs-full:DisclosureOfRiskManagementStrategyRelatedToHedgeAccountingLineItems
1908	Notional amount	Concept (Monetary)	As Of		ifrs-full:NotionalAmount
1909	Derivative assets held for trading	Concept (Monetary)	As Of	Debit	ifrs-full:DerivativeFinancialAssetsHeldForTrading
1910	Derivative assets held for held for risk management	Concept (Monetary)	As Of	Debit	ifrs-full:DerivativeFinancialAssetsHeldForHedging
1911	Derivative assets	Concept (Monetary)	As Of	Debit	ifrs-full:DerivativeFinancialAssets
1912	Derivative liabilities held for trading	Concept (Monetary)	As Of	Credit	ifrs-full:DerivativeFinancialLiabilitiesHeldForTrading
1913	Derivative liabilities held for risk management	Concept (Monetary)	As Of	Credit	ifrs-full:DerivativeFinancialLiabilitiesHeldForHedging
1914	Derivative liabilities	Concept (Monetary)	As Of	Credit	ifrs-full:DerivativeFinancialLiabilities
1915	041605 - Disclosure - Derivative financial instruments - Derivatives held for trading (Details)	Network	*	*	http://www.barclays.co.uk/role/DerivativeFinancialInstrumentsDerivativesHeldForTradingDetails
1916	Disclosure of detailed information about financial instruments [table]	Table	*	*	ifrs-full:DisclosureOfFinancialInstrumentsTable
1917	Classes of financial instruments [axis]	Axis			ifrs-full:ClassesOfFinancialInstrumentsAxis
1918	Financial instruments, class [member]	Member			ifrs-full:ClassesOfFinancialInstrumentsMember
1919	Held for trading [member]	Member			c070:HeldForTradingMember
1920	Types of risks [axis]	Axis			ifrs-full:TypesOfRisksAxis
1921	Risks [member]	Member			ifrs-full:TypesOfRisksMember
1922	Foreign exchange derivatives [member]	Member			ifrs-full:CurrencyRiskMember
1923	Interest rate derivatives [member]	Member			ifrs-full:InterestRateRiskMember
1924	Credit derivatives [member]	Member			ifrs-full:CreditRiskMember
1925	Equity and stock index derivatives [member]	Member			ifrs-full:EquityPriceRiskMember
1926	Commodity derivatives [member]	Member			ifrs-full:CommodityPriceRiskMember
1927	Classes of financial assets [axis]	Axis			ifrs-full:ClassesOfFinancialAssetsAxis
1928	Financial assets, class [member]	Member			ifrs-full:FinancialAssetsMember
1929	Derivatives [member]	Member			ifrs-full:DerivativesMember
1930	Forward contract [member]	Member			ifrs-full:ForwardContractMember
1931	Currency swaps [member]	Member			ifrs-full:CurrencySwapContractMember
1932	Interest rate swaps [member]	Member			ifrs-full:InterestRateSwapContractMember
1933	Swaps [member]	Member			ifrs-full:SwapContractMember
1934	Swaps and forwards [member]	Member			c070:SwapsAndForwardsMember
1935	Options bought and sold [member]	Member			ifrs-full:OptionContractMember
1936	Futures and options bought and sold [Member]	Member			c070:FuturesAndOptionsBoughtAndSoldMember
1937	Measurement [axis]	Axis			ifrs-full:MeasurementAxis
1938	Aggregated measurement [member]	Member			ifrs-full:AggregatedMeasurementMember
1939	At fair value [member]	Member			ifrs-full:AtFairValueMember
1940	Counterparties [axis]	Axis			ifrs-full:CounterpartiesAxis
1941	Counterparties [member]	Member			ifrs-full:CounterpartiesMember
1942	OTC derivatives [member]	Member			c070:OverTheCounterDerivativesMember
1943	Cleared by central counterparty [member]	Member			c070:ClearedByCentralCounterpartyMember
1944	Exchange traded derivatives [member]	Member			c070:ExchangeTradedFuturesAndOptionsMember
1945	Consolidated Entities [Axis]	Axis			srt:ConsolidatedEntitiesAxis
1946	Consolidated Entities [Domain]	Member			srt:ConsolidatedEntitiesDomain
1947	Barclays Bank Group [member]	Member			c070:BarclaysBankGroupMember
1948	Subsidiaries [axis]	Axis			ifrs-full:SignificantInvestmentsInSubsidiariesAxis
1949	Entity's total for subsidiaries [member]	Member			ifrs-full:EntitysTotalForSubsidiariesMember
1950	Subsidiaries [member]	Member			ifrs-full:SubsidiariesMember
1951	Disclosure of detailed information about financial instruments [line items]	LineItems			ifrs-full:DisclosureOfFinancialInstrumentsLineItems
1952	Notional amount	Concept (Monetary)	As Of		ifrs-full:NotionalAmount
1953	Derivative assets held for trading	Concept (Monetary)	As Of	Debit	ifrs-full:DerivativeFinancialAssetsHeldForTrading
1954	Derivative liabilities held for trading	Concept (Monetary)	As Of	Credit	ifrs-full:DerivativeFinancialLiabilitiesHeldForTrading
1955	041610 - Disclosure - Derivative financial instruments - Derivatives held for risk management (Details)	Network	*	*	http://www.barclays.co.uk/role/DerivativeFinancialInstrumentsDerivativesHeldForRiskManagementDetails
1956	Disclosure of detailed information about hedges [table]	Table	*	*	ifrs-full:DisclosureOfHedgeAccountingTable
1957	Hedging instruments [axis]	Axis			ifrs-full:HedgingInstrumentsAxis
1958	Hedging instruments [member]	Member			ifrs-full:HedgingInstrumentsMember
1959	Held for risk management [Member]	Member			c070:HeldForRiskManagementMember
1960	Types of hedges [axis]	Axis			ifrs-full:TypesOfHedgesAxis
1961	Hedges [member]	Member			ifrs-full:TypesOfHedgesMember
1962	Cash flow hedges [member]	Member			ifrs-full:CashFlowHedgesMember
1963	Fair value hedges [member]	Member			ifrs-full:FairValueHedgesMember
1964	Hedges of net investment in foreign operations [member]	Member			ifrs-full:HedgesOfNetInvestmentInForeignOperationsMember
1965	Classes of financial assets [axis]	Axis			ifrs-full:ClassesOfFinancialAssetsAxis
1966	Financial assets, class [member]	Member			ifrs-full:FinancialAssetsMember
1967	Derivatives [member]	Member			ifrs-full:DerivativesMember
1968	Currency swaps [member]	Member			ifrs-full:CurrencySwapContractMember
1969	Interest rate swaps [member]	Member			ifrs-full:InterestRateSwapContractMember
1970	Forward foreign exchange [member]	Member			ifrs-full:ForwardContractMember
1971	Measurement [axis]	Axis			ifrs-full:MeasurementAxis
1972	Aggregated measurement [member]	Member			ifrs-full:AggregatedMeasurementMember
1973	At fair value [member]	Member			ifrs-full:AtFairValueMember
1974	Counterparties [axis]	Axis			ifrs-full:CounterpartiesAxis
1975	Counterparties [member]	Member			ifrs-full:CounterpartiesMember
1976	OTC derivatives [member]	Member			c070:OverTheCounterDerivativesMember
1977	Cleared by central counterparty [member]	Member			c070:ClearedByCentralCounterpartyMember
1978	Types of risks [axis]	Axis			ifrs-full:TypesOfRisksAxis
1979	Risks [member]	Member			ifrs-full:TypesOfRisksMember
1980	Interest rate derivatives [member]	Member			ifrs-full:InterestRateRiskMember
1981	Foreign exchange risk [member]	Member			ifrs-full:CurrencyRiskMember
1982	Consolidated Entities [Axis]	Axis			srt:ConsolidatedEntitiesAxis
1983	Consolidated Entities [Domain]	Member			srt:ConsolidatedEntitiesDomain
1984	Barclays Bank Group [member]	Member			c070:BarclaysBankGroupMember
1985	Subsidiaries [axis]	Axis			ifrs-full:SignificantInvestmentsInSubsidiariesAxis
1986	Entity's total for subsidiaries [member]	Member			ifrs-full:EntitysTotalForSubsidiariesMember
1987	Subsidiaries [member]	Member			ifrs-full:SubsidiariesMember
1988	Disclosure of detailed information about financial instruments [line items]	LineItems			ifrs-full:DisclosureOfFinancialInstrumentsLineItems
1989	Notional amount	Concept (Monetary)	As Of		ifrs-full:NotionalAmount
1990	Derivative assets held for held for risk management	Concept (Monetary)	As Of	Debit	ifrs-full:DerivativeFinancialAssetsHeldForHedging
1991	Derivative liabilities held for risk management	Concept (Monetary)	As Of	Credit	ifrs-full:DerivativeFinancialLiabilitiesHeldForHedging
1992	041615 - Disclosure - Derivative financial instruments - Hedged forecast cash flows (Details)	Network	*	*	http://www.barclays.co.uk/role/DerivativeFinancialInstrumentsHedgedForecastCashFlowsDetails
1993	Disclosure of significant unobservable inputs used in fair value measurement of assets [table]	Table	*	*	ifrs-full:DisclosureOfSignificantUnobservableInputsUsedInFairValueMeasurementOfAssetsTable
1994	Maturity [axis]	Axis			ifrs-full:MaturityAxis
1995	Aggregated time bands [member]	Member			ifrs-full:AggregatedTimeBandsMember
1996	Up to one year [member]	Member			ifrs-full:NotLaterThanOneYearMember
1997	One to two years [member]	Member			ifrs-full:LaterThanOneYearAndNotLaterThanTwoYearsMember
1998	Two to three years [member]	Member			ifrs-full:LaterThanTwoYearsAndNotLaterThanThreeYearsMember
1999	Three to four years [member]	Member			ifrs-full:LaterThanThreeYearsAndNotLaterThanFourYearsMember
2000	Four to five years [member]	Member			ifrs-full:LaterThanFourYearsAndNotLaterThanFiveYearsMember
2001	More than five years [member]	Member			ifrs-full:LaterThanFiveYearsMember
2002	Consolidated Entities [Axis]	Axis			srt:ConsolidatedEntitiesAxis
2003	Consolidated Entities [Domain]	Member			srt:ConsolidatedEntitiesDomain
2004	Barclays Bank Group [member]	Member			c070:BarclaysBankGroupMember
2005	Disclosure of significant unobservable inputs used in fair value measurement of assets [line items]	LineItems			ifrs-full:DisclosureOfSignificantUnobservableInputsUsedInFairValueMeasurementOfAssetsLineItems
2006	Forecast receivable cash flows	Concept (Monetary)	For Period		ifrs-full:FinancialForecastOfCashFlowsForCashgeneratingUnitSignificantUnobservableInputsAssets
2007	Forecast payable cash flows	Concept (Monetary)	For Period		ifrs-full:FinancialForecastOfCashFlowsForCashgeneratingUnitSignificantUnobservableInputsLiabilities
2008	041620 - Disclosure - Derivative financial instruments - Amounts recognised in net interest income (Details)	Network	*	*	http://www.barclays.co.uk/role/DerivativeFinancialInstrumentsAmountsRecognisedInNetInterestIncomeDetails
2009	Condensed Income Statement [Table]	Table	*	*	srt:CondensedIncomeStatementTable
2010	Consolidated Entities [Axis]	Axis			srt:ConsolidatedEntitiesAxis
2011	Consolidated Entities [Domain]	Member			srt:ConsolidatedEntitiesDomain
2012	Barclays Bank Group [member]	Member			c070:BarclaysBankGroupMember
2013	Condensed Income Statements, Captions [Line Items]	LineItems			srt:CondensedIncomeStatementsCaptionsLineItems
2014	Gains on the hedged items attributable to the hedged risk	Concept (Monetary)	For Period	Credit	ifrs-full:GainsLossesOnHedgedItemAttributableToHedgedRisk
2015	Losses on the hedging instruments	Concept (Monetary)	For Period	Credit	ifrs-full:GainsLossesOnHedgingInstrument
2016	Fair value ineffectiveness	Concept (Monetary)	For Period	Credit	ifrs-full:GainLossOnChangeInFairValueOfHedgingInstrumentUsedAsBasisForRecognisingHedgeIneffectiveness
2017	Cash flow hedging ineffectiveness	Concept (Monetary)	For Period	Credit	ifrs-full:GainsLossesOnIneffectivenessOfCashFlowHedgesRecognisedInProfitOrLoss
2018	Net investment hedging ineffectiveness	Concept (Monetary)	For Period	Credit	ifrs-full:GainsLossesOnIneffectivenessOfHedgesOfNetInvestmentsInForeignOperations
2019	041625 - Disclosure - Derivative financial instruments - Hedging instruments which are carried on the Barclays Bank Group's balance sheet (Details)	Network	*	*	http://www.barclays.co.uk/role/DerivativeFinancialInstrumentsHedgingInstrumentsWhichAreCarriedOnTheBarclaysBankGroupsBalanceSheetDetails
2020	Disclosure of detailed information about hedging instruments [table]	Table	*	*	ifrs-full:DisclosureOfDetailedInformationAboutHedgingInstrumentsTable
2021	Hedging instruments [axis]	Axis			ifrs-full:HedgingInstrumentsAxis
2022	Hedging instruments [member]	Member			ifrs-full:HedgingInstrumentsMember
2023	Derivatives [member]	Member			ifrs-full:DerivativesMember
2024	Loans and advances [member]	Member			ifrs-full:LoansAndReceivablesCategoryMember
2025	Types of hedges [axis]	Axis			ifrs-full:TypesOfHedgesAxis
2026	Hedges [member]	Member			ifrs-full:TypesOfHedgesMember
2027	Fair value hedges [member]	Member			ifrs-full:FairValueHedgesMember
2028	Cash flow hedges [member]	Member			ifrs-full:CashFlowHedgesMember
2029	Hedges of net investment [member]	Member			ifrs-full:HedgesOfNetInvestmentInForeignOperationsMember
2030	Types of risks [axis]	Axis			ifrs-full:TypesOfRisksAxis
2031	Risks [member]	Member			ifrs-full:TypesOfRisksMember
2032	Interest rate risk [member]	Member			ifrs-full:InterestRateRiskMember
2033	Foreign exchange risk [member]	Member			ifrs-full:CurrencyRiskMember
2034	Inflation risk [member]	Member			ifrs-full:OtherPriceRiskMember
2035	Consolidated Entities [Axis]	Axis			srt:ConsolidatedEntitiesAxis
2036	Consolidated Entities [Domain]	Member			srt:ConsolidatedEntitiesDomain
2037	Barclays Bank Group [member]	Member			c070:BarclaysBankGroupMember
2038	Disclosure of detailed information about hedging instruments [line items]	LineItems			ifrs-full:DisclosureOfDetailedInformationAboutHedgingInstrumentsLineItems
2039	Hedging instrument, assets	Concept (Monetary)	As Of	Debit	ifrs-full:HedgingInstrumentAssets
2040	Hedging instrument, liabilities	Concept (Monetary)	As Of	Credit	ifrs-full:HedgingInstrumentLiabilities
2041	Nominal amount	Concept (Decimal)	As Of		ifrs-full:NominalAmountOfHedgingInstrument
2042	Change in fair value used as a basis to determine hedge ineffectiveness	Concept (Monetary)	For Period	Credit	ifrs-full:GainLossOnChangeInFairValueOfHedgingInstrumentUsedAsBasisForRecognisingHedgeIneffectiveness
2043	041630 - Disclosure - Derivative financial instruments - The expected notional values of current hedging instruments in future years (Details)	Network	*	*	http://www.barclays.co.uk/role/DerivativeFinancialInstrumentsTheExpectedNotionalValuesOfCurrentHedgingInstrumentsInFutureYearsDetails
2044	Disclosure of information about terms and conditions of hedging instruments and how they affect future cash flows [table]	Table	*	*	ifrs-full:DisclosureOfInformationAboutTermsAndConditionsOfHedgingInstrumentsAndHowTheyAffectFutureCashFlowsTable
2045	Types of hedges [axis]	Axis			ifrs-full:TypesOfHedgesAxis
2046	Hedges [member]	Member			ifrs-full:TypesOfHedgesMember
2047	Fair value hedges [member]	Member			ifrs-full:FairValueHedgesMember
2048	Maturity [axis]	Axis			ifrs-full:MaturityAxis
2049	Aggregated time bands [member]	Member			ifrs-full:AggregatedTimeBandsMember
2050	2018 [member]	Member			ifrs-full:CurrentMember
2051	2019 [member]	Member			ifrs-full:LaterThanOneYearAndNotLaterThanTwoYearsMember
2052	2020 [member]	Member			ifrs-full:LaterThanTwoYearsAndNotLaterThanThreeYearsMember
2053	2021 [member]	Member			ifrs-full:LaterThanThreeYearsAndNotLaterThanFourYearsMember
2054	2022 [member]	Member			ifrs-full:LaterThanFourYearsAndNotLaterThanFiveYearsMember
2055	Later than five years [member]	Member			ifrs-full:LaterThanFiveYearsMember
2056	Consolidated Entities [Axis]	Axis			srt:ConsolidatedEntitiesAxis
2057	Consolidated Entities [Domain]	Member			srt:ConsolidatedEntitiesDomain
2058	Barclays Bank Group [member]	Member			c070:BarclaysBankGroupMember
2059	Types of risks [axis]	Axis			ifrs-full:TypesOfRisksAxis
2060	Risks [member]	Member			ifrs-full:TypesOfRisksMember
2061	Interest rate risk [member]	Member			ifrs-full:InterestRateRiskMember
2062	Inflation risk [member]	Member			ifrs-full:OtherPriceRiskMember
2063	Types of interest rates [axis]	Axis			ifrs-full:TypesOfInterestRatesAxis
2064	Interest rate types [member]	Member			ifrs-full:InterestRateTypesMember
2065	Fixed interest rate [member]	Member			ifrs-full:FixedInterestRateMember
2066	Disclosure of information about terms and conditions of hedging instruments and how they affect future cash flows [line items]	LineItems			ifrs-full:DisclosureOfInformationAboutTermsAndConditionsOfHedgingInstrumentsAndHowTheyAffectFutureCashFlowsLineItems
2067	Nominal amount	Concept (Decimal)	As Of		ifrs-full:NominalAmountOfHedgingInstrument
2068	The average rate % of the hedging instruments across the relationships is:	Concept (Percent)	As Of		ifrs-full:AverageRateOfHedgingInstrument
2069	For number of hedges	Concept (Integer)	For Period		c070:NumberOfHedges
2070	041635 - Disclosure - Derivative financial instruments - Hedged items in fair value hedge accounting relationships including the ineffectiveness recognised in the income statement (Details)	Network	*	*	http://www.barclays.co.uk/role/DerivativeFinancialInstrumentsHedgedItemsInFairValueHedgeAccountingRelationshipsIncludingTheIneffectivenessRecognisedInTheIncomeStatementDetails
2071	Disclosure of detailed information about hedged items [table]	Table	*	*	ifrs-full:DisclosureOfDetailedInformationAboutHedgedItemsTable
2072	Hedged items [axis]	Axis			ifrs-full:HedgedItemsAxis
2073	Hedged items [member]	Member			ifrs-full:HedgedItemsMember
2074	Loans and advances [member]	Member			ifrs-full:LoansAndReceivablesCategoryMember
2075	Debt securities in issue [member]	Member			ifrs-full:DebtSecuritiesMember
2076	Types of hedges [axis]	Axis			ifrs-full:TypesOfHedgesAxis
2077	Hedges [member]	Member			ifrs-full:TypesOfHedgesMember
2078	Fair value hedges [member]	Member			ifrs-full:FairValueHedgesMember
2079	Types of risks [axis]	Axis			ifrs-full:TypesOfRisksAxis
2080	Risks [member]	Member			ifrs-full:TypesOfRisksMember
2081	Interest rate risk [member]	Member			ifrs-full:InterestRateRiskMember
2082	Foreign exchange risk [member]	Member			ifrs-full:CurrencyRiskMember
2083	Inflation risk [member]	Member			ifrs-full:OtherPriceRiskMember
2084	Consolidated Entities [Axis]	Axis			srt:ConsolidatedEntitiesAxis
2085	Consolidated Entities [Domain]	Member			srt:ConsolidatedEntitiesDomain
2086	Barclays Bank Group [member]	Member			c070:BarclaysBankGroupMember
2087	Categories of financial assets [axis]	Axis			ifrs-full:CategoriesOfFinancialAssetsAxis
2088	Financial assets, category [member]	Member			ifrs-full:FinancialAssetsCategoryMember
2089	Financial assets at amortised cost [member]	Member			ifrs-full:FinancialAssetsAtAmortisedCostCategoryMember
2090	Financial assets at fair value through other comprehensive income [member]	Member			ifrs-full:FinancialAssetsAtFairValueThroughOtherComprehensiveIncomeCategoryMember
2091	Categories of financial liabilities [axis]	Axis			ifrs-full:CategoriesOfFinancialLiabilitiesAxis
2092	Financial liabilities, category [member]	Member			ifrs-full:FinancialLiabilitiesCategoryMember
2093	Financial liabilities at amortised cost [member]	Member			ifrs-full:FinancialLiabilitiesAtAmortisedCostCategoryMember
2094	Disclosure of detailed information about hedged items [line items]	LineItems			ifrs-full:DisclosureOfDetailedInformationAboutHedgedItemsLineItems
2095	Hedged item, assets	Concept (Monetary)	As Of	Debit	ifrs-full:HedgedItemAssets
2096	Hedged item, liabilities	Concept (Monetary)	As Of	Credit	ifrs-full:HedgedItemLiabilities
2097	Accumulated fair value hedge adjustment included in carrying amount	Concept (Monetary)	As Of	Debit	ifrs-full:AccumulatedFairValueHedgeAdjustmentOnHedgedItemIncludedInCarryingAmountAssets
2098	Accumulated fair value hedge adjustment included in carrying amount	Concept (Monetary)	As Of	Credit	ifrs-full:AccumulatedFairValueHedgeAdjustmentOnHedgedItemIncludedInCarryingAmountLiabilities
2099	Change in fair value used as a basis to determine hedge ineffectiveness	Concept (Monetary)	For Period	Credit	ifrs-full:GainLossOnChangeInFairValueOfHedgedItemUsedAsBasisForRecognisingHedgeIneffectiveness
2100	Of which: Accumulated fair value adjustment on items no longer in a hedge relationship	Concept (Monetary)	As Of	Debit	ifrs-full:AccumulatedFairValueHedgeAdjustmentRemainingInStatementOfFinancialPositionForHedgedItemThatCeasedToBeAdjustedForHedgingGainsAndLossesAssets
2101	Of which: Accumulated fair value adjustment on items no longer in a hedge relationship	Concept (Monetary)	As Of	Credit	ifrs-full:AccumulatedFairValueHedgeAdjustmentRemainingInStatementOfFinancialPositionForHedgedItemThatCeasedToBeAdjustedForHedgingGainsAndLossesLiabilities
2102	Hedge ineffectiveness recognised in the income statement	Concept (Monetary)	For Period	Credit	ifrs-full:GainLossOnHedgeIneffectivenessRecognisedInProfitOrLoss
2103	Line item in the income statement used to recognised ineffectiveness	Concept (Text/String)	For Period		ifrs-full:DescriptionOfLineItemInStatementOfComprehensiveIncomeThatIncludesRecognisedHedgeIneffectiveness
2104	041640 - Disclosure - Derivative financial instruments - Hedged items in cash flow hedge accounting and hedges of net investments in foreign operations including the effect on the income statement and OCI (Details)	Network	*	*	http://www.barclays.co.uk/role/DerivativeFinancialInstrumentsHedgedItemsInCashFlowHedgeAccountingAndHedgesOfNetInvestmentsInForeignOperationsIncludingTheEffectOnTheIncomeStatementAndOCIDetails
2105	Disclosure of detailed information about hedged items [table]	Table	*	*	ifrs-full:DisclosureOfDetailedInformationAboutHedgedItemsTable
2106	Consolidated Entities [Axis]	Axis			srt:ConsolidatedEntitiesAxis
2107	Consolidated Entities [Domain]	Member			srt:ConsolidatedEntitiesDomain
2108	Barclays Bank Group [member]	Member			c070:BarclaysBankGroupMember
2109	Categories of financial liabilities [axis]	Axis			ifrs-full:CategoriesOfFinancialLiabilitiesAxis
2110	Financial liabilities, category [member]	Member			ifrs-full:FinancialLiabilitiesCategoryMember
2111	Financial liabilities at amortised cost [member]	Member			ifrs-full:FinancialLiabilitiesAtAmortisedCostCategoryMember
2112	Categories of financial assets [axis]	Axis			ifrs-full:CategoriesOfFinancialAssetsAxis
2113	Financial assets, category [member]	Member			ifrs-full:FinancialAssetsCategoryMember
2114	Financial assets at amortised cost [member]	Member			ifrs-full:FinancialAssetsAtAmortisedCostCategoryMember
2115	Types of risks [axis]	Axis			ifrs-full:TypesOfRisksAxis
2116	Risks [member]	Member			ifrs-full:TypesOfRisksMember
2117	Interest rate risk [member]	Member			ifrs-full:InterestRateRiskMember
2118	Types of hedges [axis]	Axis			ifrs-full:TypesOfHedgesAxis
2119	Hedges [member]	Member			ifrs-full:TypesOfHedgesMember
2120	Cash flow hedges [member]	Member			ifrs-full:CashFlowHedgesMember
2121	Hedges of net investment [member]	Member			ifrs-full:HedgesOfNetInvestmentInForeignOperationsMember
2122	Hedged items [axis]	Axis			ifrs-full:HedgedItemsAxis
2123	Hedged items [member]	Member			ifrs-full:HedgedItemsMember
2124	Loans and advances [member]	Member			ifrs-full:LoansAndReceivablesCategoryMember
2125	Currency [Axis}	Axis			srt:CurrencyAxis
2126	All Currencies [Domain]	Member			currency:AllCurrenciesDomain
2127	USD foreign operations	Member			currency:USD
2128	EUR foreign operations	Member			currency:EUR
2129	ZAR foreign operations	Member			currency:ZAR
2130	CAD foreign operations	Member			currency:CAD
2131	CHF foreign operations	Member			currency:CHF
2132	HKD foreign operations	Member			currency:HKD
2133	JPY foreign operations	Member			currency:JPY
2134	MXN foreign operations	Member			currency:MXN
2135	SEK foreign operations	Member			currency:SEK
2136	SGD foreign operations	Member			currency:SGD
2137	THB foreign operations	Member			currency:THB
2138	KRW foreign operations	Member			currency:KRW
2139	TWD foreign operations	Member			currency:TWD
2140	BRL foreign operations	Member			currency:BRL
2141	CNY foreign operations	Member			currency:CNY
2142	INR foreign operations	Member			currency:INR
2143	Disclosure of detailed information about hedged items [line items]	LineItems			ifrs-full:DisclosureOfDetailedInformationAboutHedgedItemsLineItems
2144	Change in fair value used as a basis to determine hedge ineffectiveness	Concept (Monetary)	For Period	Credit	ifrs-full:GainLossOnChangeInFairValueOfHedgedItemUsedAsBasisForRecognisingHedgeIneffectiveness
2145	Balance in cash flow hedge reserve for continuing hedges	Concept (Monetary)	As Of	Credit	ifrs-full:ReserveOfCashFlowHedgesContinuingHedges
2146	Balance in foreign currency reserve for continuing hedges	Concept (Monetary)	As Of	Credit	ifrs-full:ReserveOfExchangeDifferencesOnTranslationContinuingHedges
2147	Balances remaining in cash flow hedge reserve for which hedge accounting is no longer applied	Concept (Monetary)	As Of	Credit	ifrs-full:ReserveOfCashFlowHedgesHedgingRelationshipsForWhichHedgeAccountingIsNoLongerApplied
2148	Balances remaining in foreign currency translation reserve for which hedge accounting is no longer applied	Concept (Monetary)	As Of	Credit	ifrs-full:ReserveOfExchangeDifferencesOnTranslationHedgingRelationshipsForWhichHedgeAccountingIsNoLongerApplied
2149	Hedging gains or losses recognised in other comprehensive income	Concept (Monetary)	For Period	Credit	ifrs-full:GainLossOnHedgeIneffectivenessRecognisedInOtherComprehensiveIncome
2150	Hedge ineffectiveness recognised in the income statement	Concept (Monetary)	For Period	Credit	ifrs-full:GainLossOnHedgeIneffectivenessRecognisedInProfitOrLoss
2151	Line item in the statement of comprehensive used to recognised ineffectiveness	Concept (Text/String)	For Period		ifrs-full:DescriptionOfLineItemInStatementOfComprehensiveIncomeThatIncludesRecognisedHedgeIneffectiveness
2152	041641 - Disclosure - Derivative financial instruments - Impact on the income statement and OCI of recycling amounts in respect of Cash flow hedges and Net investment hedges of foreign operations (Details)	Network	*	*	http://www.barclays.co.uk/role/DerivativeFinancialInstrumentsImpactOnTheIncomeStatementAndOCIOfRecyclingAmountsInRespectOfCashFlowHedgesAndNetInvestmentHedgesOfForeignOperationsDetails
2153	Disclosure of information about amounts that affected statement of comprehensive income as result of hedge accounting [table]	Table	*	*	ifrs-full:DisclosureOfInformationAboutAmountsThatAffectedStatementOfComprehensiveIncomeAsResultOfHedgeAccountingTable
2154	Consolidated Entities [Axis]	Axis			srt:ConsolidatedEntitiesAxis
2155	Consolidated Entities [Domain]	Member			srt:ConsolidatedEntitiesDomain
2156	Barclays Bank Group [member]	Member			c070:BarclaysBankGroupMember
2157	Types of risks [axis]	Axis			ifrs-full:TypesOfRisksAxis
2158	Risks [member]	Member			ifrs-full:TypesOfRisksMember
2159	Interest rate risk [member]	Member			ifrs-full:InterestRateRiskMember
2160	Financial statement location [Axis]	Axis			c070:FinancialStatementLocationAxis
2161	Financial statement location [Member]	Member			c070:FinancialStatementLocationDomain
2162	Interest income [member]	Member			c070:InterestIncomeMember
2163	Other income [member]	Member			c070:OtherIncomeMember
2164	Disclosure of information about amounts that affected statement of comprehensive income as result of hedge accounting [line items]	LineItems			ifrs-full:DisclosureOfInformationAboutAmountsThatAffectedStatementOfComprehensiveIncomeAsResultOfHedgeAccountingLineItems
2165	Amount recycled from OCI due to hedged item affecting income statement	Concept (Monetary)	For Period	Debit	ifrs-full:ReclassificationAdjustmentsOnCashFlowHedgesForWhichHedgedItemAffectedProfitOrLossNetOfTax
2166	Amount recycled from OCI due to hedged cash flow no longer expected to occur	Concept (Monetary)	For Period	Debit	ifrs-full:ReclassificationAdjustmentsOnCashFlowHedgesForWhichHedgedFutureCashFlowsAreNoLongerExpectedToOccurNetOfTax
2167	Amount recycled from OCI due to hedged item affecting income statement	Concept (Monetary)	For Period	Debit	ifrs-full:ReclassificationAdjustmentsOnHedgesOfNetInvestmentsInForeignOperationsNetOfTax
2168	Amount recycled from OCI due to hedged net investments in foreign operations no longer expected to occur	Concept (Monetary)	For Period	Debit	c070:ReclassificationAdjustmentsOnHedgesOfNetInvestmentsInForeignOperationsForWhichHedgedFutureCashFlowsAreNoLongerExpectedToOccurNetOfTax
2169	041645 - Disclosure - Derivative financial instruments - Reconciliation of the movements of the cash flow hedge reserve and the currency translation reserve (Details)	Network	*	*	http://www.barclays.co.uk/role/DerivativeFinancialInstrumentsReconciliationOfTheMovementsOfTheCashFlowHedgeReserveAndTheCurrencyTranslationReserveDetails
2170	Disclosure of information about amounts that affected statement of comprehensive income as result of hedge accounting [table]	Table	*	*	ifrs-full:DisclosureOfInformationAboutAmountsThatAffectedStatementOfComprehensiveIncomeAsResultOfHedgeAccountingTable
2171	Consolidated Entities [Axis]	Axis			srt:ConsolidatedEntitiesAxis
2172	Consolidated Entities [Domain]	Member			srt:ConsolidatedEntitiesDomain
2173	Barclays Bank Group [member]	Member			c070:BarclaysBankGroupMember
2174	Types of hedges [axis]	Axis			ifrs-full:TypesOfHedgesAxis
2175	Hedges [member]	Member			ifrs-full:TypesOfHedgesMember
2176	Hedges of net investment [member]	Member			ifrs-full:HedgesOfNetInvestmentInForeignOperationsMember
2177	Disclosure of information about amounts that affected statement of comprehensive income as result of hedge accounting [line items]	LineItems			ifrs-full:DisclosureOfInformationAboutAmountsThatAffectedStatementOfComprehensiveIncomeAsResultOfHedgeAccountingLineItems
2178	Reserve of cash flow hedges, beginning balance	Concept (Monetary)	As Of	Credit	ifrs-full:ReserveOfCashFlowHedges
2179	Currency translation movements, cash flow hedge reserve	Concept (Monetary)	For Period	Credit	c070:CurrencyTranslationMovementsCashFlowHedgeReserve
2180	Hedging gains / losses for the reporting period, currency translation reseve	Concept (Monetary)	For Period	Credit	ifrs-full:GainsLossesOnExchangeDifferencesOnTranslationBeforeTax
2181	Amounts reclassified to profit or loss - In relation to cash flows affecting profit or loss, cash flow hedge reserve	Concept (Monetary)	For Period	Debit	ifrs-full:ReclassificationAdjustmentsOnCashFlowHedgesBeforeTax
2182	Tax, cash flow hedge reserve	Concept (Monetary)	For Period	Debit	ifrs-full:IncomeTaxRelatingToCashFlowHedgesOfOtherComprehensiveIncome
2183	Reserve of cash flow hedges, ending balance	Concept (Monetary)	As Of	Credit	ifrs-full:ReserveOfCashFlowHedges
2184	Currency translation reserve, beginning balance	Concept (Monetary)	As Of	Credit	ifrs-full:ReserveOfExchangeDifferencesOnTranslation
2185	Currency translation movements, currency translation reseve	Concept (Monetary)	For Period	Credit	c070:CurrencyTranslationMovementsCurrencyTranslationReserve
2186	Amounts reclassified to profit or loss - In relation to cash flows no longer expected to occur, currency translation reserve	Concept (Monetary)	For Period	Debit	ifrs-full:ReclassificationAdjustmentsOnCashFlowHedgesForWhichHedgedFutureCashFlowsAreNoLongerExpectedToOccurNetOfTax
2187	Amounts reclassified to profit or loss - In relation to cash flows affecting profit or loss, currency translation reseve	Concept (Monetary)	For Period	Debit	ifrs-full:ReclassificationAdjustmentsOnExchangeDifferencesOnTranslationBeforeTax
2188	Tax, currency translation reseve	Concept (Monetary)	For Period	Debit	ifrs-full:IncomeTaxRelatingToExchangeDifferencesOnTranslationOfOtherComprehensiveIncome
2189	Currency translation reserve, ending balance	Concept (Monetary)	As Of	Credit	ifrs-full:ReserveOfExchangeDifferencesOnTranslation
2190	041650 - Disclosure - Derivative financial instruments (Narrative) (Details)	Network	*	*	http://www.barclays.co.uk/role/DerivativeFinancialInstrumentsNarrativeDetails
2191	Disclosure of fair value measurement of assets [table]	Table	*	*	ifrs-full:DisclosureOfFairValueMeasurementOfAssetsTable
2192	Types of hedges [axis]	Axis			ifrs-full:TypesOfHedgesAxis
2193	Hedges [member]	Member			ifrs-full:TypesOfHedgesMember
2194	Cash flow hedges [member]	Member			ifrs-full:CashFlowHedgesMember
2195	Consolidated Entities [Axis]	Axis			srt:ConsolidatedEntitiesAxis
2196	Consolidated Entities [Domain]	Member			srt:ConsolidatedEntitiesDomain
2197	Barclays Bank Group [member]	Member			c070:BarclaysBankGroupMember
2198	Disclosure of fair value measurement of assets [line items]	LineItems			ifrs-full:DisclosureOfFairValueMeasurementOfAssetsLineItems
2199	Maximum period hedge exposure to variability in future cash flows	Concept (xbrli:durationItemType)	For Period		c070:MaximumPeriodHedgeExposureToVariabilityInFutureCashFlows
2200	Description of how entity establishes hedge ratio and what sources of hedge ineffectiveness are	Concept (Text/String)	For Period		ifrs-full:DescriptionOfHowEntityEstablishesHedgeRatioAndWhatSourcesOfHedgeIneffectivenessAre
2201	Net interest income	Concept (Monetary)	For Period	Credit	ifrs-full:InterestRevenueExpense
2202	041701 - Disclosure - Financial assets at fair value through other comprehensive income and Financial Investments (Details)	Network	*	*	http://www.barclays.co.uk/role/FinancialAssetsAtFairValueThroughOtherComprehensiveIncomeAndFinancialInvestmentsDetails
2203	Disclosure of financial assets [table]	Table	*	*	ifrs-full:DisclosureOfFinancialAssetsTable
2204	Categories of financial assets [axis]	Axis			ifrs-full:CategoriesOfFinancialAssetsAxis
2205	Financial assets, category [member]	Member			ifrs-full:FinancialAssetsCategoryMember
2206	Available for sale investments [member]	Member			ifrs-full:FinancialAssetsAvailableforsaleCategoryMember
2207	Held to maturity debt securities [member]	Member			ifrs-full:HeldtomaturityInvestmentsCategoryMember
2208	Loans and advances [member]	Member			ifrs-full:LoansAndReceivablesCategoryMember
2209	Classes of assets [axis]	Axis			ifrs-full:ClassesOfAssetsAxis
2210	Assets [member]	Member			ifrs-full:ClassesOfAssetsMember
2211	Debt securities and other eligible bills [member]	Member			ifrs-full:DebtSecuritiesMember
2212	Equity securities [member]	Member			ifrs-full:EquityInvestmentsMember
2213	Consolidated Entities [Axis]	Axis			srt:ConsolidatedEntitiesAxis
2214	Consolidated Entities [Domain]	Member			srt:ConsolidatedEntitiesDomain
2215	Barclays Bank Group [member]	Member			c070:BarclaysBankGroupMember
2216	Disclosure of financial assets [line items]	LineItems			ifrs-full:DisclosureOfFinancialAssetsLineItems
2217	Financial assets at fair value through other comprehensive income	Concept (Monetary)	As Of	Debit	ifrs-full:FinancialAssetsAtFairValueThroughOtherComprehensiveIncome
2218	Financial investments	Concept (Monetary)	As Of	Debit	c070:FinancialInvestments
2219	041801 - Disclosure - Financial liabilities designated at fair value (Details)	Network	*	*	http://www.barclays.co.uk/role/FinancialLiabilitiesDesignatedAtFairValueDetails
2220	Disclosure of financial liabilities [table]	Table	*	*	ifrs-full:DisclosureOfFinancialLiabilitiesTable
2221	Categories of financial liabilities [axis]	Axis			ifrs-full:CategoriesOfFinancialLiabilitiesAxis
2222	Financial liabilities, category [member]	Member			ifrs-full:FinancialLiabilitiesCategoryMember
2223	Contractual amount due on maturity [member]	Member			c070:ContractualCarryingAmountDueOnMaturityMember
2224	Consolidated Entities [Axis]	Axis			srt:ConsolidatedEntitiesAxis
2225	Consolidated Entities [Domain]	Member			srt:ConsolidatedEntitiesDomain
2226	Barclays Bank Group [member]	Member			c070:BarclaysBankGroupMember
2227	Measurement [axis]	Axis			ifrs-full:MeasurementAxis
2228	Aggregated measurement [member]	Member			ifrs-full:AggregatedMeasurementMember
2229	Fair value [member]	Member			ifrs-full:AtFairValueMember
2230	Disclosure of financial liabilities [line items]	LineItems			ifrs-full:DisclosureOfFinancialLiabilitiesLineItems
2231	Debt securities	Concept (Monetary)	As Of	Credit	ifrs-full:DebtSecurities
2232	Deposits	Concept (Monetary)	As Of	Credit	c070:DepositsFromBanksAndCustomers
2233	Repurchase agreements	Concept (Monetary)	As Of	Credit	ifrs-full:RepurchaseAgreementsAndCashCollateralOnSecuritiesLent
2234	Other financial liabilities	Concept (Monetary)	As Of	Credit	ifrs-full:OtherFinancialLiabilities
2235	Financial liabilities designated at fair value	Concept (Monetary)	As Of	Credit	ifrs-full:FinancialLiabilitiesAtFairValueThroughProfitOrLossDesignatedAsUponInitialRecognition
2236	Cumulative own credit net loss recognised	Concept (Monetary)	As Of	Credit	ifrs-full:AccumulatedChangesInFairValueOfFinancialLiabilityAttributableToChangesInCreditRiskOfLiability
2237	041900 - Disclosure - Fair value of financial instruments - Assets and liabilities held at fair value (Details)	Network	*	*	http://www.barclays.co.uk/role/FairValueOfFinancialInstrumentsAssetsAndLiabilitiesHeldAtFairValueDetails
2238	Disclosure of detailed information about financial instruments [table]	Table	*	*	ifrs-full:DisclosureOfFinancialInstrumentsTable
2239	All levels of fair value hierarchy [axis]	Axis			ifrs-full:LevelsOfFairValueHierarchyAxis
2240	All levels of fair value hierarchy [member]	Member			ifrs-full:AllLevelsOfFairValueHierarchyMember
2241	Level 1 of fair value hierarchy [member]	Member			ifrs-full:Level1OfFairValueHierarchyMember
2242	Level 2 of fair value hierarchy [member]	Member			ifrs-full:Level2OfFairValueHierarchyMember
2243	Level 3 of fair value hierarchy [member]	Member			ifrs-full:Level3OfFairValueHierarchyMember
2244	Measurement [axis]	Axis			ifrs-full:MeasurementAxis
2245	Aggregated measurement [member]	Member			ifrs-full:AggregatedMeasurementMember
2246	At fair value [member]	Member			ifrs-full:AtFairValueMember
2247	Consolidated Entities [Axis]	Axis			srt:ConsolidatedEntitiesAxis
2248	Consolidated Entities [Domain]	Member			srt:ConsolidatedEntitiesDomain
2249	Barclays Bank Group [member]	Member			c070:BarclaysBankGroupMember
2250	Disclosure of detailed information about financial instruments [line items]	LineItems			ifrs-full:DisclosureOfFinancialInstrumentsLineItems
2251	Assets	Abstract			ifrs-full:AssetsAbstract
2252	Trading portfolio assets	Concept (Monetary)	As Of	Debit	ifrs-full:FinancialAssetsAtFairValueThroughProfitOrLossClassifiedAsHeldForTrading
2253	Financial assets at fair value through the income statement	Concept (Monetary)	As Of	Debit	ifrs-full:FinancialAssetsAtFairValueThroughProfitOrLoss
2254	Derivative financial assets	Concept (Monetary)	As Of	Debit	ifrs-full:DerivativeFinancialAssets
2255	Available for sale investments	Concept (Monetary)	As Of	Debit	ifrs-full:FinancialAssetsAvailableforsale
2256	Financial assets at fair value through other comprehensive income	Concept (Monetary)	As Of	Debit	ifrs-full:FinancialAssetsAtFairValueThroughOtherComprehensiveIncome
2257	Investment property	Concept (Monetary)	As Of	Debit	ifrs-full:InvestmentProperty
2258	Assets included in disposal groups classified as held for sale	Concept (Monetary)	As Of	Debit	ifrs-full:NoncurrentAssetsOrDisposalGroupsClassifiedAsHeldForSaleOrAsHeldForDistributionToOwners
2259	Total assets	Concept (Monetary)	As Of	Debit	ifrs-full:FinancialAssetsAtFairValue
2260	Liabilities	Abstract			ifrs-full:LiabilitiesAbstract
2261	Trading portfolio liabilities	Concept (Monetary)	As Of	Credit	ifrs-full:FinancialLiabilitiesAtFairValueThroughProfitOrLossClassifiedAsHeldForTrading
2262	Financial liabilities designated at fair value	Concept (Monetary)	As Of	Credit	ifrs-full:FinancialLiabilitiesAtFairValueThroughProfitOrLossDesignatedAsUponInitialRecognition
2263	Derivative financial liabilities	Concept (Monetary)	As Of	Credit	ifrs-full:DerivativeFinancialLiabilities
2264	Total liabilities	Concept (Monetary)	As Of	Credit	ifrs-full:FinancialLiabilitiesAtFairValue
2265	041901 - Disclosure - Fair value of financial instruments - Assets and liabilities held at fair value by product type (Details)	Network	*	*	http://www.barclays.co.uk/role/FairValueOfFinancialInstrumentsAssetsAndLiabilitiesHeldAtFairValueByProductTypeDetails
2266	Disclosure of detailed information about financial instruments [table]	Table	*	*	ifrs-full:DisclosureOfFinancialInstrumentsTable
2267	All levels of fair value hierarchy [axis]	Axis			ifrs-full:LevelsOfFairValueHierarchyAxis
2268	All levels of fair value hierarchy [member]	Member			ifrs-full:AllLevelsOfFairValueHierarchyMember
2269	Level 1 of fair value hierarchy [member]	Member			ifrs-full:Level1OfFairValueHierarchyMember
2270	Level 2 of fair value hierarchy [member]	Member			ifrs-full:Level2OfFairValueHierarchyMember
2271	Level 3 of fair value hierarchy [member]	Member			ifrs-full:Level3OfFairValueHierarchyMember
2272	Types of risks [axis]	Axis			ifrs-full:TypesOfRisksAxis
2273	Risks [member]	Member			ifrs-full:TypesOfRisksMember
2274	Interest rate derivatives [member]	Member			ifrs-full:InterestRateRiskMember
2275	Foreign exchange derivatives [member]	Member			ifrs-full:CurrencyRiskMember
2276	Credit derivatives [member]	Member			ifrs-full:CreditRiskMember
2277	Equity derivatives [member]	Member			ifrs-full:EquityPriceRiskMember
2278	Commodity derivatives [member]	Member			ifrs-full:CommodityPriceRiskMember
2279	Classes of financial instruments [axis]	Axis			ifrs-full:ClassesOfFinancialInstrumentsAxis
2280	Financial instruments, class [member]	Member			ifrs-full:ClassesOfFinancialInstrumentsMember
2281	Government and government sponsored debt [member]	Member			ifrs-full:LoansToGovernmentMember
2282	Corporate debt [member]	Member			ifrs-full:CorporateLoansMember
2283	Certificates of deposit, commercial paper and other money market instruments [member]	Member			c070:MoneyMarktetInstrumentsMember
2284	Margin lending [member]	Member			c070:MarginLendingMember
2285	Reverse repurchase and repurchase agreements [member]	Member			c070:ReverseRepurchaseAndRepurchaseAgreementsMember
2286	Non-asset-backed loans [member]	Member			c070:NonassetbackedLoansMember
2287	Equity cash products [member]	Member			c070:EquityCashProductsMember
2288	Private equity investments [member]	Member			c070:PrivateEquityInvestmentsMember
2289	Other [member]	Member			c070:OtherFinancialAssetsAndLiabilitiesGroupOneMember
2290	Unconsolidated structured entities [axis]	Axis			ifrs-full:UnconsolidatedStructuredEntitiesAxis
2291	Entity's total for unconsolidated structured entities [member]	Member			ifrs-full:EntitysTotalForUnconsolidatedStructuredEntitiesMember
2292	Asset-backed securities [member]	Member			ifrs-full:AssetbackedFinancingsMember
2293	Assets and liabilities classified as held for sale [axis]	Axis			ifrs-full:AssetsAndLiabilitiesClassifiedAsHeldForSaleAxis
2294	Assets and liabilities not classified as held for sale [member]	Member			ifrs-full:AssetsAndLiabilitiesNotClassifiedAsHeldForSaleMember
2295	Assets and liabilities classified as held for sale [member]	Member			ifrs-full:AssetsAndLiabilitiesClassifiedAsHeldForSaleMember
2296	Borrowings by name [axis]	Axis			ifrs-full:BorrowingsByNameAxis
2297	Borrowings by name [member]	Member			ifrs-full:BorrowingsByNameMember
2298	Issued debt [member]	Member			c070:IssuedDebtMember
2299	Consolidated Entities [Axis]	Axis			srt:ConsolidatedEntitiesAxis
2300	Consolidated Entities [Domain]	Member			srt:ConsolidatedEntitiesDomain
2301	Barclays Bank Group [member]	Member			c070:BarclaysBankGroupMember
2302	Disclosure of detailed information about financial instruments [line items]	LineItems			ifrs-full:DisclosureOfFinancialInstrumentsLineItems
2303	Financial assets, at fair value	Concept (Monetary)	As Of	Debit	ifrs-full:FinancialAssetsAtFairValue
2304	Financial liabilities, at fair value	Concept (Monetary)	As Of	Credit	ifrs-full:FinancialLiabilitiesAtFairValue
2305	041902 - Disclosure - Fair value of financial instruments - Assets and liabilities held at fair value by product type (Narrative) (Details)	Network	*	*	http://www.barclays.co.uk/role/FairValueOfFinancialInstrumentsAssetsAndLiabilitiesHeldAtFairValueByProductTypeNarrativeDetails
2306	Disclosure of detailed information about financial instruments [table]	Table	*	*	ifrs-full:DisclosureOfFinancialInstrumentsTable
2307	Consolidated Entities [Axis]	Axis			srt:ConsolidatedEntitiesAxis
2308	Consolidated Entities [Domain]	Member			srt:ConsolidatedEntitiesDomain
2309	Barclays Bank Group [member]	Member			c070:BarclaysBankGroupMember
2310	Classes of financial instruments [axis]	Axis			ifrs-full:ClassesOfFinancialInstrumentsAxis
2311	Financial instruments, class [member]	Member			ifrs-full:ClassesOfFinancialInstrumentsMember
2312	Equity cash products [member]	Member			c070:EquityCashProductsMember
2313	Other [member]	Member			c070:OtherFinancialAssetsAndLiabilitiesGroupOneMember
2314	Classes of share capital [axis]	Axis			ifrs-full:ClassesOfShareCapitalAxis
2315	Share capital [member]	Member			ifrs-full:ClassesOfShareCapitalMember
2316	Preference shares [member]	Member			ifrs-full:PreferenceSharesMember
2317	Disclosure of detailed information about financial instruments [line items]	LineItems			ifrs-full:DisclosureOfFinancialInstrumentsLineItems
2318	Increase (decrease) through reclassification of financial instruments	Concept (Monetary)	For Period	Debit	c070:IncreaseDecreaseThroughReclassificationOfFinancialInstruments
2319	041903 - Disclosure - Fair value of financial instruments - Analysis of movements in Level 3 assets and liabilities (Details)	Network	*	*	http://www.barclays.co.uk/role/FairValueOfFinancialInstrumentsAnalysisOfMovementsInLevel3AssetsAndLiabilitiesDetails
2320	Disclosure of detailed information about financial instruments [table]	Table	*	*	ifrs-full:DisclosureOfFinancialInstrumentsTable
2321	Categories of financial assets [axis]	Axis			ifrs-full:CategoriesOfFinancialAssetsAxis
2322	Financial assets, category [member]	Member			ifrs-full:FinancialAssetsCategoryMember
2323	Trading portfolio assets [member]	Member			ifrs-full:FinancialAssetsAtFairValueThroughProfitOrLossClassifiedAsHeldForTradingCategoryMember
2324	Financial assets at fair value through the income statement [member]	Member			ifrs-full:FinancialAssetsAtFairValueThroughProfitOrLossCategoryMember
2325	Available for sale investments [member]	Member			ifrs-full:FinancialAssetsAvailableforsaleCategoryMember
2326	Financial assets at fair value through other comprehensive income [member]	Member			ifrs-full:FinancialAssetsAtFairValueThroughOtherComprehensiveIncomeCategoryMember
2327	Classes of financial instruments [axis]	Axis			ifrs-full:ClassesOfFinancialInstrumentsAxis
2328	Financial instruments, class [member]	Member			ifrs-full:ClassesOfFinancialInstrumentsMember
2329	Government and government sponsored debt [member]	Member			ifrs-full:LoansToGovernmentMember
2330	Corporate debt [member]	Member			ifrs-full:CorporateLoansMember
2331	Non-asset-backed loans [member]	Member			c070:NonassetbackedLoansMember
2332	Private equity investments [member]	Member			c070:PrivateEquityInvestmentsMember
2333	Certificates of deposit, commercial paper and other money market instruments [member]	Member			c070:MoneyMarktetInstrumentsMember
2334	Equity cash products [member]	Member			c070:EquityCashProductsMember
2335	Other [member]	Member			c070:OtherFinancialAssetsAndLiabilitiesGroupOneMember
2336	Types of risks [axis]	Axis			ifrs-full:TypesOfRisksAxis
2337	Risks [member]	Member			ifrs-full:TypesOfRisksMember
2338	Interest rate derivatives [member]	Member			ifrs-full:InterestRateRiskMember
2339	Foreign exchange derivatives [member]	Member			ifrs-full:CurrencyRiskMember
2340	Credit derivatives [member]	Member			ifrs-full:CreditRiskMember
2341	Equity derivatives [member]	Member			ifrs-full:EquityPriceRiskMember
2342	Commodity derivatives [member]	Member			ifrs-full:CommodityPriceRiskMember
2343	Assets and liabilities classified as held for sale [axis]	Axis			ifrs-full:AssetsAndLiabilitiesClassifiedAsHeldForSaleAxis
2344	Assets and liabilities not classified as held for sale [member]	Member			ifrs-full:AssetsAndLiabilitiesNotClassifiedAsHeldForSaleMember
2345	Assets and liabilities held for sale [member]	Member			ifrs-full:AssetsAndLiabilitiesClassifiedAsHeldForSaleMember
2346	Unconsolidated structured entities [axis]	Axis			ifrs-full:UnconsolidatedStructuredEntitiesAxis
2347	Entity's total for unconsolidated structured entities [member]	Member			ifrs-full:EntitysTotalForUnconsolidatedStructuredEntitiesMember
2348	Asset-backed loans [member]	Member			ifrs-full:AssetbackedFinancingsMember
2349	Categories of financial liabilities [axis]	Axis			ifrs-full:CategoriesOfFinancialLiabilitiesAxis
2350	Financial liabilities, category [member]	Member			ifrs-full:FinancialLiabilitiesCategoryMember
2351	Trading portfolio liabilities [member]	Member			ifrs-full:FinancialLiabilitiesAtFairValueThroughProfitOrLossThatMeetDefinitionOfHeldForTradingCategoryMember
2352	Financial liabilities designated at fair value [member]	Member			ifrs-full:FinancialLiabilitiesAtFairValueThroughProfitOrLossDesignatedUponInitialRecognitionCategoryMember
2353	Borrowings by name [axis]	Axis			ifrs-full:BorrowingsByNameAxis
2354	Borrowings by name [member]	Member			ifrs-full:BorrowingsByNameMember
2355	Issued debt [member]	Member			c070:IssuedDebtMember
2356	Measurement [axis]	Axis			ifrs-full:MeasurementAxis
2357	Aggregated measurement [member]	Member			ifrs-full:AggregatedMeasurementMember
2358	Recurring fair value measurement [member]	Member			ifrs-full:RecurringFairValueMeasurementMember
2359	Non-recurring fair value measurement [member]	Member			ifrs-full:NonrecurringFairValueMeasurementMember
2360	Classes of financial assets [axis]	Axis			ifrs-full:ClassesOfFinancialAssetsAxis
2361	Financial assets, class [member]	Member			ifrs-full:FinancialAssetsMember
2362	Net derivative financial instruments [member]	Member			ifrs-full:DerivativesMember
2363	Investment property [member]	Member			ifrs-full:InvestmentPropertyMember
2364	All levels of fair value hierarchy [axis]	Axis			ifrs-full:LevelsOfFairValueHierarchyAxis
2365	All levels of fair value hierarchy [member]	Member			ifrs-full:AllLevelsOfFairValueHierarchyMember
2366	Significant unobservable inputs (Level 3) [member]	Member			ifrs-full:Level3OfFairValueHierarchyMember
2367	Assets and liabilities [axis]	Axis			ifrs-full:AssetsAndLiabilitiesAxis
2368	Assets and liabilities [member]	Member			ifrs-full:AssetsAndLiabilitiesMember
2369	Financial assets at fair value through profit or loss, category trading [member]	Member			c070:FinancialAssetsAtFairValueThroughProfitOrLossCategoryTradingIncomeMember
2370	Financial assets at fair value through profit or loss, category other income [member]	Member			c070:FinancialAssetsAtFairValueThroughProfitOrLossCategoryOtherIncomeMember
2371	Financial liabilities at fair value through profit or loss, category trading [member]	Member			c070:FinancialLiabilitiesAtFairValueThroughProfitOrLossCategoryTradingIncomeMember
2372	Financial liabilities at fair value through profit or loss, category other income [member]	Member			c070:FinancialLiabilitiesAtFairValueThroughProfitOrLossCategoryOtherIncomeMember
2373	Net assets (liabilities) at fair value through profit or loss, category trading income [Member]	Member			c070:NetAssetsLiabilitiesAtFairValueThroughProfitOrLossCategoryTradingIncomeMember
2374	Net assets (liabilities) at fair value through profit or loss, category other income [Member]	Member			c070:NetAssetsLiabilitiesAtFairValueThroughProfitOrLossCategoryOtherIncomeMember
2375	Initially applied IFRSs [axis]	Axis			ifrs-full:InitiallyAppliedIFRSsAxis
2376	Initially applied IFRSs [member]	Member			ifrs-full:InitiallyAppliedIFRSsMember
2377	IFRS 9 transition impact included [member]	Member			c070:IFRSs9Member
2378	Consolidated Entities [Axis]	Axis			srt:ConsolidatedEntitiesAxis
2379	Consolidated Entities [Domain]	Member			srt:ConsolidatedEntitiesDomain
2380	Barclays Bank Group [member]	Member			c070:BarclaysBankGroupMember
2381	Disclosure of detailed information about financial instruments [line items]	LineItems			ifrs-full:DisclosureOfFinancialInstrumentsLineItems
2382	Assets	Abstract			ifrs-full:AssetsAbstract
2383	Beginning balance, financial assets	Concept (Monetary)	As Of	Debit	ifrs-full:FinancialAssetsAtFairValue
2384	Purchases, fair value measurement, assets	Concept (Monetary)	For Period	Debit	ifrs-full:PurchasesFairValueMeasurementAssets
2385	Sales, fair value measurement, assets	Concept (Monetary)	For Period	Credit	ifrs-full:SalesFairValueMeasurementAssets
2386	Issues, fair value measurement, assets	Concept (Monetary)	For Period	Debit	ifrs-full:IssuesFairValueMeasurementAssets
2387	Settlements, fair value measurement, assets	Concept (Monetary)	For Period	Credit	ifrs-full:SettlementsFairValueMeasurementAssets
2388	Total gains and losses in the period recognised in the income statement, assets	Concept (Monetary)	For Period		ifrs-full:GainsLossesRecognisedInProfitOrLossFairValueMeasurementAssets
2389	Total gains or losses recognised in OCI, assets	Concept (Monetary)	For Period		ifrs-full:GainsLossesRecognisedInOtherComprehensiveIncomeFairValueMeasurementAssets
2390	Transfers into Level 3 of fair value hierarchy, assets	Concept (Monetary)	For Period	Debit	ifrs-full:TransfersIntoLevel3OfFairValueHierarchyAssets
2391	Transfers out of Level 3 of fair value hierarchy, assets	Concept (Monetary)	For Period	Credit	ifrs-full:TransfersOutOfLevel3OfFairValueHierarchyAssets
2392	Ending balance, financial assets	Concept (Monetary)	As Of	Debit	ifrs-full:FinancialAssetsAtFairValue
2393	Liabilities	Abstract			ifrs-full:LiabilitiesAbstract
2394	Beginning balance, financial liabilities	Concept (Monetary)	As Of	Credit	ifrs-full:FinancialLiabilitiesAtFairValue
2395	Purchases, fair value measurement, liabilities	Concept (Monetary)	For Period	Credit	ifrs-full:PurchasesFairValueMeasurementLiabilities
2396	Sales, fair value measurement, liabilities	Concept (Monetary)	For Period	Debit	ifrs-full:SalesFairValueMeasurementLiabilities
2397	Issues, fair value measurement, liabilities	Concept (Monetary)	For Period	Credit	ifrs-full:IssuesFairValueMeasurementLiabilities
2398	Settlements, fair value measurement, liabilities	Concept (Monetary)	For Period	Debit	ifrs-full:SettlementsFairValueMeasurementLiabilities
2399	Total gains and losses in the period recognised in the income statement, liabilities	Concept (Monetary)	For Period		ifrs-full:GainsLossesRecognisedInProfitOrLossFairValueMeasurementLiabilities
2400	Total gains or losses recognised in OCI, liabilities	Concept (Monetary)	For Period		ifrs-full:GainsLossesRecognisedInOtherComprehensiveIncomeFairValueMeasurementLiabilities
2401	Transfers into Level 3 of fair value hierarchy, liabilities	Concept (Monetary)	For Period	Credit	ifrs-full:TransfersIntoLevel3OfFairValueHierarchyLiabilities
2402	Transfers out of Level 3 of fair value hierarchy, liabilities	Concept (Monetary)	For Period	Debit	ifrs-full:TransfersOutOfLevel3OfFairValueHierarchyLiabilities
2403	Ending balance, financial liabilities	Concept (Monetary)	As Of	Credit	ifrs-full:FinancialLiabilitiesAtFairValue
2404	Assets (liabilities)	Abstract			ifrs-full:NetAssetsLiabilitiesAbstract
2405	Beginning balance, Assets (liabilities) net	Concept (Monetary)	As Of	Debit	ifrs-full:NetAssetsLiabilities
2406	Purchases, fair value measurement, assets (liabilities) net	Concept (Monetary)	For Period	Debit	c070:PurchasesFairValueMeasurementAssetsLiabilitiesNet
2407	Sales, fair value measurement, assets (liabilities) net	Concept (Monetary)	For Period	Credit	c070:SalesFairValueMeasurementAssetsLiabilitiesNet
2408	Issues, fair value measurement, assets (liabilities) net	Concept (Monetary)	For Period	Debit	c070:IssuesFairValueMeasurementAssetsLiabilitiesNet
2409	Settlements, fair value measurement, assets (liabilities) net	Concept (Monetary)	For Period	Credit	c070:SettlementsFairValueMeasurementAssetsLiabilitiesNet
2410	Gains (losses) recognised in profit or loss, fair value measurement, assets (liabilities) net	Concept (Monetary)	For Period		c070:GainsLossesRecognisedInProfitOrLossFairValueMeasurementAssetsLiabilitiesNet
2411	Gains (losses) recognised in other comprehensive income, fair value measurement, assets (liabilities) net	Concept (Monetary)	For Period		c070:GainsLossesRecognisedInOtherComprehensiveIncomeFairValueMeasurementAssetsLiabilitiesNet
2412	Transfers into Level 3 of fair value hierarchy, assets (liabilities) net	Concept (Monetary)	For Period	Debit	c070:TransfersIntoLevel3OfFairValueHierarchyAssetsLiabilitiesNet
2413	Transfers out of Level 3 of fair value hierarchy, assets (liabilities) net	Concept (Monetary)	For Period	Credit	c070:TransfersOutOfLevel3OfFairValueHierarchyAssetsLiabilitiesNet
2414	Ending balance, Assets (liabilities) net	Concept (Monetary)	As Of	Debit	ifrs-full:NetAssetsLiabilities
2415	041904 - Disclosure - Fair value of financial instruments - Analysis of movements in Level 3 assets and liabilities (Narrative) (Details)	Network	*	*	http://www.barclays.co.uk/role/FairValueOfFinancialInstrumentsAnalysisOfMovementsInLevel3AssetsAndLiabilitiesNarrativeDetails
2416	Disclosure of detailed information about financial instruments [table]	Table	*	*	ifrs-full:DisclosureOfFinancialInstrumentsTable
2417	All levels of fair value hierarchy [axis]	Axis			ifrs-full:LevelsOfFairValueHierarchyAxis
2418	All levels of fair value hierarchy [member]	Member			ifrs-full:AllLevelsOfFairValueHierarchyMember
2419	Significant unobservable inputs (Level 3) [member]	Member			ifrs-full:Level3OfFairValueHierarchyMember
2420	Measurement [axis]	Axis			ifrs-full:MeasurementAxis
2421	Aggregated measurement [member]	Member			ifrs-full:AggregatedMeasurementMember
2422	Recurring fair value measurement [member]	Member			ifrs-full:RecurringFairValueMeasurementMember
2423	Consolidated Entities [Axis]	Axis			srt:ConsolidatedEntitiesAxis
2424	Consolidated Entities [Domain]	Member			srt:ConsolidatedEntitiesDomain
2425	Barclays Bank Group [member]	Member			c070:BarclaysBankGroupMember
2426	Disclosure of detailed information about financial instruments [line items]	LineItems			ifrs-full:DisclosureOfFinancialInstrumentsLineItems
2427	Derivative financial assets	Concept (Monetary)	As Of	Debit	ifrs-full:DerivativeFinancialAssets
2428	Derivative financial liabilities	Concept (Monetary)	As Of	Credit	ifrs-full:DerivativeFinancialLiabilities
2429	041905 - Disclosure - Fair value of financial instruments - Unrealised gains and losses recognised during the period on Level 3 assets and liabilities held at year end (Details)	Network	*	*	http://www.barclays.co.uk/role/FairValueOfFinancialInstrumentsUnrealisedGainsAndLossesRecognisedDuringThePeriodOnLevel3AssetsAndLiabilitiesHeldAtYearEndDetails
2430	Disclosure of detailed information about financial instruments [table]	Table	*	*	ifrs-full:DisclosureOfFinancialInstrumentsTable
2431	Categories of financial assets [axis]	Axis			ifrs-full:CategoriesOfFinancialAssetsAxis
2432	Financial assets, category [member]	Member			ifrs-full:FinancialAssetsCategoryMember
2433	Trading portfolio assets [member]	Member			ifrs-full:FinancialAssetsAtFairValueThroughProfitOrLossClassifiedAsHeldForTradingCategoryMember
2434	Financial assets at fair value through the income statement [member]	Member			ifrs-full:FinancialAssetsAtFairValueThroughProfitOrLossCategoryMember
2435	Available for sale investments [member]	Member			ifrs-full:FinancialAssetsAvailableforsaleCategoryMember
2436	Financial assets at fair value through other comprehensive income [member]	Member			ifrs-full:FinancialAssetsAtFairValueThroughOtherComprehensiveIncomeCategoryMember
2437	Categories of financial liabilities [axis]	Axis			ifrs-full:CategoriesOfFinancialLiabilitiesAxis
2438	Financial liabilities, category [member]	Member			ifrs-full:FinancialLiabilitiesCategoryMember
2439	Trading portfolio liabilities [member]	Member			ifrs-full:FinancialLiabilitiesAtFairValueThroughProfitOrLossThatMeetDefinitionOfHeldForTradingCategoryMember
2440	Financial liabilities designated at fair value [member]	Member			ifrs-full:FinancialLiabilitiesAtFairValueThroughProfitOrLossDesignatedUponInitialRecognitionCategoryMember
2441	All levels of fair value hierarchy [axis]	Axis			ifrs-full:LevelsOfFairValueHierarchyAxis
2442	All levels of fair value hierarchy [member]	Member			ifrs-full:AllLevelsOfFairValueHierarchyMember
2443	Significant unobservable inputs (Level 3) [member]	Member			ifrs-full:Level3OfFairValueHierarchyMember
2444	Classes of financial assets [axis]	Axis			ifrs-full:ClassesOfFinancialAssetsAxis
2445	Financial assets, class [member]	Member			ifrs-full:FinancialAssetsMember
2446	Investment property [member]	Member			ifrs-full:InvestmentPropertyMember
2447	Net derivative financial instruments [member]	Member			ifrs-full:DerivativesMember
2448	Consolidated Entities [Axis]	Axis			srt:ConsolidatedEntitiesAxis
2449	Consolidated Entities [Domain]	Member			srt:ConsolidatedEntitiesDomain
2450	Barclays Bank Group [member]	Member			c070:BarclaysBankGroupMember
2451	Disclosure of detailed information about financial instruments [line items]	LineItems			ifrs-full:DisclosureOfFinancialInstrumentsLineItems
2452	Trading income	Concept (Monetary)	For Period	Credit	ifrs-full:TradingIncomeExpense
2453	Other income	Concept (Monetary)	For Period	Credit	ifrs-full:OtherIncome
2454	Other comprehensive income	Concept (Monetary)	For Period	Credit	ifrs-full:OtherComprehensiveIncome
2455	Total unrealised gains and losses recognised during the period on Level 3 assets and liabilities held at period end	Concept (Monetary)	For Period	Credit	ifrs-full:GainsLossesRecognisedInProfitOrLossAttributableToChangeInUnrealisedGainsOrLossesForAssetsHeldAtEndOfPeriodFairValueMeasurement
2456	041906 - Disclosure - Fair value of financial instruments - Unrealised gains and losses recognised during the period on Level 3 assets and liabilities held at year end (Narrative) (Details)	Network	*	*	http://www.barclays.co.uk/role/FairValueOfFinancialInstrumentsUnrealisedGainsAndLossesRecognisedDuringThePeriodOnLevel3AssetsAndLiabilitiesHeldAtYearEndNarrativeDetails
2457	Disclosure of detailed information about financial instruments [table]	Table	*	*	ifrs-full:DisclosureOfFinancialInstrumentsTable
2458	All levels of fair value hierarchy [axis]	Axis			ifrs-full:LevelsOfFairValueHierarchyAxis
2459	All levels of fair value hierarchy [member]	Member			ifrs-full:AllLevelsOfFairValueHierarchyMember
2460	Significant unobservable inputs (Level 3) [member]	Member			ifrs-full:Level3OfFairValueHierarchyMember
2461	Consolidated Entities [Axis]	Axis			srt:ConsolidatedEntitiesAxis
2462	Consolidated Entities [Domain]	Member			srt:ConsolidatedEntitiesDomain
2463	Barclays Bank Group [member]	Member			c070:BarclaysBankGroupMember
2464	Disclosure of detailed information about financial instruments [line items]	LineItems			ifrs-full:DisclosureOfFinancialInstrumentsLineItems
2465	Unrealised gains and losses recognised during the period on Level 3 assets and liabilities held at period end	Concept (Monetary)	For Period	Credit	ifrs-full:GainsLossesRecognisedInProfitOrLossAttributableToChangeInUnrealisedGainsOrLossesForAssetsHeldAtEndOfPeriodFairValueMeasurement
2466	041907 - Disclosure - Fair value of financial instruments - Sensitivity analysis of valuations using unobservable inputs (Details)	Network	*	*	http://www.barclays.co.uk/role/FairValueOfFinancialInstrumentsSensitivityAnalysisOfValuationsUsingUnobservableInputsDetails
2467	Disclosure of detailed information about financial instruments [table]	Table	*	*	ifrs-full:DisclosureOfFinancialInstrumentsTable
2468	All levels of fair value hierarchy [axis]	Axis			ifrs-full:LevelsOfFairValueHierarchyAxis
2469	All levels of fair value hierarchy [member]	Member			ifrs-full:AllLevelsOfFairValueHierarchyMember
2470	Significant unobservable inputs (Level 3) [member]	Member			ifrs-full:Level3OfFairValueHierarchyMember
2471	Types of risks [axis]	Axis			ifrs-full:TypesOfRisksAxis
2472	Risks [member]	Member			ifrs-full:TypesOfRisksMember
2473	Interest rate derivatives [member]	Member			ifrs-full:InterestRateRiskMember
2474	Foreign exchange derivatives [member]	Member			ifrs-full:CurrencyRiskMember
2475	Credit derivatives [member]	Member			ifrs-full:CreditRiskMember
2476	Equity derivatives [member]	Member			ifrs-full:EquityPriceRiskMember
2477	Commodity derivatives [member]	Member			ifrs-full:CommodityPriceRiskMember
2478	Classes of financial instruments [axis]	Axis			ifrs-full:ClassesOfFinancialInstrumentsAxis
2479	Financial instruments, class [member]	Member			ifrs-full:ClassesOfFinancialInstrumentsMember
2480	Corporate debt [member]	Member			ifrs-full:CorporateLoansMember
2481	Non-asset-backed loans [member]	Member			c070:NonassetbackedLoansMember
2482	Equity cash products [member]	Member			c070:EquityCashProductsMember
2483	Private equity investments [member]	Member			c070:PrivateEquityInvestmentsMember
2484	Other [member]	Member			c070:OtherFinancialAssetsAndLiabilitiesGroupOneMember
2485	Unconsolidated structured entities [axis]	Axis			ifrs-full:UnconsolidatedStructuredEntitiesAxis
2486	Entity's total for unconsolidated structured entities [member]	Member			ifrs-full:EntitysTotalForUnconsolidatedStructuredEntitiesMember
2487	Asset-backed securities [member]	Member			ifrs-full:AssetbackedFinancingsMember
2488	Range [axis]	Axis			ifrs-full:RangeAxis
2489	Ranges [member]	Member			ifrs-full:RangesMember
2490	Favourable changes [member]	Member			ifrs-full:TopOfRangeMember
2491	Unfavourable changes [member]	Member			ifrs-full:BottomOfRangeMember
2492	Classes of financial assets [axis]	Axis			ifrs-full:ClassesOfFinancialAssetsAxis
2493	Financial assets, class [member]	Member			ifrs-full:FinancialAssetsMember
2494	Derivatives [member]	Member			ifrs-full:DerivativesMember
2495	Measurement [axis]	Axis			ifrs-full:MeasurementAxis
2496	Aggregated measurement [member]	Member			ifrs-full:AggregatedMeasurementMember
2497	Recurring fair value measurement [member]	Member			ifrs-full:RecurringFairValueMeasurementMember
2498	Financial statement location [Axis]	Axis			c070:FinancialStatementLocationAxis
2499	Financial statement location [Member]	Member			c070:FinancialStatementLocationDomain
2500	Income statement [member]	Member			c070:IncomeStatementCategoryMember
2501	Equity [member]	Member			c070:StatementOfChangesInEquityCategoryMember
2502	Disclosure of detailed information about financial instruments [line items]	LineItems			ifrs-full:DisclosureOfFinancialInstrumentsLineItems
2503	Sensitivity analysis of valuations due to change in one or more unobservable inputs to reflect reasonably possible alternative assumptions	Concept (Monetary)	As Of		c070:SensitivityAnalysisValuationDueToChangeInOneOrMoreUnobservableInputsToReflectReasonablyPossibleAlternativeAssumptions
2504	041908 - Disclosure - Fair value of financial instruments - Significant unobservable inputs (Details)	Network	*	*	http://www.barclays.co.uk/role/FairValueOfFinancialInstrumentsSignificantUnobservableInputsDetails
2505	Disclosure of detailed information about financial instruments [table]	Table	*	*	ifrs-full:DisclosureOfFinancialInstrumentsTable
2506	All levels of fair value hierarchy [axis]	Axis			ifrs-full:LevelsOfFairValueHierarchyAxis
2507	All levels of fair value hierarchy [member]	Member			ifrs-full:AllLevelsOfFairValueHierarchyMember
2508	Level 3 of fair value hierarchy [member]	Member			ifrs-full:Level3OfFairValueHierarchyMember
2509	Types of risks [axis]	Axis			ifrs-full:TypesOfRisksAxis
2510	Risks [member]	Member			ifrs-full:TypesOfRisksMember
2511	Interest rate derivatives [member]	Member			ifrs-full:InterestRateRiskMember
2512	Credit derivatives [member]	Member			ifrs-full:CreditRiskMember
2513	Equity derivatives [member]	Member			ifrs-full:EquityPriceRiskMember
2514	Classes of financial instruments [axis]	Axis			ifrs-full:ClassesOfFinancialInstrumentsAxis
2515	Financial instruments, class [member]	Member			ifrs-full:ClassesOfFinancialInstrumentsMember
2516	Non-asset-backed loans [member]	Member			c070:NonassetbackedLoansMember
2517	Reverse repurchase and repurchase agreements [member]	Member			c070:ReverseRepurchaseAndRepurchaseAgreementsMember
2518	Other [member]	Member			c070:OtherFinancialAssetsAndLiabilitiesGroupOneMember
2519	Unconsolidated structured entities [axis]	Axis			ifrs-full:UnconsolidatedStructuredEntitiesAxis
2520	Entity's total for unconsolidated structured entities [member]	Member			ifrs-full:EntitysTotalForUnconsolidatedStructuredEntitiesMember
2521	Asset-backed securities [member]	Member			ifrs-full:AssetbackedFinancingsMember
2522	Range [axis]	Axis			ifrs-full:RangeAxis
2523	Ranges [member]	Member			ifrs-full:RangesMember
2524	Min [member]	Member			ifrs-full:BottomOfRangeMember
2525	Max [member]	Member			ifrs-full:TopOfRangeMember
2526	Valuation techniques used in fair value measurement [axis]	Axis			ifrs-full:ValuationTechniquesUsedInFairValueMeasurementAxis
2527	Valuation techniques [member]	Member			ifrs-full:ValuationTechniquesMember
2528	Discounted cash flow [member]	Member			ifrs-full:DiscountedCashFlowMember
2529	Comparable pricing [member]	Member			ifrs-full:MarketComparablePricesMember
2530	Option model [member]	Member			ifrs-full:OptionPricingModelMember
2531	EBITA [member]	Member			ifrs-full:MultiperiodExcessEarningsMethodMember
2532	Disclosure of detailed information about financial instruments [line items]	LineItems			ifrs-full:DisclosureOfFinancialInstrumentsLineItems
2533	Inflation forwards, significant unobservable inputs, assets and liabilities	Concept (Percent)	For Period		c070:InflationForwardsSignificantUnobservableInputs
2534	Credit spread, significant unobservable inputs, assets and liabilities	Concept (Percent)	For Period		c070:CreditSpreadRateSignificantUnobservableInputsAssetsAndLiabilities
2535	Yield, significant unobservable inputs, assets and liabilities	Concept (Percent)	For Period		c070:YieldpreadSignificantUnobservableInputsAssetsAndLiabilities
2536	Inflation volitility, significant unobservable inputs, assets and liabilities	Concept (Percent)	For Period		c070:InflationVolatilitySignificantUnobservableInputsAssetsAndLiabilities
2537	IR IR correlation, significant unobservable inputs, assets and liabilities	Concept (Percent)	For Period		c070:IRIrCorrelationSignificantUnobservableInputsAssetsLiabilities
2538	IFX IR correlation, significant unobservable inputs, assets and liabilities	Concept (Percent)	For Period		c070:FXIrCorrelationSignificantUnobservableInputsAssetsLiabilities
2539	Interest rate volatility, significant unobservable inputs, assets and liabilities	Concept (Percent)	For Period		c070:InterestRateVolatilitySignificantUnobservableInputsAssetsLiabilities
2540	Equity Volatility, significant unobservable inputs, assets and liabilities	Concept (Percent)	For Period		c070:EquityVolatilitySignificantUnobservableInputsAssetsLiabilities
2541	Adjustment to mid market consensus price, significant unobservable inputs, assets and liabilities	Concept (Pure)	For Period		c070:AdjustmentToMidmarketConsensusPriceSignificantUnobservableInputsAssetsLiabilities
2542	Equity correlation, significant unobservable inputs, assets and liabilities	Concept (Percent)	For Period		c070:EquityCorrelationSignificantUnobservableInputsAssetsLiabilities
2543	Loan spread, significant unobservable inputs, assets and liabilities	Concept (Percent)	For Period		c070:LoanSpreadSignificantUnobservableInputsAssetsLiabilities
2544	Discounted margin, significant unobservable inputs, assets and liabilities	Concept (Percent)	For Period		c070:DiscountedMarginSignificantUnobservableInputsAssetsLiabilities
2545	Revenue multiple, significant unobservable inputs, assets and liabilities	Concept (Pure)	For Period		c070:RevenueMultipleSignificantUnobservableInputsAssetsLiabilities
2546	EBITDA, significant unobservable inputs, assets and liabilities	Concept (Monetary)	For Period		c070:EarningsBeforeInterestTaxesDepreciationAndAmortisationSignificantUnobservableInputsAssetsAndLiabilities
2547	041909 - Disclosure - Fair value of financial instruments - Significant unobservable inputs (Narrative) (Details)	Network	*	*	http://www.barclays.co.uk/role/FairValueOfFinancialInstrumentsSignificantUnobservableInputsNarrativeDetails
2548	Disclosure of detailed information about financial instruments [table]	Table	*	*	ifrs-full:DisclosureOfFinancialInstrumentsTable
2549	All levels of fair value hierarchy [axis]	Axis			ifrs-full:LevelsOfFairValueHierarchyAxis
2550	All levels of fair value hierarchy [member]	Member			ifrs-full:AllLevelsOfFairValueHierarchyMember
2551	Level 3 of fair value hierarchy [member]	Member			ifrs-full:Level3OfFairValueHierarchyMember
2552	Range [axis]	Axis			ifrs-full:RangeAxis
2553	Ranges [member]	Member			ifrs-full:RangesMember
2554	Max [member]	Member			ifrs-full:TopOfRangeMember
2555	Min [member]	Member			ifrs-full:BottomOfRangeMember
2556	Valuation techniques used in fair value measurement [axis]	Axis			ifrs-full:ValuationTechniquesUsedInFairValueMeasurementAxis
2557	Valuation techniques [member]	Member			ifrs-full:ValuationTechniquesMember
2558	Derivative credit valuation adjustments [member]	Member			c070:DerivativeCreditValuationAdjustmentsMember
2559	Disclosure of detailed information about financial instruments [line items]	LineItems			ifrs-full:DisclosureOfFinancialInstrumentsLineItems
2560	Credit spread, significant unobservable inputs, assets and liabilities	Concept (Percent)	For Period		c070:CreditSpreadRateSignificantUnobservableInputsAssetsAndLiabilities
2561	041910 - Disclosure - Fair value of financial instruments - Fair value adjustments (Details)	Network	*	*	http://www.barclays.co.uk/role/FairValueOfFinancialInstrumentsFairValueAdjustmentsDetails
2562	Disclosure of detailed information about financial instruments [table]	Table	*	*	ifrs-full:DisclosureOfFinancialInstrumentsTable
2563	Valuation techniques used in fair value measurement [axis]	Axis			ifrs-full:ValuationTechniquesUsedInFairValueMeasurementAxis
2564	Valuation techniques [member]	Member			ifrs-full:ValuationTechniquesMember
2565	Exit price adjustments derived from market bid-offer spreads [member]	Member			c070:ExitPriceAdjustmentsDerivedFromMarketBidofferSpreadsMember
2566	Uncollateralised derivative funding [member]	Member			c070:UncollateralisedDerivativeFundingMember
2567	Derivative credit valuation adjustments [member]	Member			c070:DerivativeCreditValuationAdjustmentsMember
2568	Derivative debit valuation adjustments [member]	Member			c070:DerivativeDebitValuationAdjustmentsMember
2569	Disclosure of detailed information about financial instruments [line items]	LineItems			ifrs-full:DisclosureOfFinancialInstrumentsLineItems
2570	Fair value adjustments	Concept (Monetary)	As Of	Credit	c070:AccumulatedFairValueHedgeAdjustmentOnHedgedItemIncludedInCarryingAmountAssetsLiabilities
2571	041911 - Disclosure - Fair value of financial instruments - Comparison of carrying amounts and fair values for assets and liabilities not held at fair value (Details)	Network	*	*	http://www.barclays.co.uk/role/FairValueOfFinancialInstrumentsComparisonOfCarryingAmountsAndFairValuesForAssetsAndLiabilitiesNotHeldAtFairValueDetails
2572	Disclosure of detailed information about financial instruments [table]	Table	*	*	ifrs-full:DisclosureOfFinancialInstrumentsTable
2573	Carrying amount, accumulated depreciation, amortisation and impairment and gross carrying amount [axis]	Axis			ifrs-full:CarryingAmountAccumulatedDepreciationAmortisationAndImpairmentAndGrossCarryingAmountAxis
2574	Carrying amount [member]	Member			ifrs-full:CarryingAmountMember
2575	Carrying amount [member]	Member			ifrs-full:GrossCarryingAmountMember
2576	Measurement [axis]	Axis			ifrs-full:MeasurementAxis
2577	Aggregated measurement [member]	Member			ifrs-full:AggregatedMeasurementMember
2578	Not held at fair value [member]	Member			ifrs-full:NotMeasuredAtFairValueInStatementOfFinancialPositionButForWhichFairValueIsDisclosedMember
2579	All levels of fair value hierarchy [axis]	Axis			ifrs-full:LevelsOfFairValueHierarchyAxis
2580	All levels of fair value hierarchy [member]	Member			ifrs-full:AllLevelsOfFairValueHierarchyMember
2581	Level 1 of fair value hierarchy [member]	Member			ifrs-full:Level1OfFairValueHierarchyMember
2582	Level 2 of fair value hierarchy [member]	Member			ifrs-full:Level2OfFairValueHierarchyMember
2583	Level 3 of fair value hierarchy [member]	Member			ifrs-full:Level3OfFairValueHierarchyMember
2584	Classes of financial assets [axis]	Axis			ifrs-full:ClassesOfFinancialAssetsAxis
2585	Financial assets, class [member]	Member			ifrs-full:FinancialAssetsMember
2586	Financial assets at amortised cost [member]	Member			ifrs-full:FinancialAssetsAtAmortisedCostMember
2587	Classes of financial liabilities [axis]	Axis			ifrs-full:ClassesOfFinancialLiabilitiesAxis
2588	Financial liabilities, class [member]	Member			ifrs-full:FinancialLiabilitiesMember
2589	Financial liabilities at amortised cost [member]	Member			ifrs-full:FinancialLiabilitiesAtAmortisedCostMember
2590	Classes of financial instruments [axis]	Axis			ifrs-full:ClassesOfFinancialInstrumentsAxis
2591	Financial instruments, class [member]	Member			ifrs-full:ClassesOfFinancialInstrumentsMember
2592	Home loans [member]	Member			ifrs-full:MortgagesMember
2593	Credit cards, unsecured and other retail lending [member]	Member			c070:CreditCardsUnsecuredAndOtherRetailLendingMember
2594	Finance lease receivables [member]	Member			c070:FinanceLeaseReceivablesMember
2595	Corporate loans [member]	Member			ifrs-full:CorporateLoansMember
2596	Consolidated Entities [Axis]	Axis			srt:ConsolidatedEntitiesAxis
2597	Consolidated Entities [Domain]	Member			srt:ConsolidatedEntitiesDomain
2598	Barclays Bank Group [member]	Member			c070:BarclaysBankGroupMember
2599	Disclosure of detailed information about financial instruments [line items]	LineItems			ifrs-full:DisclosureOfFinancialInstrumentsLineItems
2600	Financial assets [abstract]	Abstract			ifrs-full:CategoriesOfFinancialAssetsAbstract
2601	Loans and advances at amortised cost	Concept (Monetary)	As Of	Debit	ifrs-full:LoansAndReceivables
2602	Reverse repurchase agreements and other similar secured lending	Concept (Monetary)	As Of	Debit	ifrs-full:ReverseRepurchaseAgreementsAndCashCollateralOnSecuritiesBorrowed
2603	Assets included in disposal groups classified as held for sale	Concept (Monetary)	As Of	Debit	ifrs-full:NoncurrentAssetsOrDisposalGroupsClassifiedAsHeldForSaleOrAsHeldForDistributionToOwners
2604	Financial liabilities [abstract]	Abstract			ifrs-full:CategoriesOfFinancialLiabilitiesAbstract
2605	Banks	Concept (Monetary)	As Of	Credit	ifrs-full:DepositsFromBanks
2606	Current and demand accounts	Concept (Monetary)	As Of	Credit	c070:BalancesCurrentAndOnDemandDepositsFromCustomers
2607	Savings accounts	Concept (Monetary)	As Of	Credit	c070:BalancesCurrentAndSavingsAccountsFromCustomers
2608	Other time deposits	Concept (Monetary)	As Of	Credit	ifrs-full:BalancesOnOtherDepositsFromCustomers
2609	Repurchase agreements and other similar secured borrowing	Concept (Monetary)	As Of	Credit	ifrs-full:RepurchaseAgreementsAndCashCollateralOnSecuritiesLent
2610	Debt securities in issue	Concept (Monetary)	As Of	Credit	ifrs-full:DebtSecurities
2611	Subordinated liabilities	Concept (Monetary)	As Of	Credit	ifrs-full:SubordinatedLiabilities
2612	041920 - Disclosure - Fair value of financial instruments (Narrative) (Details)	Network	*	*	http://www.barclays.co.uk/role/FairValueOfFinancialInstrumentsNarrativeDetails
2613	Disclosure of detailed information about financial instruments [table]	Table	*	*	ifrs-full:DisclosureOfFinancialInstrumentsTable
2614	Classes of financial instruments [axis]	Axis			ifrs-full:ClassesOfFinancialInstrumentsAxis
2615	Financial instruments, class [member]	Member			ifrs-full:ClassesOfFinancialInstrumentsMember
2616	Goverment bonds [member]	Member			ifrs-full:LoansToGovernmentMember
2617	Education, Social Housing, and Local Authority Porfolio [member]	Member			c070:EducationSocialHousingAndLocalAuthorityPorfolioMember
2618	Financial instruments at fair value, category [member]	Member			c070:FinancialInstrumentsAtFairValueCategoryMember
2619	Financial instruments at amortised cost, category [member]	Member			c070:FinancialInstrumentsAtAmortisedCostCategoryMember
2620	Range [axis]	Axis			ifrs-full:RangeAxis
2621	Ranges [member]	Member			ifrs-full:RangesMember
2622	Min [member]	Member			ifrs-full:BottomOfRangeMember
2623	Max [member]	Member			ifrs-full:TopOfRangeMember
2624	Valuation techniques used in fair value measurement [axis]	Axis			ifrs-full:ValuationTechniquesUsedInFairValueMeasurementAxis
2625	Valuation techniques [member]	Member			ifrs-full:ValuationTechniquesMember
2626	Exit price adjustments derived from market bid-offer spreads [member]	Member			c070:ExitPriceAdjustmentsDerivedFromMarketBidofferSpreadsMember
2627	Uncollateralised derivative funding [member]	Member			c070:UncollateralisedDerivativeFundingMember
2628	Derivative credit valuation adjustments [member]	Member			c070:DerivativeCreditValuationAdjustmentsMember
2629	Derivative debit valuation adjustments [member]	Member			c070:DerivativeDebitValuationAdjustmentsMember
2630	Majority of loan spreads [Member]	Member			c070:MajorityOfLoanSpreadsMember
2631	All levels of fair value hierarchy [axis]	Axis			ifrs-full:LevelsOfFairValueHierarchyAxis
2632	All levels of fair value hierarchy [member]	Member			ifrs-full:AllLevelsOfFairValueHierarchyMember
2633	Significant unobservable inputs (Level 3) [member]	Member			ifrs-full:Level3OfFairValueHierarchyMember
2634	Measurement [axis]	Axis			ifrs-full:MeasurementAxis
2635	Aggregated measurement [member]	Member			ifrs-full:AggregatedMeasurementMember
2636	Scaling factor [member]	Member			c070:ScalingFactorMember
2637	Recovery assumptions in CDS levels [member]	Member			c070:RecoveryAssumptionsInCdsLevelsMember
2638	Recurring fair value measurement [member]	Member			ifrs-full:RecurringFairValueMeasurementMember
2639	Liabilities measured at fair value and issued with inseparable third-party credit enhancement [axis]	Axis			ifrs-full:LiabilitiesMeasuredAtFairValueAndIssuedWithInseparableThirdpartyCreditEnhancementAxis
2640	Liabilities measured at fair value and issued with inseparable third-party credit enhancement [member]	Member			ifrs-full:LiabilitiesMeasuredAtFairValueAndIssuedWithInseparableThirdpartyCreditEnhancementMember
2641	Brokered certificates of deposit [member]	Member			c070:BrokeredCertificatesOfDepositMember
2642	Classes of financial assets [axis]	Axis			ifrs-full:ClassesOfFinancialAssetsAxis
2643	Financial assets, class [member]	Member			ifrs-full:FinancialAssetsMember
2644	Derivatives [member]	Member			ifrs-full:DerivativesMember
2645	Classes of assets [axis]	Axis			ifrs-full:ClassesOfAssetsAxis
2646	Assets [member]	Member			ifrs-full:ClassesOfAssetsMember
2647	Significant unobservable inputs (Level 3) [member]	Member			ifrs-full:Level3OfFairValueHierarchyMember
2648	Types of risks [axis]	Axis			ifrs-full:TypesOfRisksAxis
2649	Risks [member]	Member			ifrs-full:TypesOfRisksMember
2650	Commodity derivatives [member]	Member			ifrs-full:CommodityPriceRiskMember
2651	Consolidated Entities [Axis]	Axis			srt:ConsolidatedEntitiesAxis
2652	Consolidated Entities [Domain]	Member			srt:ConsolidatedEntitiesDomain
2653	Barclays Bank Group [member]	Member			c070:BarclaysBankGroupMember
2654	Barclays Bank UK PLC [member]	Member			c070:BarclaysBankUkPlcMember
2655	Classes of financial liabilities [axis]	Axis			ifrs-full:ClassesOfFinancialLiabilitiesAxis
2656	Financial liabilities, class [member]	Member			ifrs-full:FinancialLiabilitiesMember
2657	Derivatives [member]	Member			ifrs-full:DerivativesMember
2658	Disclosure of detailed information about financial instruments [line items]	LineItems			ifrs-full:DisclosureOfFinancialInstrumentsLineItems
2659	Transfers out of Level 1 into Level 2 of fair value hierarchy, assets held at end of reporting period	Concept (Monetary)	For Period		ifrs-full:TransfersOutOfLevel1IntoLevel2OfFairValueHierarchyAssets
2660	Transfers out of Level 1 into Level 2 of fair value hierarchy, liabilities held at end of reporting period	Concept (Monetary)	For Period		ifrs-full:TransfersOutOfLevel1IntoLevel2OfFairValueHierarchyLiabilities
2661	Increase in fair value measurement due to change in one or more unobservable inputs to reflect reasonably possible alternative assumptions, assets (liabilities)	Concept (Monetary)	For Period		c070:IncreaseInFairValueMeasurementDueToChangeInOneOrMoreUnobservableInputsToReflectReasonablyPossibleAlternativeAssumptionsAssetsLiabilities
2662	Decrease in fair value measurement due to change in one or more unobservable inputs to reflect reasonably possible alternative assumptions, assets (liabilities)	Concept (Monetary)	For Period		c070:DecreaseInFairValueMeasurementDueToChangeInOneOrMoreUnobservableInputsToReflectReasonablyPossibleAlternativeAssumptionsAssetsLiabilities
2663	Loan spread, significant unobservable inputs, assets and liabilities	Concept (Percent)	For Period		c070:LoanSpreadSignificantUnobservableInputsAssetsLiabilities
2664	Percentage of fixed rate loan notional amount concentrated towards bottom of range	Concept (Percent)	For Period		c070:PercentageOfFixedRateLoanNotionalAmountConcentratedTowardsBottomOfRange
2665	Increase (decrease) in fair value adjustments of derivatives	Concept (Monetary)	For Period		c070:IncreaseDecreaseInDerivativeFairValueAdjustments
2666	Fair value adjustments	Concept (Monetary)	As Of	Credit	c070:AccumulatedFairValueHedgeAdjustmentOnHedgedItemIncludedInCarryingAmountAssetsLiabilities
2667	Potential increase (decrease) in fair value adjustments of derivatives	Concept (Monetary)	For Period		c070:PotentialIncreaseDecreaseInDerivativeFairValueAdjustments
2668	Aggregate difference between fair value at initial recognition and transaction price yet to be recognised in profit or loss	Concept (Monetary)	As Of		ifrs-full:AggregateDifferenceBetweenFairValueAtInitialRecognitionAndAmountDeterminedUsingValuationTechniqueYetToBeRecognised
2669	Increase (decrease) in aggregate difference between fair value at initial recognition and transaction price yet to be recognised in profit or loss	Concept (Monetary)	For Period		ifrs-full:IncreaseDecreaseInAggregateDifferenceBetweenFairValueAtInitialRecognitionAndAmountDeterminedUsingValuationTechniqueYetToBeRecognised
2670	Additions, aggregate difference between fair value at initial recognition and transaction price yet to be recognised in profit or loss	Concept (Monetary)	For Period		ifrs-full:IncreaseDecreaseThroughNewTransactionsAggregateDifferenceBetweenFairValueAtInitialRecognitionAndAmountDeterminedUsingValuationTechniqueYetToBeRecognised
2671	Transfer out, aggregate difference between fair value at initial recognition and transaction price yet to be recognised in profit or loss	Concept (Monetary)	For Period		ifrs-full:OtherDecreasesAggregateDifferenceBetweenFairValueAtInitialRecognitionAndAmountDeterminedUsingValuationTechniqueYetToBeRecognised
2672	Amortisation and releases, aggregate difference between fair value at initial recognition and transaction price yet to be recognised in profit or loss	Concept (Monetary)	For Period		ifrs-full:IncreaseDecreaseThroughAmountsRecognisedInProfitOrLossAggregateDifferenceBetweenFairValueAtInitialRecognitionAndAmountDeterminedUsingValuationTechniqueYetToBeRecognised
2673	Description of existence of third-party credit enhancement	Concept (Text/String)	For Period		ifrs-full:DescriptionOfExistenceOfThirdpartyCreditEnhancement
2674	Description of whether third-party credit enhancement is reflected in fair value measurement	Concept (Text/String)	For Period		ifrs-full:DescriptionOfWhetherThirdpartyCreditEnhancementIsReflectedInFairValueMeasurement
2675	Deposits at amortised cost	Concept (Monetary)	As Of	Credit	c070:DepositsAtAmortisedCost
2676	042001 - Disclosure - Offsetting financial assets and financial liabilities (Details)	Network	*	*	http://www.barclays.co.uk/role/OffsettingFinancialAssetsAndFinancialLiabilitiesDetails
2677	Disclosure of offsetting of financial assets [table]	Table	*	*	ifrs-full:DisclosureOfOffsettingOfFinancialAssetsTable
2678	Types of financial assets [axis]	Axis			ifrs-full:TypesOfFinancialAssetsAxis
2679	Financial assets, type [member]	Member			ifrs-full:FinancialAssetsTypeMember
2680	Derivatives [member]	Member			ifrs-full:DerivativesMember
2681	Reverse repurchase agreements and other similar secured lending [member]	Member			c070:ReverseRepurchaseAgreementsAndOtherSimilarSecuredLendingMember
2682	Consolidated Entities [Axis]	Axis			srt:ConsolidatedEntitiesAxis
2683	Consolidated Entities [Domain]	Member			srt:ConsolidatedEntitiesDomain
2684	Barclays Bank Group [member]	Member			c070:BarclaysBankGroupMember
2685	Disclosure of offsetting of financial assets [line items]	LineItems			ifrs-full:DisclosureOfOffsettingOfFinancialAssetsLineItems
2686	Gross amounts	Concept (Monetary)	As Of	Debit	ifrs-full:GrossFinancialAssetsSubjectToOffsettingEnforceableMasterNettingArrangementsOrSimilarAgreements
2687	Amounts offset	Concept (Monetary)	As Of	Credit	ifrs-full:GrossFinancialLiabilitiesSetOffAgainstFinancialAssetsSubjectToOffsettingEnforceableMasterNettingArrangementsOrSimilarAgreements
2688	Net amounts reported on the balance sheet	Concept (Monetary)	As Of	Debit	ifrs-full:NetFinancialAssetsSubjectToOffsettingEnforceableMasterNettingArrangementsOrSimilarAgreementsInStatementOfFinancialPosition
2689	Financial instruments	Concept (Monetary)	As Of	Credit	ifrs-full:FinancialInstrumentsSubjectToEnforceableMasterNettingArrangementOrSimilarAgreementNotSetOffAgainstFinancialAssets
2690	Financial collateral	Concept (Monetary)	As Of	Credit	c070:FinancialCollateralReceivedSubjectToEnforceableMasterNettingArrangementOrSimilarAgreementNotSetOffAgainstFinancialAssets
2691	Net amount	Concept (Monetary)	As Of	Credit	ifrs-full:AmountsSubjectToEnforceableMasterNettingArrangementOrSimilarAgreementNotSetOffAgainstFinancialAssets
2692	Amounts not subject to enforceable netting arrangements	Concept (Monetary)	As Of	Debit	c070:FinancialAssetsNotSubjectToEnforceableMasterNettingArrangementOrSimilarAgreement
2693	Balance sheet total	Concept (Monetary)	As Of	Debit	ifrs-full:NetFinancialAssetsSubjectToOffsettingEnforceableMasterNettingArrangementsOrSimilarAgreements
2694	042001 - Disclosure - Offsetting financial assets and financial liabilities (Details)	Network	*	*	http://www.barclays.co.uk/role/OffsettingFinancialAssetsAndFinancialLiabilitiesDetails
2695	Disclosure of offsetting of financial liabilities [table]	Table	*	*	ifrs-full:DisclosureOfOffsettingOfFinancialLiabilitiesTable
2696	Types of financial liabilities [axis]	Axis			ifrs-full:TypesOfFinancialLiabilitiesAxis
2697	Financial liabilities, type [member]	Member			ifrs-full:FinancialLiabilitiesTypeMember
2698	Derivatives [member]	Member			ifrs-full:DerivativesMember
2699	Repurchase agreements and other similar secured borrowing [member]	Member			c070:RepurchaseAgreementsAndOtherSimilarSecuredBorrowingMember
2700	Consolidated Entities [Axis]	Axis			srt:ConsolidatedEntitiesAxis
2701	Consolidated Entities [Domain]	Member			srt:ConsolidatedEntitiesDomain
2702	Barclays Bank Group [member]	Member			c070:BarclaysBankGroupMember
2703	Disclosure of offsetting of financial liabilities [line items]	LineItems			ifrs-full:DisclosureOfOffsettingOfFinancialLiabilitiesLineItems
2704	Gross amounts	Concept (Monetary)	As Of	Credit	ifrs-full:GrossFinancialLiabilitiesSubjectToOffsettingEnforceableMasterNettingArrangementsOrSimilarAgreements
2705	Amounts offset	Concept (Monetary)	As Of	Debit	ifrs-full:GrossFinancialAssetsSetOffAgainstFinancialLiabilitiesSubjectToOffsettingEnforceableMasterNettingArrangementsOrSimilarAgreements
2706	Net amounts reported on the balance sheet	Concept (Monetary)	As Of	Credit	ifrs-full:NetFinancialLiabilitiesSubjectToOffsettingEnforceableMasterNettingArrangementsOrSimilarAgreementsInStatementOfFinancialPosition
2707	Financial instruments	Concept (Monetary)	As Of	Debit	ifrs-full:FinancialInstrumentsSubjectToEnforceableMasterNettingArrangementOrSimilarAgreementNotSetOffAgainstFinancialLiabilities
2708	Financial collateral	Concept (Monetary)	As Of	Debit	c070:FinancialCollateralPledgedSubjectToEnforceableMasterNettingArrangementOrSimilarAgreementNotSetOffAgainstFinancialLiabilities
2709	Net amount	Concept (Monetary)	As Of	Debit	ifrs-full:AmountsSubjectToEnforceableMasterNettingArrangementOrSimilarAgreementNotSetOffAgainstFinancialLiabilities
2710	Amounts not subject to enforceable netting arrangements	Concept (Monetary)	As Of	Credit	c070:FinancialLiabilitiesNotSubjectToEnforceableMasterNettingArrangementOrSimilarAgreement
2711	Balance sheet total	Concept (Monetary)	As Of	Credit	ifrs-full:NetFinancialLiabilitiesSubjectToOffsettingEnforceableMasterNettingArrangementsOrSimilarAgreements
2712	042002 - Disclosure - Offsetting financial assets and financial liabilities - Financial assets (Narrative) (Details)	Network	*	*	http://www.barclays.co.uk/role/OffsettingFinancialAssetsAndFinancialLiabilitiesFinancialAssetsNarrativeDetails
2713	Disclosure of offsetting of financial assets [table]	Table	*	*	ifrs-full:DisclosureOfOffsettingOfFinancialAssetsTable
2714	Types of financial assets [axis]	Axis			ifrs-full:TypesOfFinancialAssetsAxis
2715	Financial assets, type [member]	Member			ifrs-full:FinancialAssetsTypeMember
2716	Derivatives [member]	Member			ifrs-full:DerivativesMember
2717	Reverse repurchase agreements and other similar secured lending [member]	Member			c070:ReverseRepurchaseAgreementsAndOtherSimilarSecuredLendingMember
2718	Classes of financial assets [axis]	Axis			ifrs-full:ClassesOfFinancialAssetsAxis
2719	Financial assets, class [member]	Member			ifrs-full:FinancialAssetsMember
2720	Financial assets designated at fair value [member]	Member			ifrs-full:FinancialAssetsAtFairValueThroughProfitOrLossDesignatedUponInitialRecognitionCategoryMember
2721	Financial assets at amortised cost [member]	Member			ifrs-full:FinancialAssetsAtAmortisedCostMember
2722	Classes of financial instruments [axis]	Axis			ifrs-full:ClassesOfFinancialInstrumentsAxis
2723	Financial instruments, class [member]	Member			ifrs-full:ClassesOfFinancialInstrumentsMember
2724	Cash collateral netted [member]	Member			c070:CashCollateralNettedMember
2725	Consolidated Entities [Axis]	Axis			srt:ConsolidatedEntitiesAxis
2726	Consolidated Entities [Domain]	Member			srt:ConsolidatedEntitiesDomain
2727	Barclays Bank Group [member]	Member			c070:BarclaysBankGroupMember
2728	Disclosure of offsetting of financial assets [line items]	LineItems			ifrs-full:DisclosureOfOffsettingOfFinancialAssetsLineItems
2729	Financial collateral	Concept (Monetary)	As Of	Credit	c070:FinancialCollateralReceivedSubjectToEnforceableMasterNettingArrangementOrSimilarAgreementNotSetOffAgainstFinancialAssets
2730	Cash collateral	Concept (Monetary)	As Of	Credit	ifrs-full:CashCollateralReceivedSubjectToEnforceableMasterNettingArrangementOrSimilarAgreementNotSetOffAgainstFinancialAssets
2731	Non-cash collateral	Concept (Monetary)	As Of	Credit	c070:NoncashCollateralReceivedSubjectToEnforceableMasterNettingArrangementsOrSimilarAgreementNotSetOffAgainstFinancialAssets
2732	Amounts offset	Concept (Monetary)	As Of	Credit	ifrs-full:GrossFinancialLiabilitiesSetOffAgainstFinancialAssetsSubjectToOffsettingEnforceableMasterNettingArrangementsOrSimilarAgreements
2733	Maximum Exposure	Concept (Monetary)	As Of	Debit	ifrs-full:NetFinancialAssetsSubjectToOffsettingEnforceableMasterNettingArrangementsOrSimilarAgreements
2734	042003 - Disclosure - Offsetting financial assets and financial liabilities - Financial liabilities (Narrative) (Details)	Network	*	*	http://www.barclays.co.uk/role/OffsettingFinancialAssetsAndFinancialLiabilitiesFinancialLiabilitiesNarrativeDetails
2735	Disclosure of offsetting of financial liabilities [table]	Table	*	*	ifrs-full:DisclosureOfOffsettingOfFinancialLiabilitiesTable
2736	Types of financial liabilities [axis]	Axis			ifrs-full:TypesOfFinancialLiabilitiesAxis
2737	Financial liabilities, type [member]	Member			ifrs-full:FinancialLiabilitiesTypeMember
2738	Derivatives [member]	Member			ifrs-full:DerivativesMember
2739	Repurchase agreements and other similar secured borrowing [member]	Member			c070:RepurchaseAgreementsAndOtherSimilarSecuredBorrowingMember
2740	Classes of financial liabilities [axis]	Axis			ifrs-full:ClassesOfFinancialLiabilitiesAxis
2741	Financial liabilities, class [member]	Member			ifrs-full:FinancialLiabilitiesMember
2742	Financial liabilities at fair value, class [member]	Member			ifrs-full:FinancialLiabilitiesAtFairValueMember
2743	Financial liabilities at amortised cost [member]	Member			ifrs-full:FinancialLiabilitiesAtAmortisedCostMember
2744	Classes of financial instruments [axis]	Axis			ifrs-full:ClassesOfFinancialInstrumentsAxis
2745	Financial instruments, class [member]	Member			ifrs-full:ClassesOfFinancialInstrumentsMember
2746	Cash collateral netted [member]	Member			c070:CashCollateralNettedMember
2747	Consolidated Entities [Axis]	Axis			srt:ConsolidatedEntitiesAxis
2748	Consolidated Entities [Domain]	Member			srt:ConsolidatedEntitiesDomain
2749	Barclays Bank Group [member]	Member			c070:BarclaysBankGroupMember
2750	Disclosure of offsetting of financial liabilities [line items]	LineItems			ifrs-full:DisclosureOfOffsettingOfFinancialLiabilitiesLineItems
2751	Financial collateral	Concept (Monetary)	As Of	Debit	c070:FinancialCollateralPledgedSubjectToEnforceableMasterNettingArrangementOrSimilarAgreementNotSetOffAgainstFinancialLiabilities
2752	Cash collateral pledged	Concept (Monetary)	As Of	Debit	ifrs-full:CashCollateralPledgedSubjectToEnforceableMasterNettingArrangementOrSimilarAgreementNotSetOffAgainstFinancialLiabilities
2753	Non-cash assets pledged as collateral	Concept (Monetary)	As Of	Debit	ifrs-full:NoncashAssetsPledgedAsCollateralForWhichTransfereeHasRightByContractOrCustomToSellOrRepledgeCollateral
2754	Amounts offset	Concept (Monetary)	As Of	Debit	ifrs-full:GrossFinancialAssetsSetOffAgainstFinancialLiabilitiesSubjectToOffsettingEnforceableMasterNettingArrangementsOrSimilarAgreements
2755	Settlements assets liabilities offset amounts	Concept (Monetary)	As Of	Credit	c070:SettlementsAssetsLiabilitiesOffsetAmounts
2756	Derivative liability expsoure	Concept (Monetary)	As Of	Credit	ifrs-full:NetFinancialLiabilitiesSubjectToOffsettingEnforceableMasterNettingArrangementsOrSimilarAgreements
2757	042101 - Disclosure - Loans and advances and deposits held at amortised cost (Details)	Network	*	*	http://www.barclays.co.uk/role/LoansAndAdvancesAndDepositsHeldAtAmortisedCostDetails
2758	Disclosure of detailed information about financial instruments [table]	Table	*	*	ifrs-full:DisclosureOfFinancialInstrumentsTable
2759	Consolidated Entities [Axis]	Axis			srt:ConsolidatedEntitiesAxis
2760	Consolidated Entities [Domain]	Member			srt:ConsolidatedEntitiesDomain
2761	Barclays Bank Group [member]	Member			c070:BarclaysBankGroupMember
2762	Categories of financial assets [axis]	Axis			ifrs-full:CategoriesOfFinancialAssetsAxis
2763	Financial assets, category [member]	Member			ifrs-full:FinancialAssetsCategoryMember
2764	Loans and advances at amortised cost excluding debt securities at amortised cost [Member]	Member			c070:LoansAndAdvancesAtAmortisedCostExcludingDebtSecuritiesAtAmortisedCostMember
2765	Debt securities [member]	Member			ifrs-full:DebtSecuritiesMember
2766	Loans and advances [member]	Member			ifrs-full:LoansAndReceivablesCategoryMember
2767	Counterparties [axis]	Axis			ifrs-full:CounterpartiesAxis
2768	Counterparties [member]	Member			ifrs-full:CounterpartiesMember
2769	Banks [member]	Member			c070:BanksMember
2770	Customers [member]	Member			ifrs-full:MarketsOfCustomersMember
2771	Categories of financial liabilities [axis]	Axis			ifrs-full:CategoriesOfFinancialLiabilitiesAxis
2772	Financial liabilities, category [member]	Member			ifrs-full:FinancialLiabilitiesCategoryMember
2773	Deposits at amortised cost [member]	Member			c070:DepositsAtAmortisedCostMember
2774	Disclosure of detailed information about financial instruments [line items]	LineItems			ifrs-full:DisclosureOfFinancialInstrumentsLineItems
2775	Gross amount	Concept (Monetary)	As Of		ifrs-full:NotionalAmount
2776	Less: allowance for impairment	Concept (Monetary)	As Of	Credit	ifrs-full:AllowanceAccountForCreditLossesOfFinancialAssets
2777	Financial assets at amortised cost	Concept (Monetary)	As Of	Debit	ifrs-full:FinancialAssetsAtAmortisedCost
2778	Deposits at amortised cost	Concept (Monetary)	As Of	Credit	ifrs-full:FinancialLiabilitiesAtAmortisedCost
2779	042201 - Disclosure - Finance leases - Finance lease receivables (Details)	Network	*	*	http://www.barclays.co.uk/role/FinanceLeasesFinanceLeaseReceivablesDetails
2780	Disclosure of finance lease and operating lease by lessee [table]	Table	*	*	ifrs-full:DisclosureOfFinanceLeaseAndOperatingLeaseByLesseeTable
2781	Maturity [axis]	Axis			ifrs-full:MaturityAxis
2782	Aggregated time bands [member]	Member			ifrs-full:AggregatedTimeBandsMember
2783	Not later than one year [member]	Member			ifrs-full:NotLaterThanOneYearMember
2784	Over one year but not more than five years [member]	Member			ifrs-full:LaterThanOneYearAndNotLaterThanFiveYearsMember
2785	Over five years [member]	Member			ifrs-full:LaterThanFiveYearsMember
2786	Consolidated Entities [Axis]	Axis			srt:ConsolidatedEntitiesAxis
2787	Consolidated Entities [Domain]	Member			srt:ConsolidatedEntitiesDomain
2788	Barclays Bank Group [member]	Member			c070:BarclaysBankGroupMember
2789	Disclosure of finance lease and operating lease by lessee [line items]	LineItems			ifrs-full:DisclosureOfFinanceLeaseAndOperatingLeaseByLesseeLineItems
2790	Gross investment in finance lease receivables	Concept (Monetary)	As Of	Debit	ifrs-full:GrossInvestmentInFinanceLease
2791	Future finance income	Concept (Monetary)	As Of	Credit	ifrs-full:FutureFinanceChargeOnFinanceLease
2792	Present value of minimum lease payments receivable	Concept (Monetary)	As Of	Debit	ifrs-full:MinimumFinanceLeasePaymentsReceivableAtPresentValue
2793	Un-guaranteed residual values	Concept (Monetary)	As Of	Debit	ifrs-full:DiscountedUnguaranteedResidualValueOfAssetsSubjectToFinanceLease
2794	042202 - Disclosure - Finance leases - Finance lease receivables (Narrative) (Details)	Network	*	*	http://www.barclays.co.uk/role/FinanceLeasesFinanceLeaseReceivablesNarrativeDetails
2795	Disclosure of detailed information about financial instruments [table]	Table	*	*	ifrs-full:DisclosureOfFinancialInstrumentsTable
2796	Consolidated Entities [Axis]	Axis			srt:ConsolidatedEntitiesAxis
2797	Consolidated Entities [Domain]	Member			srt:ConsolidatedEntitiesDomain
2798	Barclays Bank Group [member]	Member			c070:BarclaysBankGroupMember
2799	Disclosure of detailed information about financial instruments [line items]	LineItems			ifrs-full:DisclosureOfFinancialInstrumentsLineItems
2800	Impairment allowance for uncollectable finance lease receivables	Concept (Monetary)	As Of	Credit	ifrs-full:AccumulatedAllowanceForUncollectibleMinimumLeasePaymentsReceivable
2801	Minimum finance lease payments payable	Concept (Monetary)	As Of	Credit	ifrs-full:MinimumFinanceLeasePaymentsPayable
2802	Recognised finance lease as assets	Concept (Monetary)	As Of	Debit	ifrs-full:RecognisedFinanceLeaseAsAssets
2803	042301 - Disclosure - Property, plant and equipment (Narrative) (Details)	Network	*	*	http://www.barclays.co.uk/role/PropertyPlantAndEquipmentNarrativeDetails
2804	Disclosure of detailed information about property, plant and equipment [table]	Table	*	*	ifrs-full:DisclosureOfPropertyPlantAndEquipmentTable
2805	Classes of property, plant and equipment [axis]	Axis			ifrs-full:ClassesOfPropertyPlantAndEquipmentAxis
2806	Property, plant and equipment [member]	Member			ifrs-full:PropertyPlantAndEquipmentMember
2807	Freehold land [member]	Member			ifrs-full:LandMember
2808	Freehold buildings and long-leasehold property (more than 50 years to run) [member]	Member			ifrs-full:BuildingsMember
2809	Leasehold property over the remaining life of the lease (less than 50 years to run) [member]	Member			ifrs-full:PropertyPlantAndEquipmentUnderOperatingLeasesMember
2810	Costs of adaptation of freehold and leasehold property [member]	Member			ifrs-full:LeaseholdImprovementsMember
2811	Equipment installed in freehold and leasehold property [member]	Member			ifrs-full:CommunicationAndNetworkEquipmentMember
2812	Computers and similar equipment [member]	Member			ifrs-full:ComputerEquipmentMember
2813	Fixtures and fittings and other equipment [member]	Member			ifrs-full:FixturesAndFittingsMember
2814	Range [axis]	Axis			ifrs-full:RangeAxis
2815	Ranges [member]	Member			ifrs-full:RangesMember
2816	Min [member]	Member			ifrs-full:BottomOfRangeMember
2817	Max [member]	Member			ifrs-full:TopOfRangeMember
2818	Property, plant and equipment by operating lease status [axis]	Axis			ifrs-full:PropertyPlantAndEquipmentByOperatingLeaseStatusAxis
2819	Property, plant and equipment by operating lease status [member]	Member			ifrs-full:PropertyPlantAndEquipmentByOperatingLeaseStatusMember
2820	More than 50 years to run [member]	Member			c070:MoreThanFiftyYearsToRunMember
2821	Less than 50 years to run [member]	Member			c070:LessThanFiftyYearsToRunMember
2822	Classes of assets [axis]	Axis			ifrs-full:ClassesOfAssetsAxis
2823	Assets [member]	Member			ifrs-full:ClassesOfAssetsMember
2824	Property rentals [member]	Member			ifrs-full:InvestmentPropertyMember
2825	Consolidated Entities [Axis]	Axis			srt:ConsolidatedEntitiesAxis
2826	Consolidated Entities [Domain]	Member			srt:ConsolidatedEntitiesDomain
2827	Barclays Bank Group [member]	Member			c070:BarclaysBankGroupMember
2828	Disclosure of detailed information about property, plant and equipment [line items]	LineItems			ifrs-full:DisclosureOfPropertyPlantAndEquipmentLineItems
2829	Annual rates in calculating depreciation	Concept (Text/String)	For Period		ifrs-full:UsefulLivesOrDepreciationRatesPropertyPlantAndEquipment
2830	Depreciation rates, property, plant and equipment	Concept (Percent)	For Period		c070:DepreciationRatesPropertyPlantAndEquipment
2831	Net investment income	Concept (Monetary)	For Period	Credit	c070:InvestmentIncomeExpense
2832	Other income	Concept (Monetary)	For Period	Credit	ifrs-full:OtherIncome
2833	042302 - Disclosure - Property, plant and equipment - Investment property (Details)	Network	*	*	http://www.barclays.co.uk/role/PropertyPlantAndEquipmentInvestmentPropertyDetails
2834	Disclosure of detailed information about property, plant and equipment [table]	Table	*	*	ifrs-full:DisclosureOfPropertyPlantAndEquipmentTable
2835	Classes of assets [axis]	Axis			ifrs-full:ClassesOfAssetsAxis
2836	Assets [member]	Member			ifrs-full:ClassesOfAssetsMember
2837	Investment property [member]	Member			ifrs-full:InvestmentPropertyMember
2838	Classes of property, plant and equipment [axis]	Axis			ifrs-full:ClassesOfPropertyPlantAndEquipmentAxis
2839	Property, plant and equipment [member]	Member			ifrs-full:PropertyPlantAndEquipmentMember
2840	Property [member]	Member			ifrs-full:LandAndBuildingsMember
2841	Equipment [member]	Member			ifrs-full:CommunicationAndNetworkEquipmentMember
2842	Leased assets [member]	Member			ifrs-full:PropertyPlantAndEquipmentUnderOperatingLeasesMember
2843	Carrying amount, accumulated depreciation, amortisation and impairment and gross carrying amount [axis]	Axis			ifrs-full:CarryingAmountAccumulatedDepreciationAmortisationAndImpairmentAndGrossCarryingAmountAxis
2844	Carrying amount [member]	Member			ifrs-full:CarryingAmountMember
2845	Cost [member]	Member			ifrs-full:GrossCarryingAmountMember
2846	Accumulated depreciation and impairment [member]	Member			ifrs-full:AccumulatedDepreciationAmortisationAndImpairmentMember
2847	Consolidated Entities [Axis]	Axis			srt:ConsolidatedEntitiesAxis
2848	Consolidated Entities [Domain]	Member			srt:ConsolidatedEntitiesDomain
2849	Barclays Bank Group [member]	Member			c070:BarclaysBankGroupMember
2850	Disclosure of detailed information about property, plant and equipment [line items]	LineItems			ifrs-full:DisclosureOfPropertyPlantAndEquipmentLineItems
2851	Beginning balance, Property, plant and equipment	Concept (Monetary)	As Of	Debit	ifrs-full:PropertyPlantAndEquipment
2852	Additions	Concept (Monetary)	For Period	Debit	ifrs-full:AdditionsOtherThanThroughBusinessCombinationsPropertyPlantAndEquipment
2853	Depreciation charge	Concept (Monetary)	For Period		ifrs-full:DepreciationPropertyPlantAndEquipment
2854	Impairment	Concept (Monetary)	For Period		ifrs-full:ImpairmentLossRecognisedInProfitOrLossPropertyPlantAndEquipment
2855	Disposals	Concept (Monetary)	For Period	Credit	ifrs-full:DisposalsPropertyPlantAndEquipment
2856	Change in fair value of investment properties	Concept (Monetary)	For Period	Debit	ifrs-full:RevaluationIncreaseDecreasePropertyPlantAndEquipment
2857	Exchange and other movements	Concept (Monetary)	For Period	Debit	ifrs-full:IncreaseDecreaseThroughNetExchangeDifferencesPropertyPlantAndEquipment
2858	Ending balance, Property, plant and equipment	Concept (Monetary)	As Of	Debit	ifrs-full:PropertyPlantAndEquipment
2859	042401 - Disclosure - Goodwill and intangible assets (Narrative) (Details)	Network	*	*	http://www.barclays.co.uk/role/GoodwillAndIntangibleAssetsNarrativeDetails
2860	Disclosure of information for impairment loss recognised or reversed for individual asset or cash-generating unit [table]	Table	*	*	ifrs-full:DisclosureOfInformationForEachMaterialImpairmentLossRecognisedOrReversedForIndividualAssetOrCashgeneratingUnitTable
2861	Individual assets or cash-generating units [axis]	Axis			ifrs-full:IndividualAssetsOrCashgeneratingUnitsAxis
2862	Entity's total for individual assets or cash-generating units [member]	Member			ifrs-full:EntitysTotalForIndividualAssetsOrCashgeneratingUnitsMember
2863	Individual assets or cash-generating units [member]	Member			ifrs-full:IndividualAssetsOrCashgeneratingUnitsMember
2864	Barclaycard International [member]	Member			c070:BarclaycardInternationalPaymentsLimitedMember
2865	Range [axis]	Axis			ifrs-full:RangeAxis
2866	Ranges [member]	Member			ifrs-full:RangesMember
2867	Min [member]	Member			ifrs-full:BottomOfRangeMember
2868	Max [member]	Member			ifrs-full:TopOfRangeMember
2869	Disclosure of information for impairment loss recognised or reversed for individual asset or cash-generating unit [line items]	LineItems			ifrs-full:DisclosureOfInformationForEachMaterialImpairmentLossRecognisedOrReversedForIndividualAssetOrCashgeneratingUnitLineItems
2870	Goodwill	Concept (Monetary)	As Of	Debit	ifrs-full:Goodwill
2871	Explanation of period over which management has projected cash flows	Concept (Text/String)	For Period		ifrs-full:ExplanationOfPeriodOverWhichManagementHasProjectedCashFlows
2872	Terminal growth rate	Concept (Percent)	As Of		ifrs-full:DescriptionOfGrowthRateUsedToExtrapolateCashFlowProjections
2873	Amount by which unit's recoverable amount exceeds its carrying amount	Concept (Monetary)	As Of	Debit	ifrs-full:AmountByWhichUnitsRecoverableAmountExceedsItsCarryingAmount
2874	Discount rate applied to cash flow projections	Concept (Percent)	As Of		ifrs-full:DescriptionOfDiscountRatesAppliedToCashFlowProjections
2875	Description of key assumptions on which management has based cash flow projections	Concept (Text/String)	For Period		ifrs-full:DescriptionOfKeyAssumptionsOnWhichManagementHasBasedCashFlowProjections
2876	Increase in recoverable amount of asset or cash-generating unit, discount rate or terminal rate	Concept (Monetary)	For Period	Debit	c070:IncreaseInRecoverableAmountOfAssetOrCashgeneratingUnitDiscountOrTerminalRate
2877	Decrease in recoverable amount of asset or cash-generating unit, discount rate or terminal rate	Concept (Monetary)	For Period	Credit	c070:DecreaseInRecoverableAmountOfAssetOrCashgeneratingUnitDiscountOrTerminalRate
2878	Decrease in recoverable amount of asset or cash-generating unit, reduction in forecast cash flows	Concept (Monetary)	For Period	Credit	c070:DecreaseInRecoverableAmountOfAssetOrCashGeneratingUnitReductionInForecastCashFlows
2879	042401 - Disclosure - Goodwill and intangible assets (Narrative) (Details)	Network	*	*	http://www.barclays.co.uk/role/GoodwillAndIntangibleAssetsNarrativeDetails
2880	Disclosure of reconciliation of changes in intangible assets and goodwill [table]	Table	*	*	ifrs-full:DisclosureOfReconciliationOfChangesInIntangibleAssetsAndGoodwillTable
2881	Classes of intangible assets and goodwill [axis]	Axis			ifrs-full:ClassesOfIntangibleAssetsAndGoodwillAxis
2882	Goodwill and intangible assets [member]	Member			ifrs-full:IntangibleAssetsAndGoodwillMember
2883	Internally generated software [member]	Member			c070:InternallyGeneratedSoftwareMember
2884	Core banking platforms [Member]	Member			c070:CoreBankingPlatformsMember
2885	Other software [member]	Member			ifrs-full:OtherIntangibleAssetsMember
2886	Customer lists [member]	Member			ifrs-full:CustomerrelatedIntangibleAssetsMember
2887	Licences and other [member]	Member			c070:LicencesAndOtherMember
2888	Range [axis]	Axis			ifrs-full:RangeAxis
2889	Ranges [member]	Member			ifrs-full:RangesMember
2890	Min [member]	Member			ifrs-full:BottomOfRangeMember
2891	Max [member]	Member			ifrs-full:TopOfRangeMember
2892	Disclosure of reconciliation of changes in intangible assets and goodwill [line items]	LineItems			ifrs-full:DisclosureOfReconciliationOfChangesInIntangibleAssetsAndGoodwillLineItems
2893	Annual rates in calculating amortisation	Concept (xbrli:durationItemType)	For Period		c070:UsefulLivesOrAmortisationRatesIntangibleAssetsOtherThanGoodwillDuration
2894	Goodwill impairment	Concept (Monetary)	For Period		ifrs-full:ImpairmentLossRecognisedInProfitOrLossGoodwill
2895	042402 - Disclosure - Goodwill and intangible assets (Details)	Network	*	*	http://www.barclays.co.uk/role/GoodwillAndIntangibleAssetsDetails
2896	Disclosure of reconciliation of changes in intangible assets and goodwill [table]	Table	*	*	ifrs-full:DisclosureOfReconciliationOfChangesInIntangibleAssetsAndGoodwillTable
2897	Classes of intangible assets and goodwill [axis]	Axis			ifrs-full:ClassesOfIntangibleAssetsAndGoodwillAxis
2898	Goodwill and intangible assets [member]	Member			ifrs-full:IntangibleAssetsAndGoodwillMember
2899	Goodwill [member]	Member			ifrs-full:GoodwillMember
2900	Internally generated software [member]	Member			c070:InternallyGeneratedSoftwareMember
2901	Other software [member]	Member			ifrs-full:OtherIntangibleAssetsMember
2902	Customer lists [member]	Member			ifrs-full:CustomerrelatedIntangibleAssetsMember
2903	Licences and other [member]	Member			c070:LicencesAndOtherMember
2904	Carrying amount, accumulated depreciation, amortisation and impairment and gross carrying amount [axis]	Axis			ifrs-full:CarryingAmountAccumulatedDepreciationAmortisationAndImpairmentAndGrossCarryingAmountAxis
2905	Carrying amount [member]	Member			ifrs-full:CarryingAmountMember
2906	Cost [member]	Member			ifrs-full:GrossCarryingAmountMember
2907	Accumulated depreciation, amortisation and impairment [member]	Member			ifrs-full:AccumulatedDepreciationAmortisationAndImpairmentMember
2908	Consolidated Entities [Axis]	Axis			srt:ConsolidatedEntitiesAxis
2909	Consolidated Entities [Domain]	Member			srt:ConsolidatedEntitiesDomain
2910	Barclays Bank Group [member]	Member			c070:BarclaysBankGroupMember
2911	Disclosure of reconciliation of changes in intangible assets and goodwill [line items]	LineItems			ifrs-full:DisclosureOfReconciliationOfChangesInIntangibleAssetsAndGoodwillLineItems
2912	Intangible assets and goodwill	Concept (Monetary)	As Of	Debit	ifrs-full:IntangibleAssetsAndGoodwill
2913	Additions and disposals	Concept (Monetary)	For Period	Debit	c070:AdditionsAndDisposalsOtherThanThroughBusinessCombinationsIntangibleAssetsOtherThanGoodwill
2914	Disposals	Concept (Monetary)	For Period	Credit	ifrs-full:DisposalsIntangibleAssetsAndGoodwill
2915	Amortisation charge	Concept (Monetary)	For Period		ifrs-full:AmortisationIntangibleAssetsOtherThanGoodwill
2916	Impairment charge	Concept (Monetary)	For Period		ifrs-full:ImpairmentLossRecognisedInProfitOrLossIntangibleAssetsAndGoodwill
2917	Exchange and other movements	Concept (Monetary)	For Period	Debit	ifrs-full:IncreaseDecreaseThroughNetExchangeDifferencesIntangibleAssetsAndGoodwill
2918	Intangible assets and goodwill	Concept (Monetary)	As Of	Debit	ifrs-full:IntangibleAssetsAndGoodwill
2919	042403 - Disclosure - Goodwill and intangible assets - Goodwill (Details)	Network	*	*	http://www.barclays.co.uk/role/GoodwillAndIntangibleAssetsGoodwillDetails
2920	Disclosure of operating segments [table]	Table	*	*	ifrs-full:DisclosureOfOperatingSegmentsTable
2921	Segments [axis]	Axis			ifrs-full:SegmentsAxis
2922	Segments [member]	Member			ifrs-full:SegmentsMember
2923	Consumer, cards and payments [member]	Member			c070:ConsumerCardsAndPaymentsMember
2924	Consolidated Entities [Axis]	Axis			srt:ConsolidatedEntitiesAxis
2925	Consolidated Entities [Domain]	Member			srt:ConsolidatedEntitiesDomain
2926	Barclays Bank Group [member]	Member			c070:BarclaysBankGroupMember
2927	Disclosure of reconciliation of changes in intangible assets and goodwill [line items]	LineItems			ifrs-full:DisclosureOfReconciliationOfChangesInIntangibleAssetsAndGoodwillLineItems
2928	Goodwill	Concept (Monetary)	As Of	Debit	ifrs-full:Goodwill
2929	042501 - Disclosure - Operating leases (Details)	Network	*	*	http://www.barclays.co.uk/role/OperatingLeasesDetails
2930	Disclosure of finance lease and operating lease by lessee [table]	Table	*	*	ifrs-full:DisclosureOfFinanceLeaseAndOperatingLeaseByLesseeTable
2931	Maturity [axis]	Axis			ifrs-full:MaturityAxis
2932	Aggregated time bands [member]	Member			ifrs-full:AggregatedTimeBandsMember
2933	Not later than one year [member]	Member			ifrs-full:NotLaterThanOneYearMember
2934	Over one year but not more than five years [member]	Member			ifrs-full:LaterThanOneYearAndNotLaterThanFiveYearsMember
2935	Over five years [member]	Member			ifrs-full:LaterThanFiveYearsMember
2936	Classes of property, plant and equipment [axis]	Axis			ifrs-full:ClassesOfPropertyPlantAndEquipmentAxis
2937	Property, plant and equipment [member]	Member			ifrs-full:PropertyPlantAndEquipmentMember
2938	Property [member]	Member			ifrs-full:BuildingsMember
2939	Equipment [member]	Member			ifrs-full:CommunicationAndNetworkEquipmentMember
2940	Consolidated Entities [Axis]	Axis			srt:ConsolidatedEntitiesAxis
2941	Consolidated Entities [Domain]	Member			srt:ConsolidatedEntitiesDomain
2942	Barclays Bank Group [member]	Member			c070:BarclaysBankGroupMember
2943	Disclosure of finance lease and operating lease by lessee [line items]	LineItems			ifrs-full:DisclosureOfFinanceLeaseAndOperatingLeaseByLesseeLineItems
2944	Total	Concept (Monetary)	As Of	Credit	ifrs-full:MinimumLeasePaymentsPayableUnderNoncancellableOperatingLease
2945	042502 - Disclosure - Operating leases (Narrative) (Details)	Network	*	*	http://www.barclays.co.uk/role/OperatingLeasesNarrativeDetails
2946	Disclosure of finance lease and operating lease by lessee [table]	Table	*	*	ifrs-full:DisclosureOfFinanceLeaseAndOperatingLeaseByLesseeTable
2947	Consolidated Entities [Axis]	Axis			srt:ConsolidatedEntitiesAxis
2948	Consolidated Entities [Domain]	Member			srt:ConsolidatedEntitiesDomain
2949	Barclays Bank Group [member]	Member			c070:BarclaysBankGroupMember
2950	Disclosure of finance lease and operating lease by lessee [line items]	LineItems			ifrs-full:DisclosureOfFinanceLeaseAndOperatingLeaseByLesseeLineItems
2951	Minimum operating lease payments recognised as expense	Concept (Monetary)	For Period	Debit	ifrs-full:MinimumOperatingLeasePayments
2952	Expected future minimum sublease payments receivable under non-cancellable subleases, classified as operating lease	Concept (Monetary)	As Of	Debit	ifrs-full:ExpectedFutureMinimumSubleasePaymentsReceivableUnderNoncancellableSubleasesClassifiedAsOperatingLease
2953	042601 - Disclosure - Other liabilities (Details)	Network	*	*	http://www.barclays.co.uk/role/OtherLiabilitiesDetails
2954	Condensed Balance Sheet Statement [Table]	Table	*	*	srt:CondensedBalanceSheetStatementTable
2955	Consolidated Entities [Axis]	Axis			srt:ConsolidatedEntitiesAxis
2956	Consolidated Entities [Domain]	Member			srt:ConsolidatedEntitiesDomain
2957	Barclays Bank Group [member]	Member			c070:BarclaysBankGroupMember
2958	Condensed Balance Sheet Statements, Captions [Line Items]	LineItems			srt:CondensedBalanceSheetStatementsCaptionsLineItems
2959	Accruals and deferred income	Concept (Monetary)	As Of	Credit	ifrs-full:AccrualsAndDeferredIncome
2960	Other ceditors	Concept (Monetary)	As Of	Credit	c070:OtherCreditors
2961	Items in the course of collection due to other banks	Concept (Monetary)	As Of	Credit	ifrs-full:ItemsInCourseOfTransmissionToOtherBanks
2962	Obligations under finance leases (see Note 21)	Concept (Monetary)	As Of	Credit	ifrs-full:GrossFinanceLeaseObligations
2963	Insurance contract liabilities, including unit-linked liabilities	Concept (Monetary)	As Of	Credit	ifrs-full:LiabilitiesArisingFromInsuranceContracts
2964	Other liabilities	Concept (Monetary)	As Of	Credit	ifrs-full:OtherLiabilities
2965	042701 - Disclosure - Provisions (Details)	Network	*	*	http://www.barclays.co.uk/role/ProvisionsDetails
2966	Disclosure of other provisions [table]	Table	*	*	ifrs-full:DisclosureOfOtherProvisionsTable
2967	Classes of other provisions [axis]	Axis			ifrs-full:ClassesOfProvisionsAxis
2968	Other provisions [member]	Member			ifrs-full:OtherProvisionsMember
2969	Onerous contracts [member]	Member			ifrs-full:OnerousContractsProvisionMember
2970	Redundancy and restructuring [member]	Member			ifrs-full:RestructuringProvisionMember
2971	Undrawn contractually committed facilities and guarantees [member]	Member			c070:UndrawnContractuallyCommittedFacilitiesAndGuaranteesMember
2972	Customer redress [Member]	Member			c070:CustomerRedressMember
2973	Payment protection insurance redress [Member]	Member			c070:PaymentProtectionInsuranceRedressMember
2974	Other customer redress [Member]	Member			c070:OtherCustomerRedressMember
2975	Legal, competition and regulatory matters [member]	Member			ifrs-full:LegalProceedingsProvisionMember
2976	Sundry provisions [member]	Member			ifrs-full:MiscellaneousOtherProvisionsMember
2977	Consolidated Entities [Axis]	Axis			srt:ConsolidatedEntitiesAxis
2978	Consolidated Entities [Domain]	Member			srt:ConsolidatedEntitiesDomain
2979	Barclays Bank Group [member]	Member			c070:BarclaysBankGroupMember
2980	Disclosure of other provisions [line items]	LineItems			ifrs-full:DisclosureOfOtherProvisionsLineItems
2981	Provisions, Beginning balance	Concept (Monetary)	As Of	Credit	ifrs-full:OtherProvisions
2982	Additions	Concept (Monetary)	For Period	Credit	ifrs-full:AdditionalProvisionsOtherProvisions
2983	Amounts utilised	Concept (Monetary)	For Period	Debit	ifrs-full:ProvisionUsedOtherProvisions
2984	Unused amounts reversed	Concept (Monetary)	For Period	Debit	ifrs-full:UnusedProvisionReversedOtherProvisions
2985	Transfer of UK banking business	Concept (Monetary)	For Period	Debit	ifrs-full:DecreaseThroughTransferToLiabilitiesIncludedInDisposalGroupsClassifiedAsHeldForSaleOtherProvisions
2986	Exchange and other movements	Concept (Monetary)	For Period	Credit	ifrs-full:IncreaseDecreaseThroughNetExchangeDifferencesOtherProvisions
2987	Provisions, Ending balance	Concept (Monetary)	As Of	Credit	ifrs-full:OtherProvisions
2988	042704 - Disclosure - Provisions (Narrative) (Details)	Network	*	*	http://www.barclays.co.uk/role/ProvisionsNarrativeDetails
2989	Disclosure of other provisions [table]	Table	*	*	ifrs-full:DisclosureOfOtherProvisionsTable
2990	Maturity [axis]	Axis			ifrs-full:MaturityAxis
2991	Aggregated time bands [member]	Member			ifrs-full:AggregatedTimeBandsMember
2992	Not later than one year [member]	Member			ifrs-full:NotLaterThanOneYearMember
2993	Consolidated Entities [Axis]	Axis			srt:ConsolidatedEntitiesAxis
2994	Consolidated Entities [Domain]	Member			srt:ConsolidatedEntitiesDomain
2995	Barclays Bank Group [member]	Member			c070:BarclaysBankGroupMember
2996	Classes of other provisions [axis]	Axis			ifrs-full:ClassesOfProvisionsAxis
2997	Other provisions [member]	Member			ifrs-full:OtherProvisionsMember
2998	Customer redress [Member]	Member			c070:CustomerRedressMember
2999	Payment protection insurance redress [Member]	Member			c070:PaymentProtectionInsuranceRedressMember
3000	Disclosure of other provisions [line items]	LineItems			ifrs-full:DisclosureOfOtherProvisionsLineItems
3001	Expected reimbursement, other provisions	Concept (Monetary)	As Of	Debit	ifrs-full:ExpectedReimbursementOtherProvisions
3002	Additions	Concept (Monetary)	For Period	Credit	ifrs-full:AdditionalProvisionsOtherProvisions
3003	042801 - Disclosure - Contingent liabilities and commitments (Details)	Network	*	*	http://www.barclays.co.uk/role/ContingentLiabilitiesAndCommitmentsDetails
3004	Disclosure of contingent liabilities [table]	Table	*	*	ifrs-full:DisclosureOfContingentLiabilitiesTable
3005	Classes of contingent liabilities [axis]	Axis			ifrs-full:ClassesOfContingentLiabilitiesAxis
3006	Contingent liabilities [member]	Member			ifrs-full:ContingentLiabilitiesMember
3007	Guarantees and letters of credit pledged as collateral security [member]	Member			c070:GuaranteesAndLettersOfCreditPledgedAsCollateralSecurityMember
3008	Performance guarantees, acceptances and endorsements [member]	Member			c070:PerformanceGuaranteesAcceptancesAndEndorsementsMember
3009	Documentary credits and other short-term trade related transactions [member]	Member			c070:DocumentaryCreditsAndOtherShortTermTradeRelatedTransactionsMember
3010	Standby facilities, credit lines and other commitments [member]	Member			c070:StandbyFacilitiesCreditLinesAndOtherCommitmentsMember
3011	Measurement [axis]	Axis			ifrs-full:MeasurementAxis
3012	Aggregated measurement [member]	Member			ifrs-full:AggregatedMeasurementMember
3013	of which: Carried at fair value [member]	Member			ifrs-full:AtFairValueMember
3014	Classes of other provisions [axis]	Axis			ifrs-full:ClassesOfProvisionsAxis
3015	Other provisions [member]	Member			ifrs-full:OtherProvisionsMember
3016	Provision on loan commitment and financial guarantees [member]	Member			ifrs-full:ProvisionForCreditCommitmentsMember
3017	Classes of financial instruments [axis]	Axis			ifrs-full:ClassesOfFinancialInstrumentsAxis
3018	Financial instruments, class [member]	Member			ifrs-full:ClassesOfFinancialInstrumentsMember
3019	Financial guarantee contracts [member]	Member			ifrs-full:FinancialGuaranteeContractsMember
3020	Loan commitments [member]	Member			ifrs-full:LoanCommitmentsMember
3021	Disclosure of contingent liabilities [line items]	LineItems			ifrs-full:DisclosureOfContingentLiabilitiesLineItems
3022	Notional amount	Concept (Monetary)	As Of		ifrs-full:NotionalAmount
3023	Provisions	Concept (Monetary)	As Of	Credit	ifrs-full:Provisions
3024	Total contingent liabilities and commitments net of provisions	Concept (Monetary)	As Of		ifrs-full:EstimatedFinancialEffectOfContingentLiabilities
3025	042802 - Disclosure - Contingent liabilities and commitments (Narrative) (Details)	Network	*	*	http://www.barclays.co.uk/role/ContingentLiabilitiesAndCommitmentsNarrativeDetails
3026	Disclosure of contingent liabilities [table]	Table	*	*	ifrs-full:DisclosureOfContingentLiabilitiesTable
3027	Classes of contingent liabilities [axis]	Axis			ifrs-full:ClassesOfContingentLiabilitiesAxis
3028	Contingent liabilities [member]	Member			ifrs-full:ContingentLiabilitiesMember
3029	Financial Services Compensation Scheme [member]	Member			c070:FinancialServicesCompensationSchemeMember
3030	Guarantees and letters of credit pledged as collateral security [member]	Member			c070:GuaranteesAndLettersOfCreditPledgedAsCollateralSecurityMember
3031	Standby facilities, credit lines and other commitments [member]	Member			c070:StandbyFacilitiesCreditLinesAndOtherCommitmentsMember
3032	Borrowings by name [axis]	Axis			ifrs-full:BorrowingsByNameAxis
3033	Borrowings by name [member]	Member			ifrs-full:BorrowingsByNameMember
3034	HM Treasury loan facility [member]	Member			c070:HmTreasuryLoanFacilityMember
3035	Consolidated Entities [Axis]	Axis			srt:ConsolidatedEntitiesAxis
3036	Consolidated Entities [Domain]	Member			srt:ConsolidatedEntitiesDomain
3037	Barclays Bank Group [member]	Member			c070:BarclaysBankGroupMember
3038	Classes of financial assets [axis]	Axis			ifrs-full:ClassesOfFinancialAssetsAxis
3039	Financial assets, class [member]	Member			ifrs-full:FinancialAssetsMember
3040	Derivatives [member]	Member			ifrs-full:DerivativesMember
3041	Categories of related parties [axis]	Axis			ifrs-full:CategoriesOfRelatedPartiesAxis
3042	Entity's total for related parties [member]	Member			ifrs-full:EntitysTotalForRelatedPartiesMember
3043	Barclays Bank UK PLC [member]	Member			c070:BarclaysBankUkPlcMember
3044	Continuing and discontinued operations [axis]	Axis			ifrs-full:ContinuingAndDiscontinuedOperationsAxis
3045	Aggregate continuing and discontinued operations [member]	Member			ifrs-full:AggregateContinuingAndDiscontinuedOperationsMember
3046	Discontinued operations [member]	Member			ifrs-full:DiscontinuedOperationsMember
3047	UK Banking Business [member]	Member			c070:BarclaysUkMember
3048	Disclosure of contingent liabilities [line items]	LineItems			ifrs-full:DisclosureOfContingentLiabilitiesLineItems
3049	Repayment of loan facility	Concept (Monetary)	For Period	Credit	ifrs-full:RepaymentsOfBondsNotesAndDebentures
3050	Contingent liabilities	Concept (Monetary)	As Of		ifrs-full:EstimatedFinancialEffectOfContingentLiabilities
3051	Notional amount	Concept (Monetary)	As Of		ifrs-full:NotionalAmount
3052	042901 - Disclosure - Legal, competition and regulatory matters (Narrative) (Details)	Network	*	*	http://www.barclays.co.uk/role/LegalCompetitionAndRegulatoryMattersNarrativeDetails
3053	Disclosure of contingent liabilities [table]	Table	*	*	ifrs-full:DisclosureOfContingentLiabilitiesTable
3054	Classes of contingent liabilities [axis]	Axis			ifrs-full:ClassesOfContingentLiabilitiesAxis
3055	Contingent liabilities [member]	Member			ifrs-full:ContingentLiabilitiesMember
3056	Legal proceedings contingent liability [member]	Member			ifrs-full:LegalProceedingsContingentLiabilityMember
3057	Investigations into certain advisory services agreements and other matters and civil action [Member]	Member			c070:InvestigationsIntoCertainAdvisoryServicesAgreementsAndOtherMattersAndCivilActionMember
3058	SFO Proceedings [member]	Member			c070:UkSeriousFraudOfficeProceedingsMember
3059	FCA Proceedings and other investigations [Member]	Member			c070:FcaProceedingsAndOtherInvestigationsMember
3060	Civil action [Member]	Member			c070:CivilActionMember
3061	Investigations into LIBOR and other benchmarks [Member]	Member			c070:InvestigationsIntoLiborAndOtherBenchmarksMember
3062	LIBOR and other benchmark civil actions [Member]	Member			c070:LiborAndOtherBenchmarkCivilActionsMember
3063	USD LIBOR Cases in MDL Court [Member]	Member			c070:UsdLiborCasesInMdlCourtMember
3064	EURIBOR Case in the SDNY [Member]	Member			c070:EuriborCaseInTheSdnyMember
3065	Foreign Exchange investigations [Member]	Member			c070:ForeignExchangeInvestigationsMember
3066	Civil actions in respect of Foreign Exchange [Member]	Member			c070:CivilActionsInRespectOfForeignExchangeMember
3067	Consolidated FX Action [Member]	Member			c070:ConsolidatedFxActionMember
3068	Civil actions in respect of ISDAFIX [Member]	Member			c070:CivilActionsInRespectOfIsdafixMember
3069	US residential and commercial mortgage-related activity and litigation [Member]	Member			c070:UsResidentialAndCommercialMortgageRelatedActivityAndLitigationMember
3070	Alternative trading systems and high-frequency trading [Member]	Member			c070:AlternativeTradingSystemsAndHighFrequencyTradingMember
3071	Electricity market action [Member]	Member			c070:ElectricityMarketActionMember
3072	American Depositary Shares [Member]	Member			c070:AmericanDepositarySharesMember
3073	Civil actions in respect of the US Anti-Terrorism Act [Member]	Member			c070:CivilActionsInRespectOfTheUsAntiTerrorismActMember
3074	Portuguese Competition Authority investigation [Member]	Member			c070:PortugueseCompetitionAuthorityInvestigationMember
3075	BDC Finance LLC [Member]	Member			c070:BdcFinanceLlcMember
3076	HM Revenue and Customs (HMRC) assessments concerning UK Value Added Tax [member]	Member			c070:HmRevenueAndCustomsHmrcAssessmentsConcerningUkValueAddedTaxMember
3077	Classes of other provisions [axis]	Axis			ifrs-full:ClassesOfProvisionsAxis
3078	Other provisions [member]	Member			ifrs-full:OtherProvisionsMember
3079	Lawsuits with specified damages sought [Member]	Member			c070:LawsuitsWithSpecifiedDamagesSoughtMember
3080	Exchange-Based Class claims [Member]	Member			c070:ExchangeBasedClassClaimsMember
3081	OTC Class claims [Member]	Member			c070:OtcClassClaimsMember
3082	Debt Securities Class claims [Member]	Member			c070:DebtSecuritiesClassClaimsMember
3083	Issued loans linked to USD LIBOR [Member]	Member			c070:IssuedLoansLinkedToUnitedStatesDollarLiborMember
3084	Fines settlement [Member]	Member			c070:FineSettlementMember
3085	Violation of NPA [Member]	Member			c070:ViolationOfNpaMember
3086	Disgorgement and restitution settlement [Member]	Member			c070:DisgorgementAndRestitutionSettlementMember
3087	RMBS Repurchase Requests [Member]	Member			c070:RmbsRepurchaseRequestsMember
3088	Civil penalty [Member]	Member			c070:CivilPenaltyMember
3089	Disgorgement [Member]	Member			c070:DisgorgementMember
3090	Classes of financial instruments [axis]	Axis			ifrs-full:ClassesOfFinancialInstrumentsAxis
3091	Financial instruments, class [member]	Member			ifrs-full:ClassesOfFinancialInstrumentsMember
3092	United States Residential Mortgages [Member]	Member			c070:UnitedStatesResidentialMortgagesMember
3093	Private-label securitisations [Member]	Member			c070:PrivateLabelSecuritisationsMember
3094	Other private-label securitisations [Member]	Member			c070:OtherPrivateLabelSecuritisationsMember
3095	Subsquently repurchased [Member]	Member			c070:SubsquentlyRepurchasedMember
3096	Originated and sold to third parties by Acquired Subsidiary [Member]	Member			c070:OriginatedAndSoldToThirdPartiesByAcquiredSubsidiaryMember
3097	Sponsored securitisations [Member]	Member			c070:SponsoredSecuritisationsMember
3098	Types of customers [axis]	Axis			ifrs-full:TypesOfCustomersAxis
3099	Types of customers [member]	Member			ifrs-full:TypesOfCustomersMember
3100	Government sponsored enterprises [Member]	Member			c070:GovernmentSponsoredEnterprisesMember
3101	Other customers [Member]	Member			c070:OtherCustomersMember
3102	Categories of related parties [axis]	Axis			ifrs-full:CategoriesOfRelatedPartiesAxis
3103	Entity's total for related parties [member]	Member			ifrs-full:EntitysTotalForRelatedPartiesMember
3104	Barclays Capital Inc [member]	Member			c070:BarclaysCapitalIncMember
3105	Corporate and investment bank [member]	Member			c070:CorporateAndInvestmentBankMember
3106	UK Banking Business [member]	Member			c070:BarclaysUkMember
3107	Counterparties [axis]	Axis			ifrs-full:CounterpartiesAxis
3108	Counterparties [member]	Member			ifrs-full:CounterpartiesMember
3109	Securities and Exchange Commission [Member]	Member			c070:SecuritiesAndExchangeCommissionMember
3110	New York Attorney General [Member]	Member			c070:NewYorkAttorneyGeneralMember
3111	Consolidated Entities [Axis]	Axis			srt:ConsolidatedEntitiesAxis
3112	Consolidated Entities [Domain]	Member			srt:ConsolidatedEntitiesDomain
3113	Barclays PLC [member]	Member			srt:ParentCompanyMember
3114	Disclosure of contingent liabilities [line items]	LineItems			ifrs-full:DisclosureOfContingentLiabilitiesLineItems
3115	Explanation of general nature of dispute and of reason for non-disclosure of information regarding contingent liability	Concept (Text/String)	For Period		ifrs-full:ExplanationOfReasonForNondisclosureOfInformationRegardingContingentLiability
3116	Service agreement fees payable	Concept (Monetary)	As Of	Credit	ifrs-full:TradeAndOtherPayables
3117	Advisory service fees payable, term	Concept (xbrli:durationItemType)	For Period		c070:AdvisoryServiceFeesPayableTerm
3118	Loans to government	Concept (Monetary)	As Of	Debit	ifrs-full:LoansToGovernment
3119	Loss contingency, Financial penalty warning	Concept (Monetary)	For Period	Debit	c070:LossContingencyFinancialPenaltyWarning
3120	Loss Contingency, Damages Sought, claimed amounts, Value	Concept (Monetary)	For Period	Debit	c070:LossContingencyDamagesSoughtClaimedAmountsValue
3121	Information about contingent liabilities that disclosure is not practicable	Concept (Text/String)	For Period		ifrs-full:InformationAboutContingentLiabilitiesThatDisclosureIsNotPracticable
3122	Losses on litigation settlements	Concept (Monetary)	For Period	Debit	ifrs-full:LossesOnLitigationSettlements
3123	Number of lawsuits with specified damages sought	Concept (Integer)	For Period		c070:NumberOfLawsuitsWithSpecifiedDamagesSought
3124	Period under investigation of competition law infringment	Concept (xbrli:durationItemType)	For Period		c070:PeriodUnderInvestigationOfCompetitionLawInfringment
3125	Number of years probation	Concept (xbrli:durationItemType)	For Period		c070:NumberOfYearsProbation
3126	Provisions recognised	Concept (Monetary)	For Period	Debit	ifrs-full:ProvisionUsedOtherProvisions
3127	Revenue	Concept (Monetary)	For Period	Credit	ifrs-full:Revenue
3128	Cumulative realised gain (loss)	Concept (Monetary)	As Of	Credit	c070:CumulativeRealisedGainLoss
3129	Original unpaid principal balance at time of sale	Concept (Monetary)	As Of	Credit	c070:OriginalUnpaidPrincipalBalanceAtTimeOfSale
3130	Issued capital	Concept (Monetary)	As Of	Credit	ifrs-full:IssuedCapital
3131	Alleged excess collateral in response to demand	Concept (Monetary)	For Period	Credit	c070:AllegedExcessCollateralInResponseToDemand
3132	Litigation settlements approved, value	Concept (Monetary)	For Period	Credit	c070:LitigationSettlementsApprovedValue
3133	043001 - Disclosure - Subordinated Liabilities - Undated and dated loan capital (Details)	Network	*	*	http://www.barclays.co.uk/role/SubordinatedLiabilitiesUndatedAndDatedLoanCapitalDetails
3134	Condensed Balance Sheet Statement [Table]	Table	*	*	srt:CondensedBalanceSheetStatementTable
3135	Consolidated Entities [Axis]	Axis			srt:ConsolidatedEntitiesAxis
3136	Consolidated Entities [Domain]	Member			srt:ConsolidatedEntitiesDomain
3137	Barclays Bank Group [member]	Member			c070:BarclaysBankGroupMember
3138	Barclays Bank PLC [member]	Member			c070:BarclaysBankPlcMember
3139	Condensed Balance Sheet Statements, Captions [Line Items]	LineItems			srt:CondensedBalanceSheetStatementsCaptionsLineItems
3140	Opening balance as at 1 January	Concept (Monetary)	As Of	Credit	ifrs-full:SubordinatedLiabilities
3141	Issuances	Concept (Monetary)	For Period	Debit	ifrs-full:ProceedsFromIssueOfSubordinatedLiabilities
3142	Redemptions	Concept (Monetary)	For Period	Credit	ifrs-full:RepaymentsOfSubordinatedLiabilities
3143	Other	Concept (Monetary)	For Period	Credit	c070:OtherRepaymentsProceedsOfBorrowingsClassifiedAsFinancingActivities
3144	Total subordinated liabilities	Concept (Monetary)	As Of	Credit	ifrs-full:SubordinatedLiabilities
3145	Undated subordinated liabilities	Concept (Monetary)	As Of	Credit	ifrs-full:UndatedSubordinatedLiabilities
3146	Dated subordinated liabilities	Concept (Monetary)	As Of	Credit	ifrs-full:DatedSubordinatedLiabilities
3147	Total subordinated liabilities	Concept (Monetary)	As Of	Credit	ifrs-full:SubordinatedLiabilities
3148	043002 - Disclosure - Subordinated Liabilities - Undated (Details)	Network	*	*	http://www.barclays.co.uk/role/SubordinatedLiabilitiesUndatedDetails
3149	Disclosure of detailed information about borrowings [table]	Table	*	*	ifrs-full:DisclosureOfDetailedInformationAboutBorrowingsTable
3150	Borrowings by name [axis]	Axis			ifrs-full:BorrowingsByNameAxis
3151	Borrowings by name [member]	Member			ifrs-full:BorrowingsByNameMember
3152	6% Callable Perpetual Core Tier One Notes	Member			c070:SixPercentCallablePerpetualCoreTierOneNotesMember
3153	6.86% Callable Perpetual Core Tier One Notes (USD 179m)	Member			c070:SixPointEightSixPercentCallablePerpetualCoreTierOneNotesUsdOriginalCurrencyMember
3154	6.3688% Step-up Callable Perpetual Reserve Capital Instruments	Member			c070:SixPointThreeSixEightEightPercentStepUpCallablePerpetualReserveCapitalInstrumentsMember
3155	14% Step-up Callable Perpetual Reserve Capital Instruments	Member			c070:FourteenPercentStepUpCallablePerpetualReserveCapitalInstrumentsMember
3156	5.3304% Step-up Callable Perpetual Reserve Capital Instruments	Member			c070:FivePointThreeThreeZeroFourPercentStepUpCallablePerpetualReserveCapitalInstrumentsMember
3157	7.7% Undated Subordinated Notes (USD 99m)	Member			c070:SevenPointSevenPercentUndatedSubordinatedNotesUsdOriginalCurrencyMember
3158	8.25% Undated Subordinated Notes	Member			c070:EightPointTwoFivePercentUndatedSubordinatedNotesMember
3159	7.125% Undated Subordinated Notes	Member			c070:SevenPointOneTwoFivePercentUndatedSubordinatedNotesMember
3160	6.125% Undated Subordinated Notes	Member			c070:SixPointOneTwoFivePercentUndatedSubordinatedNotesMember
3161	Junior Undated Floating Rate Notes (USD 38m)	Member			c070:JuniorUndatedNotesUsdOriginalCurrencyMember
3162	Undated Floating Rate Primary Capital Notes Series 1 (USD 167m)	Member			c070:UndatedPrimaryCapitalNotesSeriesOneUsdOrginalCurrencyMember
3163	Undated Floating Rate Primary Capital Notes Series 2 (USD 295m)	Member			c070:UndatedPrimaryCapitalNotesSeriesTwoUsdOrginalCurrencyMember
3164	Undated Floating Rate Primary Capital Notes Series 3	Member			c070:UndatedPrimaryCapitalNotesSeriesThreeMember
3165	9.25% Perpetual Subordinated Bonds (ex-Woolwich PLC)	Member			c070:NinePointTwoFivePercentPerpetualSubordinatedBondsExWoolwichPlcMember
3166	9% Permanent Interest Bearing Capital Bonds	Member			c070:NinePercentPermanentInterestBearingCapitalBondsMember
3167	5.03% Reverse Dual Currency Undated Subordinated Loan (JPY 8,000m)	Member			c070:FivePointZeroThreePercentReverseDualCurrencyUndatedSubordinatedLoanMember
3168	5% Reverse Dual Currency Undated Subordinated Loan (JPY 12,000m)	Member			c070:FivePercentReverseDualCurrencyUndatedSubordinatedLoanJpyOriginalCurrencyMember
3169	Types of interest rates [axis]	Axis			ifrs-full:TypesOfInterestRatesAxis
3170	Interest rate types [member]	Member			ifrs-full:InterestRateTypesMember
3171	Floating interest rate [member]	Member			ifrs-full:FloatingInterestRateMember
3172	Consolidated Entities [Axis]	Axis			srt:ConsolidatedEntitiesAxis
3173	Consolidated Entities [Domain]	Member			srt:ConsolidatedEntitiesDomain
3174	Barclays Bank Group [member]	Member			c070:BarclaysBankGroupMember
3175	Barclays Bank PLC [member]	Member			c070:BarclaysBankPlcMember
3176	Disclosure of detailed information about borrowings [line items]	LineItems			ifrs-full:DisclosureOfDetailedInformationAboutBorrowingsLineItems
3177	Undated subordinated liabilities	Concept (Monetary)	As Of	Credit	ifrs-full:UndatedSubordinatedLiabilities
3178	Initial call date	Concept (Text/String)	For Period		c070:BorrowingsInitialCallDate
3179	043003 - Disclosure - Subordinated Liabilities - Undated (Parenthetical) (Details)	Network	*	*	http://www.barclays.co.uk/role/SubordinatedLiabilitiesUndatedParentheticalDetails
3180	Disclosure of detailed information about borrowings [table]	Table	*	*	ifrs-full:DisclosureOfDetailedInformationAboutBorrowingsTable
3181	Borrowings by name [axis]	Axis			ifrs-full:BorrowingsByNameAxis
3182	Borrowings by name [member]	Member			ifrs-full:BorrowingsByNameMember
3183	6% Callable Perpetual Core Tier One Notes	Member			c070:SixPercentCallablePerpetualCoreTierOneNotesMember
3184	6.86% Callable Perpetual Core Tier One Notes (USD 179m)	Member			c070:SixPointEightSixPercentCallablePerpetualCoreTierOneNotesUsdOriginalCurrencyMember
3185	6.3688% Step-up Callable Perpetual Reserve Capital Instruments	Member			c070:SixPointThreeSixEightEightPercentStepUpCallablePerpetualReserveCapitalInstrumentsMember
3186	14% Step-up Callable Perpetual Reserve Capital Instruments	Member			c070:FourteenPercentStepUpCallablePerpetualReserveCapitalInstrumentsMember
3187	5.3304% Step-up Callable Perpetual Reserve Capital Instruments	Member			c070:FivePointThreeThreeZeroFourPercentStepUpCallablePerpetualReserveCapitalInstrumentsMember
3188	7.7% Undated Subordinated Notes (USD 99m)	Member			c070:SevenPointSevenPercentUndatedSubordinatedNotesUsdOriginalCurrencyMember
3189	8.25% Undated Subordinated Notes	Member			c070:EightPointTwoFivePercentUndatedSubordinatedNotesMember
3190	7.125% Undated Subordinated Notes	Member			c070:SevenPointOneTwoFivePercentUndatedSubordinatedNotesMember
3191	6.125% Undated Subordinated Notes	Member			c070:SixPointOneTwoFivePercentUndatedSubordinatedNotesMember
3192	Junior Undated Floating Rate Notes (USD 38m)	Member			c070:JuniorUndatedNotesUsdOriginalCurrencyMember
3193	Undated Floating Rate Primary Capital Notes Series 1 (USD 167m)	Member			c070:UndatedPrimaryCapitalNotesSeriesOneUsdOrginalCurrencyMember
3194	Undated Floating Rate Primary Capital Notes Series 2 (USD 295m)	Member			c070:UndatedPrimaryCapitalNotesSeriesTwoUsdOrginalCurrencyMember
3195	9.25% Perpetual Subordinated Bonds (ex-Woolwich PLC)	Member			c070:NinePointTwoFivePercentPerpetualSubordinatedBondsExWoolwichPlcMember
3196	9% Permanent Interest Bearing Capital Bonds	Member			c070:NinePercentPermanentInterestBearingCapitalBondsMember
3197	5.03% Reverse Dual Currency Undated Subordinated Loan (JPY 8,000m)	Member			c070:FivePointZeroThreePercentReverseDualCurrencyUndatedSubordinatedLoanMember
3198	5% Reverse Dual Currency Undated Subordinated Loan (JPY 12,000m)	Member			c070:FivePercentReverseDualCurrencyUndatedSubordinatedLoanJpyOriginalCurrencyMember
3199	Types of interest rates [axis]	Axis			ifrs-full:TypesOfInterestRatesAxis
3200	Interest rate types [member]	Member			ifrs-full:InterestRateTypesMember
3201	Floating interest rate [member]	Member			ifrs-full:FloatingInterestRateMember
3202	Consolidated Entities [Axis]	Axis			srt:ConsolidatedEntitiesAxis
3203	Consolidated Entities [Domain]	Member			srt:ConsolidatedEntitiesDomain
3204	Barclays Bank Group [member]	Member			c070:BarclaysBankGroupMember
3205	Barclays Bank PLC [member]	Member			c070:BarclaysBankPlcMember
3206	Disclosure of detailed information about borrowings [line items]	LineItems			ifrs-full:DisclosureOfDetailedInformationAboutBorrowingsLineItems
3207	Interest rate	Concept (Percent)	As Of		ifrs-full:BorrowingsInterestRate
3208	Notional amount	Concept (Monetary)	As Of		ifrs-full:NotionalAmount
3209	043004 - Disclosure - Subordinated Liabilities - Dated (Details)	Network	*	*	http://www.barclays.co.uk/role/SubordinatedLiabilitiesDatedDetails
3210	Disclosure of detailed information about borrowings [table]	Table	*	*	ifrs-full:DisclosureOfDetailedInformationAboutBorrowingsTable
3211	Borrowings by name [axis]	Axis			ifrs-full:BorrowingsByNameAxis
3212	Borrowings by name [member]	Member			ifrs-full:BorrowingsByNameMember
3213	Barclays Bank PLC externally issued	Member			c070:SubordinatedLiabilitiesExternallyIssuedMember
3214	Floating Rate Subordinated Notes (EUR 40m), Due 2018	Member			c070:SubordinatedNotesDueTwentyEighteenEurOriginalCurrencyMember
3215	6% Fixed Rate Subordinated Notes (EUR 1,750m), Due 2018	Member			c070:SixPercentSubordinatedNotesOneMember
3216	CMS-Linked Subordinated Notes (EUR 100m), Due 2018	Member			c070:CmsLinkSubordinatedLoansOneMember
3217	CMS-Linked Subordinated Notes (EUR 135m), Due 2018	Member			c070:CmsLinkSubordinatedLoansTwoMember
3218	Fixed/Floating Rate Subordinated Callable Notes, Due 2023	Member			c070:FixedOrFloatingRateSubordinatedCallableNotesMember
3219	7.75% Contingent Capital Notes (USD 1,000m), Due 2023	Member			c070:SevenPointSevenFiveContingentCapitalNotesMember
3220	Floating Rate Subordinated Notes (EUR 50m), Due 2019	Member			c070:SubordinatedNotesTwoMember
3221	5.14% Lower Tier 2 Notes (USD 1,094m), Due 2020	Member			c070:FivePointOneFourPercentLowerTierTwoNotesMember
3222	6% Fixed Rate Subordinated Notes (EUR 1,500m), Due 2021	Member			c070:SixPercentSubordinatedNotesTwoMember
3223	9.5% Subordinated Bonds (ex-Woolwich Plc), Due 2021	Member			c070:NinePointFivePercentSubordinatedBondsExWoolwichPlcMember
3224	Subordinated Floating Rate Notes (EUR 100m), Due 2021	Member			c070:SubordinatedNotesThreeMember
3225	10% Fixed Rate Subordinated Notes , Due 2021	Member			c070:TenPercentSubordinatedNotesMember
3226	10.179% Fixed Rate Subordinated Notes (USD 1,521m), Due 2021	Member			c070:TenPointOneSevenNinePercentSubordinatedNotesMember
3227	Subordinated Floating Rate Notes (EUR 50m), Due 2022	Member			c070:SubordinatedNotesFourMember
3228	6.625% Fixed Rate Subordinated Notes (EUR 1,000m), Due 2022	Member			c070:SixPointSixTwoFivePercentSubordinatedNotesMember
3229	7.625% Contingent Capital Notes (USD 3,000m), Due 2022	Member			c070:SevenPointSixTwoFivePercentContingentCapitalNotesMember
3230	Subordinated Floating Rate Notes (EUR 50m), Due 2023	Member			c070:SubordinatedNotesFiveMember
3231	5.75% Fixed Rate Subordinated Notes, Due 2026	Member			c070:FivePointSevenFivePercentSubordinatedNotesMember
3232	5.4% Reverse Dual Currency Subordinated Loan (JPY 15,000m), Due 2027	Member			c070:FivePointFourPercentReverseDualCurrencySubordinatedLoanMember
3233	6.33% Subordinated Notes, Due 2032	Member			c070:SixPointThreeThreePercentSubordinatedNotesMember
3234	Subordinated Floating Rate Notes (EUR 68m), Due 2040	Member			c070:SubordinatedNotesSixMember
3235	Barclays Bank PLC issued intra-group to Barclays PLC	Member			c070:SubordinatedLiabilitiesNotesIssuedIntraGroupToUltimateParentMember
3236	2.625% Fixed Rate Subordinated Callable Notes (EUR 1,250m), Due 2025	Member			c070:TwoPointSixTwoFivePercentSubordinatedCallableNotesMember
3237	2% Fixed Rate Subordinated Callable Notes (EUR 1,500m), Due 2028	Member			c070:TwoPercentSubordinatedNotesMember
3238	4.375% Fixed Rate Subordinated Notes (USD 1,250m) , Due 2024	Member			c070:FourPointThreeSevenFivePercentSubordinatedNotesMember
3239	3.75% Resetting Subordinated Callable Note Due 2030	Member			c070:ThreePointSevenFivePercentResettingSubordinatedCallableNoteDueTwentyThirtyMember
3240	5.20% Fixed Rate Subordinated Notes (USD 1,367m), Due 2026	Member			c070:FivePointTwoZeroPercentSubordinatedNotesMember
3241	4.836% Fixed Rate Subordinated Callable Notes (USD 1,200m), Due 2028	Member			c070:FourPointThreeEightSixPercentSubordinatedNotesMember
3242	Barclays Bank PLC loans issued intra-group to Barclays PLC	Member			c070:SubordinatedLiabilitiesLoansIssuedIntragroupToUltimateParentMember
3243	2.875% Fixed Rate Subordinated Loans (USD 1,000m), Due 2020	Member			c070:TwoPointEightSevenFivePercentSubordinatedLoansDueTwentyTwentyUnitedStatesOfAmericaDollarOriginalCurrencyMember
3244	0.823% Subordinated Loans	Member			c070:ZeroPointEightTwoThreePercentSubordinatedLoansDueTwentyTwentyJapanYenOriginalCurrencyMember
3245	Subordinated Floating Rate Loans (JPY 4,000m), Due 2020	Member			c070:SubordinatedLoansDueTwentyTwentyJapanYenOriginalCurrencyMember
3246	3.25% Fixed Rate Subordinated Loans (USD 1,500m), Due 2021	Member			c070:ThreePointTwoFivePercentSubordinatedLoansDueTwentyTwentyOneUnitedStatesOfAmericaDollarOriginalCurrencyMember
3247	1.43% Fixed Rate Subordinated Loans (EUR 100m), Due 2021	Member			c070:OnePointFourThreePercentSubordinatedLoansDueTwentyTwentyOneEuroOriginalCurrencyMember
3248	1.875% Fixed Rate Subordinated Loans (EUR 1,000m), Due 2021	Member			c070:OnePointEightSevenFivePercentSubordinatedLoansDueTwentyTwentyOneEuroOriginalCurrencyMember
3249	1.67% Fixed Rate Subordinated Loans (EUR 15m), Due 2021	Member			c070:OnePointSixSevenPercentSubordinatedLoansDueTwentyTwentyOneEuroOriginalCurrencyMember
3250	3.20% Fixed Rate Subordinated Loans (USD 1,000m), Due 2021	Member			c070:ThreePointTwoPercentSubordinatedLoansDueTwentyTwentyOneUnitedStatesOfAmericaDollarOriginalCurrencyMember
3251	1.35% Fixed Rate Subordinated Loans (JPY 20,000m), Due 2021	Member			c070:OnePointThreeFiveSubordinatedLoansDueTwentyTwentyOneJapanYenOriginalCurrencyMember
3252	3.684% Fixed Rate Subordinated Callable Loans (USD 1,500m), Due 2023	Member			c070:ThreePointSixEightFourPercentSubordinatedLoansDueTwentyTwentyThreeUnitedStatesOfAmericaDollarOriginalCurrencyMember
3253	Subordinated Floating Rate Callable Loans (USD 750m), Due 2023	Member			c070:SubordinatedCallableLoansDueTwentyTwentyThreeUnitedStatesOfAmericaDollarOriginalCurrencyOneMember
3254	4.61% Fixed Rate Subordinated Callable Loans (USD 762m), Due 2023	Member			c070:FourPointSixOnePercentSubordinatedCallableLoansDueTwentyTwentyThreeUnitedStatesOfAmericaDollarOriginalCurrencyMember
3255	Subordinated Floating Rate Callable Loans (USD 375m), Due 2023	Member			c070:SubordinatedCallableLoansDueTwentyTwentyThreeUnitedStatesOfAmericaDollarOriginalCurrencyTwoMember
3256	Subordinated Floating Rate Loans (USD 1,500m), Due 2024	Member			c070:SubordinatedLoansDueTwentyTwentyFourUnitedStatesOfAmericaDollarOriginalCurrencyMember
3257	4.327% Fixed Rate Subordinated Loans (AUD 200m), Due 2023	Member			c070:FourPointThreeTwoSevenPercentSubordinatedLoansDueTwentyTwentyThreeAustraliaDollarOriginalCurrencyMember
3258	Subordinated Floating Rate Loans (AUD 225m), Due 2023	Member			c070:SubordinatedLoansDueTwentyTwentyThreeAustraliaDollarOriginalCurrencyMember
3259	Subordinated Floating Rate Loans (EUR 44m), Due 2023	Member			c070:SubordinatedLoansDueTwentyTwentyThreeEuroOriginalCurrencyMember
3260	1.125% Fixed Rate Subordinated Loans (CHF 175m), Due 2023	Member			c070:OnePointOneTwoFivePercentSubordinatedLoansDueTwentyTwentyThreeSwitzerlandFrancsOriginalCurrencyMember
3261	1.5% Fixed Rate Subordinated Loans (EUR 750m), Due 2023	Member			c070:OnePointFivePercentSubordinatedLoansDueTwentyTwentyThreeEuroOriginalCurrencyMember
3262	Subordinated Floating Rate Loans (SEK 500m), Due 2023	Member			c070:SubordinatedLoansDueTwentyTwentyThreeSwedenKronorOriginalCurrencyMember
3263	1.232% Fixed Rate Subordinated Callable Loans (JPY 130,500m), Due 2024	Member			c070:OnePointTwoThreeTwoPercentSubordinatedCallableLoansDueTwentyTwentyFourJapanYenOriginalCurrencyMember
3264	3.36% Fixed Rate Subordinated Loans (NOK 750m), Due 2023	Member			c070:ThreePointThreeSixPercentSubordinatedLoansDueTwentyTwentyThreeNorwayKroneOriginalCurrencyMember
3265	1.875% Fixed Rate Subordinated Loans (EUR 1,000m), Due 2023	Member			c070:OnePointEightSevenFivePercentSubordinatedCallableLoansDueTwentyTwentyThreeEuroOriginalCurrencyMember
3266	3.125% Fixed Rate Subordinated Loans, Due 2024	Member			c070:ThreePointOneTwoFivePercentSubordinatedLoansDueTwentyTwentyFourMember
3267	1.375% Fixed Rate Subordinated Callable Loans (EUR 1,000m), Due 2026	Member			c070:OnePointThreeSevenFivePercentSubordinatedCallableLoansDueTwentyTwentySixEuroOriginalCurrencyMember
3268	3.65% Fixed Rate Subordinated Loans (USD 900m), Due 2025	Member			c070:ThreePointSixFivePercentSubordinatedLoansDueTwentyTwentyFiveUnitedStatesOfAmericaDollarOriginalCurrencyMember
3269	4.375% Fixed Rate Subordinated Loans (USD 1,707m), Due 2026	Member			c070:FourPointThreeSevenFivePercentSubordinatedLoansDueTwentyTwentySixUnitedStatesOfAmericaDollarOriginalCurrencyMember
3270	1.635% Fixed Rate Subordinated Callable Loans (JPY 17,100m), Due 2028	Member			c070:OnePointSixThreeFivePercentSubordinatedCallableLoansDueTwentyTwentyEightJapanYenOriginalCurrencyMember
3271	5.244% Fixed Rate Subordinated Loans (AUD 175m), Due 2028	Member			c070:FivePointTwoFourFourPercentSubordinatedLoansDueTwentyTwentyEightAustraliaDollarOriginalCurrencyMember
3272	5.02% Fixed Rate Subordinated Loans (AUD 30m), Due 2028	Member			c070:FivePointZeroTwoPercentSubordinatedLoansDueTwentyTwentyEightAustraliaDollarOriginalCurrencyMember
3273	3.773% Fixed Rate Subordinated Loans (NOK 220m), Due 2028	Member			c070:ThreePointSevenSevenThreePercentSubordinatedLoansDueTwentyTwentyEightNorwayKroneOriginalCurrencyMember
3274	2.291% Fixed Rate Subordinated Loans (EUR 115m), Due 2029	Member			c070:TwoPointTwoNineOnePercentSubordinatedLoansDueTwentyTwentyNineEuroOriginalCurrencyMember
3275	6.10% Fixed Rate Subordinated Loans (AUD 130m), Due 2031	Member			c070:SixPointOneZeroPercentSubordinatedLoansDueTwentyTwentyThirthyOneAustraliaDollarOriginalCurrencyMember
3276	5.16% Fixed Rate Subordinated Loans (AUD 15m), Due 2031	Member			c070:FivePointTwoFivePercentSubordinatedLoansDueTwentyTwentyFortyFiveUnitedStatesOfAmericaDollarOriginalCurrencyMember
3277	5.25% Fixed Rate Subordinated Loans (USD 1,500m), Due 2045	Member			c070:FivePointOneSixPercentSubordinatedLoansDueTwentyTwentyThirthyOneAustraliaDollarOriginalCurrencyMember
3278	4.95% Fixed Rate Subordinated Loans (USD 1,500m), Due 2047	Member			c070:FourPointNineFivePercentSubordinatedLoansDueTwentyTwentyFortySevenUnitedStatesOfAmericaDollarOriginalCurrencyMember
3279	Types of interest rates [axis]	Axis			ifrs-full:TypesOfInterestRatesAxis
3280	Interest rate types [member]	Member			ifrs-full:InterestRateTypesMember
3281	Fixed interest rate [member]	Member			ifrs-full:FixedInterestRateMember
3282	Floating interest rate [member]	Member			ifrs-full:FloatingInterestRateMember
3283	Fixed or Floating Interest Rate [member]	Member			c070:FixedOrFloatingInterestRateMember
3284	Range [axis]	Axis			ifrs-full:RangeAxis
3285	Ranges [member]	Member			ifrs-full:RangesMember
3286	Min [member]	Member			ifrs-full:BottomOfRangeMember
3287	Max [member]	Member			ifrs-full:TopOfRangeMember
3288	Consolidated Entities [Axis]	Axis			srt:ConsolidatedEntitiesAxis
3289	Consolidated Entities [Domain]	Member			srt:ConsolidatedEntitiesDomain
3290	Barclays Bank Group [member]	Member			c070:BarclaysBankGroupMember
3291	Barclays Bank PLC [member]	Member			c070:BarclaysBankPlcMember
3292	Categories of related parties [axis]	Axis			ifrs-full:CategoriesOfRelatedPartiesAxis
3293	Entity's total for related parties [member]	Member			ifrs-full:EntitysTotalForRelatedPartiesMember
3294	Barclays PLC [member]	Member			srt:ParentCompanyMember
3295	Other subsidiaries [member]	Member			c070:OtherSubsidiariesMember
3296	Customer [Axis]	Axis			srt:MajorCustomersAxis
3297	Customer [Domain]	Member			srt:NameOfMajorCustomerDomain
3298	Barclays Bank PLC externally issued	Member			c070:ExternalCustomersMember
3299	Disclosure of detailed information about borrowings [line items]	LineItems			ifrs-full:DisclosureOfDetailedInformationAboutBorrowingsLineItems
3300	Dated subordinated liabilities	Concept (Monetary)	As Of	Credit	ifrs-full:DatedSubordinatedLiabilities
3301	Initial call date	Concept (Text/String)	For Period		c070:BorrowingsInitialCallDate
3302	Maturity Date	Concept (Year)	For Period		c070:BorrowingsMaturityDate
3303	043005 - Disclosure - Subordinated Liabilities - Dated (Parenthetical) (Details)	Network	*	*	http://www.barclays.co.uk/role/SubordinatedLiabilitiesDatedParentheticalDetails
3304	Disclosure of detailed information about borrowings [table]	Table	*	*	ifrs-full:DisclosureOfDetailedInformationAboutBorrowingsTable
3305	Types of interest rates [axis]	Axis			ifrs-full:TypesOfInterestRatesAxis
3306	Interest rate types [member]	Member			ifrs-full:InterestRateTypesMember
3307	Fixed interest rate [member]	Member			ifrs-full:FixedInterestRateMember
3308	Floating interest rate [member]	Member			ifrs-full:FloatingInterestRateMember
3309	Fixed or Floating Interest Rate [member]	Member			c070:FixedOrFloatingInterestRateMember
3310	Consolidated Entities [Axis]	Axis			srt:ConsolidatedEntitiesAxis
3311	Consolidated Entities [Domain]	Member			srt:ConsolidatedEntitiesDomain
3312	Barclays Bank Group [member]	Member			c070:BarclaysBankGroupMember
3313	Barclays Bank PLC [member]	Member			c070:BarclaysBankPlcMember
3314	Categories of related parties [axis]	Axis			ifrs-full:CategoriesOfRelatedPartiesAxis
3315	Entity's total for related parties [member]	Member			ifrs-full:EntitysTotalForRelatedPartiesMember
3316	Barclays PLC [member]	Member			srt:ParentCompanyMember
3317	Customer [Axis]	Axis			srt:MajorCustomersAxis
3318	Customer [Domain]	Member			srt:NameOfMajorCustomerDomain
3319	Barclays Bank PLC externally issued	Member			c070:ExternalCustomersMember
3320	Borrowings by name [axis]	Axis			ifrs-full:BorrowingsByNameAxis
3321	Borrowings by name [member]	Member			ifrs-full:BorrowingsByNameMember
3322	Barclays Bank PLC externally issued	Member			c070:SubordinatedLiabilitiesExternallyIssuedMember
3323	Floating Rate Subordinated Notes (EUR 40m), Due 2018	Member			c070:SubordinatedNotesDueTwentyEighteenEurOriginalCurrencyMember
3324	6% Fixed Rate Subordinated Notes (EUR 1,750m), Due 2018	Member			c070:SixPercentSubordinatedNotesOneMember
3325	CMS-Linked Subordinated Notes (EUR 100m), Due 2018	Member			c070:CmsLinkSubordinatedLoansOneMember
3326	CMS-Linked Subordinated Notes (EUR 135m), Due 2018	Member			c070:CmsLinkSubordinatedLoansTwoMember
3327	Fixed/Floating Rate Subordinated Callable Notes, Due 2023	Member			c070:FixedOrFloatingRateSubordinatedCallableNotesMember
3328	7.75% Contingent Capital Notes (USD 1,000m), Due 2023	Member			c070:SevenPointSevenFiveContingentCapitalNotesMember
3329	Floating Rate Subordinated Notes (EUR 50m), Due 2019	Member			c070:SubordinatedNotesTwoMember
3330	5.14% Lower Tier 2 Notes (USD 1,094m), Due 2020	Member			c070:FivePointOneFourPercentLowerTierTwoNotesMember
3331	6% Fixed Rate Subordinated Notes (EUR 1,500m), Due 2021	Member			c070:SixPercentSubordinatedNotesTwoMember
3332	9.5% Subordinated Bonds (ex-Woolwich Plc), Due 2021	Member			c070:NinePointFivePercentSubordinatedBondsExWoolwichPlcMember
3333	Subordinated Floating Rate Notes (EUR 100m), Due 2021	Member			c070:SubordinatedNotesThreeMember
3334	10% Fixed Rate Subordinated Notes , Due 2021	Member			c070:TenPercentSubordinatedNotesMember
3335	10.179% Fixed Rate Subordinated Notes (USD 1,521m), Due 2021	Member			c070:TenPointOneSevenNinePercentSubordinatedNotesMember
3336	Subordinated Floating Rate Notes (EUR 50m), Due 2022	Member			c070:SubordinatedNotesFourMember
3337	6.625% Fixed Rate Subordinated Notes (EUR 1,000m), Due 2022	Member			c070:SixPointSixTwoFivePercentSubordinatedNotesMember
3338	7.625% Contingent Capital Notes (USD 3,000m), Due 2022	Member			c070:SevenPointSixTwoFivePercentContingentCapitalNotesMember
3339	Subordinated Floating Rate Notes (EUR 50m), Due 2023	Member			c070:SubordinatedNotesFiveMember
3340	5.75% Fixed Rate Subordinated Notes, Due 2026	Member			c070:FivePointSevenFivePercentSubordinatedNotesMember
3341	5.4% Reverse Dual Currency Subordinated Loan (JPY 15,000m), Due 2027	Member			c070:FivePointFourPercentReverseDualCurrencySubordinatedLoanMember
3342	6.33% Subordinated Notes, Due 2032	Member			c070:SixPointThreeThreePercentSubordinatedNotesMember
3343	Subordinated Floating Rate Notes (EUR 68m), Due 2040	Member			c070:SubordinatedNotesSixMember
3344	Barclays Bank PLC issued intra-group to Barclays PLC	Member			c070:SubordinatedLiabilitiesNotesIssuedIntraGroupToUltimateParentMember
3345	2.625% Fixed Rate Subordinated Callable Notes (EUR 1,250m), Due 2025	Member			c070:TwoPointSixTwoFivePercentSubordinatedCallableNotesMember
3346	2% Fixed Rate Subordinated Callable Notes (EUR 1,500m), Due 2028	Member			c070:TwoPercentSubordinatedNotesMember
3347	4.375% Fixed Rate Subordinated Notes (USD 1,250m) , Due 2024	Member			c070:FourPointThreeSevenFivePercentSubordinatedNotesMember
3348	3.75% Resetting Subordinated Callable Note Due 2030	Member			c070:ThreePointSevenFivePercentResettingSubordinatedCallableNoteDueTwentyThirtyMember
3349	5.20% Fixed Rate Subordinated Notes (USD 1,367m), Due 2026	Member			c070:FivePointTwoZeroPercentSubordinatedNotesMember
3350	4.836% Fixed Rate Subordinated Callable Notes (USD 1,200m), Due 2028	Member			c070:FourPointThreeEightSixPercentSubordinatedNotesMember
3351	Barclays Bank PLC loans issued intra-group to Barclays PLC	Member			c070:SubordinatedLiabilitiesLoansIssuedIntragroupToUltimateParentMember
3352	2.875% Fixed Rate Subordinated Loans (USD 1,000m), Due 2020	Member			c070:TwoPointEightSevenFivePercentSubordinatedLoansDueTwentyTwentyUnitedStatesOfAmericaDollarOriginalCurrencyMember
3353	0.823% Subordinated Loans	Member			c070:ZeroPointEightTwoThreePercentSubordinatedLoansDueTwentyTwentyJapanYenOriginalCurrencyMember
3354	Subordinated Floating Rate Loans (JPY 4,000m), Due 2020	Member			c070:SubordinatedLoansDueTwentyTwentyJapanYenOriginalCurrencyMember
3355	3.25% Fixed Rate Subordinated Loans (USD 1,500m), Due 2021	Member			c070:ThreePointTwoFivePercentSubordinatedLoansDueTwentyTwentyOneUnitedStatesOfAmericaDollarOriginalCurrencyMember
3356	1.43% Fixed Rate Subordinated Loans (EUR 100m), Due 2021	Member			c070:OnePointFourThreePercentSubordinatedLoansDueTwentyTwentyOneEuroOriginalCurrencyMember
3357	1.875% Fixed Rate Subordinated Loans (EUR 1,000m), Due 2021	Member			c070:OnePointEightSevenFivePercentSubordinatedLoansDueTwentyTwentyOneEuroOriginalCurrencyMember
3358	1.67% Fixed Rate Subordinated Loans (EUR 15m), Due 2021	Member			c070:OnePointSixSevenPercentSubordinatedLoansDueTwentyTwentyOneEuroOriginalCurrencyMember
3359	3.20% Fixed Rate Subordinated Loans (USD 1,000m), Due 2021	Member			c070:ThreePointTwoPercentSubordinatedLoansDueTwentyTwentyOneUnitedStatesOfAmericaDollarOriginalCurrencyMember
3360	1.35% Fixed Rate Subordinated Loans (JPY 20,000m), Due 2021	Member			c070:OnePointThreeFiveSubordinatedLoansDueTwentyTwentyOneJapanYenOriginalCurrencyMember
3361	3.684% Fixed Rate Subordinated Callable Loans (USD 1,500m), Due 2023	Member			c070:ThreePointSixEightFourPercentSubordinatedLoansDueTwentyTwentyThreeUnitedStatesOfAmericaDollarOriginalCurrencyMember
3362	Subordinated Floating Rate Callable Loans (USD 750m), Due 2023	Member			c070:SubordinatedCallableLoansDueTwentyTwentyThreeUnitedStatesOfAmericaDollarOriginalCurrencyOneMember
3363	4.61% Fixed Rate Subordinated Callable Loans (USD 762m), Due 2023	Member			c070:FourPointSixOnePercentSubordinatedCallableLoansDueTwentyTwentyThreeUnitedStatesOfAmericaDollarOriginalCurrencyMember
3364	Subordinated Floating Rate Callable Loans (USD 375m), Due 2023	Member			c070:SubordinatedCallableLoansDueTwentyTwentyThreeUnitedStatesOfAmericaDollarOriginalCurrencyTwoMember
3365	Subordinated Floating Rate Loans (USD 1,500m), Due 2024	Member			c070:SubordinatedLoansDueTwentyTwentyFourUnitedStatesOfAmericaDollarOriginalCurrencyMember
3366	4.327% Fixed Rate Subordinated Loans (AUD 200m), Due 2023	Member			c070:FourPointThreeTwoSevenPercentSubordinatedLoansDueTwentyTwentyThreeAustraliaDollarOriginalCurrencyMember
3367	Subordinated Floating Rate Loans (AUD 225m), Due 2023	Member			c070:SubordinatedLoansDueTwentyTwentyThreeAustraliaDollarOriginalCurrencyMember
3368	Subordinated Floating Rate Loans (EUR 44m), Due 2023	Member			c070:SubordinatedLoansDueTwentyTwentyThreeEuroOriginalCurrencyMember
3369	1.125% Fixed Rate Subordinated Loans (CHF 175m), Due 2023	Member			c070:OnePointOneTwoFivePercentSubordinatedLoansDueTwentyTwentyThreeSwitzerlandFrancsOriginalCurrencyMember
3370	1.5% Fixed Rate Subordinated Loans (EUR 750m), Due 2023	Member			c070:OnePointFivePercentSubordinatedLoansDueTwentyTwentyThreeEuroOriginalCurrencyMember
3371	Subordinated Floating Rate Loans (SEK 500m), Due 2023	Member			c070:SubordinatedLoansDueTwentyTwentyThreeSwedenKronorOriginalCurrencyMember
3372	1.232% Fixed Rate Subordinated Callable Loans (JPY 130,500m), Due 2024	Member			c070:OnePointTwoThreeTwoPercentSubordinatedCallableLoansDueTwentyTwentyFourJapanYenOriginalCurrencyMember
3373	3.36% Fixed Rate Subordinated Loans (NOK 750m), Due 2023	Member			c070:ThreePointThreeSixPercentSubordinatedLoansDueTwentyTwentyThreeNorwayKroneOriginalCurrencyMember
3374	1.875% Fixed Rate Subordinated Loans (EUR 1,000m), Due 2023	Member			c070:OnePointEightSevenFivePercentSubordinatedCallableLoansDueTwentyTwentyThreeEuroOriginalCurrencyMember
3375	3.125% Fixed Rate Subordinated Loans, Due 2024	Member			c070:ThreePointOneTwoFivePercentSubordinatedLoansDueTwentyTwentyFourMember
3376	1.375% Fixed Rate Subordinated Callable Loans (EUR 1,000m), Due 2026	Member			c070:OnePointThreeSevenFivePercentSubordinatedCallableLoansDueTwentyTwentySixEuroOriginalCurrencyMember
3377	3.65% Fixed Rate Subordinated Loans (USD 900m), Due 2025	Member			c070:ThreePointSixFivePercentSubordinatedLoansDueTwentyTwentyFiveUnitedStatesOfAmericaDollarOriginalCurrencyMember
3378	4.375% Fixed Rate Subordinated Loans (USD 1,707m), Due 2026	Member			c070:FourPointThreeSevenFivePercentSubordinatedLoansDueTwentyTwentySixUnitedStatesOfAmericaDollarOriginalCurrencyMember
3379	1.635% Fixed Rate Subordinated Callable Loans (JPY 17,100m), Due 2028	Member			c070:OnePointSixThreeFivePercentSubordinatedCallableLoansDueTwentyTwentyEightJapanYenOriginalCurrencyMember
3380	5.244% Fixed Rate Subordinated Loans (AUD 175m), Due 2028	Member			c070:FivePointTwoFourFourPercentSubordinatedLoansDueTwentyTwentyEightAustraliaDollarOriginalCurrencyMember
3381	5.02% Fixed Rate Subordinated Loans (AUD 30m), Due 2028	Member			c070:FivePointZeroTwoPercentSubordinatedLoansDueTwentyTwentyEightAustraliaDollarOriginalCurrencyMember
3382	3.773% Fixed Rate Subordinated Loans (NOK 220m), Due 2028	Member			c070:ThreePointSevenSevenThreePercentSubordinatedLoansDueTwentyTwentyEightNorwayKroneOriginalCurrencyMember
3383	2.291% Fixed Rate Subordinated Loans (EUR 115m), Due 2029	Member			c070:TwoPointTwoNineOnePercentSubordinatedLoansDueTwentyTwentyNineEuroOriginalCurrencyMember
3384	6.10% Fixed Rate Subordinated Loans (AUD 130m), Due 2031	Member			c070:SixPointOneZeroPercentSubordinatedLoansDueTwentyTwentyThirthyOneAustraliaDollarOriginalCurrencyMember
3385	5.16% Fixed Rate Subordinated Loans (AUD 15m), Due 2031	Member			c070:FivePointTwoFivePercentSubordinatedLoansDueTwentyTwentyFortyFiveUnitedStatesOfAmericaDollarOriginalCurrencyMember
3386	5.25% Fixed Rate Subordinated Loans (USD 1,500m), Due 2045	Member			c070:FivePointOneSixPercentSubordinatedLoansDueTwentyTwentyThirthyOneAustraliaDollarOriginalCurrencyMember
3387	4.95% Fixed Rate Subordinated Loans (USD 1,500m), Due 2047	Member			c070:FourPointNineFivePercentSubordinatedLoansDueTwentyTwentyFortySevenUnitedStatesOfAmericaDollarOriginalCurrencyMember
3388	Disclosure of detailed information about borrowings [line items]	LineItems			ifrs-full:DisclosureOfDetailedInformationAboutBorrowingsLineItems
3389	Notional amount	Concept (Monetary)	As Of		ifrs-full:NotionalAmount
3390	Interest rate	Concept (Percent)	As Of		ifrs-full:BorrowingsInterestRate
3391	Equity to debt reclassification	Concept (Monetary)	For Period		ifrs-full:EquityReclassifiedIntoFinancialLiabilities
3392	043006 - Disclosure - Subordinated Liabilities (Narrative) (Details)	Network	*	*	http://www.barclays.co.uk/role/SubordinatedLiabilitiesNarrativeDetails
3393	Disclosure of detailed information about borrowings [table]	Table	*	*	ifrs-full:DisclosureOfDetailedInformationAboutBorrowingsTable
3394	Borrowings by name [axis]	Axis			ifrs-full:BorrowingsByNameAxis
3395	Borrowings by name [member]	Member			ifrs-full:BorrowingsByNameMember
3396	Barclays Bank PLC externally issued	Member			c070:SubordinatedLiabilitiesExternallyIssuedMember
3397	Fixed/Floating Rate Subordinated Callable Notes, Due 2023	Member			c070:FixedOrFloatingRateSubordinatedCallableNotesMember
3398	6% Fixed Rate Subordinated Notes (EUR 1,750m), Due 2018	Member			c070:SixPercentSubordinatedNotesOneMember
3399	7.75% Contingent Capital Notes (USD 1,000m), Due 2023	Member			c070:SevenPointSevenFiveContingentCapitalNotesMember
3400	7.7% Undated Subordinated Notes (USD 99m)	Member			c070:SevenPointSevenPercentUndatedSubordinatedNotesUsdOriginalCurrencyMember
3401	Floating Rate Subordinated Notes (EUR 40m), Due 2018	Member			c070:SubordinatedNotesDueTwentyEighteenEurOriginalCurrencyMember
3402	CMS-Linked Subordinated Notes (EUR 100m) and CMS-Linked Subordinated Notes (EUR 135m)	Member			c070:CmsLinkedSubordinatedNotesDueTwentyEighteenEurOriginalCurrencyMember
3403	8.25% Undated Subordinated Notes	Member			c070:EightPointTwoFivePercentUndatedSubordinatedNotesMember
3404	7.625% Contingent Capital Notes (USD 3,000m), Due 2022	Member			c070:SevenPointSixTwoFivePercentContingentCapitalNotesMember
3405	Types of interest rates [axis]	Axis			ifrs-full:TypesOfInterestRatesAxis
3406	Interest rate types [member]	Member			ifrs-full:InterestRateTypesMember
3407	Fixed interest rate [member]	Member			ifrs-full:FixedInterestRateMember
3408	Floating interest rate [member]	Member			ifrs-full:FloatingInterestRateMember
3409	Fixed or Floating Interest Rate [member]	Member			c070:FixedOrFloatingInterestRateMember
3410	Classes of liabilities [axis]	Axis			ifrs-full:ClassesOfLiabilitiesAxis
3411	Liabilities [member]	Member			ifrs-full:LiabilitiesMember
3412	Subordinated liabilities [member]	Member			c070:SubordinatedLiabilitiesMember
3413	Undated Subordinated liabilities [member]	Member			c070:UndatedSubordinatedLiabilitiesMember
3414	Dated subordinated liabilities [member]	Member			c070:DatedSubordinatedLiabilitiesMember
3415	Continuing and discontinued operations [axis]	Axis			ifrs-full:ContinuingAndDiscontinuedOperationsAxis
3416	Aggregate continuing and discontinued operations [member]	Member			ifrs-full:AggregateContinuingAndDiscontinuedOperationsMember
3417	Discontinued operations [member]	Member			ifrs-full:DiscontinuedOperationsMember
3418	Disposal of major subsidiary [member]	Member			ifrs-full:DisposalOfMajorSubsidiaryMember
3419	UK Banking Business [member]	Member			c070:BarclaysUkMember
3420	Categories of related parties [axis]	Axis			ifrs-full:CategoriesOfRelatedPartiesAxis
3421	Entity's total for related parties [member]	Member			ifrs-full:EntitysTotalForRelatedPartiesMember
3422	Barclays Bank UK PLC [member]	Member			c070:BarclaysBankUkPlcMember
3423	Other subsidiaries [member]	Member			ifrs-full:AllOtherSegmentsMember
3424	Barclays Securities Japan Limited [member]	Member			c070:BarclaysSecuritiesJapanLimitedMember
3425	Consolidated Entities [Axis]	Axis			srt:ConsolidatedEntitiesAxis
3426	Consolidated Entities [Domain]	Member			srt:ConsolidatedEntitiesDomain
3427	Barclays Bank Group [member]	Member			c070:BarclaysBankGroupMember
3428	Barclays Bank PLC [member]	Member			c070:BarclaysBankPlcMember
3429	Customer [Axis]	Axis			srt:MajorCustomersAxis
3430	Customer [Domain]	Member			srt:NameOfMajorCustomerDomain
3431	Barclays Bank PLC externally issued	Member			c070:ExternalCustomersMember
3432	Reclassified items [axis]	Axis			ifrs-full:ReclassifiedItemsAxis
3433	Reclassified items [member]	Member			ifrs-full:ReclassifiedItemsMember
3434	MREL [Member]	Member			c070:MinimumRequirementForOwnFundsAndEligibleLiabilitiesMember
3435	Components of equity [axis]	Axis			ifrs-full:ComponentsOfEquityAxis
3436	Equity [member]	Member			ifrs-full:EquityMember
3437	Other reserves and other shareholders equity [member]	Member			c070:OtherReservesAndOtherShareholdersEquityMember
3438	Disclosure of detailed information about borrowings [line items]	LineItems			ifrs-full:DisclosureOfDetailedInformationAboutBorrowingsLineItems
3439	Issuance of subordinated debt	Concept (Monetary)	For Period	Debit	ifrs-full:ProceedsFromIssueOfSubordinatedLiabilities
3440	Redemption of subordinated debt	Concept (Monetary)	For Period	Credit	ifrs-full:RepaymentsOfSubordinatedLiabilities
3441	Notional amount	Concept (Monetary)	As Of		ifrs-full:NotionalAmount
3442	Borrowings, interest rate	Concept (Percent)	As Of		ifrs-full:BorrowingsInterestRate
3443	Amount of reclassifications or presentation changes	Concept (Monetary)	For Period		ifrs-full:AmountOfReclassificationsOrChangesInPresentation
3444	Description of nature of changes in presentation	Concept (Text/String)	For Period		ifrs-full:DescriptionOfNatureOfReclassificationOrChangesInPresentation
3445	Description of reason for reclassifications or changes in presentation	Concept (Text/String)	For Period		ifrs-full:DescriptionOfReasonForReclassificationOrChangesInPresentation
3446	Equity reclassified into financial liabilities, net of income recognised	Concept (Monetary)	For Period		c070:EquityReclassifiedIntoFinancialLiabilitiesNetOfIncomeLossRecognised
3447	Subordinated liabilities	Concept (Monetary)	For Period	Credit	c070:IncreaseDecreaseInSubordinatedLiabilities
3448	Description of interest rate	Concept (Text/String)	For Period		c070:DescriptionOfDividendRate
3449	Description of interest payments	Concept (Text/String)	For Period		c070:DescriptionOfInterestPayments
3450	Description of repayment period	Concept (Text/String)	For Period		c070:DescriptionOfRepaymentPeriod
3451	Description of arrangement for contingent consideration arrangements and indemnification assets	Concept (Text/String)	For Period		ifrs-full:DescriptionOfArrangementForContingentConsiderationArrangementsAndIndemnificationAssets
3452	043101 - Disclosure - Ordinary shares, share premium, and other equity - Called up share capital, allotted and fully paid (Details)	Network	*	*	http://www.barclays.co.uk/role/OrdinarySharesSharePremiumAndOtherEquityCalledUpShareCapitalAllottedAndFullyPaidDetails
3453	Statement of changes in equity [table]	Table	*	*	ifrs-full:StatementOfChangesInEquityTable
3454	Components of equity [axis]	Axis			ifrs-full:ComponentsOfEquityAxis
3455	Equity [member]	Member			ifrs-full:EquityMember
3456	Share premium [member]	Member			ifrs-full:SharePremiumMember
3457	Total share capital and share premium [member]	Member			c070:IssuedCapitalAndSharePremiumMember
3458	Other equity instruments [member]	Member			ifrs-full:OtherEquityInterestMember
3459	Classes of share capital [axis]	Axis			ifrs-full:ClassesOfShareCapitalAxis
3460	Share capital [member]	Member			ifrs-full:ClassesOfShareCapitalMember
3461	Ordinary share capital [member]	Member			ifrs-full:OrdinarySharesMember
3462	Preference share capital [member]	Member			ifrs-full:PreferenceSharesMember
3463	Consolidated Entities [Axis]	Axis			srt:ConsolidatedEntitiesAxis
3464	Consolidated Entities [Domain]	Member			srt:ConsolidatedEntitiesDomain
3465	Barclays Bank Group [member]	Member			c070:BarclaysBankGroupMember
3466	Statement of changes in equity [line items]	LineItems			ifrs-full:StatementOfChangesInEquityLineItems
3467	Beginning Balance, equity	Concept (Monetary)	As Of	Credit	ifrs-full:Equity
3468	At securities redemption	Concept (Monetary)	For Period	Debit	ifrs-full:ReductionOfIssuedCapital
3469	Redemption of preference shares, value	Concept (Monetary)	For Period	Credit	c070:RedemptionOfPreferenceSharesValue
3470	Capital reorganisation	Concept (Monetary)	For Period	Credit	ifrs-full:IncreaseDecreaseThroughTransferBetweenRevaluationReserveAndRetainedEarnings
3471	Net equity impact of intra-group transfers	Concept (Monetary)	For Period	Credit	ifrs-full:IncreaseDecreaseThroughChangeInEquityOfSubsidiaries
3472	Proceeds from issuing shares and other equity instruments	Concept (Monetary)	For Period	Debit	c070:ProceedsFromIssuingSharesAndOtherEquityInstruments
3473	Ending Balance, equity	Concept (Monetary)	As Of	Credit	ifrs-full:Equity
3474	043102 - Disclosure - Ordinary shares, share premium, and other equity - AT1 Equity instruments (Details)	Network	*	*	http://www.barclays.co.uk/role/OrdinarySharesSharePremiumAndOtherEquityAT1EquityInstrumentsDetails
3475	Statement of changes in equity [table]	Table	*	*	ifrs-full:StatementOfChangesInEquityTable
3476	Components of equity [axis]	Axis			ifrs-full:ComponentsOfEquityAxis
3477	Equity [member]	Member			ifrs-full:EquityMember
3478	Other equity instruments [member]	Member			ifrs-full:OtherEquityInterestMember
3479	AT1 equity instruments [member]	Member			c070:AdditionalTierOneSecuritiesMember
3480	Classes of share capital [axis]	Axis			ifrs-full:ClassesOfShareCapitalAxis
3481	Share capital [member]	Member			ifrs-full:ClassesOfShareCapitalMember
3482	Fixed Rate Resetting Perpetual Subordinated Contingent Convertible Securities [member]	Member			c070:FixedRateResettingPerpetualSubordinatedContingentConvertibleSecuritiesMember
3483	8.25% Perpetual Subordinated Contingent Convertible Securities (USD 2,000m)	Member			c070:EightPointTwoFivePercentPerpetualSubordinatedContingentConvertibleSecuritiesMember
3484	7.0% Perpetual Subordinated Contingent Convertible Securities	Member			c070:SevenPointZeroPercentPerpetualSubordinatedContingentConvertibleSecuritiesMember
3485	6.625% Perpetual Subordinated Contingent Convertible Securities (USD 1,211m)	Member			c070:SixPointSixTwoFivePercentPerpetualSubordinatedContingentConvertibleSecuritiesMember
3486	6.5% Perpetual Subordinated Contingent Convertible Securities (EUR 1,077m)	Member			c070:SixPointFivePercentPerpetualSubordinatedContingentConvertibleSecuritiesMember
3487	8.0% Perpetual Subordinated Contingent Convertible Securities (EUR 1,000m)	Member			c070:EightPointZeroPercentPerpetualSubordinatedContingentConvertibleSecuritiesMember
3488	7.875% Perpetual Subordinated Contingent Convertible Securities	Member			c070:SevenPointEightSevenFivePercentPerpetualSubordinatedContingentConvertibleSecuritiesOneMember
3489	7.875% Perpetual Subordinated Contingent Convertible Securities (USD 1,500m)	Member			c070:SevenPointEightSevenFivePercentPerpetualSubordinatedContingentConvertibleSecuritiesTwoMember
3490	7.25% Perpetual Subordinated Contingent Convertible Securities	Member			c070:SevenPointTwoFivePercentPerpetualSubordinatedContingentConvertibleSecuritiesMember
3491	7.75% Perpetual Subordinated Contingent Convertible Securities (USD 2,500m)	Member			c070:SevenPointSevenFivePercentPerpetualSubordinatedContingentConvertibleSecuritiesMember
3492	5.875% Perpetual Subordinated Contingent Convertible Securities	Member			c070:FivePointEightSevenFivePercentPerpetualSubordinatedContingentConvertibleSecuritiesMember
3493	Consolidated Entities [Axis]	Axis			srt:ConsolidatedEntitiesAxis
3494	Consolidated Entities [Domain]	Member			srt:ConsolidatedEntitiesDomain
3495	Barclays Bank Group [member]	Member			c070:BarclaysBankGroupMember
3496	Types of interest rates [axis]	Axis			ifrs-full:TypesOfInterestRatesAxis
3497	Interest rate types [member]	Member			ifrs-full:InterestRateTypesMember
3498	Fixed interest rate [member]	Member			ifrs-full:FixedInterestRateMember
3499	Statement of changes in equity [line items]	LineItems			ifrs-full:StatementOfChangesInEquityLineItems
3500	Total AT1 equity instruments	Concept (Monetary)	As Of	Credit	ifrs-full:OtherEquityInterest
3501	Initial call date	Concept (Text/String)	For Period		c070:BorrowingsInitialCallDate
3502	043103 - Disclosure - Ordinary shares, share premium, and other equity - AT1 Equity instruments (Parenthetical) (Details)	Network	*	*	http://www.barclays.co.uk/role/OrdinarySharesSharePremiumAndOtherEquityAT1EquityInstrumentsParentheticalDetails
3503	Statement of changes in equity [table]	Table	*	*	ifrs-full:StatementOfChangesInEquityTable
3504	Components of equity [axis]	Axis			ifrs-full:ComponentsOfEquityAxis
3505	Equity [member]	Member			ifrs-full:EquityMember
3506	Other equity instruments [member]	Member			ifrs-full:OtherEquityInterestMember
3507	AT1 Securities [member]	Member			c070:AdditionalTierOneSecuritiesMember
3508	Classes of share capital [axis]	Axis			ifrs-full:ClassesOfShareCapitalAxis
3509	Share capital [member]	Member			ifrs-full:ClassesOfShareCapitalMember
3510	Fixed Rate Resetting Perpetual Subordinated Contingent Convertible Securities [member]	Member			c070:FixedRateResettingPerpetualSubordinatedContingentConvertibleSecuritiesMember
3511	8.25% Perpetual Subordinated Contingent Convertible Securities (USD 2,000m)	Member			c070:EightPointTwoFivePercentPerpetualSubordinatedContingentConvertibleSecuritiesMember
3512	7.0% Perpetual Subordinated Contingent Convertible Securities	Member			c070:SevenPointZeroPercentPerpetualSubordinatedContingentConvertibleSecuritiesMember
3513	6.625% Perpetual Subordinated Contingent Convertible Securities (USD 1,211m)	Member			c070:SixPointSixTwoFivePercentPerpetualSubordinatedContingentConvertibleSecuritiesMember
3514	6.5% Perpetual Subordinated Contingent Convertible Securities (EUR 1,077m)	Member			c070:SixPointFivePercentPerpetualSubordinatedContingentConvertibleSecuritiesMember
3515	8.0% Perpetual Subordinated Contingent Convertible Securities (EUR 1,000m)	Member			c070:EightPointZeroPercentPerpetualSubordinatedContingentConvertibleSecuritiesMember
3516	7.875% Perpetual Subordinated Contingent Convertible Securities	Member			c070:SevenPointEightSevenFivePercentPerpetualSubordinatedContingentConvertibleSecuritiesOneMember
3517	7.875% Perpetual Subordinated Contingent Convertible Securities (USD 1,500m)	Member			c070:SevenPointEightSevenFivePercentPerpetualSubordinatedContingentConvertibleSecuritiesTwoMember
3518	7.25% Perpetual Subordinated Contingent Convertible Securities	Member			c070:SevenPointTwoFivePercentPerpetualSubordinatedContingentConvertibleSecuritiesMember
3519	7.75% Perpetual Subordinated Contingent Convertible Securities (USD 2,500m)	Member			c070:SevenPointSevenFivePercentPerpetualSubordinatedContingentConvertibleSecuritiesMember
3520	5.875% Perpetual Subordinated Contingent Convertible Securities	Member			c070:FivePointEightSevenFivePercentPerpetualSubordinatedContingentConvertibleSecuritiesMember
3521	Consolidated Entities [Axis]	Axis			srt:ConsolidatedEntitiesAxis
3522	Consolidated Entities [Domain]	Member			srt:ConsolidatedEntitiesDomain
3523	Barclays Bank Group [member]	Member			c070:BarclaysBankGroupMember
3524	Types of interest rates [axis]	Axis			ifrs-full:TypesOfInterestRatesAxis
3525	Interest rate types [member]	Member			ifrs-full:InterestRateTypesMember
3526	Fixed interest rate [member]	Member			ifrs-full:FixedInterestRateMember
3527	Statement of changes in equity [line items]	LineItems			ifrs-full:StatementOfChangesInEquityLineItems
3528	Notional amount	Concept (Monetary)	As Of		ifrs-full:NotionalAmount
3529	Interest rate	Concept (Percent)	As Of		ifrs-full:BorrowingsInterestRate
3530	043104 - Disclosure - Ordinary shares, share premium, and other equity (Narrative) (Details)	Network	*	*	http://www.barclays.co.uk/role/OrdinarySharesSharePremiumAndOtherEquityNarrativeDetails
3531	Statement of changes in equity [table]	Table	*	*	ifrs-full:StatementOfChangesInEquityTable
3532	Components of equity [axis]	Axis			ifrs-full:ComponentsOfEquityAxis
3533	Equity [member]	Member			ifrs-full:EquityMember
3534	Called up share capital [member]	Member			ifrs-full:IssuedCapitalMember
3535	Share repurchase program [member]	Member			c070:ShareRepurchaseProgramMember
3536	Other equity instruments [member]	Member			ifrs-full:OtherEquityInterestMember
3537	AT1 Securities [member]	Member			c070:AdditionalTierOneSecuritiesMember
3538	Issuances of AT1 equity instruments [member]	Member			c070:IssuancesOfAdditionalTierOneSecuritiesMember
3539	Redemptions of AT1 equity instruments [member]	Member			c070:RedemptionsOfAdditionalTierOneSecuritiesMember
3540	Share premium [member]	Member			ifrs-full:SharePremiumMember
3541	Retained earnings [member]	Member			ifrs-full:RetainedEarningsMember
3542	Classes of share capital [axis]	Axis			ifrs-full:ClassesOfShareCapitalAxis
3543	Share capital [member]	Member			ifrs-full:ClassesOfShareCapitalMember
3544	Ordinary share capital [member]	Member			ifrs-full:OrdinarySharesMember
3545	Preference share capital [member]	Member			ifrs-full:PreferenceSharesMember
3546	Sterling 1 Preference Shares [member]	Member			c070:SterlingOneThousandPreferenceSharesMember
3547	Euro Preference Shares [member]	Member			c070:FourPointSevenFivePercentEuroOneHundredParValueMember
3548	US Dollar Preference Shares $ 100 [member]	Member			c070:UsDollarPreferenceSharesOneHundredParValueMember
3549	6.278% USD 100 [member]	Member			c070:SixPointTwoSevenEightPercentUsdOneHundredParValueMember
3550	American Depositary Shares, Series 1 [member]	Member			c070:AmericanDepositarySharesSeriesOneMember
3551	US Dollar Preference Shares $.25 [member]	Member			c070:UsDollarPreferenceSharesPointTwentyFiveParValueMember
3552	8.125% USD 0.25 [member]	Member			c070:EightPointOneTwoFivePercentUsdTwentyFiveCentsParValueMember
3553	American Depositary Shares, Series 5 [member]	Member			c070:AmericanDepositarySharesSeriesFiveMember
3554	6.625% USD 0.25 [member]	Member			c070:SixPointSixTwoFivePercentUsdTwentyFiveCentsParValueMember
3555	7.75% USD 0.25 [member]	Member			c070:SevenPointSevenFivePercentUsdTwentyFiveCentsParValueMember
3556	Fixed Rate Resetting Perpetual Subordinated Contingent Convertible Securities [member]	Member			c070:FixedRateResettingPerpetualSubordinatedContingentConvertibleSecuritiesMember
3557	Borrowings by name [axis]	Axis			ifrs-full:BorrowingsByNameAxis
3558	Borrowings by name [member]	Member			ifrs-full:BorrowingsByNameMember
3559	6% Callable Perpetual Core Tier One Notes	Member			c070:SixPercentCallablePerpetualCoreTierOneNotesMember
3560	6.86% Callable Perpetual Core Tier One Notes (USD 179m)	Member			c070:SixPointEightSixPercentCallablePerpetualCoreTierOneNotesUsdOriginalCurrencyMember
3561	5.3304% Step-up Callable Perpetual Reserve Capital Instruments	Member			c070:FivePointThreeThreeZeroFourPercentStepUpCallablePerpetualReserveCapitalInstrumentsMember
3562	6.3688% Step-up Callable Perpetual Reserve Capital Instruments	Member			c070:SixPointThreeSixEightEightPercentStepUpCallablePerpetualReserveCapitalInstrumentsMember
3563	7.434% Step-up Callable Perpetual Reserve Capital Instruments	Member			c070:SevenPointFourThreeFourPercentStepUpCallablePerpetualReserveCapitalInstrumentsMember
3564	14% Step-up Callable Perpetual Reserve Capital Instruments	Member			c070:FourteenPercentStepUpCallablePerpetualReserveCapitalInstrumentsMember
3565	Categories of related parties [axis]	Axis			ifrs-full:CategoriesOfRelatedPartiesAxis
3566	Entity's total for related parties [member]	Member			ifrs-full:EntitysTotalForRelatedPartiesMember
3567	Barclays Bank UK PLC [member]	Member			c070:BarclaysBankUkPlcMember
3568	Continuing and discontinued operations [axis]	Axis			ifrs-full:ContinuingAndDiscontinuedOperationsAxis
3569	Aggregate continuing and discontinued operations [member]	Member			ifrs-full:AggregateContinuingAndDiscontinuedOperationsMember
3570	Discontinued operations [member]	Member			ifrs-full:DiscontinuedOperationsMember
3571	Disposal of major subsidiary [member]	Member			ifrs-full:DisposalOfMajorSubsidiaryMember
3572	UK Banking Business [member]	Member			c070:BarclaysUkMember
3573	Statement of changes in equity [line items]	LineItems			ifrs-full:StatementOfChangesInEquityLineItems
3574	Issued capital	Concept (Monetary)	As Of	Credit	ifrs-full:IssuedCapital
3575	Percentage of issued share capital	Concept (Percent)	As Of		c070:PercentageOfIssuedShareCapital
3576	Par value per share	Concept (Share)	As Of		ifrs-full:ParValuePerShare
3577	Issued share capital	Concept (Shares)	As Of		ifrs-full:NumberOfSharesIssuedAndFullyPaid
3578	Redemption of preference shares, shares	Concept (Shares)	For Period		c070:RedemptionOfPreferenceSharesShares
3579	Share premium	Concept (Monetary)	As Of	Credit	ifrs-full:SharePremium
3580	Notional amount	Concept (Monetary)	As Of		ifrs-full:NotionalAmount
3581	Description of interest rate	Concept (Text/String)	For Period		c070:DescriptionOfDividendRate
3582	Rights, preferences and restrictions attaching to class of share capital	Concept (Text/String)	For Period		ifrs-full:RightsPreferencesAndRestrictionsAttachingToClassOfShareCapital
3583	Interest rate	Concept (Percent)	As Of		ifrs-full:BorrowingsInterestRate
3584	Description of redemption terms	Concept (Text/String)	For Period		c070:DescriptionOfRedemptionTerms
3585	Equity	Concept (Monetary)	As Of	Credit	ifrs-full:Equity
3586	Capital reorganisation	Concept (Monetary)	For Period	Credit	ifrs-full:IncreaseDecreaseThroughTransferBetweenRevaluationReserveAndRetainedEarnings
3587	Proceeds from issuing shares	Concept (Monetary)	For Period	Debit	ifrs-full:ProceedsFromIssuingShares
3588	Number of convertible instruments issued	Concept (Integer)	For Period		c070:NumberOfConvertibleInstrumentsIssued
3589	Number of convertible instruments redeemed	Concept (Integer)	For Period		c070:NumberOfConvertibleInstrumentsRedeemed
3590	Net equity impact of intra-group transfers	Concept (Monetary)	For Period	Credit	ifrs-full:IncreaseDecreaseThroughChangeInEquityOfSubsidiaries
3591	Liquidating distributions subject to the ranking of reserve capital instruments	Concept (Share)	As Of		c070:LiquidatingDistributionsSubjectToTheRankingOfReserveCapitalInstruments
3592	043201 - Disclosure - Reserves (Details)	Network	*	*	http://www.barclays.co.uk/role/ReservesDetails
3593	Disclosure of reserves within equity [table]	Table	*	*	ifrs-full:DisclosureOfReservesWithinEquityTable
3594	Reserves within equity [axis]	Axis			ifrs-full:ReservesWithinEquityAxis
3595	Other reserves [member]	Member			ifrs-full:OtherReservesMember
3596	Currency translation reserve [member]	Member			ifrs-full:ReserveOfExchangeDifferencesOnTranslationMember
3597	Available for sale reserve [member]	Member			ifrs-full:ReserveOfGainsAndLossesOnRemeasuringAvailableforsaleFinancialAssetsMember
3598	Fair value through other comprehensive income reserve [member]	Member			ifrs-full:ReserveOfGainsAndLossesOnFinancialAssetsMeasuredAtFairValueThroughOtherComprehensiveIncomeMember
3599	Cash flow hedging reserve [member]	Member			ifrs-full:ReserveOfCashFlowHedgesMember
3600	Own credit reserve [member]	Member			ifrs-full:ReserveOfChangeInFairValueOfFinancialLiabilityAttributableToChangeInCreditRiskOfLiabilityMember
3601	Other reserves and other shareholders equity [member]	Member			c070:OtherReservesAndOtherShareholdersEquityMember
3602	Consolidated Entities [Axis]	Axis			srt:ConsolidatedEntitiesAxis
3603	Consolidated Entities [Domain]	Member			srt:ConsolidatedEntitiesDomain
3604	Barclays Bank Group [member]	Member			c070:BarclaysBankGroupMember
3605	Disclosure of reserves within equity [line items]	LineItems			ifrs-full:DisclosureOfReservesWithinEquityLineItems
3606	Total Reserves	Concept (Monetary)	As Of	Credit	ifrs-full:OtherReserves
3607	043202 - Disclosure - Reserves (Narrative) (Details)	Network	*	*	http://www.barclays.co.uk/role/ReservesNarrativeDetails
3608	Disclosure of reserves within equity [table]	Table	*	*	ifrs-full:DisclosureOfReservesWithinEquityTable
3609	Initially applied IFRSs [axis]	Axis			ifrs-full:InitiallyAppliedIFRSsAxis
3610	Initially applied IFRSs [member]	Member			ifrs-full:InitiallyAppliedIFRSsMember
3611	IFRSs 9 [member]	Member			c070:IFRSs9Member
3612	Consolidated Entities [Axis]	Axis			srt:ConsolidatedEntitiesAxis
3613	Consolidated Entities [Domain]	Member			srt:ConsolidatedEntitiesDomain
3614	Barclays Bank Group [member]	Member			c070:BarclaysBankGroupMember
3615	Disclosure of reserves within equity [line items]	LineItems			ifrs-full:DisclosureOfReservesWithinEquityLineItems
3616	Fair value previously recognised in the available for sale reserve are now recorded in fair value through other comprehensive income	Concept (Monetary)	For Period	Credit	ifrs-full:FairValueGainsLossesOnFinancialAssetsReclassifiedOutOfAvailableforsaleFinancialAssetsRecognisedInOtherComprehensiveIncome
3617	043301 - Disclosure - Non-controlling interests (Details)	Network	*	*	http://www.barclays.co.uk/role/NoncontrollingInterestsDetails
3618	Statement of changes in equity [table]	Table	*	*	ifrs-full:StatementOfChangesInEquityTable
3619	Categories of related parties [axis]	Axis			ifrs-full:CategoriesOfRelatedPartiesAxis
3620	Entity's total for related parties [member]	Member			ifrs-full:EntitysTotalForRelatedPartiesMember
3621	Barclay's Africa Banking Group Limited [member]	Member			c070:BarclaysAfricaBankingGroupLimitedMember
3622	Components of equity [axis]	Axis			ifrs-full:ComponentsOfEquityAxis
3623	Equity [member]	Member			ifrs-full:EquityMember
3624	Other non-controlling interests [member]	Member			c070:OtherNoncontrollingInterestMember
3625	Ownership [Axis]	Axis			srt:OwnershipAxis
3626	Ownership [Domain]	Member			srt:OwnershipDomain
3627	Barclay's Africa Banking Group Limited [member]	Member			c070:BarclaysAfricaBankingGroupLimitedMember
3628	Statement of changes in equity [line items]	LineItems			ifrs-full:StatementOfChangesInEquityLineItems
3629	Profit (loss), attributable to non-controlling interests	Concept (Monetary)	For Period	Credit	ifrs-full:ProfitLossAttributableToNoncontrollingInterests
3630	Equity attributable to non-controlling interest	Concept (Monetary)	As Of	Credit	ifrs-full:NoncontrollingInterests
3631	Dividends paid to non-controlling interest	Concept (Monetary)	For Period	Credit	ifrs-full:DividendsPaidToNoncontrollingInterests
3632	Proportion of ownership interest, non-controlling	Concept (Percent)	For Period		ifrs-full:ProportionOfOwnershipInterestsHeldByNoncontrollingInterests
3633	043401 - Disclosure - Staff costs (Details)	Network	*	*	http://www.barclays.co.uk/role/StaffCostsDetails
3634	Disclosure of net defined benefit liability (asset) [table]	Table	*	*	ifrs-full:DisclosureOfNetDefinedBenefitLiabilityAssetTable
3635	Characteristics of defined benefit plans [axis]	Axis			ifrs-full:CharacteristicsOfDefinedBenefitPlansAxis
3636	Characteristics of defined benefit plans [member]	Member			ifrs-full:CharacteristicsOfDefinedBenefitPlansMember
3637	Pension defined benefit plans [member]	Member			ifrs-full:PensionDefinedBenefitPlansMember
3638	Post-employment medical defined benefit plans [member]	Member			ifrs-full:PostemploymentMedicalDefinedBenefitPlansMember
3639	Defined contribution Schemes [member]	Member			c070:DefinedContributionPlansMember
3640	Classes of intangible assets and goodwill [axis]	Axis			ifrs-full:ClassesOfIntangibleAssetsAndGoodwillAxis
3641	Goodwill and intangible assets [member]	Member			ifrs-full:IntangibleAssetsAndGoodwillMember
3642	Internally generated software [member]	Member			c070:InternallyGeneratedSoftwareMember
3643	Consolidated Entities [Axis]	Axis			srt:ConsolidatedEntitiesAxis
3644	Consolidated Entities [Domain]	Member			srt:ConsolidatedEntitiesDomain
3645	Barclays Bank Group [member]	Member			c070:BarclaysBankGroupMember
3646	Disclosure of net defined benefit liability (asset) [line items]	LineItems			ifrs-full:DisclosureOfNetDefinedBenefitLiabilityAssetLineItems
3647	Compensation costs	Abstract			ifrs-full:ShorttermEmployeeBenefitsExpenseAbstract
3648	Performance costs	Concept (Monetary)	For Period	Debit	c070:PerformanceCosts
3649	Salaries	Concept (Monetary)	For Period	Debit	ifrs-full:WagesAndSalaries
3650	Social security costs	Concept (Monetary)	For Period	Debit	ifrs-full:SocialSecurityContributions
3651	Post-retirement benefits	Concept (Monetary)	For Period	Debit	ifrs-full:PostemploymentBenefitExpenseDefinedBenefitPlans
3652	Other compensation costs	Concept (Monetary)	For Period	Debit	ifrs-full:OtherEmployeeExpense
3653	Total compensation costs	Concept (Monetary)	For Period	Debit	c070:StaffCompensationCosts
3654	Other resourcing costs	Abstract			c070:OtherResourcingCostsAbstract
3655	Outsourcing	Concept (Monetary)	For Period	Debit	c070:OutsourcingCosts
3656	Redundancy and restructuring	Concept (Monetary)	For Period	Debit	ifrs-full:ExpenseOfRestructuringActivities
3657	Temporary staff costs	Concept (Monetary)	For Period	Debit	c070:TemporaryStaffCosts
3658	Other	Concept (Monetary)	For Period	Debit	c070:OtherResourcingCosts
3659	Total other resourcing costs	Concept (Monetary)	For Period	Debit	c070:ResourcingCosts
3660	Total staff costs	Concept (Monetary)	For Period	Debit	ifrs-full:EmployeeBenefitsExpense
3661	043501 - Disclosure - Share-based payments - Share based payments (Details)	Network	*	*	http://www.barclays.co.uk/role/SharebasedPaymentsShareBasedPaymentsDetails
3662	Disclosure of terms and conditions of share-based payment arrangement [table]	Table	*	*	ifrs-full:DisclosureOfTermsAndConditionsOfSharebasedPaymentArrangementTable
3663	Types of share-based payment arrangements [axis]	Axis			ifrs-full:TypesOfSharebasedPaymentArrangementsAxis
3664	Share-based payment arrangements [member]	Member			ifrs-full:SharebasedPaymentArrangementsMember
3665	Share value plan [member]	Member			c070:ShareValuePlanMember
3666	Deferred share value plan [member]	Member			c070:DeferredShareValuePlanMember
3667	Others [member]	Member			c070:OtherSchemesMember
3668	Disclosure of terms and conditions of share-based payment arrangement [line items]	LineItems			ifrs-full:DisclosureOfTermsAndConditionsOfSharebasedPaymentArrangementLineItems
3669	Total equity settled	Concept (Monetary)	For Period	Debit	ifrs-full:ExpenseFromEquitysettledSharebasedPaymentTransactionsInWhichGoodsOrServicesReceivedDidNotQualifyForRecognitionAsAssets
3670	Cash settled	Concept (Monetary)	For Period	Debit	ifrs-full:ExpenseFromCashsettledSharebasedPaymentTransactionsInWhichGoodsOrServicesReceivedDidNotQualifyForRecognitionAsAssets
3671	Total share based payments	Concept (Monetary)	For Period	Debit	ifrs-full:ExpenseFromSharebasedPaymentTransactionsInWhichGoodsOrServicesReceivedDidNotQualifyForRecognitionAsAssets
3672	043502 - Disclosure - Share-based payments - Share options and awards (Details)	Network	*	*	http://www.barclays.co.uk/role/SharebasedPaymentsShareOptionsAndAwardsDetails
3673	Disclosure of terms and conditions of share-based payment arrangement [table]	Table	*	*	ifrs-full:DisclosureOfTermsAndConditionsOfSharebasedPaymentArrangementTable
3674	Types of share-based payment arrangements [axis]	Axis			ifrs-full:TypesOfSharebasedPaymentArrangementsAxis
3675	Share-based payment arrangements [member]	Member			ifrs-full:SharebasedPaymentArrangementsMember
3676	Share value plan [member]	Member			c070:ShareValuePlanMember
3677	Deferred share value plan [member]	Member			c070:DeferredShareValuePlanMember
3678	Others [member]	Member			c070:OtherSchemesMember
3679	Range [axis]	Axis			ifrs-full:RangeAxis
3680	Ranges [member]	Member			ifrs-full:RangesMember
3681	Min [member]	Member			ifrs-full:BottomOfRangeMember
3682	Max [member]	Member			ifrs-full:TopOfRangeMember
3683	Disclosure of terms and conditions of share-based payment arrangement [line items]	LineItems			ifrs-full:DisclosureOfTermsAndConditionsOfSharebasedPaymentArrangementLineItems
3684	Weighted average fair value per award, granted in year	Concept (Share)	For Period		c070:WeightedAverageFairValuePerAwardInShareBasedPaymentArrangementGrantedInYear
3685	Weighted average share price at exercise/ release during year	Concept (Monetary)	For Period		ifrs-full:WeightedAverageExercisePriceOfShareOptionsInSharebasedPaymentArrangementExercisedDuringPeriodAtDateOfExercise
3686	Weighted average remaining contractual life in years	Concept (xbrli:durationItemType)	For Period		c070:WeightedAverageRemainingContractualLifeOfOutstandingShareOptionsYears
3687	Number of options/ awards outstanding	Concept (Shares)	As Of		c070:NumberOfOutstandingShareOptionsShares
3688	043503 - Disclosure - Share-based payments - Movements in option and award plans (Details)	Network	*	*	http://www.barclays.co.uk/role/SharebasedPaymentsMovementsInOptionAndAwardPlansDetails
3689	Disclosure of terms and conditions of share-based payment arrangement [table]	Table	*	*	ifrs-full:DisclosureOfTermsAndConditionsOfSharebasedPaymentArrangementTable
3690	Types of share-based payment arrangements [axis]	Axis			ifrs-full:TypesOfSharebasedPaymentArrangementsAxis
3691	Share-based payment arrangements [member]	Member			ifrs-full:SharebasedPaymentArrangementsMember
3692	Share value plan [member]	Member			c070:ShareValuePlanMember
3693	Deferred share value plan [member]	Member			c070:DeferredShareValuePlanMember
3694	Others [member]	Member			c070:OtherSchemesMember
3695	Sharesave [member]	Member			c070:SharesaveMember
3696	Disclosure of terms and conditions of share-based payment arrangement [line items]	LineItems			ifrs-full:DisclosureOfTermsAndConditionsOfSharebasedPaymentArrangementLineItems
3697	Outstanding at beginning of year/acquisition date, Number of options	Concept (Shares)	As Of		c070:NumberOfOutstandingShareOptionsShares
3698	Transfers in the year	Concept (Shares)	For Period		c070:NumberOfShareOptionsTransferredInShareBasedPaymentArrangementShares
3699	Granted in the year, number of options	Concept (Shares)	For Period		c070:NumberOfShareOptionsGrantedInSharebasedPaymentArrangementShares
3700	Exercised/released in the year, number of options	Concept (Shares)	For Period		c070:NumberOfShareOptionsExercisedInSharebasedPaymentArrangementShares
3701	Less: forfeited in the year, number of options	Concept (Shares)	For Period		c070:NumberOfShareOptionsForfeitedInSharebasedPaymentArrangementShares
3702	Less: expired in the year, number of options	Concept (Shares)	For Period		c070:NumberOfShareOptionsExpiredInSharebasedPaymentArrangementShares
3703	Outstanding at end of year, Number of options	Concept (Shares)	As Of		c070:NumberOfOutstandingShareOptionsShares
3704	Of which exercisable, number of options	Concept (Shares)	As Of		c070:NumberOfShareOptionsExercisableInSharebasedPaymentArrangementShares
3705	Outstanding at beginning of year/acquisition date, Weighted average	Concept (Monetary)	As Of		ifrs-full:WeightedAverageExercisePriceOfShareOptionsOutstandingInSharebasedPaymentArrangement
3706	Granted in the year, weighted average exercise price	Concept (Monetary)	For Period		ifrs-full:WeightedAverageExercisePriceOfShareOptionsGrantedInSharebasedPaymentArrangement
3707	Exercised/released in the year, weighted average exercise price	Concept (Monetary)	For Period		ifrs-full:WeightedAverageExercisePriceOfShareOptionsExercisedInSharebasedPaymentArrangement
3708	Less: forfeited in the year, weighted average exercise price	Concept (Monetary)	For Period		ifrs-full:WeightedAverageExercisePriceOfShareOptionsForfeitedInSharebasedPaymentArrangement
3709	Less: expired in the year, weighted average exercise price	Concept (Monetary)	For Period		ifrs-full:WeightedAverageExercisePriceOfShareOptionsExpiredInSharebasedPaymentArrangement
3710	Outstanding at end of year, Weighted average exercise price	Concept (Monetary)	As Of		ifrs-full:WeightedAverageExercisePriceOfShareOptionsOutstandingInSharebasedPaymentArrangement
3711	Of which exercisable, weighted average exercise price	Concept (Monetary)	As Of		ifrs-full:WeightedAverageExercisePriceOfShareOptionsExercisableInSharebasedPaymentArrangement
3712	043504 - Disclosure - Share-based payments - Movements in options and award plans (Narrative) (Details)	Network	*	*	http://www.barclays.co.uk/role/SharebasedPaymentsMovementsInOptionsAndAwardPlansNarrativeDetails
3713	Disclosure of terms and conditions of share-based payment arrangement [table]	Table	*	*	ifrs-full:DisclosureOfTermsAndConditionsOfSharebasedPaymentArrangementTable
3714	Types of share-based payment arrangements [axis]	Axis			ifrs-full:TypesOfSharebasedPaymentArrangementsAxis
3715	Share-based payment arrangements [member]	Member			ifrs-full:SharebasedPaymentArrangementsMember
3716	Share value plan [member]	Member			c070:ShareValuePlanMember
3717	Deferred share value plan [member]	Member			c070:DeferredShareValuePlanMember
3718	Others [member]	Member			c070:OtherSchemesMember
3719	Sharesave [member]	Member			c070:SharesaveMember
3720	Disclosure of terms and conditions of share-based payment arrangement [line items]	LineItems			ifrs-full:DisclosureOfTermsAndConditionsOfSharebasedPaymentArrangementLineItems
3721	Number of share options exercisable in share-based payment arrangement	Concept (Shares)	As Of		c070:NumberOfShareOptionsExercisableInSharebasedPaymentArrangementShares
3722	Outstanding at beginning of year/acquisition date, Weighted average	Concept (Monetary)	As Of		ifrs-full:WeightedAverageExercisePriceOfShareOptionsOutstandingInSharebasedPaymentArrangement
3723	Granted in the year, weighted average exercise price	Concept (Monetary)	For Period		ifrs-full:WeightedAverageExercisePriceOfShareOptionsGrantedInSharebasedPaymentArrangement
3724	Exercised/released in the year, weighted average exercise price	Concept (Monetary)	For Period		ifrs-full:WeightedAverageExercisePriceOfShareOptionsExercisedInSharebasedPaymentArrangement
3725	Less: forfeited in the year, weighted average exercise price	Concept (Monetary)	For Period		ifrs-full:WeightedAverageExercisePriceOfShareOptionsForfeitedInSharebasedPaymentArrangement
3726	Less: expired in the year, weighted average exercise price	Concept (Monetary)	For Period		ifrs-full:WeightedAverageExercisePriceOfShareOptionsExpiredInSharebasedPaymentArrangement
3727	Outstanding at end of year, Weighted average exercise price	Concept (Monetary)	As Of		ifrs-full:WeightedAverageExercisePriceOfShareOptionsOutstandingInSharebasedPaymentArrangement
3728	043505 - Disclosure - Share-based payments (Narrative) (Details)	Network	*	*	http://www.barclays.co.uk/role/SharebasedPaymentsNarrativeDetails
3729	Disclosure of terms and conditions of share-based payment arrangement [table]	Table	*	*	ifrs-full:DisclosureOfTermsAndConditionsOfSharebasedPaymentArrangementTable
3730	Types of share-based payment arrangements [axis]	Axis			ifrs-full:TypesOfSharebasedPaymentArrangementsAxis
3731	Share-based payment arrangements [member]	Member			ifrs-full:SharebasedPaymentArrangementsMember
3732	Share value plan [member]	Member			c070:ShareValuePlanMember
3733	Deferred share value plan [member]	Member			c070:DeferredShareValuePlanMember
3734	Others [member]	Member			c070:OtherSchemesMember
3735	Disclosure of terms and conditions of share-based payment arrangement [line items]	LineItems			ifrs-full:DisclosureOfTermsAndConditionsOfSharebasedPaymentArrangementLineItems
3736	Description of share-based payment arrangement	Concept (Text/String)	For Period		ifrs-full:ExplanationOfShareOptionsInSharebasedPaymentArrangement
3737	Total liability arising from cash-settled share-based payments transactions	Concept (Monetary)	As Of	Credit	ifrs-full:LiabilitiesFromSharebasedPaymentTransactions2011
3738	043601 - Disclosure - Pensions and post-retirement benefits - Income statement charge (Details)	Network	*	*	http://www.barclays.co.uk/role/PensionsAndPostretirementBenefitsIncomeStatementChargeDetails
3739	Condensed Income Statement [Table]	Table	*	*	srt:CondensedIncomeStatementTable
3740	Consolidated Entities [Axis]	Axis			srt:ConsolidatedEntitiesAxis
3741	Consolidated Entities [Domain]	Member			srt:ConsolidatedEntitiesDomain
3742	Barclays Bank Group [member]	Member			c070:BarclaysBankGroupMember
3743	Condensed Income Statements, Captions [Line Items]	LineItems			srt:CondensedIncomeStatementsCaptionsLineItems
3744	Current service cost	Concept (Monetary)	For Period	Credit	ifrs-full:CurrentServiceCostNetDefinedBenefitLiabilityAsset
3745	Net finance cost	Concept (Monetary)	For Period	Credit	ifrs-full:InterestExpenseIncomeNetDefinedBenefitLiabilityAsset
3746	Past service cost	Concept (Monetary)	For Period	Credit	ifrs-full:PastServiceCostNetDefinedBenefitLiabilityAsset
3747	Other movements	Concept (Monetary)	For Period	Credit	ifrs-full:IncreaseDecreaseThroughOtherChangesNetDefinedBenefitLiabilityAsset
3748	Total	Concept (Monetary)	For Period	Credit	ifrs-full:IncreaseDecreaseInNetDefinedBenefitLiabilityAsset
3749	043602 - Disclosure - Pensions and post-retirement benefits - Balance sheet reconciliation (Details)	Network	*	*	http://www.barclays.co.uk/role/PensionsAndPostretirementBenefitsBalanceSheetReconciliationDetails
3750	Disclosure of net defined benefit liability (asset) [table]	Table	*	*	ifrs-full:DisclosureOfNetDefinedBenefitLiabilityAssetTable
3751	Net defined benefit liability (asset) [axis]	Axis			ifrs-full:NetDefinedBenefitLiabilityAssetAxis
3752	Net defined benefit liability (asset) [member]	Member			ifrs-full:NetDefinedBenefitLiabilityAssetMember
3753	Defined benefit obligations [member]	Member			ifrs-full:PresentValueOfDefinedBenefitObligationMember
3754	Fair value of plan assets [member]	Member			ifrs-full:PlanAssetsMember
3755	Defined benefit plans [axis]	Axis			ifrs-full:DefinedBenefitPlansAxis
3756	Defined benefit plans [member]	Member			ifrs-full:DefinedBenefitPlansMember
3757	United Kingdom Retirement Fund (UKRF) [member]	Member			ifrs-full:DefinedBenefitPlansOtherThanMultiemployerPlansStatePlansAndPlansThatShareRisksBetweenEntitiesUnderCommonControlMember
3758	Geographical areas [axis]	Axis			ifrs-full:GeographicalAreasAxis
3759	Geographical areas [member]	Member			ifrs-full:GeographicalAreasMember
3760	UK [member]	Member			ifrs-full:CountryOfDomicileMember
3761	Characteristics of defined benefit plans [axis]	Axis			ifrs-full:CharacteristicsOfDefinedBenefitPlansAxis
3762	Characteristics of defined benefit plans [member]	Member			ifrs-full:CharacteristicsOfDefinedBenefitPlansMember
3763	Pension defined benefit plans [member]	Member			ifrs-full:PensionDefinedBenefitPlansMember
3764	Consolidated Entities [Axis]	Axis			srt:ConsolidatedEntitiesAxis
3765	Consolidated Entities [Domain]	Member			srt:ConsolidatedEntitiesDomain
3766	Barclays Bank Group [member]	Member			c070:BarclaysBankGroupMember
3767	Disclosure of net defined benefit liability (asset) [line items]	LineItems			ifrs-full:DisclosureOfNetDefinedBenefitLiabilityAssetLineItems
3768	Benefit obligation at beginning of the year	Concept (Monetary)	As Of	Credit	ifrs-full:DefinedBenefitObligationAtPresentValue
3769	Fair value of scheme assets at beginning of the year	Concept (Monetary)	As Of	Debit	ifrs-full:PlanAssetsAtFairValue
3770	Current service cost	Concept (Monetary)	For Period	Credit	ifrs-full:CurrentServiceCostNetDefinedBenefitLiabilityAsset
3771	Interest costs or income on scheme liabilities or assets	Concept (Monetary)	For Period	Credit	ifrs-full:InterestExpenseIncomeNetDefinedBenefitLiabilityAsset
3772	Past service cost	Concept (Monetary)	For Period	Credit	ifrs-full:PastServiceCostNetDefinedBenefitLiabilityAsset
3773	Remeasurement (loss)/gain - financial	Concept (Monetary)	For Period	Debit	ifrs-full:ActuarialGainsLossesArisingFromChangesInFinancialAssumptionsNetDefinedBenefitLiabilityAsset
3774	Remeasurement gain/(loss) - demographic	Concept (Monetary)	For Period	Debit	ifrs-full:ActuarialGainsLossesArisingFromChangesInDemographicAssumptionsNetDefinedBenefitLiabilityAsset
3775	Remeasurement gain - experience	Concept (Monetary)	For Period	Debit	ifrs-full:ActuarialGainsLossesArisingFromExperienceAdjustmentsNetDefinedBenefitLiabilityAsset
3776	Employer contribution	Concept (Monetary)	For Period	Debit	ifrs-full:ContributionsToPlanByEmployerNetDefinedBenefitLiabilityAsset
3777	Settlements	Concept (Monetary)	For Period	Debit	ifrs-full:PaymentsInRespectOfSettlementsNetDefinedBenefitLiabilityAsset
3778	Remeasurement - return on scheme assets greater/(less) than discount rate	Concept (Monetary)	For Period	Debit	ifrs-full:ReturnOnPlanAssetsNetDefinedBenefitLiabilityAsset
3779	Employee contributions	Concept (Monetary)	For Period	Debit	ifrs-full:ContributionsToPlanByPlanParticipantsNetDefinedBenefitLiabilityAsset
3780	Benefits paid	Concept (Monetary)	For Period	Debit	ifrs-full:BenefitsPaidOrPayable
3781	Exchange and other movements	Concept (Monetary)	For Period	Credit	ifrs-full:IncreaseDecreaseThroughChangesInForeignExchangeRatesNetDefinedBenefitLiabilityAsset
3782	Benefit obligation at end of the year	Concept (Monetary)	As Of	Credit	ifrs-full:DefinedBenefitObligationAtPresentValue
3783	Fair value of scheme assets at end of the year	Concept (Monetary)	As Of	Debit	ifrs-full:PlanAssetsAtFairValue
3784	Net surplus/(deficit)	Concept (Monetary)	As Of	Debit	ifrs-full:SurplusDeficitInPlan
3785	Retirement benefit assets	Concept (Monetary)	As Of	Debit	ifrs-full:AssetsOfBenefitPlan
3786	Retirement benefit liabilities	Concept (Monetary)	As Of	Credit	ifrs-full:LiabilitiesOtherThanActuarialPresentValueOfPromisedRetirementBenefits
3787	Net retirement benefit assets/(liabilities)	Concept (Monetary)	As Of	Credit	ifrs-full:AssetsLiabilitiesOfBenefitPlan
3788	043603 - Disclosure - Pensions and post-retirement benefits - Actuarial valuation of schemes (Details)	Network	*	*	http://www.barclays.co.uk/role/PensionsAndPostretirementBenefitsActuarialValuationOfSchemesDetails
3789	Disclosure of sensitivity analysis for actuarial assumptions [table]	Table	*	*	ifrs-full:DisclosureOfSensitivityAnalysisForActuarialAssumptionsTable
3790	Actuarial assumptions [axis]	Axis			ifrs-full:ActuarialAssumptionsAxis
3791	Actuarial assumptions [member]	Member			ifrs-full:ActuarialAssumptionsMember
3792	Key UKRF financial assumptions [member]	Member			c070:ActuarialAssumptionOfKeyFinancialAssumptionsMember
3793	Life expectancy at 60 for current pensioners, males [member]	Member			c070:ActuarialAssumptionOfLifeExpectancyAfterRetirementForMalesAtSixtyYearsAgeMember
3794	Life expectancy at 60 for current pensioners, females [member]	Member			c070:ActuarialAssumptionOfLifeExpectancyAfterRetirementForFemalesAtSixtyYearsAgeMember
3795	Life expectancy at 60 for future pensioners at 40 years, males [member]	Member			c070:ActuarialAssumptionOfLifeExpectancyAfterRetirementForMalesAtSixtyYearsAgeForFuturePensionersAtFourtyYearsMember
3796	Life expectancy at 60 for future pensioners at 40 years, females [member]	Member			c070:ActuarialAssumptionOfLifeExpectancyAfterRetirementForFemalesAtSixtyYearsAgeForFuturePensionersAtFourtyYearsMember
3797	0.5% change in discount rate per annum [member]	Member			c070:ActuarialAssumptionOfChangeInDiscountRateByFiftyBasisPointsMember
3798	0.25% change in discount rate per annum [member]	Member			c070:ActuarialAssumptionOfChangeInDiscountRateByTwentyFiveBasisPointsMember
3799	0.5% change in RPI per annum [member]	Member			c070:ActuarialAssumptionOfChangeInExpectedInflationRateByFiftyBasisPointsMember
3800	0.25% change in RPI per annum [member]	Member			c070:ActuarialAssumptionOfChangeInExpectedInflationRateByTwentyFiveBasisPointsMember
3801	Change in life expectancy by one year [member]	Member			c070:ActuarialAssumptionOfChangeInLifeExpectancyAfterRetirementMember
3802	Defined benefit plans [axis]	Axis			ifrs-full:DefinedBenefitPlansAxis
3803	Defined benefit plans [member]	Member			ifrs-full:DefinedBenefitPlansMember
3804	United Kingdom Retirement Fund (UKRF) [member]	Member			ifrs-full:DefinedBenefitPlansOtherThanMultiemployerPlansStatePlansAndPlansThatShareRisksBetweenEntitiesUnderCommonControlMember
3805	Geographical areas [axis]	Axis			ifrs-full:GeographicalAreasAxis
3806	Geographical areas [member]	Member			ifrs-full:GeographicalAreasMember
3807	UK [member]	Member			ifrs-full:CountryOfDomicileMember
3808	Characteristics of defined benefit plans [axis]	Axis			ifrs-full:CharacteristicsOfDefinedBenefitPlansAxis
3809	Characteristics of defined benefit plans [member]	Member			ifrs-full:CharacteristicsOfDefinedBenefitPlansMember
3810	Pension defined benefit plans [member]	Member			ifrs-full:PensionDefinedBenefitPlansMember
3811	Disclosure of sensitivity analysis for actuarial assumptions [line items]	LineItems			ifrs-full:DisclosureOfSensitivityAnalysisForActuarialAssumptionsLineItems
3812	Discount rate	Concept (Percent)	As Of		ifrs-full:ActuarialAssumptionOfDiscountRates
3813	Inflation rate (RPI)	Concept (Percent)	As Of		ifrs-full:ActuarialAssumptionOfExpectedRatesOfInflation
3814	Assumed life expectancy at 60	Concept (xbrli:durationItemType)	For Period		c070:ActuarialAssumptionOfLifeExpectancyAfterRetirementInYears
3815	(Decrease)/Increase in UKRF defined benefit obligations, due to increase in actuarial assumption	Concept (Monetary)	As Of	Credit	ifrs-full:IncreaseDecreaseInDefinedBenefitObligationDueToReasonablyPossibleIncreaseInActuarialAssumption
3816	(Decrease)/Increase in UKRF defined benefit obligations, due to decrease in actuarial assumption	Concept (Monetary)	As Of	Credit	ifrs-full:IncreaseDecreaseInDefinedBenefitObligationDueToReasonablyPossibleDecreaseInActuarialAssumption
3817	043604 - Disclosure - Pensions and post-retirement benefits - Analysis of scheme assets (Details)	Network	*	*	http://www.barclays.co.uk/role/PensionsAndPostretirementBenefitsAnalysisOfSchemeAssetsDetails
3818	Disclosure of fair value of plan assets [table]	Table	*	*	ifrs-full:DisclosureOfFairValueOfPlanAssetsTable
3819	Defined benefit plans [axis]	Axis			ifrs-full:DefinedBenefitPlansAxis
3820	Defined benefit plans [member]	Member			ifrs-full:DefinedBenefitPlansMember
3821	United Kingdom Retirement Fund (UKRF) [member]	Member			ifrs-full:DefinedBenefitPlansOtherThanMultiemployerPlansStatePlansAndPlansThatShareRisksBetweenEntitiesUnderCommonControlMember
3822	All levels of fair value hierarchy [axis]	Axis			ifrs-full:LevelsOfFairValueHierarchyAxis
3823	All levels of fair value hierarchy [member]	Member			ifrs-full:AllLevelsOfFairValueHierarchyMember
3824	Equities - Quoted [member]	Member			ifrs-full:Level1OfFairValueHierarchyMember
3825	Equities non-quoted [member]	Member			ifrs-full:Level2And3OfFairValueHierarchyMember
3826	Classes of assets [axis]	Axis			ifrs-full:ClassesOfAssetsAxis
3827	Assets [member]	Member			ifrs-full:ClassesOfAssetsMember
3828	Bonds Fixed Government [Member]	Member			c070:BondsFixedGovernmentMember
3829	Bonds Index Linked Government [Member]	Member			c070:BondsIndexLinkedGovernmentMember
3830	Bonds - Corporate and Other [Member]	Member			c070:BondsCorporateAndOtherMember
3831	Commerical - property [member]	Member			ifrs-full:InvestmentPropertyMember
3832	Derivatives [member]	Member			ifrs-full:DerivativesMember
3833	Other [member]	Member			c070:OtherNonquotedAssetsHeldMember
3834	Net defined benefit liability (asset) [axis]	Axis			ifrs-full:NetDefinedBenefitLiabilityAssetAxis
3835	Net defined benefit liability (asset) [member]	Member			ifrs-full:NetDefinedBenefitLiabilityAssetMember
3836	Fair value of plan assets [member]	Member			ifrs-full:PlanAssetsMember
3837	Geographical areas [axis]	Axis			ifrs-full:GeographicalAreasAxis
3838	Geographical areas [member]	Member			ifrs-full:GeographicalAreasMember
3839	Country of domicile [member]	Member			ifrs-full:CountryOfDomicileMember
3840	Characteristics of defined benefit plans [axis]	Axis			ifrs-full:CharacteristicsOfDefinedBenefitPlansAxis
3841	Characteristics of defined benefit plans [member]	Member			ifrs-full:CharacteristicsOfDefinedBenefitPlansMember
3842	Pension defined benefit plans [member]	Member			ifrs-full:PensionDefinedBenefitPlansMember
3843	Consolidated Entities [Axis]	Axis			srt:ConsolidatedEntitiesAxis
3844	Consolidated Entities [Domain]	Member			srt:ConsolidatedEntitiesDomain
3845	Barclays Bank Group [member]	Member			c070:BarclaysBankGroupMember
3846	Disclosure of fair value of plan assets [line items]	LineItems			ifrs-full:DisclosureOfFairValueOfPlanAssetsLineItems
3847	Equities	Concept (Monetary)	As Of	Debit	ifrs-full:EquityInstrumentsAmountContributedToFairValueOfPlanAssets
3848	Bonds	Concept (Monetary)	As Of	Debit	ifrs-full:DebtInstrumentsAmountContributedToFairValueOfPlanAssets
3849	Property commerical	Concept (Monetary)	As Of	Debit	ifrs-full:PropertyAmountContributedToFairValueOfPlanAssets
3850	Derivatives	Concept (Monetary)	As Of	Debit	ifrs-full:DerivativesAmountContributedToFairValueOfPlanAssets
3851	Other	Concept (Monetary)	As Of	Debit	ifrs-full:OtherAssetsAmountContributedToFairValueOfPlanAssets
3852	Fair value of scheme assets	Concept (Monetary)	As Of	Debit	ifrs-full:PlanAssetsAtFairValue
3853	% of total fair value of scheme assets	Concept (Percent)	As Of		c070:PercentageOfFairValueOfSchemeAssets
3854	043605 - Disclosure - Pensions and post-retirement benefits - Deficit reduction contributions (Details)	Network	*	*	http://www.barclays.co.uk/role/PensionsAndPostretirementBenefitsDeficitReductionContributionsDetails
3855	Disclosure of fair value of plan assets [table]	Table	*	*	ifrs-full:DisclosureOfFairValueOfPlanAssetsTable
3856	Defined benefit plans [axis]	Axis			ifrs-full:DefinedBenefitPlansAxis
3857	Defined benefit plans [member]	Member			ifrs-full:DefinedBenefitPlansMember
3858	United Kingdom Retirement Fund (UKRF) [member]	Member			ifrs-full:DefinedBenefitPlansOtherThanMultiemployerPlansStatePlansAndPlansThatShareRisksBetweenEntitiesUnderCommonControlMember
3859	Maturity [axis]	Axis			ifrs-full:MaturityAxis
3860	Aggregated time bands [member]	Member			ifrs-full:AggregatedTimeBandsMember
3861	2017 [member]	Member			c070:TwentySeventeenMember
3862	2018 [member]	Member			ifrs-full:CurrentMember
3863	2019 [member]	Member			ifrs-full:LaterThanOneYearAndNotLaterThanTwoYearsMember
3864	2020 [member]	Member			ifrs-full:LaterThanTwoYearsAndNotLaterThanThreeYearsMember
3865	2021 [member]	Member			ifrs-full:LaterThanThreeYearsAndNotLaterThanFourYearsMember
3866	2022 [member]	Member			ifrs-full:LaterThanFourYearsAndNotLaterThanFiveYearsMember
3867	2023 [member]	Member			c070:LaterThanFiveYearsAndNotLaterThanSixYearsMember
3868	2024 [member]	Member			c070:LaterThanSixYearsAndNotLaterThanSevenYearsMember
3869	2025 [member]	Member			c070:LaterThanSevenYearsAndNotLaterThanEightYearsMember
3870	2026 [member]	Member			c070:LaterThanEightYearsAndNotLaterThanNineYearsMember
3871	Valuation techniques used in fair value measurement [axis]	Axis			ifrs-full:ValuationTechniquesUsedInFairValueMeasurementAxis
3872	Valuation techniques [member]	Member			ifrs-full:ValuationTechniquesMember
3873	Deficit contributions 30 September 2016 valuation [member]	Member			c070:DeficitContributionsValuationRecoveryPlanTwentySixteenMember
3874	Characteristics of defined benefit plans [axis]	Axis			ifrs-full:CharacteristicsOfDefinedBenefitPlansAxis
3875	Characteristics of defined benefit plans [member]	Member			ifrs-full:CharacteristicsOfDefinedBenefitPlansMember
3876	Pension defined benefit plans [member]	Member			ifrs-full:PensionDefinedBenefitPlansMember
3877	Geographical areas [axis]	Axis			ifrs-full:GeographicalAreasAxis
3878	Geographical areas [member]	Member			ifrs-full:GeographicalAreasMember
3879	United Kingdom [member]	Member			ifrs-full:CountryOfDomicileMember
3880	Disclosure of fair value of plan assets [line items]	LineItems			ifrs-full:DisclosureOfFairValueOfPlanAssetsLineItems
3881	Deficit reduction contributions	Concept (Monetary)	As Of	Credit	c070:DeficitReductionContributions
3882	043607 - Disclosure - Pensions and post-retirement benefits - Contributions paid (Details)	Network	*	*	http://www.barclays.co.uk/role/PensionsAndPostretirementBenefitsContributionsPaidDetails
3883	Disclosure of fair value of plan assets [table]	Table	*	*	ifrs-full:DisclosureOfFairValueOfPlanAssetsTable
3884	Defined benefit plans [axis]	Axis			ifrs-full:DefinedBenefitPlansAxis
3885	Defined benefit plans [member]	Member			ifrs-full:DefinedBenefitPlansMember
3886	United Kingdom Retirement Fund (UKRF) [member]	Member			ifrs-full:DefinedBenefitPlansOtherThanMultiemployerPlansStatePlansAndPlansThatShareRisksBetweenEntitiesUnderCommonControlMember
3887	Geographical areas [axis]	Axis			ifrs-full:GeographicalAreasAxis
3888	Geographical areas [member]	Member			ifrs-full:GeographicalAreasMember
3889	Country of domicile [member]	Member			ifrs-full:CountryOfDomicileMember
3890	Characteristics of defined benefit plans [axis]	Axis			ifrs-full:CharacteristicsOfDefinedBenefitPlansAxis
3891	Characteristics of defined benefit plans [member]	Member			ifrs-full:CharacteristicsOfDefinedBenefitPlansMember
3892	Pension defined benefit plans [member]	Member			ifrs-full:PensionDefinedBenefitPlansMember
3893	Disclosure of fair value of plan assets [line items]	LineItems			ifrs-full:DisclosureOfFairValueOfPlanAssetsLineItems
3894	Defined benefit contributions paid	Concept (Monetary)	For Period	Debit	ifrs-full:ContributionsToPlanNetDefinedBenefitLiabilityAsset
3895	043608 - Disclosure - Pensions and post-retirement benefits (Narrative) (Details)	Network	*	*	http://www.barclays.co.uk/role/PensionsAndPostretirementBenefitsNarrativeDetails
3896	Disclosure of net defined benefit liability (asset) [table]	Table	*	*	ifrs-full:DisclosureOfNetDefinedBenefitLiabilityAssetTable
3897	Defined benefit plans [axis]	Axis			ifrs-full:DefinedBenefitPlansAxis
3898	Defined benefit plans [member]	Member			ifrs-full:DefinedBenefitPlansMember
3899	United Kingdom Retirement Fund (UKRF) [member]	Member			ifrs-full:DefinedBenefitPlansOtherThanMultiemployerPlansStatePlansAndPlansThatShareRisksBetweenEntitiesUnderCommonControlMember
3900	Afterwork [member]	Member			c070:AfterworkMember
3901	1964 Pension Scheme [member]	Member			c070:NineteenSixtyFourPensionSchemeMember
3902	BPSP [member]	Member			c070:BarclaysPensionSavingsPlanMember
3903	Other [member]	Member			c070:OtherPensionSchemesMember
3904	Section 75 contributions [member]	Member			c070:SectionSeventyFiveContributionPlanMember
3905	Net defined benefit liability (asset) [axis]	Axis			ifrs-full:NetDefinedBenefitLiabilityAssetAxis
3906	Net defined benefit liability (asset) [member]	Member			ifrs-full:NetDefinedBenefitLiabilityAssetMember
3907	Defined benefit obligations [member]	Member			ifrs-full:PresentValueOfDefinedBenefitObligationMember
3908	Fair value of plan assets [member]	Member			ifrs-full:PlanAssetsMember
3909	Classes of share capital [axis]	Axis			ifrs-full:ClassesOfShareCapitalAxis
3910	Share capital [member]	Member			ifrs-full:ClassesOfShareCapitalMember
3911	Ordinary shares [member]	Member			ifrs-full:OrdinarySharesMember
3912	Maturity [axis]	Axis			ifrs-full:MaturityAxis
3913	Aggregated time bands [member]	Member			ifrs-full:AggregatedTimeBandsMember
3914	2019 [member]	Member			ifrs-full:LaterThanOneYearAndNotLaterThanTwoYearsMember
3915	2020 [member]	Member			ifrs-full:LaterThanTwoYearsAndNotLaterThanThreeYearsMember
3916	2021 [member]	Member			ifrs-full:LaterThanThreeYearsAndNotLaterThanFourYearsMember
3917	from 2022 onwards [member]	Member			c070:LaterThanFourYearsMember
3918	Range [axis]	Axis			ifrs-full:RangeAxis
3919	Ranges [member]	Member			ifrs-full:RangesMember
3920	Max [member]	Member			ifrs-full:TopOfRangeMember
3921	Valuation techniques used in fair value measurement [axis]	Axis			ifrs-full:ValuationTechniquesUsedInFairValueMeasurementAxis
3922	Valuation techniques [member]	Member			ifrs-full:ValuationTechniquesMember
3923	Deficit contributions 30 September 2018 valuation [member]	Member			c070:DeficitContributionsValuationRecoveryPlanTwentyEighteenMember
3924	Deficit contributions 30 September 2016 valuation [member]	Member			c070:DeficitContributionsValuationRecoveryPlanTwentySixteenMember
3925	Deficit contributions 30 September 2015 valuation [member]	Member			c070:DeficitContributionsValuationRecoveryPlanTwentyFifteenMember
3926	Actuarial assumptions [axis]	Axis			ifrs-full:ActuarialAssumptionsAxis
3927	Actuarial assumptions [member]	Member			ifrs-full:ActuarialAssumptionsMember
3928	Discount rate [member]	Member			ifrs-full:ActuarialAssumptionOfDiscountRatesMember
3929	Inflation rate [member]	Member			ifrs-full:ActuarialAssumptionOfExpectedRatesOfInflationMember
3930	Mortality rates [member]	Member			ifrs-full:ActuarialAssumptionOfMortalityRatesMember
3931	Future transfers out [member]	Member			c070:FutureTransfersOutMember
3932	Geographical areas [axis]	Axis			ifrs-full:GeographicalAreasAxis
3933	Geographical areas [member]	Member			ifrs-full:GeographicalAreasMember
3934	UK [member]	Member			ifrs-full:CountryOfDomicileMember
3935	Overseas [member]	Member			ifrs-full:ForeignCountriesMember
3936	Characteristics of defined benefit plans [axis]	Axis			ifrs-full:CharacteristicsOfDefinedBenefitPlansAxis
3937	Characteristics of defined benefit plans [member]	Member			ifrs-full:CharacteristicsOfDefinedBenefitPlansMember
3938	Pension defined benefit plans [member]	Member			ifrs-full:PensionDefinedBenefitPlansMember
3939	Post-employment medical defined benefit plans [member]	Member			ifrs-full:PostemploymentMedicalDefinedBenefitPlansMember
3940	Defined contribution Schemes [member]	Member			c070:DefinedContributionPlansMember
3941	Consolidated Entities [Axis]	Axis			srt:ConsolidatedEntitiesAxis
3942	Consolidated Entities [Domain]	Member			srt:ConsolidatedEntitiesDomain
3943	Barclays PLC [member]	Member			srt:ParentCompanyMember
3944	Barclays Bank Group [member]	Member			c070:BarclaysBankGroupMember
3945	Barclays Bank UK PLC [member]	Member			c070:BarclaysBankUkPlcMember
3946	Barclays Execution Services [Member]	Member			c070:BarclaysExecutionServicesMember
3947	Products and services [axis]	Axis			ifrs-full:ProductsAndServicesAxis
3948	Products and services [member]	Member			ifrs-full:ProductsAndServicesMember
3949	Brokerage commissions and client execution fees [Member]	Member			c070:BrokerageCommissionsAndClientExecutionFeesMember
3950	Continuing and discontinued operations [axis]	Axis			ifrs-full:ContinuingAndDiscontinuedOperationsAxis
3951	Aggregate continuing and discontinued operations [member]	Member			ifrs-full:AggregateContinuingAndDiscontinuedOperationsMember
3952	Discontinued operations [member]	Member			ifrs-full:DiscontinuedOperationsMember
3953	Disclosure of net defined benefit liability (asset) [line items]	LineItems			ifrs-full:DisclosureOfNetDefinedBenefitLiabilityAssetLineItems
3954	Description of type of plan	Concept (Text/String)	For Period		ifrs-full:DescriptionOfTypeOfPlan
3955	Description of risks to which plan exposes entity	Concept (Text/String)	For Period		ifrs-full:DescriptionOfRisksToWhichPlanExposesEntity
3956	Description of regulatory framework in which plan operates	Concept (Text/String)	For Period		ifrs-full:DescriptionOfRegulatoryFrameworkInWhichPlanOperates
3957	Benefit obligation at end of the year	Concept (Monetary)	As Of	Credit	ifrs-full:DefinedBenefitObligationAtPresentValue
3958	Fair value of scheme assets	Concept (Monetary)	As Of	Debit	ifrs-full:PlanAssetsAtFairValue
3959	Net surplus/(deficit)	Concept (Monetary)	As Of	Debit	ifrs-full:SurplusDeficitInPlan
3960	Current service cost	Concept (Monetary)	For Period	Credit	ifrs-full:CurrentServiceCostNetDefinedBenefitLiabilityAsset
3961	Past service cost	Concept (Monetary)	For Period	Credit	ifrs-full:PastServiceCostNetDefinedBenefitLiabilityAsset
3962	Benefits paid	Concept (Monetary)	For Period	Debit	ifrs-full:BenefitsPaidOrPayable
3963	Transfers out of the fund and contribution refunds	Concept (Monetary)	For Period	Credit	c070:TransfersOutOfDefinedBenefitFundAndContributionRefund
3964	Description of methods and assumptions used in preparing sensitivity analysis for actuarial assumptions	Concept (Text/String)	For Period		ifrs-full:DescriptionOfMethodsAndAssumptionsUsedInPreparingSensitivityAnalysisForActuarialAssumptions
3965	Percentage of member transfers out of benefit obligation	Concept (Percent)	As Of		c070:PercentageOfMemberTransfersOutOfBenefitObligation
3966	Weighted average duration of the benefit payments reflected in defined benefit obligation, UKRF	Concept (xbrli:durationItemType)	For Period		c070:WeightedAverageDurationOfDefinedBenefitObligationYears
3967	Description of asset-liability matching strategies used by plan or entity to manage risk	Concept (Text/String)	For Period		ifrs-full:DescriptionOfAssetliabilityMatchingStrategiesUsedByPlanOrEntityToManageRisk
3968	Equity instruments, amount contributed to fair value of plan assets	Concept (Monetary)	As Of	Debit	ifrs-full:EquityInstrumentsAmountContributedToFairValueOfPlanAssets
3969	Bonds issued	Concept (Monetary)	As Of	Debit	ifrs-full:DebtInstrumentsAmountContributedToFairValueOfPlanAssets
3970	Private equity investment scheme assets	Concept (Monetary)	As Of	Debit	ifrs-full:InvestmentFundsAmountContributedToFairValueOfPlanAssets
3971	Percentage of fair value of scheme assets invested in liability driven investment strategies	Concept (Percent)	As Of		c070:PercentageOfFairValueOfSchemeAssetsInvestedInLiabilities
3972	Description of funding arrangements and funding policy that affect future contributions	Concept (Text/String)	For Period		ifrs-full:DescriptionOfFundingArrangementsAndFundingPolicyThatAffectFutureContributions
3973	Funding level percentage	Concept (Percent)	As Of		c070:DefinedBenefitPlanFundingLevelPercentage
3974	Percentage of funding deficit secured by collateral pool	Concept (Percent)	As Of		c070:PercentageOfFundingDeficitSecuredByCollateralPool
3975	Maximum funding deficit secured by collateral pool	Concept (Monetary)	As Of	Credit	c070:MaximumFundingDeficitSecuredByCollateralPool
3976	Estimate of contributions expected to be paid to plan for next annual reporting period	Concept (Monetary)	For Period	Credit	ifrs-full:EstimateOfContributionsExpectedToBePaidToPlan
3977	Scheme as a percentage of total retirement benefit obligations	Concept (Percent)	As Of		c070:SchemeAsAPercentageOfTotalRetirementBenefitObligations
3978	Inflation rate (RPI)	Concept (Percent)	As Of		ifrs-full:ActuarialAssumptionOfExpectedRatesOfInflation
3979	Investment related increase, percentage	Concept (Percent)	As Of		c070:InvestmentRelatedIncreasePercentage
3980	Discount rate	Concept (Percent)	As Of		ifrs-full:ActuarialAssumptionOfDiscountRates
3981	Defined benefit contributions paid	Concept (Monetary)	For Period	Debit	ifrs-full:ContributionsToPlanNetDefinedBenefitLiabilityAsset
3982	043701 - Disclosure - Principal subsidiaries - Significant subsidiaries (Details)	Network	*	*	http://www.barclays.co.uk/role/PrincipalSubsidiariesSignificantSubsidiariesDetails
3983	Disclosure of subsidiaries [table]	Table	*	*	ifrs-full:DisclosureOfSignificantInvestmentsInSubsidiariesTable
3984	Subsidiaries [axis]	Axis			ifrs-full:SignificantInvestmentsInSubsidiariesAxis
3985	Entity's total for subsidiaries [member]	Member			ifrs-full:EntitysTotalForSubsidiariesMember
3986	Barclays Bank Ireland PLC [member]	Member			c070:BarclaysBankIrelandPlcMember
3987	Barclays Capital Inc [member]	Member			c070:BarclaysCapitalIncMember
3988	Barclays Capital Securities Limited [member]	Member			c070:BarclaysCapitalSecuritiesLimitedMember
3989	Barclays Securities Japan Limited [member]	Member			c070:BarclaysSecuritiesJapanLimitedMember
3990	Barclays Bank Delaware [member]	Member			c070:BarclaysBankDelawareMember
3991	Consolidated Entities [Axis]	Axis			srt:ConsolidatedEntitiesAxis
3992	Consolidated Entities [Domain]	Member			srt:ConsolidatedEntitiesDomain
3993	Barclays Bank Group [member]	Member			c070:BarclaysBankGroupMember
3994	Disclosure of subsidiaries [line items]	LineItems			ifrs-full:DisclosureOfSignificantInvestmentsInSubsidiariesLineItems
3995	Company Name	Concept (Text/String)	For Period		ifrs-full:NameOfSubsidiary
3996	Principal place of business or incorporation	Concept (Text/String)	For Period		ifrs-full:PrincipalPlaceOfBusinessOfSubsidiary
3997	Nature of business	Concept (Text/String)	For Period		ifrs-full:DescriptionOfNatureOfEntitysOperationsAndPrincipalActivities
3998	Percentage of voting rights held	Concept (Percent)	For Period		ifrs-full:ProportionOfVotingPowerHeldInSubsidiary
3999	Proportion of ownership interest, non-controlling	Concept (Percent)	For Period		ifrs-full:ProportionOfOwnershipInterestsHeldByNoncontrollingInterests
4000	Proportion of voting interest, non-controlling	Concept (Percent)	For Period		ifrs-full:ProportionOfVotingRightsHeldByNoncontrollingInterests
4001	043702 - Disclosure - Principal subsidiaries - Excluded from consolidation because the Group does not have exposure to its variable returns (Details)	Network	*	*	http://www.barclays.co.uk/role/PrincipalSubsidiariesExcludedFromConsolidationBecauseTheGroupDoesNotHaveExposureToItsVariableReturnsDetails
4002	Disclosure of unconsolidated structured entities [table]	Table	*	*	ifrs-full:DisclosureOfUnconsolidatedStructuredEntitiesTable
4003	Unconsolidated structured entities [axis]	Axis			ifrs-full:UnconsolidatedStructuredEntitiesAxis
4004	Entity's total for unconsolidated structured entities [member]	Member			ifrs-full:EntitysTotalForUnconsolidatedStructuredEntitiesMember
4005	Unconsolidated structured entities [member]	Member			ifrs-full:UnconsolidatedStructuredEntitiesMember
4006	Consolidated Entities [Axis]	Axis			srt:ConsolidatedEntitiesAxis
4007	Consolidated Entities [Domain]	Member			srt:ConsolidatedEntitiesDomain
4008	Barclays Bank Group [member]	Member			c070:BarclaysBankGroupMember
4009	Disclosure of unconsolidated structured entities [line items]	LineItems			ifrs-full:DisclosureOfUnconsolidatedStructuredEntitiesLineItems
4010	Country of registration or incorporation	Concept (Text/String)	For Period		ifrs-full:CountryOfIncorporationOrResidenceOfSubsidiary
4011	Company Name	Concept (Text/String)	For Period		ifrs-full:NameOfSubsidiary
4012	Percentage of voting rights held	Concept (Percent)	For Period		ifrs-full:ProportionOfVotingPowerHeldInSubsidiary
4013	Equity shareholder's funds	Concept (Monetary)	For Period	Credit	c070:EquityFromStructuredEntities
4014	Retained profit for the year	Concept (Monetary)	For Period	Credit	ifrs-full:IncomeFromStructuredEntities
4015	043703 - Disclosure - Principal subsidiaries (Narrative) (Details)	Network	*	*	http://www.barclays.co.uk/role/PrincipalSubsidiariesNarrativeDetails
4016	Disclosure of subsidiaries [table]	Table	*	*	ifrs-full:DisclosureOfSignificantInvestmentsInSubsidiariesTable
4017	Subsidiaries [axis]	Axis			ifrs-full:SignificantInvestmentsInSubsidiariesAxis
4018	Entity's total for subsidiaries [member]	Member			ifrs-full:EntitysTotalForSubsidiariesMember
4019	Principal Subsidiary companies [member]	Member			ifrs-full:SubsidiariesMember
4020	Consolidated structured entities [axis]	Axis			ifrs-full:ConsolidatedStructuredEntitiesAxis
4021	Entity's total for consolidated structured entities [member]	Member			ifrs-full:EntitysTotalForConsolidatedStructuredEntitiesMember
4022	Consolidated structured entities [member]	Member			ifrs-full:ConsolidatedStructuredEntitiesMember
4023	Classes of assets [axis]	Axis			ifrs-full:ClassesOfAssetsAxis
4024	Assets [member]	Member			ifrs-full:ClassesOfAssetsMember
4025	Investment funds [member]	Member			ifrs-full:InvestmentFundsMember
4026	Consolidated Entities [Axis]	Axis			srt:ConsolidatedEntitiesAxis
4027	Consolidated Entities [Domain]	Member			srt:ConsolidatedEntitiesDomain
4028	Barclays Bank Group [member]	Member			c070:BarclaysBankGroupMember
4029	Carrying amount, accumulated depreciation, amortisation and impairment and gross carrying amount [axis]	Axis			ifrs-full:CarryingAmountAccumulatedDepreciationAmortisationAndImpairmentAndGrossCarryingAmountAxis
4030	Carrying amount [member]	Member			ifrs-full:CarryingAmountMember
4031	Cost [member]	Member			ifrs-full:GrossCarryingAmountMember
4032	Impairment allowance [member]	Member			ifrs-full:AccumulatedImpairmentMember
4033	Disclosure of subsidiaries [line items]	LineItems			ifrs-full:DisclosureOfSignificantInvestmentsInSubsidiariesLineItems
4034	Investments in subsidiaries	Concept (Monetary)	As Of	Debit	ifrs-full:InvestmentsInSubsidiaries
4035	Assets	Concept (Monetary)	As Of	Debit	ifrs-full:Assets
4036	Liabilities	Concept (Monetary)	As Of	Credit	ifrs-full:Liabilities
4037	Balances with banks and other regulatory authorities	Concept (Monetary)	As Of	Debit	ifrs-full:MandatoryReserveDepositsAtCentralBanks
4038	043801 - Disclosure - Structured entities - Unconsolidated (Details)	Network	*	*	http://www.barclays.co.uk/role/StructuredEntitiesUnconsolidatedDetails
4039	Disclosure of information about unconsolidated structured entities controlled by investment entity [table]	Table	*	*	ifrs-full:DisclosureOfInformationAboutUnconsolidatedStructuredEntitiesControlledByInvestmentEntityTable
4040	Unconsolidated structured entities [axis]	Axis			ifrs-full:UnconsolidatedStructuredEntitiesAxis
4041	Entity's total for unconsolidated structured entities [member]	Member			ifrs-full:EntitysTotalForUnconsolidatedStructuredEntitiesMember
4042	Structured entities [member]	Member			ifrs-full:UnconsolidatedStructuredEntitiesMember
4043	Secured financings [member]	Member			ifrs-full:AssetbackedFinancingsMember
4044	Short-term traded interests [Member]	Member			c070:ShortTermTradedInterestsMember
4045	Traded derivatives [Member]	Member			c070:TradedDerivativesMember
4046	Other interests [member]	Member			c070:OtherInterestsMember
4047	Consolidated Entities [Axis]	Axis			srt:ConsolidatedEntitiesAxis
4048	Consolidated Entities [Domain]	Member			srt:ConsolidatedEntitiesDomain
4049	Barclays Bank Group [member]	Member			c070:BarclaysBankGroupMember
4050	Disclosure of unconsolidated structured entities [line items]	LineItems			ifrs-full:DisclosureOfUnconsolidatedStructuredEntitiesLineItems
4051	Trading portfolio assets	Concept (Monetary)	As Of	Debit	ifrs-full:FinancialAssetsAtFairValueThroughProfitOrLossClassifiedAsHeldForTrading
4052	Financial assets at fair value through the income statement	Concept (Monetary)	As Of	Debit	ifrs-full:FinancialAssetsAtFairValueThroughProfitOrLoss
4053	Derivative financial instruments	Concept (Monetary)	As Of	Debit	ifrs-full:DerivativeFinancialAssets
4054	Loans and advances at amortised cost	Concept (Monetary)	As Of	Debit	ifrs-full:LoansAndReceivables
4055	Reverse repurchase agreements and other similar secured lending	Concept (Monetary)	As Of	Debit	ifrs-full:ReverseRepurchaseAgreementsAndCashCollateralOnSecuritiesBorrowed
4056	Other assets	Concept (Monetary)	As Of	Debit	ifrs-full:OtherAssets
4057	Total assets	Concept (Monetary)	As Of	Debit	ifrs-full:Assets
4058	Derivative financial instruments	Concept (Monetary)	As Of	Credit	ifrs-full:DerivativeFinancialLiabilities
4059	043802 - Disclosure - Structured entities - Nature of interests (Details)	Network	*	*	http://www.barclays.co.uk/role/StructuredEntitiesNatureOfInterestsDetails
4060	Disclosure of information about unconsolidated structured entities controlled by investment entity [table]	Table	*	*	ifrs-full:DisclosureOfInformationAboutUnconsolidatedStructuredEntitiesControlledByInvestmentEntityTable
4061	Unconsolidated structured entities [axis]	Axis			ifrs-full:UnconsolidatedStructuredEntitiesAxis
4062	Entity's total for unconsolidated structured entities [member]	Member			ifrs-full:EntitysTotalForUnconsolidatedStructuredEntitiesMember
4063	Unconsolidated structured entities [member]	Member			ifrs-full:UnconsolidatedStructuredEntitiesMember
4064	Other interests [member]	Member			c070:OtherInterestsMember
4065	Multi-seller conduit programmes [member]	Member			ifrs-full:SecuritisationVehiclesMember
4066	Lending [member]	Member			ifrs-full:SecuritiesLendingMember
4067	Investment funds and trusts [member]	Member			ifrs-full:InvestmentFundsMember
4068	Others [member]	Member			c070:OtherInvestmentProgramsMember
4069	Classes of assets [axis]	Axis			ifrs-full:ClassesOfAssetsAxis
4070	Assets [member]	Member			ifrs-full:ClassesOfAssetsMember
4071	Debt securities [member]	Member			ifrs-full:DebtSecuritiesMember
4072	Categories of financial assets [axis]	Axis			ifrs-full:CategoriesOfFinancialAssetsAxis
4073	Financial assets, category [member]	Member			ifrs-full:FinancialAssetsCategoryMember
4074	Loans and advances [member]	Member			ifrs-full:LoansAndReceivablesCategoryMember
4075	Classes of financial assets [axis]	Axis			ifrs-full:ClassesOfFinancialAssetsAxis
4076	Financial assets, class [member]	Member			ifrs-full:FinancialAssetsMember
4077	Equity investments [member]	Member			ifrs-full:EquityInvestmentsMember
4078	Financial assets at amortised cost [member]	Member			ifrs-full:FinancialAssetsAtAmortisedCostMember
4079	Consolidated Entities [Axis]	Axis			srt:ConsolidatedEntitiesAxis
4080	Consolidated Entities [Domain]	Member			srt:ConsolidatedEntitiesDomain
4081	Barclays Bank Group [member]	Member			c070:BarclaysBankGroupMember
4082	Disclosure of unconsolidated structured entities [line items]	LineItems			ifrs-full:DisclosureOfUnconsolidatedStructuredEntitiesLineItems
4083	Trading portfolio assets	Concept (Monetary)	As Of	Debit	ifrs-full:FinancialAssetsAtFairValueThroughProfitOrLossClassifiedAsHeldForTrading
4084	Financial assets at fair value through the income statement	Concept (Monetary)	As Of	Debit	ifrs-full:FinancialAssetsAtFairValueThroughProfitOrLoss
4085	Derivative financial assets	Concept (Monetary)	As Of	Debit	ifrs-full:DerivativeFinancialAssets
4086	Loans and advances at amortised cost	Concept (Monetary)	As Of	Debit	ifrs-full:LoansAndReceivables
4087	Other assets	Concept (Monetary)	As Of	Debit	ifrs-full:OtherAssets
4088	Total on balance sheet exposures	Concept (Monetary)	As Of		ifrs-full:CreditExposure
4089	Total off balance sheet notional amounts	Concept (Monetary)	As Of	Debit	c070:OffBalanceSheetNotionalAmountsOfAssets
4090	Maximum exposure to loss	Concept (Monetary)	As Of		ifrs-full:MaximumExposureToLossFromInterestsInStructuredEntities
4091	Total assets of the entity	Concept (Monetary)	As Of	Debit	ifrs-full:AssetsRecognisedInEntitysFinancialStatementsInRelationToStructuredEntities
4092	043803 - Disclosure - Structured entities (Narrative) (Details)	Network	*	*	http://www.barclays.co.uk/role/StructuredEntitiesNarrativeDetails
4093	Disclosure of information about unconsolidated structured entities controlled by investment entity [table]	Table	*	*	ifrs-full:DisclosureOfInformationAboutUnconsolidatedStructuredEntitiesControlledByInvestmentEntityTable
4094	Unconsolidated structured entities [axis]	Axis			ifrs-full:UnconsolidatedStructuredEntitiesAxis
4095	Entity's total for unconsolidated structured entities [member]	Member			ifrs-full:EntitysTotalForUnconsolidatedStructuredEntitiesMember
4096	Structured entities [member]	Member			ifrs-full:UnconsolidatedStructuredEntitiesMember
4097	Securitisation vehicles [member]	Member			ifrs-full:SecuritisationVehiclesMember
4098	Commercial paper (CP) and medium-term note conduits [member]	Member			c070:CommercialPaperAndMediumTermNoteConduitMember
4099	Investment funds and trusts [member]	Member			ifrs-full:InvestmentFundsMember
4100	Asset-backed loans [member]	Member			ifrs-full:AssetbackedFinancingsMember
4101	Lending [member]	Member			ifrs-full:SecuritiesLendingMember
4102	Employee benefit and other trusts [Member]	Member			c070:EmployeeBenefitAndOtherTrustsMember
4103	Short-term traded interests [Member]	Member			c070:ShortTermTradedInterestsMember
4104	Others [member]	Member			c070:OtherInvestmentProgramsMember
4105	Classes of assets [axis]	Axis			ifrs-full:ClassesOfAssetsAxis
4106	Assets [member]	Member			ifrs-full:ClassesOfAssetsMember
4107	Trading securities [member]	Member			ifrs-full:TradingSecuritiesMember
4108	Debt securities [member]	Member			ifrs-full:DebtSecuritiesMember
4109	Derivatives [member]	Member			ifrs-full:DerivativesMember
4110	Financial guarantee [member]	Member			ifrs-full:FinancialGuaranteeContractsMember
4111	Types of risks [axis]	Axis			ifrs-full:TypesOfRisksAxis
4112	Risks [member]	Member			ifrs-full:TypesOfRisksMember
4113	Contractual Backstop Liquidity Facilities [Member]	Member			c070:ContractualBackstopLiquidityFacilitiesMember
4114	Consolidated Entities [Axis]	Axis			srt:ConsolidatedEntitiesAxis
4115	Consolidated Entities [Domain]	Member			srt:ConsolidatedEntitiesDomain
4116	Barclays Bank Group [member]	Member			c070:BarclaysBankGroupMember
4117	Disclosure of unconsolidated structured entities [line items]	LineItems			ifrs-full:DisclosureOfUnconsolidatedStructuredEntitiesLineItems
4118	Loan commitments	Concept (Monetary)	As Of	Credit	ifrs-full:GrossLoanCommitments
4119	Undrawn contractual backstop liquidity facilities	Concept (Monetary)	As Of	Credit	ifrs-full:UndrawnBorrowingFacilities
4120	Notional value of guarantee	Concept (Monetary)	As Of		ifrs-full:NotionalAmount
4121	Short term traded interest	Concept (Monetary)	As Of	Debit	ifrs-full:CurrentInvestments
4122	Impairment cost of loan facilities	Concept (Monetary)	For Period	Debit	ifrs-full:ImpairmentLossOnFinancialAssets
4123	043901 - Disclosure - Investments in associates and joint ventures (Details)	Network	*	*	http://www.barclays.co.uk/role/InvestmentsInAssociatesAndJointVenturesDetails
4124	Disclosure of associates [table]	Table	*	*	ifrs-full:DisclosureOfSignificantInvestmentsInAssociatesTable
4125	Associates [axis]	Axis			ifrs-full:SignificantInvestmentsInAssociatesAxis
4126	Entity's total for associates [member]	Member			ifrs-full:EntitysTotalForAssociatesMember
4127	Associates [member]	Member			ifrs-full:AssociatesMember
4128	Joint ventures [axis]	Axis			ifrs-full:JointVenturesAxis
4129	Entity's total for joint ventures [member]	Member			ifrs-full:EntitysTotalForJointVenturesMember
4130	Joint ventures [member]	Member			ifrs-full:JointVenturesMember
4131	Disclosure of associates and joint ventures [line items]	LineItems			ifrs-full:DisclosureOfSignificantInvestmentsInAssociatesLineItems
4132	Investments in associates accounted for using equity method	Concept (Monetary)	As Of	Debit	ifrs-full:InvestmentsInAssociatesAccountedForUsingEquityMethod
4133	Investments in joint ventures accounted for using equity method	Concept (Monetary)	As Of	Debit	ifrs-full:InvestmentsInJointVenturesAccountedForUsingEquityMethod
4134	Equity accounted	Concept (Monetary)	As Of	Debit	ifrs-full:InvestmentAccountedForUsingEquityMethod
4135	Held at fair value through profit or loss, Associates	Concept (Monetary)	As Of	Debit	ifrs-full:FairValueOfInvestmentsInAssociatesWherePriceQuotationsPublished
4136	Investments in associates	Concept (Monetary)	As Of	Debit	ifrs-full:InvestmentsInAssociates
4137	Held at fair value through profit or loss, Joint ventures	Concept (Monetary)	As Of	Debit	ifrs-full:FairValueOfInvestmentInJointVenturesWherePriceQuotationsPublished
4138	Investments in joint ventures	Concept (Monetary)	As Of	Debit	ifrs-full:InvestmentsInJointVentures
4139	Profit from continuing operations	Concept (Monetary)	For Period	Credit	ifrs-full:ShareOfProfitLossOfContinuingOperationsOfAssociatesAndJointVenturesAccountedForUsingEquityMethod
4140	Other comprehensive income / (expenses)	Concept (Monetary)	For Period	Credit	ifrs-full:ShareOfOtherComprehensiveIncomeOfAssociatesAndJointVenturesAccountedForUsingEquityMethod
4141	Total comprehensive income from continuing operations	Concept (Monetary)	For Period	Credit	ifrs-full:ShareOfTotalComprehensiveIncomeOfAssociatesAndJointVenturesAccountedForUsingEquityMethod
4142	043902 - Disclosure - Investments in associates and joint ventures (Narrative) (Details)	Network	*	*	http://www.barclays.co.uk/role/InvestmentsInAssociatesAndJointVenturesNarrativeDetails
4143	Disclosure of associates [table]	Table	*	*	ifrs-full:DisclosureOfSignificantInvestmentsInAssociatesTable
4144	Associates [axis]	Axis			ifrs-full:SignificantInvestmentsInAssociatesAxis
4145	Entity's total for associates [member]	Member			ifrs-full:EntitysTotalForAssociatesMember
4146	Associates [member]	Member			ifrs-full:AssociatesMember
4147	Joint ventures [axis]	Axis			ifrs-full:JointVenturesAxis
4148	Entity's total for joint ventures [member]	Member			ifrs-full:EntitysTotalForJointVenturesMember
4149	Joint ventures [member]	Member			ifrs-full:JointVenturesMember
4150	Range [axis]	Axis			ifrs-full:RangeAxis
4151	Ranges [member]	Member			ifrs-full:RangesMember
4152	Min [member]	Member			ifrs-full:BottomOfRangeMember
4153	Max [member]	Member			ifrs-full:TopOfRangeMember
4154	Consolidated Entities [Axis]	Axis			srt:ConsolidatedEntitiesAxis
4155	Consolidated Entities [Domain]	Member			srt:ConsolidatedEntitiesDomain
4156	Barclays Bank Group [member]	Member			c070:BarclaysBankGroupMember
4157	Disclosure of associates and joint ventures [line items]	LineItems			ifrs-full:DisclosureOfSignificantInvestmentsInAssociatesLineItems
4158	Voting rights, Associates	Concept (Percent)	For Period		ifrs-full:ProportionOfVotingPowerHeldInAssociate
4159	Voting rights, Joint ventures	Concept (Percent)	For Period		ifrs-full:ProportionOfVotingRightsHeldInJointVenture
4160	Unrecognised share of losses of associates and joint ventures	Concept (Monetary)	For Period	Debit	c070:UnrecognisedShareOfLossesOfAssociatesAndJointVentures
4161	Unutilised credit facilities	Concept (Monetary)	As Of	Credit	ifrs-full:UndrawnBorrowingFacilities
4162	Commitments in relation to joint ventures and associates	Concept (Monetary)	As Of	Credit	c070:CommitmentsInRelationToJointVenturesAndAssociates
4163	044001 - Disclosure - Securitisations - Transfers of financial assets that do not result in derecognition (Details)	Network	*	*	http://www.barclays.co.uk/role/SecuritisationsTransfersOfFinancialAssetsThatDoNotResultInDerecognitionDetails
4164	Disclosure of transferred financial assets that are not derecognised in their entirety [table]	Table	*	*	ifrs-full:DisclosureOfFinancialAssetsTransferredDuringPeriodWhichDoNotQualifyForDerecognitionTable
4165	Consolidated Entities [Axis]	Axis			srt:ConsolidatedEntitiesAxis
4166	Consolidated Entities [Domain]	Member			srt:ConsolidatedEntitiesDomain
4167	Barclays Bank Group [member]	Member			c070:BarclaysBankGroupMember
4168	Transferred financial assets that are not derecognised in their entirety [axis]	Axis			ifrs-full:FinancialAssetsWhichDoNotQualifyForDerecognitionAxis
4169	Transferred financial assets that are not derecognised in their entirety [member]	Member			ifrs-full:FinancialAssetsWhichDoNotQualifyForDerecognitionMember
4170	Residential mortgage loans [member]	Member			ifrs-full:MortgagesMember
4171	Credit cards, unsecured and other retail lending [member]	Member			c070:CreditCardsUnsecuredAndOtherRetailLendingMember
4172	Categories of financial assets [axis]	Axis			ifrs-full:CategoriesOfFinancialAssetsAxis
4173	Financial assets, category [member]	Member			ifrs-full:FinancialAssetsCategoryMember
4174	Financial assets at amortised cost, category [member]	Member			ifrs-full:FinancialAssetsAtAmortisedCostCategoryMember
4175	Disclosure of transferred financial assets that are not derecognised in their entirety [line items]	LineItems			ifrs-full:DisclosureOfFinancialAssetsTransferredDuringPeriodWhichDoNotQualifyForDerecognitionLineItems
4176	Assets carrying amount	Concept (Monetary)	As Of	Debit	ifrs-full:AssetsThatEntityContinuesToRecognise
4177	Assets Fair value	Concept (Monetary)	As Of	Debit	ifrs-full:FairValueOfTransferredFinancialAssetsThatAreNotDerecognisedInTheirEntirety
4178	Liabilities carry amount	Concept (Monetary)	As Of	Credit	ifrs-full:AssociatedLiabilitiesThatEntityContinuesToRecognise
4179	Liabilities fair value	Concept (Monetary)	As Of	Credit	ifrs-full:FairValueOfAssociatedFinancialLiabilities
4180	044002 - Disclosure - Securitisations - Continuing involvement in financial assets that have been derecognised (Details)	Network	*	*	http://www.barclays.co.uk/role/SecuritisationsContinuingInvolvementInFinancialAssetsThatHaveBeenDerecognisedDetails
4181	Disclosure of continuing involvement in derecognised financial assets [table]	Table	*	*	ifrs-full:DisclosureOfContinuingInvolvementInDerecognisedFinancialAssetsTable
4182	Continuing involvement in derecognised financial assets by type of transfer [axis]	Axis			ifrs-full:ContinuingInvolvementInDerecognisedFinancialAssetsByTypeOfTransferAxis
4183	Types of transfer [member]	Member			ifrs-full:TypesOfTransferMember
4184	CLO and other assets [member]	Member			ifrs-full:SecuritiesLendingMember
4185	Commercial mortgage backed security [member]	Member			c070:CommercialMortgageBackedSecurityMember
4186	Consolidated Entities [Axis]	Axis			srt:ConsolidatedEntitiesAxis
4187	Consolidated Entities [Domain]	Member			srt:ConsolidatedEntitiesDomain
4188	Barclays Bank Group [member]	Member			c070:BarclaysBankGroupMember
4189	Disclosure of continuing involvement in derecognised financial assets [line items]	LineItems			ifrs-full:DisclosureOfContinuingInvolvementInDerecognisedFinancialAssetsLineItems
4190	Carrying amount	Concept (Monetary)	As Of	Debit	ifrs-full:RecognisedAssetsRepresentingContinuingInvolvementInDerecognisedFinancialAssets
4191	Fair value	Concept (Monetary)	As Of	Debit	ifrs-full:FairValueOfAssetsRepresentingContinuingInvolvementInDerecognisedFinancialAssets
4192	Maximum exposure to loss	Concept (Monetary)	As Of		ifrs-full:MaximumExposureToLossFromContinuingInvolvement
4193	Gain (loss) from continuing involvement for the year ended	Concept (Monetary)	For Period	Credit	ifrs-full:GainLossOfDerecognisedFinancialAssetsRepresentingGreatestTransferActivity
4194	Gain (loss) from continuing involvement, cumulative	Concept (Monetary)	For Period	Credit	ifrs-full:GainLossOfDerecognisedFinancialAssetsAtDateOfTransfer
4195	044101 - Disclosure - Assets pledged - Carrying amount of the assets pledged as security against liabilities (Details)	Network	*	*	http://www.barclays.co.uk/role/AssetsPledgedCarryingAmountOfTheAssetsPledgedAsSecurityAgainstLiabilitiesDetails
4196	Disclosure of offsetting of financial liabilities [table]	Table	*	*	ifrs-full:DisclosureOfOffsettingOfFinancialLiabilitiesTable
4197	Classes of financial assets [axis]	Axis			ifrs-full:ClassesOfFinancialAssetsAxis
4198	Financial assets, class [member]	Member			ifrs-full:FinancialAssetsMember
4199	Financial assets at amortised cost [member]	Member			ifrs-full:FinancialAssetsAtAmortisedCostMember
4200	Cash collateral and settlement balances [member]	Member			ifrs-full:TradeReceivablesMember
4201	Financial Investments [member]	Member			c070:FinancialInvestmentsMember
4202	Categories of financial assets [axis]	Axis			ifrs-full:CategoriesOfFinancialAssetsAxis
4203	Financial assets, category [member]	Member			ifrs-full:FinancialAssetsCategoryMember
4204	Trading portfolio assets [member]	Member			ifrs-full:FinancialAssetsAtFairValueThroughProfitOrLossClassifiedAsHeldForTradingCategoryMember
4205	Financial assets at fair value through the income statement [member]	Member			ifrs-full:FinancialAssetsAtFairValueThroughProfitOrLossCategoryMember
4206	Financial assets at fair value through other comprehensive income [member]	Member			ifrs-full:FinancialAssetsAtFairValueThroughOtherComprehensiveIncomeCategoryMember
4207	Consolidated Entities [Axis]	Axis			srt:ConsolidatedEntitiesAxis
4208	Consolidated Entities [Domain]	Member			srt:ConsolidatedEntitiesDomain
4209	Barclays Bank Group [member]	Member			c070:BarclaysBankGroupMember
4210	Disclosure of offsetting of financial liabilities [line items]	LineItems			ifrs-full:DisclosureOfOffsettingOfFinancialLiabilitiesLineItems
4211	Assets pledged	Concept (Monetary)	As Of	Debit	ifrs-full:FinancialAssetsPledgedAsCollateralForLiabilitiesOrContingentLiabilities
4212	044102 - Disclosure - Assets pledged - Fair value at the balance sheet date of collateral accepted and re-pledged to others (Details)	Network	*	*	http://www.barclays.co.uk/role/AssetsPledgedFairValueAtTheBalanceSheetDateOfCollateralAcceptedAndRepledgedToOthersDetails
4213	Condensed Balance Sheet Statement [Table]	Table	*	*	srt:CondensedBalanceSheetStatementTable
4214	Consolidated Entities [Axis]	Axis			srt:ConsolidatedEntitiesAxis
4215	Consolidated Entities [Domain]	Member			srt:ConsolidatedEntitiesDomain
4216	Barclays Bank Group [member]	Member			c070:BarclaysBankGroupMember
4217	Condensed Balance Sheet Statements, Captions [Line Items]	LineItems			srt:CondensedBalanceSheetStatementsCaptionsLineItems
4218	Fair value of securities accepted as collateral	Concept (Monetary)	As Of	Debit	ifrs-full:AssetsHeldAsCollateralPermittedToBeSoldOrRepledgedAtFairValue
4219	Of which fair value of securities re-pledged/transferred to others	Concept (Monetary)	As Of	Debit	ifrs-full:AssetsSoldOrRepledgedAsCollateralAtFairValue
4220	044103 - Disclosure - Assets Pledged (Narrative) (Details)	Network	*	*	http://www.barclays.co.uk/role/AssetsPledgedNarrativeDetails
4221	Disclosure of unconsolidated structured entities [table]	Table	*	*	ifrs-full:DisclosureOfUnconsolidatedStructuredEntitiesTable
4222	Classes of financial instruments [axis]	Axis			ifrs-full:ClassesOfFinancialInstrumentsAxis
4223	Financial instruments, class [member]	Member			ifrs-full:ClassesOfFinancialInstrumentsMember
4224	Asset backed funding programmes [member]	Member			c070:AssetBackedFundingProgrammesMember
4225	Disclosure of unconsolidated structured entities [line items]	LineItems			ifrs-full:DisclosureOfUnconsolidatedStructuredEntitiesLineItems
4226	Description of terms and conditions of financial assets pledged as collateral for liabilities or contingent liabilities	Concept (Text/String)	For Period		ifrs-full:DescriptionOfTermAndConditionsOfFinancialAssetsPledgedAsCollateralForLiabilitiesOrContingentLiabilities
4227	Loans and advances	Concept (Monetary)	As Of	Debit	ifrs-full:LoansAndReceivables
4228	044200 - Disclosure - Related party transactions and Directors' remuneration - Group's financial statements (Details)	Network	*	*	http://www.barclays.co.uk/role/RelatedPartyTransactionsAndDirectorsRemunerationGroupsFinancialStatementsDetails
4229	Disclosure of transactions between related parties [table]	Table	*	*	ifrs-full:DisclosureOfTransactionsBetweenRelatedPartiesTable
4230	Categories of related parties [axis]	Axis			ifrs-full:CategoriesOfRelatedPartiesAxis
4231	Entity's total for related parties [member]	Member			ifrs-full:EntitysTotalForRelatedPartiesMember
4232	Parent [member]	Member			ifrs-full:ParentMember
4233	Fellow subsidiaries [member]	Member			ifrs-full:OtherRelatedPartiesMember
4234	Associates [member]	Member			ifrs-full:AssociatesMember
4235	Joint Ventures [member]	Member			ifrs-full:JointVenturesWhereEntityIsVenturerMember
4236	Pension funds [member]	Member			c070:PensionFundsUnitTrustsAndInvestmentFundsMember
4237	Consolidated Entities [Axis]	Axis			srt:ConsolidatedEntitiesAxis
4238	Consolidated Entities [Domain]	Member			srt:ConsolidatedEntitiesDomain
4239	Barclays Bank Group [member]	Member			c070:BarclaysBankGroupMember
4240	Disclosure of transactions between related parties [line items]	LineItems			ifrs-full:DisclosureOfTransactionsBetweenRelatedPartiesLineItems
4241	Total income	Concept (Monetary)	For Period	Credit	c070:ProfitLossFromOperatingActivitiesBeforeImpairmentLossReversalOfImpairmentLossRecognisedInProfitOrLoss
4242	Credit impairment charges and other provisions	Concept (Monetary)	For Period	Debit	ifrs-full:ImpairmentLossReversalOfImpairmentLossRecognisedInProfitOrLoss
4243	Operating expenses	Concept (Monetary)	For Period	Debit	ifrs-full:OperatingExpense
4244	Assets	Concept (Monetary)	As Of	Debit	ifrs-full:Assets
4245	Liabilities	Concept (Monetary)	As Of	Credit	ifrs-full:Liabilities
4246	044201 - Disclosure - Related party transactions and Directors' remuneration - Bank's financial statement (Details)	Network	*	*	http://www.barclays.co.uk/role/RelatedPartyTransactionsAndDirectorsRemunerationBanksFinancialStatementDetails
4247	Disclosure of transactions between related parties [table]	Table	*	*	ifrs-full:DisclosureOfTransactionsBetweenRelatedPartiesTable
4248	Categories of related parties [axis]	Axis			ifrs-full:CategoriesOfRelatedPartiesAxis
4249	Entity's total for related parties [member]	Member			ifrs-full:EntitysTotalForRelatedPartiesMember
4250	Parent [member]	Member			ifrs-full:ParentMember
4251	Subsidiaries [member]	Member			ifrs-full:SubsidiariesMember
4252	Fellow subsidiaries [member]	Member			ifrs-full:OtherRelatedPartiesMember
4253	Associates [member]	Member			ifrs-full:AssociatesMember
4254	Joint ventures where entity is venturer [member]	Member			ifrs-full:JointVenturesWhereEntityIsVenturerMember
4255	Pension funds [member]	Member			c070:PensionFundsUnitTrustsAndInvestmentFundsMember
4256	Disclosure of transactions between related parties [line items]	LineItems			ifrs-full:DisclosureOfTransactionsBetweenRelatedPartiesLineItems
4257	Assets	Concept (Monetary)	As Of	Debit	ifrs-full:Assets
4258	Liabilities	Concept (Monetary)	As Of	Credit	ifrs-full:Liabilities
4259	044202 - Disclosure - Related party transactions and Directors' remuneration - Loans and deposits outstanding (Details)	Network	*	*	http://www.barclays.co.uk/role/RelatedPartyTransactionsAndDirectorsRemunerationLoansAndDepositsOutstandingDetails
4260	Disclosure of transactions between related parties [table]	Table	*	*	ifrs-full:DisclosureOfTransactionsBetweenRelatedPartiesTable
4261	Categories of related parties [axis]	Axis			ifrs-full:CategoriesOfRelatedPartiesAxis
4262	Entity's total for related parties [member]	Member			ifrs-full:EntitysTotalForRelatedPartiesMember
4263	Key Management Personnel and persons connected to them [member]	Member			ifrs-full:KeyManagementPersonnelOfEntityOrParentMember
4264	Consolidated Entities [Axis]	Axis			srt:ConsolidatedEntitiesAxis
4265	Consolidated Entities [Domain]	Member			srt:ConsolidatedEntitiesDomain
4266	Barclays Bank Group [member]	Member			c070:BarclaysBankGroupMember
4267	Disclosure of transactions between related parties [line items]	LineItems			ifrs-full:DisclosureOfTransactionsBetweenRelatedPartiesLineItems
4268	Loans outstanding beginning balance	Concept (Monetary)	As Of	Debit	ifrs-full:AmountsReceivableRelatedPartyTransactions
4269	Loans issued during the year	Concept (Monetary)	For Period	Credit	ifrs-full:CashAdvancesAndLoansMadeToRelatedParties
4270	Loan repayments during the year/change of key management personnel	Concept (Monetary)	For Period	Credit	ifrs-full:CashRepaymentsOfAdvancesAndLoansFromRelatedParties
4271	Loan outstanding ending balance	Concept (Monetary)	As Of	Debit	ifrs-full:AmountsReceivableRelatedPartyTransactions
4272	Deposits outstanding beginning balance	Concept (Monetary)	As Of	Credit	ifrs-full:AmountsPayableRelatedPartyTransactions
4273	Deposits received during the year	Concept (Monetary)	For Period	Debit	ifrs-full:CashAdvancesAndLoansFromRelatedParties
4274	Deposits repaid during the year/change of key management personnel	Concept (Monetary)	For Period	Credit	c070:CashRepaymentsOfAdvancesAndLoansToRelatedPartiesAndChangeOfKeyManagmentPersonnel
4275	Deposits oustanding ending balance	Concept (Monetary)	As Of	Credit	ifrs-full:AmountsPayableRelatedPartyTransactions
4276	044203 - Disclosure - Related party transactions and Directors' remuneration - Remuneration of Directors and other Key Management Personnel (Details)	Network	*	*	http://www.barclays.co.uk/role/RelatedPartyTransactionsAndDirectorsRemunerationRemunerationOfDirectorsAndOtherKeyManagementPersonnelDetails
4277	Disclosure of transactions between related parties [table]	Table	*	*	ifrs-full:DisclosureOfTransactionsBetweenRelatedPartiesTable
4278	Consolidated Entities [Axis]	Axis			srt:ConsolidatedEntitiesAxis
4279	Consolidated Entities [Domain]	Member			srt:ConsolidatedEntitiesDomain
4280	Barclays Bank Group [member]	Member			c070:BarclaysBankGroupMember
4281	Disclosure of transactions between related parties [line items]	LineItems			ifrs-full:DisclosureOfTransactionsBetweenRelatedPartiesLineItems
4282	Salaries and other short-term benefits	Concept (Monetary)	For Period	Debit	ifrs-full:KeyManagementPersonnelCompensationShorttermEmployeeBenefits
4283	Pension costs	Concept (Monetary)	For Period	Debit	ifrs-full:KeyManagementPersonnelCompensationPostemploymentBenefits
4284	Other long-term benefits	Concept (Monetary)	For Period	Debit	ifrs-full:KeyManagementPersonnelCompensationOtherLongtermBenefits
4285	Share-based payments	Concept (Monetary)	For Period	Debit	ifrs-full:KeyManagementPersonnelCompensationSharebasedPayment
4286	Employer social security charges on emoluments	Concept (Monetary)	For Period	Debit	c070:KeyManagementPersonnelCompensationSecurityChargesEmoluments
4287	Costs recognised for accounting purposes	Concept (Monetary)	For Period	Debit	c070:KeyManagementPersonnelCompensationCostsRecognisedForAccountingPurposes
4288	Employer social security charges on emoluments	Concept (Monetary)	For Period	Credit	c070:KeyManagementPersonnelCompensationSecurityChargesEmolumentsAwarded
4289	Other long-term benefits - difference between awards granted and costs recognised	Concept (Monetary)	For Period	Credit	c070:KeyManagementPersonnelCompensationOtherLongtermBenefitsDifferenceBetweenAwardsGrantedAndCostsRecognised
4290	Share-based payments - difference between awards granted and costs recognised	Concept (Monetary)	For Period	Credit	c070:KeyManagementPersonnelCompensationSharebasedPaymentsDifferenceBetweenAwardsGrantedAndCostsRecognised
4291	Total remuneration awarded	Concept (Monetary)	For Period	Debit	ifrs-full:KeyManagementPersonnelCompensation
4292	044204 - Disclosure - Related party transactions and Directors' remuneration - Disclosure required by the Companies Act 2006 (Details)	Network	*	*	http://www.barclays.co.uk/role/RelatedPartyTransactionsAndDirectorsRemunerationDisclosureRequiredByTheCompaniesAct2006Details
4293	Disclosure of transactions between related parties [table]	Table	*	*	ifrs-full:DisclosureOfTransactionsBetweenRelatedPartiesTable
4294	Categories of related parties [axis]	Axis			ifrs-full:CategoriesOfRelatedPartiesAxis
4295	Entity's total for related parties [member]	Member			ifrs-full:EntitysTotalForRelatedPartiesMember
4296	Directors [member]	Member			c070:DirectorsMember
4297	Highest paid director [member]	Member			c070:HighestPaidDirectorMember
4298	Consolidated Entities [Axis]	Axis			srt:ConsolidatedEntitiesAxis
4299	Consolidated Entities [Domain]	Member			srt:ConsolidatedEntitiesDomain
4300	Barclays Bank Group [member]	Member			c070:BarclaysBankGroupMember
4301	Disclosure of transactions between related parties [line items]	LineItems			ifrs-full:DisclosureOfTransactionsBetweenRelatedPartiesLineItems
4302	Aggregate emoluments	Concept (Monetary)	For Period	Debit	c070:AggregateEmolumentsCompainesAct2006
4303	Amounts paid under LTIPs	Concept (Monetary)	For Period	Debit	c070:AmountsPaidUnderLTIPsCompaniesAct2006
4304	Total directors expense in accordance with companies act 2006	Concept (Monetary)	For Period	Debit	c070:DirectorsExpenseCompaniesAct2006
4305	044205 - Disclosure - Related party transactions and Directors' remuneration - Disclosure required by the Companies Act 2006 (Narrative) (Details)	Network	*	*	http://www.barclays.co.uk/role/RelatedPartyTransactionsAndDirectorsRemunerationDisclosureRequiredByTheCompaniesAct2006NarrativeDetails
4306	Disclosure of transactions between related parties [table]	Table	*	*	ifrs-full:DisclosureOfTransactionsBetweenRelatedPartiesTable
4307	Categories of related parties [axis]	Axis			ifrs-full:CategoriesOfRelatedPartiesAxis
4308	Entity's total for related parties [member]	Member			ifrs-full:EntitysTotalForRelatedPartiesMember
4309	Directors [member]	Member			c070:DirectorsMember
4310	Highest paid director [member]	Member			c070:HighestPaidDirectorMember
4311	Types of share-based payment arrangements [axis]	Axis			ifrs-full:TypesOfSharebasedPaymentArrangementsAxis
4312	Share-based payment arrangements [member]	Member			ifrs-full:SharebasedPaymentArrangementsMember
4313	Deferred share value plan [member]	Member			c070:DeferredShareValuePlanMember
4314	Consolidated Entities [Axis]	Axis			srt:ConsolidatedEntitiesAxis
4315	Consolidated Entities [Domain]	Member			srt:ConsolidatedEntitiesDomain
4316	Barclays Bank Group [member]	Member			c070:BarclaysBankGroupMember
4317	Disclosure of transactions between related parties [line items]	LineItems			ifrs-full:DisclosureOfTransactionsBetweenRelatedPartiesLineItems
4318	Aggregate emoluments	Concept (Monetary)	For Period	Debit	c070:AggregateEmolumentsCompainesAct2006
4319	044206 - Disclosure - Related party transactions and Directors' remuneration (Narrative) (Details)	Network	*	*	http://www.barclays.co.uk/role/RelatedPartyTransactionsAndDirectorsRemunerationNarrativeDetails
4320	Disclosure of transactions between related parties [table]	Table	*	*	ifrs-full:DisclosureOfTransactionsBetweenRelatedPartiesTable
4321	Categories of related parties [axis]	Axis			ifrs-full:CategoriesOfRelatedPartiesAxis
4322	Entity's total for related parties [member]	Member			ifrs-full:EntitysTotalForRelatedPartiesMember
4323	Barclays PLC [member]	Member			ifrs-full:ParentMember
4324	Key Management Personnel and persons connected to them [member]	Member			ifrs-full:KeyManagementPersonnelOfEntityOrParentMember
4325	Directors [member]	Member			c070:DirectorsMember
4326	Highest paid director [member]	Member			c070:HighestPaidDirectorMember
4327	Joint Ventures [member]	Member			ifrs-full:JointVenturesWhereEntityIsVenturerMember
4328	Pension funds [member]	Member			c070:PensionFundsUnitTrustsAndInvestmentFundsMember
4329	Classes of share capital [axis]	Axis			ifrs-full:ClassesOfShareCapitalAxis
4330	Share capital [member]	Member			ifrs-full:ClassesOfShareCapitalMember
4331	Ordinary share capital [member]	Member			ifrs-full:OrdinarySharesMember
4332	Characteristics of defined benefit plans [axis]	Axis			ifrs-full:CharacteristicsOfDefinedBenefitPlansAxis
4333	Characteristics of defined benefit plans [member]	Member			ifrs-full:CharacteristicsOfDefinedBenefitPlansMember
4334	Defined contribution Schemes [member]	Member			c070:DefinedContributionPlansMember
4335	Consolidated Entities [Axis]	Axis			srt:ConsolidatedEntitiesAxis
4336	Consolidated Entities [Domain]	Member			srt:ConsolidatedEntitiesDomain
4337	Barclays Bank Group [member]	Member			c070:BarclaysBankGroupMember
4338	Barclays Bank PLC [member]	Member			c070:BarclaysBankPlcMember
4339	Disclosure of transactions between related parties [line items]	LineItems			ifrs-full:DisclosureOfTransactionsBetweenRelatedPartiesLineItems
4340	Name of ultimate parent of group	Concept (Text/String)	For Period		ifrs-full:NameOfUltimateParentOfGroup
4341	Percentage of issued share capital	Concept (Percent)	As Of		c070:PercentageOfIssuedShareCapital
4342	Guarantees, pledges or commitments	Concept (Monetary)	For Period		ifrs-full:ProvisionOfGuaranteesOrCollateralByEntityRelatedPartyTransactions
4343	Derivatives transacted	Concept (Monetary)	For Period	Debit	c070:DerivativeTransactionsDuringPeriodRelatedPartyTransactions
4344	Allowances for impairment recognised	Concept (Monetary)	For Period	Debit	ifrs-full:ImpairmentLossRecognisedInProfitOrLoss
4345	Total commitments outstanding	Concept (Monetary)	As Of	Credit	ifrs-full:OutstandingCommitmentsMadeByEntityRelatedPartyTransactions
4346	Pension contributions paid to defined contributions schemes	Concept (Monetary)	For Period	Debit	ifrs-full:ContributionsToPlanNetDefinedBenefitLiabilityAsset
4347	Notional defined benefit contributions	Concept (Monetary)	For Period	Debit	c070:NotionalContributionsToPlanNetDefinedBenefitLiabilityAsset
4348	Accruing benefits under defined benefit scheme	Concept (Monetary)	For Period	Debit	ifrs-full:PostemploymentBenefitExpenseDefinedBenefitPlans
4349	Advances and credits available	Concept (Monetary)	For Period	Credit	ifrs-full:CashAdvancesAndLoansMadeToRelatedParties
4350	Total value of guarantees entered into on behalf of Directors	Concept (Monetary)	For Period		ifrs-full:CommitmentsMadeOnBehalfOfEntityRelatedPartyTransactions
4351	044301 - Disclosure - Auditors' remuneration (Details)	Network	*	*	http://www.barclays.co.uk/role/AuditorsRemunerationDetails
4352	Auditors' Remuneration by services [table]	Table	*	*	c070:AuditorsRemunerationByServicesTable
4353	Auditors' Remuneration By Services [Axis]	Axis			c070:AuditorsRemunerationByServicesAxis
4354	All Type Of Auditors' Remuneration [member]	Member			c070:AllTypeOfAuditorsRemunerationDomain
4355	Other audit related fees [member]	Member			c070:OtherAuditRelatedFeesMember
4356	Other services [member]	Member			c070:OtherAuditorServicesMember
4357	Categories of related parties [axis]	Axis			ifrs-full:CategoriesOfRelatedPartiesAxis
4358	Entity's total for related parties [member]	Member			ifrs-full:EntitysTotalForRelatedPartiesMember
4359	Subsidiaries [member]	Member			ifrs-full:SubsidiariesMember
4360	Consolidated Entities [Axis]	Axis			srt:ConsolidatedEntitiesAxis
4361	Consolidated Entities [Domain]	Member			srt:ConsolidatedEntitiesDomain
4362	Barclays Bank Group [member]	Member			c070:BarclaysBankGroupMember
4363	Auditors' Remuneration By Services [Line Items]	LineItems			c070:AuditorsRemunerationByServicesLineItems
4364	Audit of the Group's annual accounts	Concept (Monetary)	For Period	Debit	ifrs-full:AuditorsRemunerationForAuditServices
4365	Other services	Concept (Monetary)	For Period	Debit	ifrs-full:AuditorsRemunerationForOtherServices
4366	Total Auditors' remuneration	Concept (Monetary)	For Period	Debit	ifrs-full:AuditorsRemuneration
4367	044302 - Disclosure - Auditors' remuneration (Narrative) (Details)	Network	*	*	http://www.barclays.co.uk/role/AuditorsRemunerationNarrativeDetails
4368	Auditors' Remuneration by services [table]	Table	*	*	c070:AuditorsRemunerationByServicesTable
4369	Name of auding companies [axis]	Axis			c070:NameOfAudingCompaniesAxis
4370	Name of auditing companies [member]	Member			c070:NamesOfAuditingCompaniesDomain
4371	KPMG [member]	Member			c070:KlynveldPeatMarwickGoerdelerMember
4372	PricewaterhouseCoopers LLP [member]	Member			c070:PricewaterhousecoopersLlpMember
4373	Continuing and discontinued operations [axis]	Axis			ifrs-full:ContinuingAndDiscontinuedOperationsAxis
4374	Aggregate continuing and discontinued operations [member]	Member			ifrs-full:AggregateContinuingAndDiscontinuedOperationsMember
4375	Discontinued operations [member]	Member			ifrs-full:DiscontinuedOperationsMember
4376	Consolidated Entities [Axis]	Axis			srt:ConsolidatedEntitiesAxis
4377	Consolidated Entities [Domain]	Member			srt:ConsolidatedEntitiesDomain
4378	Barclays Bank Group [member]	Member			c070:BarclaysBankGroupMember
4379	Auditors' Remuneration By Services [Line Items]	LineItems			c070:AuditorsRemunerationByServicesLineItems
4380	Auditors' remuneration	Concept (Monetary)	For Period	Debit	ifrs-full:AuditorsRemuneration
4381	044400 - Disclosure - Transition disclosures - Reconciliation of impairment allowance and provisions (Details)	Network	*	*	http://www.barclays.co.uk/role/TransitionDisclosuresReconciliationOfImpairmentAllowanceAndProvisionsDetails
4382	Disclosure of reconciliation of changes in loss allowance and explanation of changes in gross carrying amount for financial instruments [table]	Table	*	*	ifrs-full:DisclosureOfReconciliationOfChangesInLossAllowanceAndExplanationOfChangesInGrossCarryingAmountForFinancialInstrumentsTable
4383	Retrospective application and retrospective restatement [axis]	Axis			ifrs-full:RetrospectiveApplicationAndRetrospectiveRestatementAxis
4384	Currently stated [member]	Member			ifrs-full:RestatedMember
4385	Impairment allowance under IAS 39 or provision under IAS 37 [member]	Member			ifrs-full:PreviouslyStatedMember
4386	Increase (decrease) due to changes in accounting policy required by IFRSs [member]	Member			ifrs-full:IncreaseDecreaseDueToChangesInAccountingPolicyRequiredByIFRSsMember
4387	IFRSs 9 [member]	Member			c070:IFRSs9Member
4388	Carrying amount, accumulated depreciation, amortisation and impairment and gross carrying amount [axis]	Axis			ifrs-full:CarryingAmountAccumulatedDepreciationAmortisationAndImpairmentAndGrossCarryingAmountAxis
4389	Carrying amount [member]	Member			ifrs-full:CarryingAmountMember
4390	Impairment allowance [member]	Member			ifrs-full:AccumulatedImpairmentMember
4391	Classes of financial assets [axis]	Axis			ifrs-full:ClassesOfFinancialAssetsAxis
4392	Financial assets, class [member]	Member			ifrs-full:FinancialAssetsMember
4393	Financial assets at amortised cost [member]	Member			ifrs-full:FinancialAssetsAtAmortisedCostMember
4394	Loans and advances [member]	Member			ifrs-full:LoansAndReceivablesCategoryMember
4395	Available for sale investments [member]	Member			ifrs-full:FinancialAssetsAvailableforsaleCategoryMember
4396	Classes of assets [axis]	Axis			ifrs-full:ClassesOfAssetsAxis
4397	Assets [member]	Member			ifrs-full:ClassesOfAssetsMember
4398	Other assets [member]	Member			ifrs-full:OtherAssetsMember
4399	Categories of financial assets [axis]	Axis			ifrs-full:CategoriesOfFinancialAssetsAxis
4400	Financial assets, category [member]	Member			ifrs-full:FinancialAssetsCategoryMember
4401	Financial assets at fair value through other comprehensive income [member]	Member			ifrs-full:FinancialAssetsAtFairValueThroughOtherComprehensiveIncomeCategoryMember
4402	Classes of other provisions [axis]	Axis			ifrs-full:ClassesOfProvisionsAxis
4403	Other provisions [member]	Member			ifrs-full:OtherProvisionsMember
4404	Undrawn contractually committed facilities and guarantees [member]	Member			c070:UndrawnContractuallyCommittedFacilitiesAndGuaranteesMember
4405	Consolidated Entities [Axis]	Axis			srt:ConsolidatedEntitiesAxis
4406	Consolidated Entities [Domain]	Member			srt:ConsolidatedEntitiesDomain
4407	Barclays Bank Group [member]	Member			c070:BarclaysBankGroupMember
4408	Disclosure of reconciliation of changes in loss allowance and explanation of changes in gross carrying amount for financial instruments [line items]	LineItems			ifrs-full:DisclosureOfReconciliationOfChangesInLossAllowanceAndExplanationOfChangesInGrossCarryingAmountForFinancialInstrumentsLineItems
4409	On-balance sheet	Abstract			c070:OnBalanceSheetAbstract
4410	Impairment allowance	Concept (Monetary)	As Of	Credit	ifrs-full:AllowanceAccountForCreditLossesOfFinancialAssets
4411	Reclassification impact	Concept (Monetary)	For Period	Debit	ifrs-full:ReclassificationIntoFinancialAssetsAtFairValueThroughProfitOrLoss
4412	Additional impairment allowance	Concept (Monetary)	For Period		ifrs-full:AdditionalAllowanceRecognisedInProfitOrLossAllowanceAccountForCreditLossesOfFinancialAssets
4413	Provisions	Concept (Monetary)	As Of	Credit	ifrs-full:OtherProvisions
4414	Additional provisions	Concept (Monetary)	For Period	Credit	ifrs-full:AdditionalProvisionsOtherProvisions
4415	Total impairment and provision	Concept (Monetary)	As Of	Credit	c070:ImpairmentAndProvision
4416	Additional impairment allowance	Concept (Monetary)	For Period	Credit	c070:AdditionalAllowanceRecognisedInProfitOrLoss
4417	044401 - Disclosure - Transition disclosures - Reconciliation of impairment allowance and provisions (Narrative) (Details)	Network	*	*	http://www.barclays.co.uk/role/TransitionDisclosuresReconciliationOfImpairmentAllowanceAndProvisionsNarrativeDetails
4418	Disclosure of reconciliation of changes in loss allowance and explanation of changes in gross carrying amount for financial instruments [table]	Table	*	*	ifrs-full:DisclosureOfReconciliationOfChangesInLossAllowanceAndExplanationOfChangesInGrossCarryingAmountForFinancialInstrumentsTable
4419	Classes of assets [axis]	Axis			ifrs-full:ClassesOfAssetsAxis
4420	Assets [member]	Member			ifrs-full:ClassesOfAssetsMember
4421	Cash collateral and settlement balances [member]	Member			ifrs-full:TradeReceivablesMember
4422	Other assets [member]	Member			ifrs-full:OtherAssetsMember
4423	Classes of financial assets [axis]	Axis			ifrs-full:ClassesOfFinancialAssetsAxis
4424	Financial assets, class [member]	Member			ifrs-full:FinancialAssetsMember
4425	Financial assets at amortised cost [member]	Member			ifrs-full:FinancialAssetsAtAmortisedCostMember
4426	Loans and advances [member]	Member			ifrs-full:LoansAndReceivablesCategoryMember
4427	Retrospective application and retrospective restatement [axis]	Axis			ifrs-full:RetrospectiveApplicationAndRetrospectiveRestatementAxis
4428	Currently stated [member]	Member			ifrs-full:RestatedMember
4429	Impairment allowance under IAS 39 or provision under IAS 37 [member]	Member			ifrs-full:PreviouslyStatedMember
4430	Increase (decrease) due to changes in accounting policy required by IFRSs [member]	Member			ifrs-full:IncreaseDecreaseDueToChangesInAccountingPolicyRequiredByIFRSsMember
4431	IFRSs 9 [member]	Member			c070:IFRSs9Member
4432	Consolidated Entities [Axis]	Axis			srt:ConsolidatedEntitiesAxis
4433	Consolidated Entities [Domain]	Member			srt:ConsolidatedEntitiesDomain
4434	Barclays Bank Group [member]	Member			c070:BarclaysBankGroupMember
4435	Disclosure of reconciliation of changes in loss allowance and explanation of changes in gross carrying amount for financial instruments [line items]	LineItems			ifrs-full:DisclosureOfReconciliationOfChangesInLossAllowanceAndExplanationOfChangesInGrossCarryingAmountForFinancialInstrumentsLineItems
4436	Additional impairment allowance	Concept (Monetary)	For Period		ifrs-full:AdditionalAllowanceRecognisedInProfitOrLossAllowanceAccountForCreditLossesOfFinancialAssets
4437	044402 - Disclosure - Transition disclosures - Balance sheet movement - Assets, impact of transition to IFRS 9 and IFRS 15 (Details)	Network	*	*	http://www.barclays.co.uk/role/TransitionDisclosuresBalanceSheetMovementAssetsImpactOfTransitionToIFRS9AndIFRS15Details
4438	Disclosure of financial assets at date of initial application of IFRS 9 [table]	Table	*	*	ifrs-full:DisclosureOfFinancialAssetsAtDateOfInitialApplicationOfIFRS9Table
4439	Retrospective application and retrospective restatement [axis]	Axis			ifrs-full:RetrospectiveApplicationAndRetrospectiveRestatementAxis
4440	Currently stated [member]	Member			ifrs-full:RestatedMember
4441	Published IAS 39 [member]	Member			ifrs-full:PreviouslyStatedMember
4442	Balance sheet presentation changes [member]	Member			ifrs-full:IncreaseDecreaseDueToVoluntaryChangesInAccountingPolicyMember
4443	IFRSs 9 [member]	Member			c070:IFRSs9Member
4444	Increase (decrease) due to changes in accounting policy required by IFRSs [member]	Member			ifrs-full:IncreaseDecreaseDueToChangesInAccountingPolicyRequiredByIFRSsMember
4445	IFRSs 15 impact [member]	Member			ifrs-full:IncreaseDecreaseDueToApplicationOfIFRS15Member
4446	IFRS 9 classification and measurement [member]	Member			c070:Ifrs9ClassificationAndMeasurementMember
4447	Classes of assets [axis]	Axis			ifrs-full:ClassesOfAssetsAxis
4448	Assets [member]	Member			ifrs-full:ClassesOfAssetsMember
4449	Cash and balances at central banks [member]	Member			c070:CashAndBankBalancesAtCentralBanksMember
4450	Items in the course of collection from other banks [member]	Member			c070:ItemsInTheCourseOfCollectionFromOtherBanksMember
4451	Loans and advances to banks [member]	Member			c070:LoansAndAdvancesToBanksMember
4452	Loans and advances to customers [member]	Member			c070:LoansAndAdvancesToCustomersMember
4453	Cash collateral and settlement balances [member]	Member			ifrs-full:TradeReceivablesMember
4454	Reverse repurchase agreements and other similar secured lending [member]	Member			c070:ReverseRepurchaseAgreementsAndOtherSimilarSecuredLendingMember
4455	Net derivative financial instruments [member]	Member			ifrs-full:DerivativesMember
4456	Investments in associates and joint ventures [member]	Member			c070:InvestmentsInAssociatesAndJointVenturesMember
4457	Investments in subsidiaries [member]	Member			c070:InvestmentsInSubsidiariesMember
4458	Goodwill and intangible assets [member]	Member			ifrs-full:IntangibleAssetsAndGoodwillMember
4459	Property, plant and equipment [member]	Member			ifrs-full:PropertyPlantAndEquipmentMember
4460	Current tax assets [member]	Member			c070:CurrentTaxAssetsMember
4461	Deferred tax assets [member]	Member			c070:DeferredTaxAssetsMember
4462	Retirement benefit assets [member]	Member			c070:RetirementBenefitAssetsMember
4463	Prepayments, accrued income and other assets [member]	Member			c070:PrepaymentsAccruedIncomeAndOtherAssetsMember
4464	Other assets [member]	Member			ifrs-full:OtherAssetsMember
4465	Assets included in disposal groups classified as held for sale [member]	Member			ifrs-full:NoncurrentAssetsOrDisposalGroupsClassifiedAsHeldForSaleMember
4466	Categories of financial assets [axis]	Axis			ifrs-full:CategoriesOfFinancialAssetsAxis
4467	Financial assets, category [member]	Member			ifrs-full:FinancialAssetsCategoryMember
4468	Trading portfolio assets [member]	Member			ifrs-full:FinancialAssetsAtFairValueThroughProfitOrLossClassifiedAsHeldForTradingCategoryMember
4469	Financial Investments [member]	Member			c070:FinancialInvestmentsMember
4470	Financial investments, AFS - debt instruments [member]	Member			c070:FinancialInvestmentsMeasurementCategoryAvailableForSaleDebtInstrumentsImmediatelyBeforeInitialApplicationOfIfrs9Member
4471	Financial investments, AFS - equity instruments [member]	Member			c070:FinancialInvestmentsMeasurementCategoryAvailableForSaleEquityInstrumentsImmediatelyBeforeInitialApplicationOfIfrs9Member
4472	Financial investments, amortised cost [member]	Member			c070:FinancialInvestmentsMeasurementCategoryAmortisedCostImmediatelyBeforeInitialApplicationOfIfrs9Member
4473	Financial assets at fair value through the income statement [member]	Member			ifrs-full:FinancialAssetsAtFairValueThroughProfitOrLossCategoryMember
4474	Financial assets designated at fair value [member]	Member			ifrs-full:FinancialAssetsAtFairValueThroughProfitOrLossDesignatedUponInitialRecognitionCategoryMember
4475	Financial assets at fair value through other comprehensive income [member]	Member			ifrs-full:FinancialAssetsAtFairValueThroughOtherComprehensiveIncomeCategoryMember
4476	Loans and advances [member]	Member			ifrs-full:LoansAndReceivablesCategoryMember
4477	Classes of financial assets [axis]	Axis			ifrs-full:ClassesOfFinancialAssetsAxis
4478	Financial assets, class [member]	Member			ifrs-full:FinancialAssetsMember
4479	Financial assets at amortised cost [member]	Member			ifrs-full:FinancialAssetsAtAmortisedCostMember
4480	Loans and advances [member]	Member			ifrs-full:LoansAndReceivablesCategoryMember
4481	Consolidated Entities [Axis]	Axis			srt:ConsolidatedEntitiesAxis
4482	Consolidated Entities [Domain]	Member			srt:ConsolidatedEntitiesDomain
4483	Barclays Bank Group [member]	Member			c070:BarclaysBankGroupMember
4484	Disclosure of financial assets at date of initial application of IFRS 9 [line items]	LineItems			ifrs-full:DisclosureOfFinancialAssetsAtDateOfInitialApplicationOfIFRS9LineItems
4485	Assets [abstract]	Abstract			ifrs-full:AssetsAbstract
4486	IAS 39 measurement category, assets	Concept (Text/String)	For Period		ifrs-full:FinancialAssetsMeasurementCategoryImmediatelyBeforeInitialApplicationOfIFRS9
4487	IFRS 9 measurement category, assets	Concept (Text/String)	For Period		ifrs-full:FinancialAssetsMeasurementCategoryImmediatelyAfterInitialApplicationOfIFRS9
4488	Opening balance, IAS 39 carrying amount	Concept (Monetary)	As Of	Debit	ifrs-full:FinancialAssetsCarryingAmountImmediatelyBeforeInitialApplicationOfIFRS9
4489	Amount of reclassifications or changes in presentation, assets	Concept (Monetary)	For Period	Debit	c070:AmountOfReclassificationsOrChangesInPresentationAssets
4490	IFRS 9 Impairment change	Concept (Monetary)	As Of	Debit	ifrs-full:IncreaseDecreaseInFinancialAssetsArisingFromChangeInMeasurementAttributeFirstApplicationOfIFRS9
4491	Total, IFRS 9 carrying amount	Concept (Monetary)	As Of	Debit	ifrs-full:FinancialAssetsCarryingAmountImmediatelyAfterInitialApplicationOfIFRS9
4492	044403 - Disclosure - Transition disclosures - Balance sheet movement - Assets, impact of transition to IFRS 9 and IFRS 15 (Narrative) (Details)	Network	*	*	http://www.barclays.co.uk/role/TransitionDisclosuresBalanceSheetMovementAssetsImpactOfTransitionToIFRS9AndIFRS15NarrativeDetails
4493	Disclosure of reconciliation of changes in loss allowance and explanation of changes in gross carrying amount for financial instruments [table]	Table	*	*	ifrs-full:DisclosureOfReconciliationOfChangesInLossAllowanceAndExplanationOfChangesInGrossCarryingAmountForFinancialInstrumentsTable
4494	Categories of financial assets [axis]	Axis			ifrs-full:CategoriesOfFinancialAssetsAxis
4495	Financial assets, category [member]	Member			ifrs-full:FinancialAssetsCategoryMember
4496	Financial assets at fair value through the income statement [member]	Member			ifrs-full:FinancialAssetsAtFairValueThroughProfitOrLossCategoryMember
4497	Financial assets mandatory at fair value [member]	Member			ifrs-full:FinancialAssetsAtFairValueThroughProfitOrLossMandatorilyMeasuredAtFairValueCategoryMember
4498	Financial assets designated at fair value [member]	Member			ifrs-full:FinancialAssetsAtFairValueThroughProfitOrLossDesignatedUponInitialRecognitionCategoryMember
4499	Consolidated Entities [Axis]	Axis			srt:ConsolidatedEntitiesAxis
4500	Consolidated Entities [Domain]	Member			srt:ConsolidatedEntitiesDomain
4501	Barclays Bank Group [member]	Member			c070:BarclaysBankGroupMember
4502	Disclosure of reconciliation of changes in loss allowance and explanation of changes in gross carrying amount for financial instruments [line items]	LineItems			ifrs-full:DisclosureOfReconciliationOfChangesInLossAllowanceAndExplanationOfChangesInGrossCarryingAmountForFinancialInstrumentsLineItems
4503	Financial assets at fair value through the income statement	Concept (Monetary)	As Of	Debit	ifrs-full:FinancialAssetsAtFairValueThroughProfitOrLoss
4504	044404 - Disclosure - Transition disclosures - Balance sheet movement - Liabilities and Equity, impact of transition to IFRS 9 and IFRS 15 (Details)	Network	*	*	http://www.barclays.co.uk/role/TransitionDisclosuresBalanceSheetMovementLiabilitiesAndEquityImpactOfTransitionToIFRS9AndIFRS15Details
4505	Disclosure of financial liabilities at date of initial application of IFRS 9 [table]	Table	*	*	ifrs-full:DisclosureOfFinancialLiabilitiesAtDateOfInitialApplicationOfIFRS9Table
4506	Retrospective application and retrospective restatement [axis]	Axis			ifrs-full:RetrospectiveApplicationAndRetrospectiveRestatementAxis
4507	Currently stated [member]	Member			ifrs-full:RestatedMember
4508	Published IAS 39 [member]	Member			ifrs-full:PreviouslyStatedMember
4509	Balance sheet presentation changes [member]	Member			ifrs-full:IncreaseDecreaseDueToVoluntaryChangesInAccountingPolicyMember
4510	IFRSs 9 [member]	Member			c070:IFRSs9Member
4511	Increase (decrease) due to changes in accounting policy required by IFRSs [member]	Member			ifrs-full:IncreaseDecreaseDueToChangesInAccountingPolicyRequiredByIFRSsMember
4512	IFRSs 15 impact [member]	Member			ifrs-full:IncreaseDecreaseDueToApplicationOfIFRS15Member
4513	IFRS 9 classification and measurement [member]	Member			c070:Ifrs9ClassificationAndMeasurementMember
4514	Classes of liabilities [axis]	Axis			ifrs-full:ClassesOfLiabilitiesAxis
4515	Liabilities [member]	Member			ifrs-full:LiabilitiesMember
4516	Deposits at amortised cost [member]	Member			c070:DepositsAtAmortisedCostMember
4517	Deposits from banks [member]	Member			c070:DepositsFromBanksMember
4518	Items in the course of collection from other banks [member]	Member			c070:ItemsInTheCourseOfCollectionFromOtherBanksMember
4519	Customer accounts [member]	Member			c070:CustomerAccountsMember
4520	Cash collateral and settlement balances [member]	Member			c070:TradePayablesMember
4521	Repurchase agreements and other similar secured borrowing [member]	Member			c070:RepurchaseAgreementsAndOtherSimilarSecuredBorrowingMember
4522	Debt securities in issue [member]	Member			c070:DebtSecuritiesInIssueMember
4523	Subordinated liabilities [member]	Member			c070:SubordinatedLiabilitiesMember
4524	Derivatives [member]	Member			ifrs-full:DerivativesMember
4525	Current tax liabilities [member]	Member			c070:CurrentTaxLiabilitiesMember
4526	Deferred tax liabilities [member]	Member			c070:DeferredTaxLiabilitiesMember
4527	Retirement benefit liabilities [member]	Member			c070:RetirementBenefitLiabilitiesMember
4528	Accruals, deferred income and other liabilities [member]	Member			c070:AccrualsDeferredIncomeAndOtherLiabilitiesMember
4529	Other liabilities [member]	Member			c070:OtherLiabilitiesMember
4530	Provisions [member]	Member			ifrs-full:OtherProvisionsMember
4531	Categories of financial liabilities [axis]	Axis			ifrs-full:CategoriesOfFinancialLiabilitiesAxis
4532	Financial liabilities, category [member]	Member			ifrs-full:FinancialLiabilitiesCategoryMember
4533	Trading portfolio liabilities [member]	Member			ifrs-full:FinancialLiabilitiesAtFairValueThroughProfitOrLossThatMeetDefinitionOfHeldForTradingCategoryMember
4534	Financial liabilities designated at fair value [member]	Member			ifrs-full:FinancialLiabilitiesAtFairValueThroughProfitOrLossDesignatedUponInitialRecognitionCategoryMember
4535	Classes of financial liabilities [axis]	Axis			ifrs-full:ClassesOfFinancialLiabilitiesAxis
4536	Financial liabilities, class [member]	Member			ifrs-full:FinancialLiabilitiesMember
4537	Financial liabilities at amortised cost [member]	Member			ifrs-full:FinancialLiabilitiesAtAmortisedCostMember
4538	Deposits at amortised cost [member]	Member			c070:DepositsAtAmortisedCostMember
4539	Components of equity [axis]	Axis			ifrs-full:ComponentsOfEquityAxis
4540	Equity [member]	Member			ifrs-full:EquityMember
4541	Called up share capital and share premium [member]	Member			c070:IssuedCapitalAndSharePremiumMember
4542	Other reserves [member]	Member			ifrs-full:OtherReservesMember
4543	Other equity instruments [member]	Member			ifrs-full:OtherEquityInterestMember
4544	Retained earnings [member]	Member			ifrs-full:RetainedEarningsMember
4545	Total equity excluding non-controlling interests [member]	Member			ifrs-full:EquityAttributableToOwnersOfParentMember
4546	Non-controlling interests [member]	Member			ifrs-full:NoncontrollingInterestsMember
4547	Consolidated Entities [Axis]	Axis			srt:ConsolidatedEntitiesAxis
4548	Consolidated Entities [Domain]	Member			srt:ConsolidatedEntitiesDomain
4549	Barclays Bank Group [member]	Member			c070:BarclaysBankGroupMember
4550	Disclosure of financial liabilities at date of initial application of IFRS 9 [line items]	LineItems			ifrs-full:DisclosureOfFinancialLiabilitiesAtDateOfInitialApplicationOfIFRS9LineItems
4551	Liabilities	Abstract			ifrs-full:LiabilitiesAbstract
4552	IAS 39 measurement category, liabilities	Concept (Text/String)	For Period		ifrs-full:FinancialLiabilitiesMeasurementCategoryImmediatelyBeforeInitialApplicationOfIFRS9
4553	IFRS9 measurement category, liabilities	Concept (Text/String)	For Period		ifrs-full:FinancialLiabilitiesMeasurementCategoryImmediatelyAfterInitialApplicationOfIFRS9
4554	Opening balance, IAS 39 carrying amount	Concept (Monetary)	As Of	Credit	ifrs-full:FinancialLiabilitiesCarryingAmountImmediatelyBeforeInitialApplicationOfIFRS9
4555	Amount of reclassifications or changes in presentation, liabilities	Concept (Monetary)	For Period	Credit	c070:AmountOfReclassificationsOrChangesInPresentationLiabilities
4556	IFRS 9 impairment change	Concept (Monetary)	As Of	Credit	ifrs-full:IncreaseDecreaseInFinancialLiabilitiesArisingFromChangeInMeasurementAttributeFirstApplicationOfIFRS9
4557	Total, IFRS 9 carrying amount	Concept (Monetary)	As Of	Credit	ifrs-full:FinancialLiabilitiesCarryingAmountImmediatelyAfterInitialApplicationOfIFRS9
4558	Equity	Abstract			ifrs-full:EquityAbstract
4559	Opening balance, IAS 39 carrying amount	Concept (Monetary)	As Of	Credit	c070:EquityCarryingAmountImmediatelyBeforeInitialApplicationOfIfrs9
4560	Amount of reclassifications or changes in presentation, equity	Concept (Monetary)	For Period	Credit	c070:AmountOfReclassificationsOrChangesInPresentationEquity
4561	IFRS 9 impairment change	Concept (Monetary)	As Of	Credit	c070:IncreaseDecreaseInEquityArisingFromChangeInMeasurementAttributeInitialApplicationOfIfrs9
4562	Total, IFRS 9 carrying amount	Concept (Monetary)	As Of	Credit	c070:EquityCarryingAmountImmediatelyAfterInitialApplicationOfIfrs9
4563	Liabilities and Equity	Abstract			ifrs-full:EquityAndLiabilitiesAbstract
4564	Opening balance, IAS 39 carrying amount	Concept (Monetary)	As Of	Credit	c070:LiabilitiesAndEquityCarryingAmountImmediatelyBeforeInitialApplicationOfIfrs9
4565	Amount of reclassifications or changes in presentation, equity and liabilities	Concept (Monetary)	For Period	Credit	c070:AmountOfReclassificationsOrChangesInPresentationEquityAndLiabilities
4566	IFRS 9 impairment change	Concept (Monetary)	As Of	Credit	c070:IncreaseDecreaseInLiabilitiesAndEquityArisingFromChangeInMeasurementAttributeInitialApplicationOfIfrs9
4567	Total, IFRS 9 carrying amount	Concept (Monetary)	As Of	Credit	c070:LiabilitiesAndEquityCarryingAmountImmediatelyAfterInitialApplicationOfIfrs9
4568	044405 - Disclosure - Transition disclosures - Classification and measurement detail - Financial assets (Details)	Network	*	*	http://www.barclays.co.uk/role/TransitionDisclosuresClassificationAndMeasurementDetailFinancialAssetsDetails
4569	Disclosure of reclassifications or changes in presentation [table]	Table	*	*	ifrs-full:DisclosureOfReclassificationsOrChangesInPresentationTable
4570	Categories of financial assets [axis]	Axis			ifrs-full:CategoriesOfFinancialAssetsAxis
4571	Financial assets, category [member]	Member			ifrs-full:FinancialAssetsCategoryMember
4572	Financial Investments [member]	Member			c070:FinancialInvestmentsMember
4573	Available for sale investments [member]	Member			ifrs-full:FinancialAssetsAvailableforsaleCategoryMember
4574	Financial investments (held to maturity) [member]	Member			ifrs-full:HeldtomaturityInvestmentsCategoryMember
4575	Loans and advances [member]	Member			ifrs-full:LoansAndReceivablesCategoryMember
4576	Financial assets at fair value through the income statement [member]	Member			ifrs-full:FinancialAssetsAtFairValueThroughProfitOrLossCategoryMember
4577	Financial assets designated at fair value [member]	Member			ifrs-full:FinancialAssetsAtFairValueThroughProfitOrLossDesignatedUponInitialRecognitionCategoryMember
4578	Financial assets mandatory at fair value [member]	Member			ifrs-full:FinancialAssetsAtFairValueThroughProfitOrLossMandatorilyMeasuredAtFairValueCategoryMember
4579	Trading portfolio assets [member]	Member			ifrs-full:FinancialAssetsAtFairValueThroughProfitOrLossClassifiedAsHeldForTradingCategoryMember
4580	Financial assets at fair value through other comprehensive income [member]	Member			ifrs-full:FinancialAssetsAtFairValueThroughOtherComprehensiveIncomeCategoryMember
4581	Classes of financial assets [axis]	Axis			ifrs-full:ClassesOfFinancialAssetsAxis
4582	Financial assets, class [member]	Member			ifrs-full:FinancialAssetsMember
4583	Financial assets at amortised cost [member]	Member			ifrs-full:FinancialAssetsAtAmortisedCostMember
4584	Financial assets at fair value [member]	Member			ifrs-full:FinancialAssetsAtFairValueMember
4585	Classes of assets [axis]	Axis			ifrs-full:ClassesOfAssetsAxis
4586	Assets [member]	Member			ifrs-full:ClassesOfAssetsMember
4587	Reverse repurchase agreements [member]	Member			c070:ReverseRepurchaseAgreementsMember
4588	Cash collateral and settlement balances [member]	Member			ifrs-full:TradeReceivablesMember
4589	Other assets [member]	Member			ifrs-full:OtherAssetsMember
4590	Retrospective application and retrospective restatement [axis]	Axis			ifrs-full:RetrospectiveApplicationAndRetrospectiveRestatementAxis
4591	Currently stated [member]	Member			ifrs-full:RestatedMember
4592	Increase (decrease) due to changes in accounting policy [member]	Member			ifrs-full:FinancialEffectOfChangesInAccountingPolicyMember
4593	Balance sheet presentation changes [member]	Member			ifrs-full:IncreaseDecreaseDueToVoluntaryChangesInAccountingPolicyMember
4594	IFRSs 9 [member]	Member			c070:IFRSs9Member
4595	Increase (decrease) due to changes in accounting policy required by IFRSs [member]	Member			ifrs-full:IncreaseDecreaseDueToChangesInAccountingPolicyRequiredByIFRSsMember
4596	IFRSs 15 impact [member]	Member			ifrs-full:IncreaseDecreaseDueToApplicationOfIFRS15Member
4597	IFRS 9 classification and measurement [member]	Member			c070:Ifrs9ClassificationAndMeasurementMember
4598	Classification [member]	Member			c070:ClassificationMember
4599	Measurement [member]	Member			c070:MeasurementMember
4600	Consolidated Entities [Axis]	Axis			srt:ConsolidatedEntitiesAxis
4601	Consolidated Entities [Domain]	Member			srt:ConsolidatedEntitiesDomain
4602	Barclays Bank Group [member]	Member			c070:BarclaysBankGroupMember
4603	Disclosure of reclassifications or changes in presentation [line items]	LineItems			ifrs-full:DisclosureOfReclassificationsOrChangesInPresentationLineItems
4604	Disclosure of financial assets at date of initial application of IFRS 9 [abstract]	Abstract			ifrs-full:DisclosureOfFinancialAssetsAtDateOfInitialApplicationOfIFRS9Abstract
4605	Opening balance, IAS 39 carrying amount	Concept (Monetary)	As Of	Debit	ifrs-full:FinancialAssetsCarryingAmountImmediatelyBeforeInitialApplicationOfIFRS9
4606	IFRS 9 presentation changes, classification and measurement	Abstract			c070:Ifrs9PresentationChangesAbstract
4607	Amount of reclassifications or changes in presentation, assets	Concept (Monetary)	For Period	Debit	c070:AmountOfReclassificationsOrChangesInPresentationAssets
4608	Transfer in:	Abstract			c070:TransferInAbstract
4609	To loans and advances at amortised cost	Concept (Monetary)	For Period	Debit	ifrs-full:ReclassificationIntoLoansAndReceivables
4610	To financial assets designated at fair value	Concept (Monetary)	For Period	Debit	c070:ReclassificationIntoFinancialAssetsDesignatedAtFairValue
4611	To financial assets mandatory at fair value	Concept (Monetary)	For Period	Debit	c070:ReclassificationIntoFinancialAssetsMandatoryAtFairValue
4612	To financial assets at fair value through other comprehensive income	Concept (Monetary)	For Period	Debit	c070:ReclassificationOfFinancialAssetsIntoMeasuredAtFairValueThroughOtherComprehensiveIncome
4613	Transfer out:	Abstract			c070:TransferOutAbstract
4614	From loans and advances at amortised cost	Concept (Monetary)	For Period	Credit	ifrs-full:ReclassificationOutOfLoansAndReceivables
4615	From financial assets designated at fair value	Concept (Monetary)	For Period	Credit	c070:ReclassificationOutOfFinancialAssetsDesignatedAtFairValue
4616	From financial assets mandatory at fair value	Concept (Monetary)	For Period	Credit	c070:ReclassificationOutOfFinancialAssetsMandatoryAtFairValue
4617	From available for sale (FV)	Concept (Monetary)	For Period	Credit	ifrs-full:ReclassificationOutOfAvailableforsaleFinancialAssets
4618	From Held to maturity (AC)	Concept (Monetary)	For Period	Credit	ifrs-full:ReclassificationOutOfHeldtomaturityInvestments
4619	IFRS 9 Impairment change	Concept (Monetary)	As Of	Debit	ifrs-full:IncreaseDecreaseInFinancialAssetsArisingFromChangeInMeasurementAttributeFirstApplicationOfIFRS9
4620	Total, IFRS 9 carrying amount	Concept (Monetary)	As Of	Debit	ifrs-full:FinancialAssetsCarryingAmountImmediatelyAfterInitialApplicationOfIFRS9
4621	044406 - Disclosure - Transition disclosures - Classification and measurement detail - Financial liabilities (Details)	Network	*	*	http://www.barclays.co.uk/role/TransitionDisclosuresClassificationAndMeasurementDetailFinancialLiabilitiesDetails
4622	Disclosure of reclassifications or changes in presentation [table]	Table	*	*	ifrs-full:DisclosureOfReclassificationsOrChangesInPresentationTable
4623	Retrospective application and retrospective restatement [axis]	Axis			ifrs-full:RetrospectiveApplicationAndRetrospectiveRestatementAxis
4624	Currently stated [member]	Member			ifrs-full:RestatedMember
4625	Increase (decrease) due to changes in accounting policy [member]	Member			ifrs-full:FinancialEffectOfChangesInAccountingPolicyMember
4626	Balance sheet presentation changes [member]	Member			ifrs-full:IncreaseDecreaseDueToVoluntaryChangesInAccountingPolicyMember
4627	IFRSs 9 [member]	Member			c070:IFRSs9Member
4628	Increase (decrease) due to changes in accounting policy required by IFRSs [member]	Member			ifrs-full:IncreaseDecreaseDueToChangesInAccountingPolicyRequiredByIFRSsMember
4629	IFRSs 15 impact [member]	Member			ifrs-full:IncreaseDecreaseDueToApplicationOfIFRS15Member
4630	IFRS 9 classification and measurement [member]	Member			c070:Ifrs9ClassificationAndMeasurementMember
4631	Classification [member]	Member			c070:ClassificationMember
4632	Measurement [member]	Member			c070:MeasurementMember
4633	Categories of financial liabilities [axis]	Axis			ifrs-full:CategoriesOfFinancialLiabilitiesAxis
4634	Financial liabilities, category [member]	Member			ifrs-full:FinancialLiabilitiesCategoryMember
4635	Financial liabilities designated at fair value [member]	Member			ifrs-full:FinancialLiabilitiesAtFairValueThroughProfitOrLossDesignatedUponInitialRecognitionCategoryMember
4636	Classes of financial liabilities [axis]	Axis			ifrs-full:ClassesOfFinancialLiabilitiesAxis
4637	Financial liabilities, class [member]	Member			ifrs-full:FinancialLiabilitiesMember
4638	Financial liabilities at amortised cost [member]	Member			ifrs-full:FinancialLiabilitiesAtAmortisedCostMember
4639	Classes of liabilities [axis]	Axis			ifrs-full:ClassesOfLiabilitiesAxis
4640	Liabilities [member]	Member			ifrs-full:LiabilitiesMember
4641	Repurchase agreements and other similar secured borrowing [member]	Member			c070:RepurchaseAgreementsAndOtherSimilarSecuredBorrowingMember
4642	Cash collateral and settlement balances [member]	Member			c070:TradePayablesMember
4643	Deposits at amortised cost [member]	Member			c070:DepositsAtAmortisedCostMember
4644	Consolidated Entities [Axis]	Axis			srt:ConsolidatedEntitiesAxis
4645	Consolidated Entities [Domain]	Member			srt:ConsolidatedEntitiesDomain
4646	Barclays Bank Group [member]	Member			c070:BarclaysBankGroupMember
4647	Disclosure of reclassifications or changes in presentation [line items]	LineItems			ifrs-full:DisclosureOfReclassificationsOrChangesInPresentationLineItems
4648	Disclosure of financial liabilities at date of initial application of IFRS 9 [abstract]	Abstract			ifrs-full:DisclosureOfFinancialLiabilitiesAtDateOfInitialApplicationOfIFRS9Abstract
4649	Opening balance, IAS 39 carrying amount	Concept (Monetary)	As Of	Credit	ifrs-full:FinancialLiabilitiesCarryingAmountImmediatelyBeforeInitialApplicationOfIFRS9
4650	Amount of reclassifications or changes in presentation, liabilities	Concept (Monetary)	For Period	Credit	c070:AmountOfReclassificationsOrChangesInPresentationLiabilities
4651	IFRS 9 impairment change	Concept (Monetary)	As Of	Credit	ifrs-full:IncreaseDecreaseInFinancialLiabilitiesArisingFromChangeInMeasurementAttributeFirstApplicationOfIFRS9
4652	Total, IFRS 9 carrying amount	Concept (Monetary)	As Of	Credit	ifrs-full:FinancialLiabilitiesCarryingAmountImmediatelyAfterInitialApplicationOfIFRS9
4653	044407 - Disclosure - Transition disclosures - Classification and measurement detail - Equity (Details)	Network	*	*	http://www.barclays.co.uk/role/TransitionDisclosuresClassificationAndMeasurementDetailEquityDetails
4654	Disclosure of reconciliation of changes in loss allowance and explanation of changes in gross carrying amount for financial instruments [table]	Table	*	*	ifrs-full:DisclosureOfReconciliationOfChangesInLossAllowanceAndExplanationOfChangesInGrossCarryingAmountForFinancialInstrumentsTable
4655	Retrospective application and retrospective restatement [axis]	Axis			ifrs-full:RetrospectiveApplicationAndRetrospectiveRestatementAxis
4656	Currently stated [member]	Member			ifrs-full:RestatedMember
4657	Increase (decrease) due to changes in accounting policy [member]	Member			ifrs-full:FinancialEffectOfChangesInAccountingPolicyMember
4658	Balance sheet presentation changes [member]	Member			ifrs-full:IncreaseDecreaseDueToVoluntaryChangesInAccountingPolicyMember
4659	IFRSs 9 [member]	Member			c070:IFRSs9Member
4660	Increase (decrease) due to changes in accounting policy required by IFRSs [member]	Member			ifrs-full:IncreaseDecreaseDueToChangesInAccountingPolicyRequiredByIFRSsMember
4661	IFRSs 15 impact [member]	Member			ifrs-full:IncreaseDecreaseDueToApplicationOfIFRS15Member
4662	IFRS 9 classification and measurement [member]	Member			c070:Ifrs9ClassificationAndMeasurementMember
4663	Classification [member]	Member			c070:ClassificationMember
4664	Measurement [member]	Member			c070:MeasurementMember
4665	Components of equity [axis]	Axis			ifrs-full:ComponentsOfEquityAxis
4666	Equity [member]	Member			ifrs-full:EquityMember
4667	Total equity excluding non-controlling interests [member]	Member			ifrs-full:EquityAttributableToOwnersOfParentMember
4668	Other reserves [member]	Member			ifrs-full:OtherReservesMember
4669	Retained earnings [member]	Member			ifrs-full:RetainedEarningsMember
4670	Fair value through other comprehensive income reserve [member]	Member			ifrs-full:ReserveOfGainsAndLossesOnFinancialAssetsMeasuredAtFairValueThroughOtherComprehensiveIncomeMember
4671	Consolidated Entities [Axis]	Axis			srt:ConsolidatedEntitiesAxis
4672	Consolidated Entities [Domain]	Member			srt:ConsolidatedEntitiesDomain
4673	Barclays Bank Group [member]	Member			c070:BarclaysBankGroupMember
4674	Disclosure of reconciliation of changes in loss allowance and explanation of changes in gross carrying amount for financial instruments [line items]	LineItems			ifrs-full:DisclosureOfReconciliationOfChangesInLossAllowanceAndExplanationOfChangesInGrossCarryingAmountForFinancialInstrumentsLineItems
4675	Equity	Abstract			ifrs-full:EquityAbstract
4676	Opening balance, IAS 39 carrying amount	Concept (Monetary)	As Of	Credit	c070:EquityCarryingAmountImmediatelyBeforeInitialApplicationOfIfrs9
4677	Amount of reclassifications or changes in presentation, equity	Concept (Monetary)	For Period	Credit	c070:AmountOfReclassificationsOrChangesInPresentationEquity
4678	IFRS 9 impairment change	Concept (Monetary)	As Of	Credit	c070:IncreaseDecreaseInEquityArisingFromChangeInMeasurementAttributeInitialApplicationOfIfrs9
4679	Total, IFRS 9 carrying amount	Concept (Monetary)	As Of	Credit	c070:EquityCarryingAmountImmediatelyAfterInitialApplicationOfIfrs9
4680	044408 - Disclosure - Transition disclosures - Effects of the reclassification of financial assets and financial liabilities from IAS 39 categories into the amortised cost category under IFRS 9 (Details)	Network	*	*	http://www.barclays.co.uk/role/TransitionDisclosuresEffectsOfTheReclassificationOfFinancialAssetsAndFinancialLiabilitiesFromIAS39CategoriesIntoTheAmortisedCostCategoryUnderIFRS9Details
4681	Disclosure of financial assets at date of initial application of IFRS 9 [table]	Table	*	*	ifrs-full:DisclosureOfFinancialAssetsAtDateOfInitialApplicationOfIFRS9Table
4682	Categories of financial assets [axis]	Axis			ifrs-full:CategoriesOfFinancialAssetsAxis
4683	Financial assets, category [member]	Member			ifrs-full:FinancialAssetsCategoryMember
4684	From available for sale financial assets under IAS 39 [member]	Member			ifrs-full:FinancialAssetsAvailableforsaleCategoryMember
4685	From financial assets at fair value through the income statement under IAS 39 [member]	Member			ifrs-full:FinancialAssetsAtFairValueThroughProfitOrLossCategoryMember
4686	Consolidated Entities [Axis]	Axis			srt:ConsolidatedEntitiesAxis
4687	Consolidated Entities [Domain]	Member			srt:ConsolidatedEntitiesDomain
4688	Barclays Bank Group [member]	Member			c070:BarclaysBankGroupMember
4689	Disclosure of financial assets at date of initial application of IFRS 9 [line items]	LineItems			ifrs-full:DisclosureOfFinancialAssetsAtDateOfInitialApplicationOfIFRS9LineItems
4690	Disclosure of financial assets at date of initial application of IFRS 9 [abstract]	Abstract			ifrs-full:DisclosureOfFinancialAssetsAtDateOfInitialApplicationOfIFRS9Abstract
4691	Fair value	Concept (Monetary)	As Of	Debit	ifrs-full:FairValueOfFinancialAssetsReclassifiedAsMeasuredAtAmortisedCostFirstApplicationOfIFRS9
4692	Fair value gain/(loss) that would have been recognised for the year ended 31 December 2018 in other comprehensive income if the financial assets had not been reclassified	Concept (Monetary)	For Period	Credit	ifrs-full:FairValueGainLossThatWouldHaveBeenRecognisedInProfitOrLossOrOtherComprehensiveIncomeIfFinancialAssetsHadNotBeenReclassifiedFirstApplicationOfIFRS9
4693	Effective interest rate determined on the date of initial application	Concept (Percent)	As Of		ifrs-full:EffectiveInterestRateDeterminedOnDateOfReclassificationOfFinancialAssetsFirstApplicationOfIFRS9
4694	Interest expense recognised for the year ended 31 December 2018	Concept (Monetary)	For Period	Credit	ifrs-full:InterestIncomeExpenseRecognisedForFinancialAssetsReclassifiedIntoMeasuredAtAmortisedCostFirstApplicationOfIFRS9
4695	044410 - Disclosure - Transition disclosures (Narrative) (Details)	Network	*	*	http://www.barclays.co.uk/role/TransitionDisclosuresNarrativeDetails
4696	Disclosure of reconciliation of changes in loss allowance and explanation of changes in gross carrying amount for financial instruments [table]	Table	*	*	ifrs-full:DisclosureOfReconciliationOfChangesInLossAllowanceAndExplanationOfChangesInGrossCarryingAmountForFinancialInstrumentsTable
4697	Retrospective application and retrospective restatement [axis]	Axis			ifrs-full:RetrospectiveApplicationAndRetrospectiveRestatementAxis
4698	Currently stated [member]	Member			ifrs-full:RestatedMember
4699	Published IAS 39 [member]	Member			ifrs-full:PreviouslyStatedMember
4700	Increase (decrease) due to changes in accounting policy [member]	Member			ifrs-full:FinancialEffectOfChangesInAccountingPolicyMember
4701	Balance sheet presentation changes [member]	Member			ifrs-full:IncreaseDecreaseDueToVoluntaryChangesInAccountingPolicyMember
4702	IFRSs 9 [member]	Member			c070:IFRSs9Member
4703	Increase (decrease) due to changes in accounting policy required by IFRSs [member]	Member			ifrs-full:IncreaseDecreaseDueToChangesInAccountingPolicyRequiredByIFRSsMember
4704	IFRSs 15 impact [member]	Member			ifrs-full:IncreaseDecreaseDueToApplicationOfIFRS15Member
4705	IFRS 9 classification and measurement [member]	Member			c070:Ifrs9ClassificationAndMeasurementMember
4706	Classification [member]	Member			c070:ClassificationMember
4707	Measurement [member]	Member			c070:MeasurementMember
4708	Categories of financial assets [axis]	Axis			ifrs-full:CategoriesOfFinancialAssetsAxis
4709	Financial assets, category [member]	Member			ifrs-full:FinancialAssetsCategoryMember
4710	Financial Investments [member]	Member			c070:FinancialInvestmentsMember
4711	Available for sale investments [member]	Member			ifrs-full:FinancialAssetsAvailableforsaleCategoryMember
4712	Financial investments (held to maturity) [member]	Member			ifrs-full:HeldtomaturityInvestmentsCategoryMember
4713	Loans and advances [member]	Member			ifrs-full:LoansAndReceivablesCategoryMember
4714	Financial assets at fair value through the income statement [member]	Member			ifrs-full:FinancialAssetsAtFairValueThroughProfitOrLossCategoryMember
4715	Financial assets designated at fair value [member]	Member			ifrs-full:FinancialAssetsAtFairValueThroughProfitOrLossDesignatedUponInitialRecognitionCategoryMember
4716	Financial assets mandatory at fair value [member]	Member			ifrs-full:FinancialAssetsAtFairValueThroughProfitOrLossMandatorilyMeasuredAtFairValueCategoryMember
4717	Trading portfolio assets [member]	Member			ifrs-full:FinancialAssetsAtFairValueThroughProfitOrLossClassifiedAsHeldForTradingCategoryMember
4718	Financial assets at fair value through other comprehensive income [member]	Member			ifrs-full:FinancialAssetsAtFairValueThroughOtherComprehensiveIncomeCategoryMember
4719	Classes of financial assets [axis]	Axis			ifrs-full:ClassesOfFinancialAssetsAxis
4720	Financial assets, class [member]	Member			ifrs-full:FinancialAssetsMember
4721	Financial assets at amortised cost [member]	Member			ifrs-full:FinancialAssetsAtAmortisedCostMember
4722	Financial assets at fair value [member]	Member			ifrs-full:FinancialAssetsAtFairValueMember
4723	Classes of assets [axis]	Axis			ifrs-full:ClassesOfAssetsAxis
4724	Assets [member]	Member			ifrs-full:ClassesOfAssetsMember
4725	Reverse repurchase agreements [member]	Member			c070:ReverseRepurchaseAgreementsMember
4726	Cash collateral and settlement balances [member]	Member			ifrs-full:TradeReceivablesMember
4727	Other assets [member]	Member			ifrs-full:OtherAssetsMember
4728	Trading portfolio assets [member]	Member			ifrs-full:FinancialAssetsAtFairValueThroughProfitOrLossClassifiedAsHeldForTradingCategoryMember
4729	Disposal of assets [member]	Member			ifrs-full:NoncurrentAssetsOrDisposalGroupsClassifiedAsHeldForSaleMember
4730	Categories of financial liabilities [axis]	Axis			ifrs-full:CategoriesOfFinancialLiabilitiesAxis
4731	Financial liabilities, category [member]	Member			ifrs-full:FinancialLiabilitiesCategoryMember
4732	Financial liabilities designated at fair value [member]	Member			ifrs-full:FinancialLiabilitiesAtFairValueThroughProfitOrLossDesignatedUponInitialRecognitionCategoryMember
4733	Classes of financial liabilities [axis]	Axis			ifrs-full:ClassesOfFinancialLiabilitiesAxis
4734	Financial liabilities, class [member]	Member			ifrs-full:FinancialLiabilitiesMember
4735	Financial liabilities at amortised cost [member]	Member			ifrs-full:FinancialLiabilitiesAtAmortisedCostMember
4736	Classes of liabilities [axis]	Axis			ifrs-full:ClassesOfLiabilitiesAxis
4737	Liabilities [member]	Member			ifrs-full:LiabilitiesMember
4738	Repurchase agreements and other similar secured borrowing [member]	Member			c070:RepurchaseAgreementsAndOtherSimilarSecuredBorrowingMember
4739	Cash collateral and settlement balances [member]	Member			c070:TradePayablesMember
4740	Deposits at amortised cost [member]	Member			c070:DepositsAtAmortisedCostMember
4741	Components of equity [axis]	Axis			ifrs-full:ComponentsOfEquityAxis
4742	Equity [member]	Member			ifrs-full:EquityMember
4743	Total equity excluding non-controlling interests [member]	Member			ifrs-full:EquityAttributableToOwnersOfParentMember
4744	Retained earnings [member]	Member			ifrs-full:RetainedEarningsMember
4745	Other reserves [member]	Member			ifrs-full:OtherReservesMember
4746	Consolidated Entities [Axis]	Axis			srt:ConsolidatedEntitiesAxis
4747	Consolidated Entities [Domain]	Member			srt:ConsolidatedEntitiesDomain
4748	Barclays Bank Group [member]	Member			c070:BarclaysBankGroupMember
4749	Disclosure of reconciliation of changes in loss allowance and explanation of changes in gross carrying amount for financial instruments [line items]	LineItems			ifrs-full:DisclosureOfReconciliationOfChangesInLossAllowanceAndExplanationOfChangesInGrossCarryingAmountForFinancialInstrumentsLineItems
4750	Reconciliation of impairment allowance and provisions [abstract]	Abstract			c070:ReconciliationOfImpairmentAllowanceAndProvisionsAbstract
4751	Increase (decrease) in impairment allowance	Concept (Monetary)	For Period	Credit	c070:IncreaseDecreaseInImpairmentAllowance
4752	Impairment and provision	Concept (Monetary)	As Of	Credit	c070:ImpairmentAndProvision
4753	Assets	Abstract			ifrs-full:AssetsAbstract
4754	Opening balance, IAS 39 carrying amount	Concept (Monetary)	As Of	Debit	ifrs-full:FinancialAssetsCarryingAmountImmediatelyBeforeInitialApplicationOfIFRS9
4755	IFRS 9 presentation changes [abstract]	Abstract			c070:Ifrs9PresentationChangesAbstract
4756	Amount of reclassifications or changes in presentation, assets	Concept (Monetary)	For Period	Debit	c070:AmountOfReclassificationsOrChangesInPresentationAssets
4757	Transfer in:	Abstract			c070:TransferInAbstract
4758	To loans and advances at amortised cost	Concept (Monetary)	For Period	Debit	ifrs-full:ReclassificationIntoLoansAndReceivables
4759	To financial assets designated at fair value	Concept (Monetary)	For Period	Debit	c070:ReclassificationIntoFinancialAssetsDesignatedAtFairValue
4760	To financial assets mandatory at fair value	Concept (Monetary)	For Period	Debit	c070:ReclassificationIntoFinancialAssetsMandatoryAtFairValue
4761	To financial assets at fair value through the income statement	Concept (Monetary)	For Period	Debit	ifrs-full:ReclassificationIntoFinancialAssetsAtFairValueThroughProfitOrLoss
4762	To financial assets at fair value through other comprehensive income	Concept (Monetary)	For Period	Debit	c070:ReclassificationOfFinancialAssetsIntoMeasuredAtFairValueThroughOtherComprehensiveIncome
4763	Transfer out:	Abstract			c070:TransferOutAbstract
4764	From loans and advances at amortised cost	Concept (Monetary)	For Period	Credit	ifrs-full:ReclassificationOutOfLoansAndReceivables
4765	From financial assets designated at fair value	Concept (Monetary)	For Period	Credit	c070:ReclassificationOutOfFinancialAssetsDesignatedAtFairValue
4766	From financial assets mandatory at fair value	Concept (Monetary)	For Period	Credit	c070:ReclassificationOutOfFinancialAssetsMandatoryAtFairValue
4767	From financial assets at fair value through the income statement	Concept (Monetary)	For Period	Credit	ifrs-full:ReclassificationOutOfFinancialAssetsAtFairValueThroughProfitOrLoss
4768	From available for sale (FV)	Concept (Monetary)	For Period	Credit	ifrs-full:ReclassificationOutOfAvailableforsaleFinancialAssets
4769	From Held to maturity (AC)	Concept (Monetary)	For Period	Credit	ifrs-full:ReclassificationOutOfHeldtomaturityInvestments
4770	IFRS 9 Impairment change	Concept (Monetary)	As Of	Debit	ifrs-full:IncreaseDecreaseInFinancialAssetsArisingFromChangeInMeasurementAttributeFirstApplicationOfIFRS9
4771	Total, IFRS 9 carrying amount	Concept (Monetary)	As Of	Debit	ifrs-full:FinancialAssetsCarryingAmountImmediatelyAfterInitialApplicationOfIFRS9
4772	Liabilities	Abstract			ifrs-full:LiabilitiesAbstract
4773	Opening balance, IAS 39 carrying amount	Concept (Monetary)	As Of	Credit	ifrs-full:FinancialLiabilitiesCarryingAmountImmediatelyBeforeInitialApplicationOfIFRS9
4774	Amount of reclassifications or changes in presentation, liabilities	Concept (Monetary)	For Period	Credit	c070:AmountOfReclassificationsOrChangesInPresentationLiabilities
4775	IFRS 9 impairment change	Concept (Monetary)	As Of	Credit	ifrs-full:IncreaseDecreaseInFinancialLiabilitiesArisingFromChangeInMeasurementAttributeFirstApplicationOfIFRS9
4776	Total, IFRS 9 carrying amount	Concept (Monetary)	As Of	Credit	ifrs-full:FinancialLiabilitiesCarryingAmountImmediatelyAfterInitialApplicationOfIFRS9
4777	Equity	Abstract			ifrs-full:EquityAbstract
4778	Opening balance, IAS 39 carrying amount	Concept (Monetary)	As Of	Credit	c070:EquityCarryingAmountImmediatelyBeforeInitialApplicationOfIfrs9
4779	Amount of reclassifications or changes in presentation, equity	Concept (Monetary)	For Period	Credit	c070:AmountOfReclassificationsOrChangesInPresentationEquity
4780	IFRS 9 impairment change	Concept (Monetary)	As Of	Credit	c070:IncreaseDecreaseInEquityArisingFromChangeInMeasurementAttributeInitialApplicationOfIfrs9
4781	Total, IFRS 9 carrying amount	Concept (Monetary)	As Of	Credit	c070:EquityCarryingAmountImmediatelyAfterInitialApplicationOfIfrs9
4782	Fair value of financial assets reclassified as measured at amortised cost, initial application of IFRS 9	Concept (Monetary)	As Of	Debit	ifrs-full:FairValueOfFinancialAssetsReclassifiedAsMeasuredAtAmortisedCostFirstApplicationOfIFRS9
4783	Fair value gain/(loss) that would have been recognised for the year ended 31 December 2018 in other comprehensive income if the financial assets had not been reclassified	Concept (Monetary)	For Period	Credit	ifrs-full:FairValueGainLossThatWouldHaveBeenRecognisedInProfitOrLossOrOtherComprehensiveIncomeIfFinancialAssetsHadNotBeenReclassifiedFirstApplicationOfIFRS9
4784	044700 - Disclosure - Other disclosures - Risk Management and Principal Risks - Maximum exposure and effects of collateral and other credit enhancements (audited) (Details)	Network	*	*	http://www.barclays.co.uk/role/OtherDisclosuresRiskManagementAndPrincipalRisksMaximumExposureAndEffectsOfCollateralAndOtherCreditEnhancementsauditedDetails
4785	Disclosure of nature and extent of risks arising from financial instruments [table]	Table	*	*	ifrs-full:DisclosureOfNatureAndExtentOfRisksArisingFromFinancialInstrumentsTable
4786	Classes of financial instruments [axis]	Axis			ifrs-full:ClassesOfFinancialInstrumentsAxis
4787	Financial instruments, class [member]	Member			ifrs-full:ClassesOfFinancialInstrumentsMember
4788	Debt securities [member]	Member			ifrs-full:DebtSecuritiesMember
4789	Loan commitments [member]	Member			ifrs-full:LoanCommitmentsMember
4790	Classes of financial assets [axis]	Axis			ifrs-full:ClassesOfFinancialAssetsAxis
4791	Financial assets, class [member]	Member			ifrs-full:FinancialAssetsMember
4792	Reverse repurchase agreements [member]	Member			c070:ReverseRepurchaseAgreementsMember
4793	Other financial assets [member]	Member			c070:OtherFinancialAssetsMember
4794	Derivative financial instruments [member]	Member			ifrs-full:DerivativesMember
4795	Traded loans [member]	Member			c070:TradedLoansMember
4796	Loans and advances [member]	Member			ifrs-full:LoansAndReceivablesCategoryMember
4797	Home loans [member]	Member			ifrs-full:MortgagesMember
4798	Credit cards, unsecured and other retail lending [member]	Member			c070:CreditCardsUnsecuredAndOtherRetailLendingMember
4799	Corporate loans [member]	Member			ifrs-full:CorporateLoansMember
4800	Categories of financial assets [axis]	Axis			ifrs-full:CategoriesOfFinancialAssetsAxis
4801	Financial assets, category [member]	Member			ifrs-full:FinancialAssetsCategoryMember
4802	Financial assets at amortised cost [member]	Member			ifrs-full:FinancialAssetsAtAmortisedCostCategoryMember
4803	Financial assets at fair value through the income statement [member]	Member			ifrs-full:FinancialAssetsAtFairValueThroughProfitOrLossCategoryMember
4804	Financial assets at fair value through other comprehensive income [member]	Member			ifrs-full:FinancialAssetsAtFairValueThroughOtherComprehensiveIncomeCategoryMember
4805	Trading portfolio assets [member]	Member			ifrs-full:FinancialAssetsAtFairValueThroughProfitOrLossClassifiedAsHeldForTradingCategoryMember
4806	Classes of assets [axis]	Axis			ifrs-full:ClassesOfAssetsAxis
4807	Assets [member]	Member			ifrs-full:ClassesOfAssetsMember
4808	On-balance sheet [member]	Member			c070:OnBalanceSheetAssetsMember
4809	Cash and balances at central banks [member]	Member			c070:CashAndBankBalancesAtCentralBanksMember
4810	Cash collateral and settlement balances [member]	Member			ifrs-full:TradeReceivablesMember
4811	Reverse repurchase agreements and other similar secured lending [member]	Member			c070:ReverseRepurchaseAgreementsAndOtherSimilarSecuredLendingMember
4812	Other assets [member]	Member			ifrs-full:OtherAssetsMember
4813	Off-balance sheet [member]	Member			c070:OffBalanceSheetAssetsMember
4814	Classes of contingent liabilities [axis]	Axis			ifrs-full:ClassesOfContingentLiabilitiesAxis
4815	Contingent liabilities [member]	Member			ifrs-full:ContingentLiabilitiesMember
4816	Contingent liabilities [member]	Member			ifrs-full:ItemsOfContingentLiabilitiesMember
4817	Types of risks [axis]	Axis			ifrs-full:TypesOfRisksAxis
4818	Risks [member]	Member			ifrs-full:TypesOfRisksMember
4819	Exposure to credit risk [member]	Member			ifrs-full:CreditRiskMember
4820	Credit impairment of financial instruments [axis]	Axis			ifrs-full:CreditImpairmentOfFinancialInstrumentsAxis
4821	Credit impairment of financial instruments [member]	Member			ifrs-full:CreditImpairmentOfFinancialInstrumentsMember
4822	Credit-impaired [member]	Member			ifrs-full:FinancialInstrumentsCreditimpairedMember
4823	Consolidated Entities [Axis]	Axis			srt:ConsolidatedEntitiesAxis
4824	Consolidated Entities [Domain]	Member			srt:ConsolidatedEntitiesDomain
4825	Barclays Bank Group [member]	Member			c070:BarclaysBankGroupMember
4826	Disclosure of detailed information about financial instruments [line items]	LineItems			ifrs-full:DisclosureOfFinancialInstrumentsLineItems
4827	Maximum Exposure	Concept (Monetary)	As Of	Debit	ifrs-full:NetFinancialAssetsSubjectToOffsettingEnforceableMasterNettingArrangementsOrSimilarAgreements
4828	Netting and set-off	Concept (Monetary)	As Of	Credit	ifrs-full:FinancialInstrumentsSubjectToEnforceableMasterNettingArrangementOrSimilarAgreementNotSetOffAgainstFinancialAssets
4829	Cash collateral	Concept (Monetary)	As Of	Credit	ifrs-full:CashCollateralReceivedSubjectToEnforceableMasterNettingArrangementOrSimilarAgreementNotSetOffAgainstFinancialAssets
4830	Non-cash collateral	Concept (Monetary)	As Of	Credit	c070:NoncashCollateralReceivedSubjectToEnforceableMasterNettingArrangementsOrSimilarAgreementNotSetOffAgainstFinancialAssets
4831	Risk transfer	Concept (Monetary)	As Of	Credit	c070:TransfersExposureToCreditRisk
4832	Net exposure	Concept (Monetary)	As Of	Debit	c070:NetExposureToCreditRisk
4833	044705 - Disclosure - Other disclosures - Risk Management and Principal Risks - Loans and advances at amortised cost by product (audited) (Details)	Network	*	*	http://www.barclays.co.uk/role/OtherDisclosuresRiskManagementAndPrincipalRisksLoansAndAdvancesAtAmortisedCostByProductauditedDetails
4834	Disclosure of financial assets [table]	Table	*	*	ifrs-full:DisclosureOfFinancialAssetsTable
4835	Past due status [axis]	Axis			ifrs-full:PastDueStatusAxis
4836	Past due status [member]	Member			ifrs-full:PastDueStatusMember
4837	Not past due [member]	Member			ifrs-full:CurrentMember
4838	Equal to or Less than 30 days past due [member]	Member			ifrs-full:NotLaterThanOneMonthMember
4839	Greater than 30 days past due [member]	Member			c070:GreaterThanOneMonthPastDueMember
4840	Classes of financial assets [axis]	Axis			ifrs-full:ClassesOfFinancialAssetsAxis
4841	Financial assets, class [member]	Member			ifrs-full:FinancialAssetsMember
4842	Financial assets at amortised cost [member]	Member			ifrs-full:FinancialAssetsAtAmortisedCostMember
4843	Categories of financial assets [axis]	Axis			ifrs-full:CategoriesOfFinancialAssetsAxis
4844	Financial assets, category [member]	Member			ifrs-full:FinancialAssetsCategoryMember
4845	Loans and advances [member]	Member			ifrs-full:LoansAndReceivablesCategoryMember
4846	Home loans [member]	Member			ifrs-full:MortgagesMember
4847	Credit cards, unsecured and other retail lending [member]	Member			c070:CreditCardsUnsecuredAndOtherRetailLendingMember
4848	Loans to corporate entities [member]	Member			ifrs-full:CorporateLoansMember
4849	Type of measurement of expected credit losses [axis]	Axis			ifrs-full:TypeOfMeasurementOfExpectedCreditLossesAxis
4850	Type of measurement of expected credit losses [member]	Member			ifrs-full:TypeOfMeasurementOfExpectedCreditLossesMember
4851	Stage 1 [member]	Member			ifrs-full:TwelvemonthExpectedCreditLossesMember
4852	Lifetime expected credit losses [member]	Member			ifrs-full:LifetimeExpectedCreditLossesMember
4853	Credit impairment of financial instruments [axis]	Axis			ifrs-full:CreditImpairmentOfFinancialInstrumentsAxis
4854	Credit impairment of financial instruments [member]	Member			ifrs-full:CreditImpairmentOfFinancialInstrumentsMember
4855	Stage 2 [member]	Member			ifrs-full:FinancialInstrumentsNotCreditimpairedMember
4856	Credit Impaired - Stage 3 [member]	Member			ifrs-full:FinancialInstrumentsCreditimpairedMember
4857	Carrying amount, accumulated depreciation, amortisation and impairment and gross carrying amount [axis]	Axis			ifrs-full:CarryingAmountAccumulatedDepreciationAmortisationAndImpairmentAndGrossCarryingAmountAxis
4858	Carrying amount [member]	Member			ifrs-full:CarryingAmountMember
4859	Gross exposure [member]	Member			ifrs-full:GrossCarryingAmountMember
4860	Impairment allowance [member]	Member			ifrs-full:AccumulatedImpairmentMember
4861	Consolidated Entities [Axis]	Axis			srt:ConsolidatedEntitiesAxis
4862	Consolidated Entities [Domain]	Member			srt:ConsolidatedEntitiesDomain
4863	Barclays Bank Group [member]	Member			c070:BarclaysBankGroupMember
4864	Disclosure of financial assets [line items]	LineItems			ifrs-full:DisclosureOfFinancialAssetsLineItems
4865	Financial assets	Concept (Monetary)	As Of	Debit	ifrs-full:FinancialAssets
4866	Coverage ratio	Concept (Pure)	As Of		c070:ImpairmentAllowanceCoverageRatio
4867	044706 - Disclosure - Other disclosures - Risk Management and Principal Risks - Loans and advances at amortised cost by product (audited) (Narrative) (Details)	Network	*	*	http://www.barclays.co.uk/role/OtherDisclosuresRiskManagementAndPrincipalRisksLoansAndAdvancesAtAmortisedCostByProductauditedNarrativeDetails
4868	Disclosure of reconciliation of changes in loss allowance and explanation of changes in gross carrying amount for financial instruments [table]	Table	*	*	ifrs-full:DisclosureOfReconciliationOfChangesInLossAllowanceAndExplanationOfChangesInGrossCarryingAmountForFinancialInstrumentsTable
4869	Categories of financial assets [axis]	Axis			ifrs-full:CategoriesOfFinancialAssetsAxis
4870	Financial assets, category [member]	Member			ifrs-full:FinancialAssetsCategoryMember
4871	Off balance sheet loan commitments and financial guarantee contracts [member]	Member			c070:OffBalanceSheetLoanCommitmentsAndFinancialGuaranteeContractsMember
4872	Loans and advances at amortised cost, including off balance sheet loan commitments and financial guarantee contracts [member]	Member			c070:LoansAndAdvancesAtAmortisedCostIncludingOffBalanceSheetLoanCommitmentsAndFinancialGuaranteeContractsMember
4873	Other financial assets subject to impairment [member]	Member			c070:OtherFinancialAssetsSubjectToImpairmentMember
4874	Carrying amount, accumulated depreciation, amortisation and impairment and gross carrying amount [axis]	Axis			ifrs-full:CarryingAmountAccumulatedDepreciationAmortisationAndImpairmentAndGrossCarryingAmountAxis
4875	Carrying amount [member]	Member			ifrs-full:CarryingAmountMember
4876	Gross exposure [member]	Member			ifrs-full:GrossCarryingAmountMember
4877	Impairment allowance [member]	Member			ifrs-full:AccumulatedImpairmentMember
4878	Classes of financial assets [axis]	Axis			ifrs-full:ClassesOfFinancialAssetsAxis
4879	Financial assets, class [member]	Member			ifrs-full:FinancialAssetsMember
4880	Financial assets at fair value [member]	Member			ifrs-full:FinancialAssetsAtFairValueMember
4881	Financial assets at amortised cost [member]	Member			ifrs-full:FinancialAssetsAtAmortisedCostMember
4882	Consolidated Entities [Axis]	Axis			srt:ConsolidatedEntitiesAxis
4883	Consolidated Entities [Domain]	Member			srt:ConsolidatedEntitiesDomain
4884	Barclays Bank Group [member]	Member			c070:BarclaysBankGroupMember
4885	Type of measurement of expected credit losses [axis]	Axis			ifrs-full:TypeOfMeasurementOfExpectedCreditLossesAxis
4886	Type of measurement of expected credit losses [member]	Member			ifrs-full:TypeOfMeasurementOfExpectedCreditLossesMember
4887	Stage 1 [member]	Member			ifrs-full:TwelvemonthExpectedCreditLossesMember
4888	Lifetime expected credit losses [member]	Member			ifrs-full:LifetimeExpectedCreditLossesMember
4889	Credit impairment of financial instruments [axis]	Axis			ifrs-full:CreditImpairmentOfFinancialInstrumentsAxis
4890	Credit impairment of financial instruments [member]	Member			ifrs-full:CreditImpairmentOfFinancialInstrumentsMember
4891	Stage 2 [member]	Member			ifrs-full:FinancialInstrumentsNotCreditimpairedMember
4892	Disclosure of reconciliation of changes in loss allowance and explanation of changes in gross carrying amount for financial instruments [line items]	LineItems			ifrs-full:DisclosureOfReconciliationOfChangesInLossAllowanceAndExplanationOfChangesInGrossCarryingAmountForFinancialInstrumentsLineItems
4893	Exposure to credit risk on loan commitments and financial guarantee contracts	Concept (Monetary)	As Of	Credit	ifrs-full:ExposureToCreditRiskOnLoanCommitmentsAndFinancialGuaranteeContracts
4894	Financial assets	Concept (Monetary)	As Of	Debit	ifrs-full:FinancialAssets
4895	044707 - Disclosure - Other disclosures - Risk Management and Principal Risks - Gross exposure for loans and advances at amortised cost (audited) (Details)	Network	*	*	http://www.barclays.co.uk/role/OtherDisclosuresRiskManagementAndPrincipalRisksGrossExposureForLoansAndAdvancesAtAmortisedCostauditedDetails
4896	Disclosure of reconciliation of changes in loss allowance and explanation of changes in gross carrying amount for financial instruments [table]	Table	*	*	ifrs-full:DisclosureOfReconciliationOfChangesInLossAllowanceAndExplanationOfChangesInGrossCarryingAmountForFinancialInstrumentsTable
4897	Credit impairment of financial instruments [axis]	Axis			ifrs-full:CreditImpairmentOfFinancialInstrumentsAxis
4898	Credit impairment of financial instruments [member]	Member			ifrs-full:CreditImpairmentOfFinancialInstrumentsMember
4899	Stage 2 [member]	Member			ifrs-full:FinancialInstrumentsNotCreditimpairedMember
4900	Credit Impaired - Stage 3 [member]	Member			ifrs-full:FinancialInstrumentsCreditimpairedMember
4901	Type of measurement of expected credit losses [axis]	Axis			ifrs-full:TypeOfMeasurementOfExpectedCreditLossesAxis
4902	Type of measurement of expected credit losses [member]	Member			ifrs-full:TypeOfMeasurementOfExpectedCreditLossesMember
4903	Stage 1 [member]	Member			ifrs-full:TwelvemonthExpectedCreditLossesMember
4904	Lifetime expected credit losses [member]	Member			ifrs-full:LifetimeExpectedCreditLossesMember
4905	Carrying amount, accumulated depreciation, amortisation and impairment and gross carrying amount [axis]	Axis			ifrs-full:CarryingAmountAccumulatedDepreciationAmortisationAndImpairmentAndGrossCarryingAmountAxis
4906	Carrying amount [member]	Member			ifrs-full:CarryingAmountMember
4907	Gross exposure [member]	Member			ifrs-full:GrossCarryingAmountMember
4908	Categories of financial assets [axis]	Axis			ifrs-full:CategoriesOfFinancialAssetsAxis
4909	Financial assets, category [member]	Member			ifrs-full:FinancialAssetsCategoryMember
4910	Loans and advances [member]	Member			ifrs-full:LoansAndReceivablesCategoryMember
4911	Classes of financial assets [axis]	Axis			ifrs-full:ClassesOfFinancialAssetsAxis
4912	Financial assets, class [member]	Member			ifrs-full:FinancialAssetsMember
4913	Financial assets at amortised cost [member]	Member			ifrs-full:FinancialAssetsAtAmortisedCostMember
4914	Continuing and discontinued operations [axis]	Axis			ifrs-full:ContinuingAndDiscontinuedOperationsAxis
4915	Aggregate continuing and discontinued operations [member]	Member			ifrs-full:AggregateContinuingAndDiscontinuedOperationsMember
4916	Continuing operations [member]	Member			ifrs-full:ContinuingOperationsMember
4917	Discontinued operations [member]	Member			ifrs-full:DiscontinuedOperationsMember
4918	UK Banking Business [member]	Member			c070:BarclaysUkMember
4919	Categories of related parties [axis]	Axis			ifrs-full:CategoriesOfRelatedPartiesAxis
4920	Entity's total for related parties [member]	Member			ifrs-full:EntitysTotalForRelatedPartiesMember
4921	Barclays Bank UK PLC [member]	Member			c070:BarclaysBankUkPlcMember
4922	Disclosure of reconciliation of changes in loss allowance and explanation of changes in gross carrying amount for financial instruments [line items]	LineItems			ifrs-full:DisclosureOfReconciliationOfChangesInLossAllowanceAndExplanationOfChangesInGrossCarryingAmountForFinancialInstrumentsLineItems
4923	Loans and advances at amortised cost	Abstract			ifrs-full:IncreaseDecreaseInFinancialAssetsAbstract
4924	Impairment allowance	Concept (Monetary)	As Of	Credit	ifrs-full:AllowanceAccountForCreditLossesOfFinancialAssets
4925	Disposal of business to Barclays Bank UK PLC	Concept (Monetary)	For Period	Credit	c070:DecreaseThroughDisposalOfBusinessFinancialAssets
4926	Net transfers between stages	Concept (Monetary)	For Period	Debit	ifrs-full:IncreaseDecreaseThroughTransfersFinancialAssets
4927	Business activity in the year	Concept (Monetary)	For Period	Debit	ifrs-full:IncreaseThroughOriginationOrPurchaseFinancialAssets
4928	Net drawdowns and repayments	Concept (Monetary)	For Period	Credit	c070:IncreaseDecreaseFromDrawdownsRepaymentsRiskParameterChangesAndOtherMovementsFinancialAssets
4929	Final repayments	Concept (Monetary)	For Period	Credit	ifrs-full:DecreaseThroughDerecognitionFinancialAssets
4930	Disposals	Concept (Monetary)	For Period	Credit	c070:DecreaseThroughDisposalFinancialAssets
4931	Write-offs	Concept (Monetary)	For Period	Credit	ifrs-full:DecreaseThroughWriteoffFinancialAssets
4932	Impairment allowance	Concept (Monetary)	As Of	Credit	ifrs-full:AllowanceAccountForCreditLossesOfFinancialAssets
4933	044708 - Disclosure - Other disclosures - Risk Management and Principal Risks - Impairment allowance on loans and advances at amortised cost (audited) (Details)	Network	*	*	http://www.barclays.co.uk/role/OtherDisclosuresRiskManagementAndPrincipalRisksImpairmentAllowanceOnLoansAndAdvancesAtAmortisedCostauditedDetails
4934	Disclosure of reconciliation of changes in loss allowance and explanation of changes in gross carrying amount for financial instruments [table]	Table	*	*	ifrs-full:DisclosureOfReconciliationOfChangesInLossAllowanceAndExplanationOfChangesInGrossCarryingAmountForFinancialInstrumentsTable
4935	Credit impairment of financial instruments [axis]	Axis			ifrs-full:CreditImpairmentOfFinancialInstrumentsAxis
4936	Credit impairment of financial instruments [member]	Member			ifrs-full:CreditImpairmentOfFinancialInstrumentsMember
4937	Stage 2 [member]	Member			ifrs-full:FinancialInstrumentsNotCreditimpairedMember
4938	Credit Impaired - Stage 3 [member]	Member			ifrs-full:FinancialInstrumentsCreditimpairedMember
4939	Type of measurement of expected credit losses [axis]	Axis			ifrs-full:TypeOfMeasurementOfExpectedCreditLossesAxis
4940	Type of measurement of expected credit losses [member]	Member			ifrs-full:TypeOfMeasurementOfExpectedCreditLossesMember
4941	Stage 1 [member]	Member			ifrs-full:TwelvemonthExpectedCreditLossesMember
4942	Lifetime expected credit losses [member]	Member			ifrs-full:LifetimeExpectedCreditLossesMember
4943	Carrying amount, accumulated depreciation, amortisation and impairment and gross carrying amount [axis]	Axis			ifrs-full:CarryingAmountAccumulatedDepreciationAmortisationAndImpairmentAndGrossCarryingAmountAxis
4944	Carrying amount [member]	Member			ifrs-full:CarryingAmountMember
4945	Impairment allowance [member]	Member			ifrs-full:AccumulatedImpairmentMember
4946	Continuing and discontinued operations [axis]	Axis			ifrs-full:ContinuingAndDiscontinuedOperationsAxis
4947	Aggregate continuing and discontinued operations [member]	Member			ifrs-full:AggregateContinuingAndDiscontinuedOperationsMember
4948	Continuing operations [member]	Member			ifrs-full:ContinuingOperationsMember
4949	Discontinued operations [member]	Member			ifrs-full:DiscontinuedOperationsMember
4950	UK Banking Business [member]	Member			c070:BarclaysUkMember
4951	Categories of related parties [axis]	Axis			ifrs-full:CategoriesOfRelatedPartiesAxis
4952	Entity's total for related parties [member]	Member			ifrs-full:EntitysTotalForRelatedPartiesMember
4953	Barclays Bank UK PLC [member]	Member			c070:BarclaysBankUkPlcMember
4954	Categories of financial assets [axis]	Axis			ifrs-full:CategoriesOfFinancialAssetsAxis
4955	Financial assets, category [member]	Member			ifrs-full:FinancialAssetsCategoryMember
4956	Loans and advances [member]	Member			ifrs-full:LoansAndReceivablesCategoryMember
4957	Classes of financial assets [axis]	Axis			ifrs-full:ClassesOfFinancialAssetsAxis
4958	Financial assets, class [member]	Member			ifrs-full:FinancialAssetsMember
4959	Financial assets at amortised cost [member]	Member			ifrs-full:FinancialAssetsAtAmortisedCostMember
4960	Other financial assets [member]	Member			c070:OtherFinancialAssetsMember
4961	Classes of financial instruments [axis]	Axis			ifrs-full:ClassesOfFinancialInstrumentsAxis
4962	Financial instruments, class [member]	Member			ifrs-full:ClassesOfFinancialInstrumentsMember
4963	Loan commitments and financial guarantee contracts [member]	Member			c070:OffBalanceSheetLoanCommitmentsAndFinancialGuaranteeContractsMember
4964	Disclosure of reconciliation of changes in loss allowance and explanation of changes in gross carrying amount for financial instruments [line items]	LineItems			ifrs-full:DisclosureOfReconciliationOfChangesInLossAllowanceAndExplanationOfChangesInGrossCarryingAmountForFinancialInstrumentsLineItems
4965	Loans and advances at amortised cost	Abstract			ifrs-full:IncreaseDecreaseInFinancialAssetsAbstract
4966	Impairment allowance	Concept (Monetary)	As Of	Credit	ifrs-full:AllowanceAccountForCreditLossesOfFinancialAssets
4967	Disposal of business to Barclays Bank UK PLC	Concept (Monetary)	For Period	Credit	c070:DecreaseThroughDisposalOfBusinessFinancialAssets
4968	Net transfers between stages	Concept (Monetary)	For Period	Debit	ifrs-full:IncreaseDecreaseThroughTransfersFinancialAssets
4969	Business activity in the year	Concept (Monetary)	For Period	Debit	ifrs-full:IncreaseThroughOriginationOrPurchaseFinancialAssets
4970	Net re-measurement and movement due to exposure and risk parameter changes	Concept (Monetary)	For Period	Credit	c070:IncreaseDecreaseFromDrawdownsRepaymentsRiskParameterChangesAndOtherMovementsFinancialAssets
4971	UK economic uncertainty adjustment	Concept (Monetary)	For Period	Debit	c070:IncreaseDecreaseThroughUnitedKingdomEconomicUncertaintyFinancialAssets
4972	Final repayments	Concept (Monetary)	For Period	Credit	ifrs-full:DecreaseThroughDerecognitionFinancialAssets
4973	Disposals	Concept (Monetary)	For Period	Credit	c070:DecreaseThroughDisposalFinancialAssets
4974	Write-offs	Concept (Monetary)	For Period	Credit	ifrs-full:DecreaseThroughWriteoffFinancialAssets
4975	Impairment allowance	Concept (Monetary)	As Of	Credit	ifrs-full:AllowanceAccountForCreditLossesOfFinancialAssets
4976	Reconciliation of ECL movement to impairment (charge)/release for the period, Loans and advances at amortised cost	Abstract			ifrs-full:DisclosureOfImpairmentLossAndReversalOfImpairmentLossAbstract
4977	ECL movement excluding assets derecognised due to disposals and write-off	Concept (Monetary)	For Period	Credit	ifrs-full:IncreaseDecreaseInAllowanceAccountForCreditLossesOfFinancialAssets
4978	Net recoveries post write-offs	Concept (Monetary)	For Period		ifrs-full:ReversalAllowanceAccountForCreditLossesOfFinancialAssets
4979	Exchange and other adjustments	Concept (Monetary)	For Period	Debit	ifrs-full:IncreaseDecreaseThroughForeignExchangeAndOtherMovementsFinancialAssets
4980	Impairment release on loan commitments and financial guarantees	Concept (Monetary)	For Period	Credit	ifrs-full:ReversalOfImpairmentLossRecognisedInProfitOrLoss
4981	Impairment charge on other financial assets	Concept (Monetary)	For Period	Debit	ifrs-full:ImpairmentLossRecognisedInProfitOrLoss
4982	Income statement charge/(release) for the period	Concept (Monetary)	For Period	Debit	ifrs-full:ImpairmentLossReversalOfImpairmentLossRecognisedInProfitOrLoss
4983	044709 - Disclosure - Other disclosures - Risk Management and Principal Risks - Gross exposure for loan commitment and financial guarantees (audited) (Details)	Network	*	*	http://www.barclays.co.uk/role/OtherDisclosuresRiskManagementAndPrincipalRisksGrossExposureForLoanCommitmentAndFinancialGuaranteesauditedDetails
4984	Disclosure of reconciliation of changes in loss allowance and explanation of changes in gross carrying amount for financial instruments [table]	Table	*	*	ifrs-full:DisclosureOfReconciliationOfChangesInLossAllowanceAndExplanationOfChangesInGrossCarryingAmountForFinancialInstrumentsTable
4985	Credit impairment of financial instruments [axis]	Axis			ifrs-full:CreditImpairmentOfFinancialInstrumentsAxis
4986	Credit impairment of financial instruments [member]	Member			ifrs-full:CreditImpairmentOfFinancialInstrumentsMember
4987	Stage 2 [member]	Member			ifrs-full:FinancialInstrumentsNotCreditimpairedMember
4988	Credit Impaired - Stage 3 [member]	Member			ifrs-full:FinancialInstrumentsCreditimpairedMember
4989	Type of measurement of expected credit losses [axis]	Axis			ifrs-full:TypeOfMeasurementOfExpectedCreditLossesAxis
4990	Type of measurement of expected credit losses [member]	Member			ifrs-full:TypeOfMeasurementOfExpectedCreditLossesMember
4991	Stage 1 [member]	Member			ifrs-full:TwelvemonthExpectedCreditLossesMember
4992	Lifetime expected credit losses [member]	Member			ifrs-full:LifetimeExpectedCreditLossesMember
4993	Carrying amount, accumulated depreciation, amortisation and impairment and gross carrying amount [axis]	Axis			ifrs-full:CarryingAmountAccumulatedDepreciationAmortisationAndImpairmentAndGrossCarryingAmountAxis
4994	Carrying amount [member]	Member			ifrs-full:CarryingAmountMember
4995	Gross exposure [member]	Member			ifrs-full:GrossCarryingAmountMember
4996	Classes of financial instruments [axis]	Axis			ifrs-full:ClassesOfFinancialInstrumentsAxis
4997	Financial instruments, class [member]	Member			ifrs-full:ClassesOfFinancialInstrumentsMember
4998	Loan commitments and financial guarantee contracts [member]	Member			c070:OffBalanceSheetLoanCommitmentsAndFinancialGuaranteeContractsMember
4999	Disclosure of reconciliation of changes in loss allowance and explanation of changes in gross carrying amount for financial instruments [line items]	LineItems			ifrs-full:DisclosureOfReconciliationOfChangesInLossAllowanceAndExplanationOfChangesInGrossCarryingAmountForFinancialInstrumentsLineItems
5000	Loan commitments and financial guarantee contracts	Abstract			ifrs-full:IncreaseDecreaseInExposureToCreditRiskOnLoanCommitmentsAndFinancialGuaranteeContractsAbstract
5001	Opening/Beginning balance	Concept (Monetary)	As Of	Credit	ifrs-full:ExposureToCreditRiskOnLoanCommitmentsAndFinancialGuaranteeContracts
5002	Disposal of business to Barclays Bank UK PLC	Concept (Monetary)	For Period	Debit	c070:DecreaseThroughDisposalOfBusinessExposureToCreditRiskOnLoanCommitmentsAndFinancialGuarantee
5003	Net transfers between stages	Concept (Monetary)	For Period	Credit	ifrs-full:IncreaseDecreaseThroughTransfersExposureToCreditRiskOnLoanCommitmentsAndFinancialGuaranteeContracts
5004	Business activity in the year	Concept (Monetary)	For Period	Credit	ifrs-full:IncreaseThroughOriginationOrPurchaseExposureToCreditRiskOnLoanCommitmentsAndFinancialGuaranteeContracts
5005	Net drawdowns and repayments	Concept (Monetary)	For Period	Credit	c070:IncreaseDecreaseInDrawdownsRepaymentsRiskParameterChangesAndOtherMovementsExposureToCreditRiskOnLoanCommitmentsAndFinancialGuaranteeContracts
5006	Asset derecognised due to final repayments	Concept (Monetary)	For Period	Debit	ifrs-full:DecreaseThroughDerecognitionExposureToCreditRiskOnLoanCommitmentsAndFinancialGuaranteeContracts
5007	Closing/Ending balance	Concept (Monetary)	As Of	Credit	ifrs-full:ExposureToCreditRiskOnLoanCommitmentsAndFinancialGuaranteeContracts
5008	044710 - Disclosure - Other disclosures - Risk Management and Principal Risks - Impairment allowance on loan commitments and financial guarantees (audited) (Details)	Network	*	*	http://www.barclays.co.uk/role/OtherDisclosuresRiskManagementAndPrincipalRisksImpairmentAllowanceOnLoanCommitmentsAndFinancialGuaranteesauditedDetails
5009	Disclosure of reconciliation of changes in loss allowance and explanation of changes in gross carrying amount for financial instruments [table]	Table	*	*	ifrs-full:DisclosureOfReconciliationOfChangesInLossAllowanceAndExplanationOfChangesInGrossCarryingAmountForFinancialInstrumentsTable
5010	Credit impairment of financial instruments [axis]	Axis			ifrs-full:CreditImpairmentOfFinancialInstrumentsAxis
5011	Credit impairment of financial instruments [member]	Member			ifrs-full:CreditImpairmentOfFinancialInstrumentsMember
5012	Stage 2 [member]	Member			ifrs-full:FinancialInstrumentsNotCreditimpairedMember
5013	Credit Impaired - Stage 3 [member]	Member			ifrs-full:FinancialInstrumentsCreditimpairedMember
5014	Type of measurement of expected credit losses [axis]	Axis			ifrs-full:TypeOfMeasurementOfExpectedCreditLossesAxis
5015	Type of measurement of expected credit losses [member]	Member			ifrs-full:TypeOfMeasurementOfExpectedCreditLossesMember
5016	Stage 1 [member]	Member			ifrs-full:TwelvemonthExpectedCreditLossesMember
5017	Lifetime expected credit losses [member]	Member			ifrs-full:LifetimeExpectedCreditLossesMember
5018	Carrying amount, accumulated depreciation, amortisation and impairment and gross carrying amount [axis]	Axis			ifrs-full:CarryingAmountAccumulatedDepreciationAmortisationAndImpairmentAndGrossCarryingAmountAxis
5019	Carrying amount [member]	Member			ifrs-full:CarryingAmountMember
5020	Impairment allowance [member]	Member			ifrs-full:AccumulatedImpairmentMember
5021	Classes of financial instruments [axis]	Axis			ifrs-full:ClassesOfFinancialInstrumentsAxis
5022	Financial instruments, class [member]	Member			ifrs-full:ClassesOfFinancialInstrumentsMember
5023	Loan commitments and financial guarantee contracts [member]	Member			c070:OffBalanceSheetLoanCommitmentsAndFinancialGuaranteeContractsMember
5024	Disclosure of reconciliation of changes in loss allowance and explanation of changes in gross carrying amount for financial instruments [line items]	LineItems			ifrs-full:DisclosureOfReconciliationOfChangesInLossAllowanceAndExplanationOfChangesInGrossCarryingAmountForFinancialInstrumentsLineItems
5025	Loan commitments and financial guarantee contracts	Abstract			ifrs-full:IncreaseDecreaseInExposureToCreditRiskOnLoanCommitmentsAndFinancialGuaranteeContractsAbstract
5026	Opening/Beginning balance	Concept (Monetary)	As Of	Credit	ifrs-full:ExposureToCreditRiskOnLoanCommitmentsAndFinancialGuaranteeContracts
5027	Disposal of business to Barclays Bank UK PLC	Concept (Monetary)	For Period	Debit	c070:DecreaseThroughDisposalOfBusinessExposureToCreditRiskOnLoanCommitmentsAndFinancialGuarantee
5028	Net transfers between stages	Concept (Monetary)	For Period	Credit	ifrs-full:IncreaseDecreaseThroughTransfersExposureToCreditRiskOnLoanCommitmentsAndFinancialGuaranteeContracts
5029	Business activity in the year	Concept (Monetary)	For Period	Credit	ifrs-full:IncreaseThroughOriginationOrPurchaseExposureToCreditRiskOnLoanCommitmentsAndFinancialGuaranteeContracts
5030	Net re-measurement and movement due to exposure and risk parameter changes	Concept (Monetary)	For Period	Credit	c070:IncreaseDecreaseInDrawdownsRepaymentsRiskParameterChangesAndOtherMovementsExposureToCreditRiskOnLoanCommitmentsAndFinancialGuaranteeContracts
5031	Asset derecognised due to final repayments	Concept (Monetary)	For Period	Debit	ifrs-full:DecreaseThroughDerecognitionExposureToCreditRiskOnLoanCommitmentsAndFinancialGuaranteeContracts
5032	Closing/Ending balance	Concept (Monetary)	As Of	Credit	ifrs-full:ExposureToCreditRiskOnLoanCommitmentsAndFinancialGuaranteeContracts
5033	044715 - Disclosure - Other disclosures - Risk Management and Principal Risks - Management adjustments to models for impairment - Portfolios that have management adjustments greater than GBP10m by product (audited) (Details)	Network	*	*	http://www.barclays.co.uk/role/OtherDisclosuresRiskManagementAndPrincipalRisksManagementAdjustmentsToModelsForImpairmentPortfoliosThatHaveManagementAdjustmentsGreaterThanGBP10mByProductauditedDetails
5034	Disclosure of nature and extent of risks arising from financial instruments [table]	Table	*	*	ifrs-full:DisclosureOfNatureAndExtentOfRisksArisingFromFinancialInstrumentsTable
5035	Categories of financial assets [axis]	Axis			ifrs-full:CategoriesOfFinancialAssetsAxis
5036	Financial assets, category [member]	Member			ifrs-full:FinancialAssetsCategoryMember
5037	Loans and advances [member]	Member			ifrs-full:LoansAndReceivablesCategoryMember
5038	Credit cards, unsecured and other retail lending [member]	Member			c070:CreditCardsUnsecuredAndOtherRetailLendingMember
5039	Loans to corporate entities [member]	Member			ifrs-full:CorporateLoansMember
5040	Classes of financial instruments [axis]	Axis			ifrs-full:ClassesOfFinancialInstrumentsAxis
5041	Financial instruments, class [member]	Member			ifrs-full:ClassesOfFinancialInstrumentsMember
5042	Key principal portfolios [Member]	Member			c070:KeyPrincipalPortfoliosMember
5043	Portfolios with management adjustments over threshold [Member]	Member			c070:PortfoliosWithManagementAdjustmentsOverThresholdMember
5044	Disclosure of nature and extent of risks arising from financial instruments [line items]	LineItems			ifrs-full:DisclosureOfNatureAndExtentOfRisksArisingFromFinancialInstrumentsLineItems
5045	Total management adjustments to impairment allowances, including forbearance	Concept (Monetary)	As Of	Debit	c070:ManagementAdjustmentsToAllowanceAccountForCreditLossesOfFinancialAssetsIncludingForbearance
5046	Proportion of total impairment allowances	Concept (Percent)	As Of		c070:ImpairmentAllowanceIncludingLoanCommitmentsAndFinancialGuaranteeContractsPercentage
5047	Threshold for adjustments excluded from sensitivity analysis	Concept (Monetary)	As Of	Debit	c070:ThresholdForAdjustmentsExcludedFromSensitivityAnalysis
5048	UK economic uncertainty adjustment	Concept (Monetary)	For Period	Debit	c070:IncreaseDecreaseThroughUnitedKingdomEconomicUncertaintyFinancialAssets
5049	044716 - Disclosure - Other disclosures - Risk Management and Principal Risks - Measurement uncertainty and sensitivity analysis - Scenario probability weighting and Macroeconomic variables (audited) (Details)	Network	*	*	http://www.barclays.co.uk/role/OtherDisclosuresRiskManagementAndPrincipalRisksMeasurementUncertaintyAndSensitivityAnalysisScenarioProbabilityWeightingAndMacroeconomicVariablesauditedDetails
5050	Disclosure of nature and extent of risks arising from financial instruments [table]	Table	*	*	ifrs-full:DisclosureOfNatureAndExtentOfRisksArisingFromFinancialInstrumentsTable
5051	Types of risks [axis]	Axis			ifrs-full:TypesOfRisksAxis
5052	Risks [member]	Member			ifrs-full:TypesOfRisksMember
5053	Credit risk [member]	Member			ifrs-full:CreditRiskMember
5054	Upside 2 [member]	Member			c070:UpsideTwoMember
5055	Upside 1 [member]	Member			c070:UpsideOneMember
5056	Baseline [Member]	Member			c070:BaselineMember
5057	Downside 1 [member]	Member			c070:DownsideOneMember
5058	Downside 2 [member]	Member			c070:DownsideTwoMember
5059	Geographical [Axis]	Axis			srt:StatementGeographicalAxis
5060	Geographical [Domain]	Member			srt:SegmentGeographicalDomain
5061	United Kingdom	Member			country:GB
5062	United States [member]	Member			country:US
5063	Method of assessment of Expected Credit Losses [axis]	Axis			ifrs-full:MethodOfAssessmentOfExpectedCreditLossesAxis
5064	Method of assessment of Expected Credit Losses [member]	Member			ifrs-full:MethodOfAssessmentOfExpectedCreditLossesMember
5065	GDP [member]	Member			c070:GrossDomesticProductEconomicVariableMember
5066	Unemployment [member]	Member			c070:UnemploymentEconomicCoreVariableMember
5067	HPI [member]	Member			c070:HousePriceIndexEconomicCoreVariableMember
5068	Disclosure of nature and extent of risks arising from financial instruments [line items]	LineItems			ifrs-full:DisclosureOfNatureAndExtentOfRisksArisingFromFinancialInstrumentsLineItems
5069	Scenario probability weighting	Concept (Percent)	As Of		c070:ScenarioProbabilityWeighting
5070	044717 - Disclosure - Other disclosures - Risk Management and Principal Risks - Measurement uncertainty and sensitivity analysis - ECL under 100% weighted scenarios for key principal portfolios (audited) (Details)	Network	*	*	http://www.barclays.co.uk/role/OtherDisclosuresRiskManagementAndPrincipalRisksMeasurementUncertaintyAndSensitivityAnalysisECLUnder100WeightedScenariosForKeyPrincipalPortfoliosauditedDetails
5071	Disclosure of nature and extent of risks arising from financial instruments [table]	Table	*	*	ifrs-full:DisclosureOfNatureAndExtentOfRisksArisingFromFinancialInstrumentsTable
5072	Types of risks [axis]	Axis			ifrs-full:TypesOfRisksAxis
5073	Risks [member]	Member			ifrs-full:TypesOfRisksMember
5074	Credit risk [member]	Member			ifrs-full:CreditRiskMember
5075	Upside 2 [member]	Member			c070:UpsideTwoMember
5076	Upside 1 [member]	Member			c070:UpsideOneMember
5077	Baseline [Member]	Member			c070:BaselineMember
5078	Downside 1 [member]	Member			c070:DownsideOneMember
5079	Downside 2 [member]	Member			c070:DownsideTwoMember
5080	Categories of financial assets [axis]	Axis			ifrs-full:CategoriesOfFinancialAssetsAxis
5081	Financial assets, category [member]	Member			ifrs-full:FinancialAssetsCategoryMember
5082	Loans and advances [member]	Member			ifrs-full:LoansAndReceivablesCategoryMember
5083	Home loans [member]	Member			ifrs-full:MortgagesMember
5084	Credit cards, unsecured and other retail lending [member]	Member			c070:CreditCardsUnsecuredAndOtherRetailLendingMember
5085	Corporate loans [member]	Member			ifrs-full:CorporateLoansMember
5086	Type of measurement of expected credit losses [axis]	Axis			ifrs-full:TypeOfMeasurementOfExpectedCreditLossesAxis
5087	Type of measurement of expected credit losses [member]	Member			ifrs-full:TypeOfMeasurementOfExpectedCreditLossesMember
5088	Stage 1 [member]	Member			ifrs-full:TwelvemonthExpectedCreditLossesMember
5089	Lifetime expected credit losses [member]	Member			ifrs-full:LifetimeExpectedCreditLossesMember
5090	Carrying amount, accumulated depreciation, amortisation and impairment and gross carrying amount [axis]	Axis			ifrs-full:CarryingAmountAccumulatedDepreciationAmortisationAndImpairmentAndGrossCarryingAmountAxis
5091	Carrying amount [member]	Member			ifrs-full:CarryingAmountMember
5092	Gross exposure [member]	Member			ifrs-full:GrossCarryingAmountMember
5093	Impairment allowance [member]	Member			ifrs-full:AccumulatedImpairmentMember
5094	Credit impairment of financial instruments [axis]	Axis			ifrs-full:CreditImpairmentOfFinancialInstrumentsAxis
5095	Credit impairment of financial instruments [member]	Member			ifrs-full:CreditImpairmentOfFinancialInstrumentsMember
5096	Stage 2 [member]	Member			ifrs-full:FinancialInstrumentsNotCreditimpairedMember
5097	Credit Impaired - Stage 3 [member]	Member			ifrs-full:FinancialInstrumentsCreditimpairedMember
5098	Disclosure of nature and extent of risks arising from financial instruments [line items]	LineItems			ifrs-full:DisclosureOfNatureAndExtentOfRisksArisingFromFinancialInstrumentsLineItems
5099	Financial assets	Concept (Monetary)	As Of	Debit	ifrs-full:FinancialAssets
5100	Coverage ratio	Concept (Pure)	As Of		c070:ImpairmentAllowanceCoverageRatio
5101	044718 - Disclosure - Other disclosures - Risk Management and Principal Risks - Measurement uncertainty and sensitivity analysis - Scenario probability weighting and Macroeconomic variables for UK Downward scenario (audited) (Details)	Network	*	*	http://www.barclays.co.uk/role/OtherDisclosuresRiskManagementAndPrincipalRisksMeasurementUncertaintyAndSensitivityAnalysisScenarioProbabilityWeightingAndMacroeconomicVariablesForUKDownwardScenarioauditedDetails
5102	Disclosure of nature and extent of risks arising from financial instruments [table]	Table	*	*	ifrs-full:DisclosureOfNatureAndExtentOfRisksArisingFromFinancialInstrumentsTable
5103	Types of risks [axis]	Axis			ifrs-full:TypesOfRisksAxis
5104	Risks [member]	Member			ifrs-full:TypesOfRisksMember
5105	Credit risk [member]	Member			ifrs-full:CreditRiskMember
5106	Upside 2 [member]	Member			c070:UpsideTwoMember
5107	Upside 1 [member]	Member			c070:UpsideOneMember
5108	Baseline [Member]	Member			c070:BaselineMember
5109	Downside 1 [member]	Member			c070:DownsideOneMember
5110	Downside 2 [member]	Member			c070:DownsideTwoMember
5111	Method of assessment of Expected Credit Losses [axis]	Axis			ifrs-full:MethodOfAssessmentOfExpectedCreditLossesAxis
5112	Method of assessment of Expected Credit Losses [member]	Member			ifrs-full:MethodOfAssessmentOfExpectedCreditLossesMember
5113	GDP [member]	Member			c070:GrossDomesticProductEconomicVariableMember
5114	Unemployment [member]	Member			c070:UnemploymentEconomicCoreVariableMember
5115	HPI [member]	Member			c070:HousePriceIndexEconomicCoreVariableMember
5116	Risk exposures [axis]	Axis			ifrs-full:RiskExposuresAxis
5117	Risk exposures [member]	Member			ifrs-full:RiskExposuresMember
5118	UK Downward scenario [Member]	Member			c070:UnitedKingdomDownwardScenarioMember
5119	Geographical [Axis]	Axis			srt:StatementGeographicalAxis
5120	Geographical [Domain]	Member			srt:SegmentGeographicalDomain
5121	United Kingdom	Member			country:GB
5122	US	Member			country:US
5123	Disclosure of nature and extent of risks arising from financial instruments [line items]	LineItems			ifrs-full:DisclosureOfNatureAndExtentOfRisksArisingFromFinancialInstrumentsLineItems
5124	Scenario probability weighting	Concept (Percent)	As Of		c070:ScenarioProbabilityWeighting
5125	044719 - Disclosure - Other disclosures - Risk Management and Principal Risks - Measurement uncertainty and sensitivity analysis - ECL under 100% weighted scenarios for key principal portfolios for UK Downward scenario (audited) (Details)	Network	*	*	http://www.barclays.co.uk/role/OtherDisclosuresRiskManagementAndPrincipalRisksMeasurementUncertaintyAndSensitivityAnalysisECLUnder100WeightedScenariosForKeyPrincipalPortfoliosForUKDownwardScenarioauditedDetails
5126	Disclosure of nature and extent of risks arising from financial instruments [table]	Table	*	*	ifrs-full:DisclosureOfNatureAndExtentOfRisksArisingFromFinancialInstrumentsTable
5127	Credit impairment of financial instruments [axis]	Axis			ifrs-full:CreditImpairmentOfFinancialInstrumentsAxis
5128	Credit impairment of financial instruments [member]	Member			ifrs-full:CreditImpairmentOfFinancialInstrumentsMember
5129	Stage 2 [member]	Member			ifrs-full:FinancialInstrumentsNotCreditimpairedMember
5130	Credit Impaired - Stage 3 [member]	Member			ifrs-full:FinancialInstrumentsCreditimpairedMember
5131	Type of measurement of expected credit losses [axis]	Axis			ifrs-full:TypeOfMeasurementOfExpectedCreditLossesAxis
5132	Type of measurement of expected credit losses [member]	Member			ifrs-full:TypeOfMeasurementOfExpectedCreditLossesMember
5133	Stage 1 [member]	Member			ifrs-full:TwelvemonthExpectedCreditLossesMember
5134	Lifetime expected credit losses [member]	Member			ifrs-full:LifetimeExpectedCreditLossesMember
5135	Categories of financial assets [axis]	Axis			ifrs-full:CategoriesOfFinancialAssetsAxis
5136	Financial assets, category [member]	Member			ifrs-full:FinancialAssetsCategoryMember
5137	Loans and advances [member]	Member			ifrs-full:LoansAndReceivablesCategoryMember
5138	Home loans [member]	Member			ifrs-full:MortgagesMember
5139	Credit cards, unsecured and other retail lending [member]	Member			c070:CreditCardsUnsecuredAndOtherRetailLendingMember
5140	Loans to corporate entities [member]	Member			ifrs-full:CorporateLoansMember
5141	Types of risks [axis]	Axis			ifrs-full:TypesOfRisksAxis
5142	Risks [member]	Member			ifrs-full:TypesOfRisksMember
5143	Credit risk [member]	Member			ifrs-full:CreditRiskMember
5144	Upside 2 [member]	Member			c070:UpsideTwoMember
5145	Upside 1 [member]	Member			c070:UpsideOneMember
5146	Baseline [Member]	Member			c070:BaselineMember
5147	Downside 1 [member]	Member			c070:DownsideOneMember
5148	Downside 2 [member]	Member			c070:DownsideTwoMember
5149	Risk exposures [axis]	Axis			ifrs-full:RiskExposuresAxis
5150	Risk exposures [member]	Member			ifrs-full:RiskExposuresMember
5151	UK Downward scenario [Member]	Member			c070:UnitedKingdomDownwardScenarioMember
5152	UK Upward scenario [member]	Member			c070:UnitedKingdomUpwardScenarioMember
5153	Carrying amount, accumulated depreciation, amortisation and impairment and gross carrying amount [axis]	Axis			ifrs-full:CarryingAmountAccumulatedDepreciationAmortisationAndImpairmentAndGrossCarryingAmountAxis
5154	Carrying amount [member]	Member			ifrs-full:CarryingAmountMember
5155	Gross exposure [member]	Member			ifrs-full:GrossCarryingAmountMember
5156	Impairment allowance [member]	Member			ifrs-full:AccumulatedImpairmentMember
5157	Disclosure of nature and extent of risks arising from financial instruments [line items]	LineItems			ifrs-full:DisclosureOfNatureAndExtentOfRisksArisingFromFinancialInstrumentsLineItems
5158	Financial assets	Concept (Monetary)	As Of	Debit	ifrs-full:FinancialAssets
5159	Coverage ratio	Concept (Pure)	As Of		c070:ImpairmentAllowanceCoverageRatio
5160	044720 - Disclosure - Other disclosures - Risk Management and Principal Risks - Measurement uncertainty and sensitivity analysis - Scenario probability weighting and Macroeconomic variables for US Downward scenario (audited) (Details)	Network	*	*	http://www.barclays.co.uk/role/OtherDisclosuresRiskManagementAndPrincipalRisksMeasurementUncertaintyAndSensitivityAnalysisScenarioProbabilityWeightingAndMacroeconomicVariablesForUSDownwardScenarioauditedDetails
5161	Disclosure of nature and extent of risks arising from financial instruments [table]	Table	*	*	ifrs-full:DisclosureOfNatureAndExtentOfRisksArisingFromFinancialInstrumentsTable
5162	Types of risks [axis]	Axis			ifrs-full:TypesOfRisksAxis
5163	Risks [member]	Member			ifrs-full:TypesOfRisksMember
5164	Credit risk [member]	Member			ifrs-full:CreditRiskMember
5165	Upside 2 [member]	Member			c070:UpsideTwoMember
5166	Upside 1 [member]	Member			c070:UpsideOneMember
5167	Baseline [Member]	Member			c070:BaselineMember
5168	Downside 1 [member]	Member			c070:DownsideOneMember
5169	Downside 2 [member]	Member			c070:DownsideTwoMember
5170	Method of assessment of Expected Credit Losses [axis]	Axis			ifrs-full:MethodOfAssessmentOfExpectedCreditLossesAxis
5171	Method of assessment of Expected Credit Losses [member]	Member			ifrs-full:MethodOfAssessmentOfExpectedCreditLossesMember
5172	GDP [member]	Member			c070:GrossDomesticProductEconomicVariableMember
5173	Unemployment [member]	Member			c070:UnemploymentEconomicCoreVariableMember
5174	HPI [member]	Member			c070:HousePriceIndexEconomicCoreVariableMember
5175	Risk exposures [axis]	Axis			ifrs-full:RiskExposuresAxis
5176	Risk exposures [member]	Member			ifrs-full:RiskExposuresMember
5177	US Downward Scenario [member]	Member			c070:UnitedStatesDownwardScenarioMember
5178	Geographical [Axis]	Axis			srt:StatementGeographicalAxis
5179	Geographical [Domain]	Member			srt:SegmentGeographicalDomain
5180	United Kingdom	Member			country:GB
5181	US	Member			country:US
5182	Disclosure of nature and extent of risks arising from financial instruments [line items]	LineItems			ifrs-full:DisclosureOfNatureAndExtentOfRisksArisingFromFinancialInstrumentsLineItems
5183	Scenario probability weighting	Concept (Percent)	As Of		c070:ScenarioProbabilityWeighting
5184	044721 - Disclosure - Other disclosures - Risk Management and Principal Risks - Measurement uncertainty and sensitivity analysis - ECL under 100% weighted scenarios for key principal portfolios for US Downward scenario (audited) (Details)	Network	*	*	http://www.barclays.co.uk/role/OtherDisclosuresRiskManagementAndPrincipalRisksMeasurementUncertaintyAndSensitivityAnalysisECLUnder100WeightedScenariosForKeyPrincipalPortfoliosForUSDownwardScenarioauditedDetails
5185	Disclosure of nature and extent of risks arising from financial instruments [table]	Table	*	*	ifrs-full:DisclosureOfNatureAndExtentOfRisksArisingFromFinancialInstrumentsTable
5186	Credit impairment of financial instruments [axis]	Axis			ifrs-full:CreditImpairmentOfFinancialInstrumentsAxis
5187	Credit impairment of financial instruments [member]	Member			ifrs-full:CreditImpairmentOfFinancialInstrumentsMember
5188	Stage 2 [member]	Member			ifrs-full:FinancialInstrumentsNotCreditimpairedMember
5189	Credit Impaired - Stage 3 [member]	Member			ifrs-full:FinancialInstrumentsCreditimpairedMember
5190	Type of measurement of expected credit losses [axis]	Axis			ifrs-full:TypeOfMeasurementOfExpectedCreditLossesAxis
5191	Type of measurement of expected credit losses [member]	Member			ifrs-full:TypeOfMeasurementOfExpectedCreditLossesMember
5192	Stage 1 [member]	Member			ifrs-full:TwelvemonthExpectedCreditLossesMember
5193	Lifetime expected credit losses [member]	Member			ifrs-full:LifetimeExpectedCreditLossesMember
5194	Categories of financial assets [axis]	Axis			ifrs-full:CategoriesOfFinancialAssetsAxis
5195	Financial assets, category [member]	Member			ifrs-full:FinancialAssetsCategoryMember
5196	Loans and advances [member]	Member			ifrs-full:LoansAndReceivablesCategoryMember
5197	Credit cards, unsecured and other retail lending [member]	Member			c070:CreditCardsUnsecuredAndOtherRetailLendingMember
5198	Loans to corporate entities [member]	Member			ifrs-full:CorporateLoansMember
5199	Types of risks [axis]	Axis			ifrs-full:TypesOfRisksAxis
5200	Risks [member]	Member			ifrs-full:TypesOfRisksMember
5201	Credit risk [member]	Member			ifrs-full:CreditRiskMember
5202	Upside 2 [member]	Member			c070:UpsideTwoMember
5203	Upside 1 [member]	Member			c070:UpsideOneMember
5204	Baseline [Member]	Member			c070:BaselineMember
5205	Downside 1 [member]	Member			c070:DownsideOneMember
5206	Downside 2 [member]	Member			c070:DownsideTwoMember
5207	Risk exposures [axis]	Axis			ifrs-full:RiskExposuresAxis
5208	Risk exposures [member]	Member			ifrs-full:RiskExposuresMember
5209	US Downward Scenario [member]	Member			c070:UnitedStatesDownwardScenarioMember
5210	US Upward Scenario [member]	Member			c070:UnitedStatesUpwardScenarioMember
5211	Carrying amount, accumulated depreciation, amortisation and impairment and gross carrying amount [axis]	Axis			ifrs-full:CarryingAmountAccumulatedDepreciationAmortisationAndImpairmentAndGrossCarryingAmountAxis
5212	Carrying amount [member]	Member			ifrs-full:CarryingAmountMember
5213	Gross exposure [member]	Member			ifrs-full:GrossCarryingAmountMember
5214	Impairment allowance [member]	Member			ifrs-full:AccumulatedImpairmentMember
5215	Disclosure of nature and extent of risks arising from financial instruments [line items]	LineItems			ifrs-full:DisclosureOfNatureAndExtentOfRisksArisingFromFinancialInstrumentsLineItems
5216	Financial assets	Concept (Monetary)	As Of	Debit	ifrs-full:FinancialAssets
5217	Coverage ratio	Concept (Pure)	As Of		c070:ImpairmentAllowanceCoverageRatio
5218	044722 - Disclosure - Other disclosures - Risk Management and Principal Risks - Measurement uncertainty and sensitivity analysis (audited) (Narrative) (Details)	Network	*	*	http://www.barclays.co.uk/role/OtherDisclosuresRiskManagementAndPrincipalRisksMeasurementUncertaintyAndSensitivityAnalysisauditedNarrativeDetails
5219	Disclosure of nature and extent of risks arising from financial instruments [table]	Table	*	*	ifrs-full:DisclosureOfNatureAndExtentOfRisksArisingFromFinancialInstrumentsTable
5220	Types of risks [axis]	Axis			ifrs-full:TypesOfRisksAxis
5221	Risks [member]	Member			ifrs-full:TypesOfRisksMember
5222	Credit risk [member]	Member			ifrs-full:CreditRiskMember
5223	Upside 1 [member]	Member			c070:UpsideOneMember
5224	Upside 2 [member]	Member			c070:UpsideTwoMember
5225	Baseline [Member]	Member			c070:BaselineMember
5226	Downside 1 [member]	Member			c070:DownsideOneMember
5227	Downside 2 [member]	Member			c070:DownsideTwoMember
5228	Geographical [Axis]	Axis			srt:StatementGeographicalAxis
5229	Geographical [Domain]	Member			srt:SegmentGeographicalDomain
5230	United Kingdom	Member			country:GB
5231	US	Member			country:US
5232	Categories of financial assets [axis]	Axis			ifrs-full:CategoriesOfFinancialAssetsAxis
5233	Financial assets, category [member]	Member			ifrs-full:FinancialAssetsCategoryMember
5234	Loans and advances [member]	Member			ifrs-full:LoansAndReceivablesCategoryMember
5235	Home loans [member]	Member			ifrs-full:MortgagesMember
5236	Credit cards, unsecured and other retail lending [member]	Member			c070:CreditCardsUnsecuredAndOtherRetailLendingMember
5237	Loans to corporate entities [member]	Member			ifrs-full:CorporateLoansMember
5238	Carrying amount, accumulated depreciation, amortisation and impairment and gross carrying amount [axis]	Axis			ifrs-full:CarryingAmountAccumulatedDepreciationAmortisationAndImpairmentAndGrossCarryingAmountAxis
5239	Carrying amount [member]	Member			ifrs-full:CarryingAmountMember
5240	Gross exposure [member]	Member			ifrs-full:GrossCarryingAmountMember
5241	Impairment allowance [member]	Member			ifrs-full:AccumulatedImpairmentMember
5242	Method of assessment of Expected Credit Losses [axis]	Axis			ifrs-full:MethodOfAssessmentOfExpectedCreditLossesAxis
5243	Method of assessment of Expected Credit Losses [member]	Member			ifrs-full:MethodOfAssessmentOfExpectedCreditLossesMember
5244	GDP [member]	Member			c070:GrossDomesticProductEconomicVariableMember
5245	Unemployment [member]	Member			c070:UnemploymentEconomicCoreVariableMember
5246	HPI [member]	Member			c070:HousePriceIndexEconomicCoreVariableMember
5247	ExpectedCreditLossesIndividuallyAssessedMember	Member			ifrs-full:ExpectedCreditLossesIndividuallyAssessedMember
5248	Classes of financial assets [axis]	Axis			ifrs-full:ClassesOfFinancialAssetsAxis
5249	Financial assets, class [member]	Member			ifrs-full:FinancialAssetsMember
5250	Financial assets at amortised cost [member]	Member			ifrs-full:FinancialAssetsAtAmortisedCostMember
5251	Classes of financial instruments [axis]	Axis			ifrs-full:ClassesOfFinancialInstrumentsAxis
5252	Financial instruments, class [member]	Member			ifrs-full:ClassesOfFinancialInstrumentsMember
5253	Key principal portfolios [Member]	Member			c070:KeyPrincipalPortfoliosMember
5254	Portfolios that have management adjustments greater than GBP 10m by product [member]	Member			c070:PortfoliosThatHaveManagementAdjustmentsGreaterThanGbp10mByProductMember
5255	Risk exposures [axis]	Axis			ifrs-full:RiskExposuresAxis
5256	Risk exposures [member]	Member			ifrs-full:RiskExposuresMember
5257	UK Downward scenario [Member]	Member			c070:UnitedKingdomDownwardScenarioMember
5258	UK Upward scenario [member]	Member			c070:UnitedKingdomUpwardScenarioMember
5259	US Downward Scenario [member]	Member			c070:UnitedStatesDownwardScenarioMember
5260	US Upward Scenario [member]	Member			c070:UnitedStatesUpwardScenarioMember
5261	Continuing and discontinued operations [axis]	Axis			ifrs-full:ContinuingAndDiscontinuedOperationsAxis
5262	Aggregate continuing and discontinued operations [member]	Member			ifrs-full:AggregateContinuingAndDiscontinuedOperationsMember
5263	Continuing operations [member]	Member			ifrs-full:ContinuingOperationsMember
5264	Discontinued operations [member]	Member			ifrs-full:DiscontinuedOperationsMember
5265	UK Banking Business [member]	Member			c070:BarclaysUkMember
5266	Categories of related parties [axis]	Axis			ifrs-full:CategoriesOfRelatedPartiesAxis
5267	Entity's total for related parties [member]	Member			ifrs-full:EntitysTotalForRelatedPartiesMember
5268	Barclays Bank UK PLC [member]	Member			c070:BarclaysBankUkPlcMember
5269	Disclosure of nature and extent of risks arising from financial instruments [line items]	LineItems			ifrs-full:DisclosureOfNatureAndExtentOfRisksArisingFromFinancialInstrumentsLineItems
5270	Description of method, parameters and assumptions used in preparing sensitivity analysis reflecting interdependencies between risk variables	Concept (Text/String)	For Period		ifrs-full:MethodsUsedInPreparingSensitivityAnalysisReflectingInterdependenciesBetweenRiskVariables
5271	Term at which scenario converges to steady state	Concept (xbrli:durationItemType)	For Period		c070:TermAtWhichScenarioConvergesToSteadyState
5272	Period applicable in scenario model to calculate expected credit losses	Concept (xbrli:durationItemType)	For Period		c070:PeriodApplicableInScenarioModelToCalculateExpectedCreditLosses
5273	Scenario probability weighting	Concept (Percent)	As Of		c070:ScenarioProbabilityWeighting
5274	Loans and advances at amortised cost, percentage	Concept (Percent)	As Of		c070:LoansAndReceivablesPercentage
5275	Impairment allowance including loan commitments and financial guarantee contracts, percentage	Concept (Percent)	As Of		c070:ImpairmentAllowanceIncludingLoanCommitmentsAndFinancialGuaranteeContractsPercentage
5276	Threshold for adjustments excluded from sensitivity analysis	Concept (Monetary)	As Of	Debit	c070:ThresholdForAdjustmentsExcludedFromSensitivityAnalysis
5277	Unemployment Rate	Concept (Percent)	As Of		c070:UnemploymentRate
5278	Increase (decrease) through transfers from stage two, financial assets	Concept (Monetary)	For Period	Debit	c070:IncreaseDecreaseThroughTransfersFromStageTwoFinancialAssets
5279	Weighted expected credit loss, uplift percentage	Concept (Percent)	For Period		c070:WeightedExpectedCreditLossUpliftPercentage
5280	Increase (decrease) through United Kingdom economic uncertainty, financial assets	Concept (Monetary)	For Period	Debit	c070:IncreaseDecreaseThroughUnitedKingdomEconomicUncertaintyFinancialAssets
5281	Financial assets	Concept (Monetary)	As Of	Debit	ifrs-full:FinancialAssets
5282	ECL movement excluding assets derecognised due to disposals and write-off	Concept (Monetary)	For Period	Credit	ifrs-full:IncreaseDecreaseInAllowanceAccountForCreditLossesOfFinancialAssets
5283	Increase (decrease) in coverate rates	Concept (Percent)	For Period		c070:IncreaseDecreaseInCoverateRates
5284	Coverage ratio	Concept (Pure)	As Of		c070:ImpairmentAllowanceCoverageRatio
5285	Increase (decrease) through transfers into stage two from stage one, financial assets	Concept (Monetary)	As Of	Credit	c070:IncreaseDecreaseThroughTransfersIntoStageTwoFromStageOneFinancialAssets
5286	Increase (decrease) through transfers into stage two from stage one, financial assets, percentage	Concept (Monetary)	As Of	Credit	c070:IncreaseDecreaseThroughTransfersIntoStageTwoFromStageOneFinancialAssetsPercentage
5287	Threshold expected credit losses	Concept (Monetary)	As Of	Credit	c070:ThresholdImpairmentAllowance
5288	Additional impairment allowance	Concept (Monetary)	For Period		ifrs-full:AdditionalAllowanceRecognisedInProfitOrLossAllowanceAccountForCreditLossesOfFinancialAssets
5289	044727 - Disclosure - Other disclosures - Risk Management and Principal Risks - Credit risk concentrations by geography (audited) (Details)	Network	*	*	http://www.barclays.co.uk/role/OtherDisclosuresRiskManagementAndPrincipalRisksCreditRiskConcentrationsByGeographyauditedDetails
5290	Disclosure of geographical areas [table]	Table	*	*	ifrs-full:DisclosureOfGeographicalAreasTable
5291	Geographical areas [axis]	Axis			ifrs-full:GeographicalAreasAxis
5292	Geographical areas [member]	Member			ifrs-full:GeographicalAreasMember
5293	United Kingdom [member]	Member			ifrs-full:CountryOfDomicileMember
5294	Europe [member]	Member			srt:EuropeMember
5295	Americas [member]	Member			srt:AmericasMember
5296	Africa and middle east [member]	Member			c070:AfricaAndMiddleEastMember
5297	Asia [member]	Member			srt:AsiaMember
5298	Types of risks [axis]	Axis			ifrs-full:TypesOfRisksAxis
5299	Risks [member]	Member			ifrs-full:TypesOfRisksMember
5300	Credit risk [member]	Member			ifrs-full:CreditRiskMember
5301	Consolidated Entities [Axis]	Axis			srt:ConsolidatedEntitiesAxis
5302	Consolidated Entities [Domain]	Member			srt:ConsolidatedEntitiesDomain
5303	Barclays Bank Group [member]	Member			c070:BarclaysBankGroupMember
5304	Disclosure of geographical areas [line items]	LineItems			ifrs-full:DisclosureOfGeographicalAreasLineItems
5305	On-balance sheet	Abstract			c070:OnBalanceSheetAbstract
5306	Cash and balances at central banks	Concept (Monetary)	As Of	Debit	ifrs-full:CashAndBankBalancesAtCentralBanks
5307	Cash collateral and settlement balances	Concept (Monetary)	As Of	Debit	ifrs-full:BankAcceptanceAssets
5308	Loans and advances at amortised cost	Concept (Monetary)	As Of	Debit	ifrs-full:LoansAndReceivables
5309	Reverse repurchase agreements and other similar secured lending	Concept (Monetary)	As Of	Debit	ifrs-full:ReverseRepurchaseAgreementsAndCashCollateralOnSecuritiesBorrowed
5310	Trading portfolio assets	Concept (Monetary)	As Of	Debit	ifrs-full:FinancialAssetsAtFairValueThroughProfitOrLossClassifiedAsHeldForTrading
5311	Financial assets at fair value through the income statement	Concept (Monetary)	As Of	Debit	ifrs-full:FinancialAssetsAtFairValueThroughProfitOrLoss
5312	Derivative financial instruments	Concept (Monetary)	As Of	Debit	ifrs-full:DerivativeFinancialAssets
5313	Financial assets at fair value through other comprehensive income	Concept (Monetary)	As Of	Debit	ifrs-full:FinancialAssetsAtFairValueThroughOtherComprehensiveIncome
5314	Financial investments - debt securities	Concept (Monetary)	As Of	Debit	c070:FinancialInvestmentsDebtSecurities
5315	Other assets	Concept (Monetary)	As Of	Debit	ifrs-full:OtherFinancialAssets
5316	Total Assets	Concept (Monetary)	As Of	Debit	ifrs-full:Assets
5317	Off-balance sheet	Abstract			c070:OffBalanceSheetAbstract
5318	Contingent liabilities	Concept (Monetary)	As Of		ifrs-full:EstimatedFinancialEffectOfContingentLiabilities
5319	Loan commitments	Concept (Monetary)	As Of	Credit	ifrs-full:GrossLoanCommitments
5320	Total off-balance sheet	Concept (Monetary)	As Of	Credit	c070:CommitmentsGiven
5321	Total	Concept (Monetary)	As Of		ifrs-full:MaximumExposureToCreditRisk
5322	044728 - Disclosure - Other disclosures - Risk Management and Principal Risks - Credit risk concentrations by industry (audited) (Details)	Network	*	*	http://www.barclays.co.uk/role/OtherDisclosuresRiskManagementAndPrincipalRisksCreditRiskConcentrationsByIndustryauditedDetails
5323	Disclosure of products and services [table]	Table	*	*	ifrs-full:DisclosureOfProductsAndServicesTable
5324	Products and services [axis]	Axis			ifrs-full:ProductsAndServicesAxis
5325	Products and services [member]	Member			ifrs-full:ProductsAndServicesMember
5326	Banks [member]	Member			c070:BanksMember
5327	Other financial institutions [member]	Member			c070:OtherFinancialInstitutionsMember
5328	Manufacturing [member]	Member			c070:ManufacturingMember
5329	Construction and Property [member]	Member			c070:ConstructionAndPropertyMember
5330	Government and central bank [member]	Member			c070:GovernmentAndCentralBankMember
5331	Energy and water [member]	Member			c070:EnergyAndWaterMember
5332	Wholesale and retail distribution and leisure [member]	Member			c070:WholesaleAndRetailDistributionAndLeisureMember
5333	Business and other services [member]	Member			c070:BusinessAndOtherServicesMember
5334	Home loans [member]	Member			ifrs-full:MortgagesMember
5335	Cards, unsecured loans and other personal lending [member]	Member			c070:CardsUnsecuredLoansAndOtherPersonalLendingMember
5336	Other [member]	Member			c070:OtherFinancialAssetsMember
5337	Types of risks [axis]	Axis			ifrs-full:TypesOfRisksAxis
5338	Risks [member]	Member			ifrs-full:TypesOfRisksMember
5339	Credit risk [member]	Member			ifrs-full:CreditRiskMember
5340	Consolidated Entities [Axis]	Axis			srt:ConsolidatedEntitiesAxis
5341	Consolidated Entities [Domain]	Member			srt:ConsolidatedEntitiesDomain
5342	Barclays Bank Group [member]	Member			c070:BarclaysBankGroupMember
5343	Disclosure of products and services [line items]	LineItems			ifrs-full:DisclosureOfProductsAndServicesLineItems
5344	On-balance sheet	Abstract			c070:OnBalanceSheetAbstract
5345	Cash and balances at central banks	Concept (Monetary)	As Of	Debit	ifrs-full:CashAndBankBalancesAtCentralBanks
5346	Cash collateral and settlement balance assets	Concept (Monetary)	As Of	Debit	ifrs-full:BankAcceptanceAssets
5347	Loans and advances at amortised cost	Concept (Monetary)	As Of	Debit	ifrs-full:LoansAndReceivables
5348	Reverse repurchase agreements and other similar secured lending	Concept (Monetary)	As Of	Debit	ifrs-full:ReverseRepurchaseAgreementsAndCashCollateralOnSecuritiesBorrowed
5349	Trading portfolio assets	Concept (Monetary)	As Of	Debit	ifrs-full:FinancialAssetsAtFairValueThroughProfitOrLossClassifiedAsHeldForTrading
5350	Financial assets at fair value through the income statement	Concept (Monetary)	As Of	Debit	ifrs-full:FinancialAssetsAtFairValueThroughProfitOrLoss
5351	Derivative financial instruments	Concept (Monetary)	As Of	Debit	ifrs-full:DerivativeFinancialAssets
5352	Financial assets at fair value through other comprehensive income	Concept (Monetary)	As Of	Debit	ifrs-full:FinancialAssetsAtFairValueThroughOtherComprehensiveIncome
5353	Financial investments - debt securities	Concept (Monetary)	As Of	Debit	c070:FinancialInvestmentsDebtSecurities
5354	Other assets	Concept (Monetary)	As Of	Debit	ifrs-full:OtherFinancialAssets
5355	Assets	Concept (Monetary)	As Of	Debit	ifrs-full:Assets
5356	Off-balance sheet	Abstract			c070:OffBalanceSheetAbstract
5357	Contingent liabilities	Concept (Monetary)	As Of		ifrs-full:EstimatedFinancialEffectOfContingentLiabilities
5358	Loan commitments	Concept (Monetary)	As Of	Credit	ifrs-full:GrossLoanCommitments
5359	Total off-balance sheet	Concept (Monetary)	As Of	Credit	c070:CommitmentsGiven
5360	Total	Concept (Monetary)	As Of		ifrs-full:MaximumExposureToCreditRisk
5361	044730 - Disclosure - Other disclosures - Risk Management and Principal Risks - Balance sheet credit quality (audited) (Details)	Network	*	*	http://www.barclays.co.uk/role/OtherDisclosuresRiskManagementAndPrincipalRisksBalanceSheetCreditQualityauditedDetails
5362	Disclosure of internal credit grades [table]	Table	*	*	ifrs-full:DisclosureOfInternalCreditExposuresTable
5363	Internal credit grades [axis]	Axis			ifrs-full:InternalCreditGradesAxis
5364	Entity's total for internal credit grades [member]	Member			ifrs-full:EntitysTotalForInternalCreditGradesMember
5365	Internal credit grades [member]	Member			ifrs-full:InternalCreditGradesMember
5366	Classes of financial instruments [axis]	Axis			ifrs-full:ClassesOfFinancialInstrumentsAxis
5367	Financial instruments, class [member]	Member			ifrs-full:ClassesOfFinancialInstrumentsMember
5368	Debt securities [member]	Member			ifrs-full:DebtSecuritiesMember
5369	Traded loans [member]	Member			c070:TradedLoansMember
5370	Classes of financial assets [axis]	Axis			ifrs-full:ClassesOfFinancialAssetsAxis
5371	Financial assets, class [member]	Member			ifrs-full:FinancialAssetsMember
5372	Reverse repurchase agreements [member]	Member			c070:ReverseRepurchaseAgreementsMember
5373	Other financial assets [member]	Member			c070:OtherFinancialAssetsMember
5374	Categories of financial assets [axis]	Axis			ifrs-full:CategoriesOfFinancialAssetsAxis
5375	Financial assets, category [member]	Member			ifrs-full:FinancialAssetsCategoryMember
5376	Financial assets at amortised cost, category [member]	Member			ifrs-full:FinancialAssetsAtAmortisedCostCategoryMember
5377	Home loans [member]	Member			ifrs-full:MortgagesMember
5378	Credit cards, unsecured and other retail lending [member]	Member			c070:CreditCardsUnsecuredAndOtherRetailLendingMember
5379	Corporate loans [member]	Member			ifrs-full:CorporateLoansMember
5380	Loans and advances [member]	Member			ifrs-full:LoansAndReceivablesCategoryMember
5381	Probability of default [axis]	Axis			ifrs-full:ProbabilityOfDefaultAxis
5382	Entity's total for probability of default [member]	Member			ifrs-full:EntitysTotalForProbabilityOfDefaultMember
5383	0.0 to less than 0.60% [member]	Member			c070:ProbabilityOfDefaultZeroToPointSixtyPercentMember
5384	0.60 to less than 11.35% [member]	Member			c070:ProbabilityOfDefaultPointSixtyToElevenPointThreeFivePercentMember
5385	11.35% to 100% [member]	Member			c070:ProbabilityOfDefaultElevenPointThreeFiveToOneHundredPercentMember
5386	Consolidated Entities [Axis]	Axis			srt:ConsolidatedEntitiesAxis
5387	Consolidated Entities [Domain]	Member			srt:ConsolidatedEntitiesDomain
5388	Barclays Bank Group [member]	Member			c070:BarclaysBankGroupMember
5389	Disclosure of internal credit grades [line items]	LineItems			ifrs-full:DisclosureOfInternalCreditExposuresLineItems
5390	On-balance sheet	Abstract			c070:OnBalanceSheetAbstract
5391	Cash and balances at central banks	Concept (Monetary)	As Of	Debit	ifrs-full:CashAndBankBalancesAtCentralBanks
5392	Cash collateral and settlement balances	Concept (Monetary)	As Of	Debit	ifrs-full:BankAcceptanceAssets
5393	Loans and advances at amortised cost	Concept (Monetary)	As Of	Debit	ifrs-full:LoansAndReceivables
5394	Reverse repurchase agreements and other similar secured lending	Concept (Monetary)	As Of	Debit	ifrs-full:ReverseRepurchaseAgreementsAndCashCollateralOnSecuritiesBorrowed
5395	Trading portfolio assets	Concept (Monetary)	As Of	Debit	ifrs-full:FinancialAssetsAtFairValueThroughProfitOrLossClassifiedAsHeldForTrading
5396	Financial assets at fair value through the income statement	Concept (Monetary)	As Of	Debit	ifrs-full:FinancialAssetsAtFairValueThroughProfitOrLoss
5397	Financial assets designated at fair value	Concept (Monetary)	As Of	Debit	ifrs-full:FinancialAssetsAtFairValueThroughProfitOrLossDesignatedAsUponInitialRecognition
5398	Derivative financial instruments	Concept (Monetary)	As Of	Debit	ifrs-full:DerivativeFinancialAssets
5399	Financial assets measured at fair value through other comprehensive income	Concept (Monetary)	As Of	Debit	ifrs-full:FinancialAssetsMeasuredAtFairValueThroughOtherComprehensiveIncome
5400	Financial investments - debt securities	Concept (Monetary)	As Of	Debit	c070:FinancialInvestmentsDebtSecurities
5401	Other assets	Concept (Monetary)	As Of	Debit	ifrs-full:OtherFinancialAssets
5402	Total Assets	Concept (Monetary)	As Of	Debit	ifrs-full:Assets
5403	On-balance sheet, percentage	Abstract			c070:OnBalanceSheetPercentageAbstract
5404	Cash and balances at central banks, percentage	Concept (Percent)	As Of		c070:CashAndBankBalancesAtCentralBanksPercentage
5405	Cash collateral and settlement balance, percentage	Concept (Percent)	As Of		c070:BankAcceptanceAssetsPercentage
5406	Loans and advances at amortised cost, percentage	Concept (Percent)	As Of		c070:LoansAndReceivablesPercentage
5407	Reverse repurchase agreements and other similar secured lending, percentage	Concept (Percent)	As Of		c070:ReverseRepurchaseAgreementsAndOtherSimilarSecuredLendingPercentage
5408	Trading portfolio assets, percentage	Concept (Percent)	As Of		c070:FinancialAssetsAtFairValueThroughProfitOrLossClassifiedAsHeldForTradingPercentage
5409	Financial assets at fair value through the income statement, percentage	Concept (Percent)	As Of		c070:FinancialAssetsAtFairValueThroughProfitOrLossPercentage
5410	Financial assets designated at fair value, percentage	Concept (Percent)	As Of		c070:FinancialAssetsAtFairValueThroughProfitOrLossDesignatedAsUponInitialRecognitionPercentage
5411	Derivative financial instruments, percentage	Concept (Percent)	As Of		c070:DerivativeFinancialAssetsPercentage
5412	Financial assets measured at fair value through other comprehensive income, percentage	Concept (Percent)	As Of		c070:FinancialAssetsMeasuredAtFairValueThroughOtherComprehensiveIncomePercentage
5413	Financial investments debt securities, percentage	Concept (Percent)	As Of		c070:FinancialInvestmentsDebtSecuritiesPercentage
5414	Other assets, percentage	Concept (Percent)	As Of		c070:OtherFinancialAssetsPercentage
5415	Total assets, percentage	Concept (Percent)	As Of		c070:AssetsPercentage
5416	Off-balance sheet	Abstract			c070:OffBalanceSheetAbstract
5417	Contingent liabilities	Concept (Monetary)	As Of		ifrs-full:EstimatedFinancialEffectOfContingentLiabilities
5418	Loan commitments	Concept (Monetary)	As Of	Credit	ifrs-full:GrossLoanCommitments
5419	Total off-balance sheet	Concept (Monetary)	As Of	Credit	c070:CommitmentsGiven
5420	Off-balance sheet percentage [abstract]	Abstract			c070:OffBalanceSheetPercentageAbstract
5421	Contingent liabilities, percentage	Concept (Percent)	As Of		c070:ContingentLiabilitiesPercentage
5422	Loan commitments, percentage	Concept (Percent)	As Of		c070:GrossLoanCommitmentsPercentage
5423	Total off-balance sheet, percentage	Concept (Percent)	As Of		c070:CommitmentsGivenPercentage
5424	044735 - Disclosure - Other disclosures - Risk Management and Principal Risks - Credit exposures by internal PD grade (audited) (Details)	Network	*	*	http://www.barclays.co.uk/role/OtherDisclosuresRiskManagementAndPrincipalRisksCreditExposuresByInternalPDGradeauditedDetails
5425	Disclosure of internal credit grades [table]	Table	*	*	ifrs-full:DisclosureOfInternalCreditExposuresTable
5426	Internal credit grades [axis]	Axis			ifrs-full:InternalCreditGradesAxis
5427	Entity's total for internal credit grades [member]	Member			ifrs-full:EntitysTotalForInternalCreditGradesMember
5428	Internal credit grades [member]	Member			ifrs-full:InternalCreditGradesMember
5429	Strong (including investment grade) [Member]	Member			c070:StrongIncludingInvestmentGradeMember
5430	Satisfactory (BB+ to B) [member]	Member			c070:SatisfactoryBbPlusToBMember
5431	Higher risk (B- and below) [member]	Member			c070:HigherRiskBMinusAndBelowMember
5432	Probability of default [axis]	Axis			ifrs-full:ProbabilityOfDefaultAxis
5433	Entity's total for probability of default [member]	Member			ifrs-full:EntitysTotalForProbabilityOfDefaultMember
5434	0.0 to less than 0.60% [member]	Member			c070:ProbabilityOfDefaultZeroToPointSixtyPercentMember
5435	0.60 to less than 11.35% [member]	Member			c070:ProbabilityOfDefaultPointSixtyToElevenPointThreeFivePercentMember
5436	11.35% to 100% [member]	Member			c070:ProbabilityOfDefaultElevenPointThreeFiveToOneHundredPercentMember
5437	100% [member]	Member			c070:ProbabilityOfDefaultOneHundredPercentMember
5438	Classes of financial instruments [axis]	Axis			ifrs-full:ClassesOfFinancialInstrumentsAxis
5439	Financial instruments, class [member]	Member			ifrs-full:ClassesOfFinancialInstrumentsMember
5440	Contingent liabilities [member]	Member			ifrs-full:ContingentLiabilitiesMember
5441	Loan commitments [member]	Member			ifrs-full:LoanCommitmentsMember
5442	Categories of financial assets [axis]	Axis			ifrs-full:CategoriesOfFinancialAssetsAxis
5443	Financial assets, category [member]	Member			ifrs-full:FinancialAssetsCategoryMember
5444	Loans and advances [member]	Member			ifrs-full:LoansAndReceivablesCategoryMember
5445	Classes of financial assets [axis]	Axis			ifrs-full:ClassesOfFinancialAssetsAxis
5446	Financial assets, class [member]	Member			ifrs-full:FinancialAssetsMember
5447	Financial assets at amortised cost [member]	Member			ifrs-full:FinancialAssetsAtAmortisedCostMember
5448	Carrying amount, accumulated depreciation, amortisation and impairment and gross carrying amount [axis]	Axis			ifrs-full:CarryingAmountAccumulatedDepreciationAmortisationAndImpairmentAndGrossCarryingAmountAxis
5449	Carrying amount [member]	Member			ifrs-full:CarryingAmountMember
5450	Gross exposure [member]	Member			ifrs-full:GrossCarryingAmountMember
5451	Impairment allowance [member]	Member			ifrs-full:AccumulatedImpairmentMember
5452	Type of measurement of expected credit losses [axis]	Axis			ifrs-full:TypeOfMeasurementOfExpectedCreditLossesAxis
5453	Type of measurement of expected credit losses [member]	Member			ifrs-full:TypeOfMeasurementOfExpectedCreditLossesMember
5454	ECL [member]	Member			c070:ExpectedCreditLossesMember
5455	Stage 1 [member]	Member			ifrs-full:TwelvemonthExpectedCreditLossesMember
5456	Lifetime expected credit losses [member]	Member			ifrs-full:LifetimeExpectedCreditLossesMember
5457	Credit impairment of financial instruments [axis]	Axis			ifrs-full:CreditImpairmentOfFinancialInstrumentsAxis
5458	Credit impairment of financial instruments [member]	Member			ifrs-full:CreditImpairmentOfFinancialInstrumentsMember
5459	Stage 2 [member]	Member			ifrs-full:FinancialInstrumentsNotCreditimpairedMember
5460	Credit Impaired - Stage 3 [member]	Member			ifrs-full:FinancialInstrumentsCreditimpairedMember
5461	Consolidated Entities [Axis]	Axis			srt:ConsolidatedEntitiesAxis
5462	Consolidated Entities [Domain]	Member			srt:ConsolidatedEntitiesDomain
5463	Barclays Bank Group [member]	Member			c070:BarclaysBankGroupMember
5464	Disclosure of internal credit grades [line items]	LineItems			ifrs-full:DisclosureOfInternalCreditExposuresLineItems
5465	Credit exposure	Concept (Monetary)	As Of		ifrs-full:CreditExposure
5466	ECL coverage	Concept (Percent)	As Of		ifrs-full:ExpectedCreditLossRate
5467	044736 - Disclosure - Other disclosures - Risk Management and Principal Risks - Credit exposures by internal PD grade (audited) (Narrative) (Details)	Network	*	*	http://www.barclays.co.uk/role/OtherDisclosuresRiskManagementAndPrincipalRisksCreditExposuresByInternalPDGradeauditedNarrativeDetails
5468	Disclosure of reconciliation of changes in loss allowance and explanation of changes in gross carrying amount for financial instruments [table]	Table	*	*	ifrs-full:DisclosureOfReconciliationOfChangesInLossAllowanceAndExplanationOfChangesInGrossCarryingAmountForFinancialInstrumentsTable
5469	Classes of financial assets [axis]	Axis			ifrs-full:ClassesOfFinancialAssetsAxis
5470	Financial assets, class [member]	Member			ifrs-full:FinancialAssetsMember
5471	Financial assets at amortised cost [member]	Member			ifrs-full:FinancialAssetsAtAmortisedCostMember
5472	Financial assets at fair value [member]	Member			ifrs-full:FinancialAssetsAtFairValueMember
5473	Categories of financial assets [axis]	Axis			ifrs-full:CategoriesOfFinancialAssetsAxis
5474	Financial assets, category [member]	Member			ifrs-full:FinancialAssetsCategoryMember
5475	Loans and advances at amortised cost, including off balance sheet loan commitments and financial guarantee contracts [member]	Member			c070:LoansAndAdvancesAtAmortisedCostIncludingOffBalanceSheetLoanCommitmentsAndFinancialGuaranteeContractsMember
5476	Other financial assets subject to impairment [member]	Member			c070:OtherFinancialAssetsSubjectToImpairmentMember
5477	Carrying amount, accumulated depreciation, amortisation and impairment and gross carrying amount [axis]	Axis			ifrs-full:CarryingAmountAccumulatedDepreciationAmortisationAndImpairmentAndGrossCarryingAmountAxis
5478	Carrying amount [member]	Member			ifrs-full:CarryingAmountMember
5479	Gross exposure [member]	Member			ifrs-full:GrossCarryingAmountMember
5480	Impairment allowance [member]	Member			ifrs-full:AccumulatedImpairmentMember
5481	Disclosure of reconciliation of changes in loss allowance and explanation of changes in gross carrying amount for financial instruments [line items]	LineItems			ifrs-full:DisclosureOfReconciliationOfChangesInLossAllowanceAndExplanationOfChangesInGrossCarryingAmountForFinancialInstrumentsLineItems
5482	Exposure to credit risk on loan commitments and financial guarantee contracts	Concept (Monetary)	As Of	Credit	ifrs-full:ExposureToCreditRiskOnLoanCommitmentsAndFinancialGuaranteeContracts
5483	Financial assets	Concept (Monetary)	As Of	Debit	ifrs-full:FinancialAssets
5484	044740 - Disclosure - Other disclosures - Risk Management and Principal Risks - Management VaR (95%, one day) (audited) (Details)	Network	*	*	http://www.barclays.co.uk/role/OtherDisclosuresRiskManagementAndPrincipalRisksManagementVaR95OneDayauditedDetails
5485	Disclosure of nature and extent of risks arising from financial instruments [table]	Table	*	*	ifrs-full:DisclosureOfNatureAndExtentOfRisksArisingFromFinancialInstrumentsTable
5486	Types of risks [axis]	Axis			ifrs-full:TypesOfRisksAxis
5487	Risks [member]	Member			ifrs-full:TypesOfRisksMember
5488	Value at risk [member]	Member			c070:ValueAtRiskMember
5489	Credit risk [member]	Member			ifrs-full:CreditRiskMember
5490	Interest rate risk [member]	Member			ifrs-full:InterestRateRiskMember
5491	Equity price risk [member]	Member			ifrs-full:EquityPriceRiskMember
5492	Basis risk [member]	Member			c070:BasisRiskMember
5493	Spread risk [member]	Member			c070:SpreadRiskMember
5494	Foreign exchange risk [member]	Member			ifrs-full:CurrencyRiskMember
5495	Commodity risk [member]	Member			ifrs-full:CommodityPriceRiskMember
5496	Inflation risk [member]	Member			c070:InflationRiskMember
5497	Diversification effect [member]	Member			ifrs-full:RiskDiversificationEffectMember
5498	Range [axis]	Axis			ifrs-full:RangeAxis
5499	Ranges [member]	Member			ifrs-full:RangesMember
5500	Average [member]	Member			ifrs-full:WeightedAverageMember
5501	High [member]	Member			ifrs-full:TopOfRangeMember
5502	Low [member]	Member			ifrs-full:BottomOfRangeMember
5503	Disclosure of nature and extent of risks arising from financial instruments [line items]	LineItems			ifrs-full:DisclosureOfNatureAndExtentOfRisksArisingFromFinancialInstrumentsLineItems
5504	Methods used to measure risk	Concept (Text/String)	For Period		ifrs-full:MethodsUsedToMeasureRisk
5505	Confidence level used to determine risk adjustment for non-financial risk	Concept (Percent)	As Of		ifrs-full:ConfidenceLevelUsedToDetermineRiskAdjustmentForNonfinancialRisk
5506	Value at risk	Concept (Monetary)	As Of		ifrs-full:ValueAtRisk
5507	044745 - Disclosure - Other disclosures - Risk Management and Principal Risks - Contractural maturity of financial assets and liabilities (audited) (Details)	Network	*	*	http://www.barclays.co.uk/role/OtherDisclosuresRiskManagementAndPrincipalRisksContracturalMaturityOfFinancialAssetsAndLiabilitiesauditedDetails
5508	Disclosure of detailed information about financial instruments [table]	Table	*	*	ifrs-full:DisclosureOfFinancialInstrumentsTable
5509	Maturity [axis]	Axis			ifrs-full:MaturityAxis
5510	Aggregated time bands [member]	Member			ifrs-full:AggregatedTimeBandsMember
5511	On demand [member]	Member			ifrs-full:OnDemandMember
5512	Not more than three months [member]	Member			ifrs-full:NotLaterThanThreeMonthsMember
5513	Over three months but not more than six months [member]	Member			ifrs-full:LaterThanThreeMonthsAndNotLaterThanSixMonthsMember
5514	Over six months and not later than nine months [member]	Member			c070:LaterThanSixMonthsAndNotLaterThanNineMonthsMember
5515	Over nine months and not later than one year [member]	Member			c070:LaterThanNineMonthsAndNotLaterThanOneYearMember
5516	Later than one year and not later than two years [member]	Member			ifrs-full:LaterThanOneYearAndNotLaterThanTwoYearsMember
5517	Later than two years and not later than three years [member]	Member			ifrs-full:LaterThanTwoYearsAndNotLaterThanThreeYearsMember
5518	Over three years but not more than five years [member]	Member			ifrs-full:LaterThanThreeYearsAndNotLaterThanFiveYearsMember
5519	Over five years and not later than ten years [member]	Member			ifrs-full:LaterThanFiveYearsAndNotLaterThanTenYearsMember
5520	Over ten years [member]	Member			ifrs-full:LaterThanTenYearsMember
5521	Consolidated Entities [Axis]	Axis			srt:ConsolidatedEntitiesAxis
5522	Consolidated Entities [Domain]	Member			srt:ConsolidatedEntitiesDomain
5523	Barclays Bank Group [member]	Member			c070:BarclaysBankGroupMember
5524	Disclosure of detailed information about financial instruments [line items]	LineItems			ifrs-full:DisclosureOfFinancialInstrumentsLineItems
5525	Assets [abstract]	Abstract			ifrs-full:AssetsAbstract
5526	Cash and balances at central banks	Concept (Monetary)	As Of	Debit	ifrs-full:CashAndBankBalancesAtCentralBanks
5527	Cash collateral and settlement balances	Concept (Monetary)	As Of	Debit	ifrs-full:BankAcceptanceAssets
5528	Loans and advances at amortised cost	Concept (Monetary)	As Of	Debit	ifrs-full:LoansAndReceivables
5529	Reverse repurchase agreements and other similar secured lending	Concept (Monetary)	As Of	Debit	ifrs-full:ReverseRepurchaseAgreementsAndCashCollateralOnSecuritiesBorrowed
5530	Trading portfolio assets	Concept (Monetary)	As Of	Debit	ifrs-full:FinancialAssetsAtFairValueThroughProfitOrLossClassifiedAsHeldForTrading
5531	Financial assets at fair value through the income statement	Concept (Monetary)	As Of	Debit	ifrs-full:FinancialAssetsAtFairValueThroughProfitOrLoss
5532	Derivative financial instruments	Concept (Monetary)	As Of	Debit	ifrs-full:DerivativeFinancialAssets
5533	Financial assets at fair value through other comprehensive income	Concept (Monetary)	As Of	Debit	ifrs-full:FinancialAssetsAtFairValueThroughOtherComprehensiveIncome
5534	Financial investments	Concept (Monetary)	As Of	Debit	c070:FinancialInvestments
5535	Other financial assets	Concept (Monetary)	As Of	Debit	ifrs-full:OtherFinancialAssets
5536	Total financial assets	Concept (Monetary)	As Of	Debit	ifrs-full:FinancialAssets
5537	Other assets	Concept (Monetary)	As Of	Debit	c070:OtherAssetsIncludingAmountsHeldForSale
5538	Total Assets	Concept (Monetary)	As Of	Debit	ifrs-full:Assets
5539	Liabilities [abstract]	Abstract			ifrs-full:LiabilitiesAbstract
5540	Deposits at amortised cost	Concept (Monetary)	As Of	Credit	c070:DepositsAtAmortisedCost
5541	Cash collateral and settlement balances	Concept (Monetary)	As Of	Credit	ifrs-full:BankAcceptanceLiabilities
5542	Repurchase agreements and other similar secured borrowing	Concept (Monetary)	As Of	Credit	ifrs-full:RepurchaseAgreementsAndCashCollateralOnSecuritiesLent
5543	Debt securities in issue	Concept (Monetary)	As Of	Credit	ifrs-full:DebtSecurities
5544	Subordinated liabilities	Concept (Monetary)	As Of	Credit	ifrs-full:SubordinatedLiabilities
5545	Trading portfolio liabilities	Concept (Monetary)	As Of	Credit	ifrs-full:FinancialLiabilitiesAtFairValueThroughProfitOrLossClassifiedAsHeldForTrading
5546	Financial liabilities designated at fair value	Concept (Monetary)	As Of	Credit	ifrs-full:FinancialLiabilitiesAtFairValueThroughProfitOrLossDesignatedAsUponInitialRecognition
5547	Derivative financial liabilities	Concept (Monetary)	As Of	Credit	ifrs-full:DerivativeFinancialLiabilities
5548	Other financial liabilities	Concept (Monetary)	As Of	Credit	ifrs-full:OtherFinancialLiabilities
5549	Total financial liabilities	Concept (Monetary)	As Of	Credit	ifrs-full:FinancialLiabilities
5550	Other liabilities	Concept (Monetary)	As Of	Credit	c070:OtherLiabilitiesIncludingAmountsHeldForSale
5551	Total liabilities	Concept (Monetary)	As Of	Credit	ifrs-full:Liabilities
5552	Cumulative liquidity gap	Concept (Monetary)	As Of	Credit	ifrs-full:Equity
5553	044746 - Disclosure - Other disclosures - Risk Management and Principal Risks - Contractural maturity of financial assets and liabilities (audited) (Narrative) (Details)	Network	*	*	http://www.barclays.co.uk/role/OtherDisclosuresRiskManagementAndPrincipalRisksContracturalMaturityOfFinancialAssetsAndLiabilitiesauditedNarrativeDetails
5554	Disclosure of detailed information about financial instruments [table]	Table	*	*	ifrs-full:DisclosureOfFinancialInstrumentsTable
5555	Consolidated Entities [Axis]	Axis			srt:ConsolidatedEntitiesAxis
5556	Consolidated Entities [Domain]	Member			srt:ConsolidatedEntitiesDomain
5557	Barclays Bank Group [member]	Member			c070:BarclaysBankGroupMember
5558	Disclosure of detailed information about financial instruments [line items]	LineItems			ifrs-full:DisclosureOfFinancialInstrumentsLineItems
5559	Assets included in disposal groups held for sale	Concept (Monetary)	As Of	Debit	ifrs-full:NoncurrentAssetsOrDisposalGroupsClassifiedAsHeldForSaleOrAsHeldForDistributionToOwners
5560	Liabilities included in disposal groups classified as held for sale	Concept (Monetary)	As Of	Credit	ifrs-full:LiabilitiesIncludedInDisposalGroupsClassifiedAsHeldForSale
5561	044750 - Disclosure - Other disclosures - Risk Management and Principal Risks - Contractural maturity of financial liabilities - undiscounted (audited) (Details)	Network	*	*	http://www.barclays.co.uk/role/OtherDisclosuresRiskManagementAndPrincipalRisksContracturalMaturityOfFinancialLiabilitiesUndiscountedauditedDetails
5562	Disclosure of financial liabilities [table]	Table	*	*	ifrs-full:DisclosureOfFinancialLiabilitiesTable
5563	Maturity [axis]	Axis			ifrs-full:MaturityAxis
5564	Aggregated time bands [member]	Member			ifrs-full:AggregatedTimeBandsMember
5565	On demand [member]	Member			ifrs-full:OnDemandMember
5566	Not more than three months [member]	Member			ifrs-full:NotLaterThanThreeMonthsMember
5567	Over three months but not more than six months [member]	Member			ifrs-full:LaterThanThreeMonthsAndNotLaterThanSixMonthsMember
5568	Over six months and not later than nine months [member]	Member			c070:LaterThanSixMonthsAndNotLaterThanNineMonthsMember
5569	Later than one year and not later than two years [member]	Member			ifrs-full:LaterThanOneYearAndNotLaterThanTwoYearsMember
5570	Over three years but not more than five years [member]	Member			ifrs-full:LaterThanThreeYearsAndNotLaterThanFiveYearsMember
5571	Over five years and not later than ten years [member]	Member			ifrs-full:LaterThanFiveYearsAndNotLaterThanTenYearsMember
5572	Over ten years [member]	Member			ifrs-full:LaterThanTenYearsMember
5573	Consolidated Entities [Axis]	Axis			srt:ConsolidatedEntitiesAxis
5574	Consolidated Entities [Domain]	Member			srt:ConsolidatedEntitiesDomain
5575	Barclays Bank Group [member]	Member			c070:BarclaysBankGroupMember
5576	Disclosure of financial liabilities [line items]	LineItems			ifrs-full:DisclosureOfFinancialLiabilitiesLineItems
5577	Deposits at amortised cost, undiscounted	Concept (Monetary)	As Of	Credit	c070:DepositsAtAmortisedCostUndiscountedCashFlows
5578	Cash collateral and settlement balances, undiscounted	Concept (Monetary)	As Of	Credit	c070:CashCollateralAndSettlementBalanceLiabilitiesUndiscounted
5579	Repurchase agreements and other similar secured lending, undiscounted	Concept (Monetary)	As Of	Credit	c070:RepurchaseAgreementsAndOtherSimilarSecuredLendingUndiscountedCashFlows
5580	Debt securities in issue, undiscounted	Concept (Monetary)	As Of	Credit	c070:DebtSecuritiesInIssueUndiscountedCashFlows
5581	Subordinated liabilities, undiscounted	Concept (Monetary)	As Of	Credit	c070:SubordinatedLiabilitiesUndiscountedCashFlows
5582	Trading portfolio liabilities, undiscounted	Concept (Monetary)	As Of	Credit	c070:FinancialLiabilitiesAtFairValueThroughProfitOrLossClassifiedAsHeldForTradingUndiscountedCashFlows
5583	Financial liabilities designated at fair value, undiscounted	Concept (Monetary)	As Of	Credit	c070:FinancialLiabilitiesAtFairValueThroughProfitOrLossDesignatedAsUponInitialRecognitionUndiscountedCashFlows
5584	Derivative financial instruments, undiscounted	Concept (Monetary)	As Of	Credit	ifrs-full:DerivativeFinancialLiabilitiesUndiscountedCashFlows
5585	Other financial liabilities, undiscounted	Concept (Monetary)	As Of	Credit	c070:OtherFinancialLiabilitiesUndiscountedCashFlows
5586	Total financial liabilities, undiscounted cash flows	Concept (Monetary)	As Of	Credit	c070:FinancialLiabilitiesUndiscountedCashFlows
5587	044755 - Disclosure - Other disclosures - Risk Management and Principal Risks - Maturity analysis of off-balance sheet commitments received (audited) (Details)	Network	*	*	http://www.barclays.co.uk/role/OtherDisclosuresRiskManagementAndPrincipalRisksMaturityAnalysisOfOffbalanceSheetCommitmentsReceivedauditedDetails
5588	Disclosure of contingent liabilities [table]	Table	*	*	ifrs-full:DisclosureOfContingentLiabilitiesTable
5589	Maturity [axis]	Axis			ifrs-full:MaturityAxis
5590	Aggregated time bands [member]	Member			ifrs-full:AggregatedTimeBandsMember
5591	On demand [member]	Member			ifrs-full:OnDemandMember
5592	Not more than three months [member]	Member			ifrs-full:NotLaterThanThreeMonthsMember
5593	Over three months but not more than six months [member]	Member			ifrs-full:LaterThanThreeMonthsAndNotLaterThanSixMonthsMember
5594	Over six months and not later than nine months [member]	Member			c070:LaterThanSixMonthsAndNotLaterThanNineMonthsMember
5595	Over nine months and not later than one year [member]	Member			c070:LaterThanNineMonthsAndNotLaterThanOneYearMember
5596	Later than one year and not later than two years [member]	Member			ifrs-full:LaterThanOneYearAndNotLaterThanTwoYearsMember
5597	Later than two years and not later than three years [member]	Member			ifrs-full:LaterThanTwoYearsAndNotLaterThanThreeYearsMember
5598	Over three years but not more than five years [member]	Member			ifrs-full:LaterThanThreeYearsAndNotLaterThanFiveYearsMember
5599	Over five years and not later than ten years [member]	Member			ifrs-full:LaterThanFiveYearsAndNotLaterThanTenYearsMember
5600	Over ten years [member]	Member			ifrs-full:LaterThanTenYearsMember
5601	Consolidated Entities [Axis]	Axis			srt:ConsolidatedEntitiesAxis
5602	Consolidated Entities [Domain]	Member			srt:ConsolidatedEntitiesDomain
5603	Barclays Bank Group [member]	Member			c070:BarclaysBankGroupMember
5604	Disclosure of contingent liabilities [line items]	LineItems			ifrs-full:DisclosureOfContingentLiabilitiesLineItems
5605	Guarantees, letters of credit and credit insurance	Concept (Monetary)	As Of	Debit	c070:GuaranteesLettersOfCreditAndCreditInsurance
5606	Other commitments received	Concept (Monetary)	As Of	Debit	c070:OtherCommitmentsReceived
5607	Total off-balance sheet commitments received	Concept (Monetary)	As Of		ifrs-full:EstimatedFinancialEffectOfContingentAssets
5608	044760 - Disclosure - Other disclosures - Risk Management and Principal Risks - Maturity analysis of off-balance sheet commitments given (audited) (Details)	Network	*	*	http://www.barclays.co.uk/role/OtherDisclosuresRiskManagementAndPrincipalRisksMaturityAnalysisOfOffbalanceSheetCommitmentsGivenauditedDetails
5609	Disclosure of contingent liabilities [table]	Table	*	*	ifrs-full:DisclosureOfContingentLiabilitiesTable
5610	Maturity [axis]	Axis			ifrs-full:MaturityAxis
5611	Aggregated time bands [member]	Member			ifrs-full:AggregatedTimeBandsMember
5612	On demand [member]	Member			ifrs-full:OnDemandMember
5613	Not more than three months [member]	Member			ifrs-full:NotLaterThanThreeMonthsMember
5614	Over three months but not more than six months [member]	Member			ifrs-full:LaterThanThreeMonthsAndNotLaterThanSixMonthsMember
5615	Over six months and not later than nine months [member]	Member			c070:LaterThanSixMonthsAndNotLaterThanNineMonthsMember
5616	Over nine months and not later than one year [member]	Member			c070:LaterThanNineMonthsAndNotLaterThanOneYearMember
5617	Later than one year and not later than two years [member]	Member			ifrs-full:LaterThanOneYearAndNotLaterThanTwoYearsMember
5618	Later than two years and not later than three years [member]	Member			ifrs-full:LaterThanTwoYearsAndNotLaterThanThreeYearsMember
5619	Over three years but not more than five years [member]	Member			ifrs-full:LaterThanThreeYearsAndNotLaterThanFiveYearsMember
5620	Over five years and not later than ten years [member]	Member			ifrs-full:LaterThanFiveYearsAndNotLaterThanTenYearsMember
5621	Over ten years [member]	Member			ifrs-full:LaterThanTenYearsMember
5622	Consolidated Entities [Axis]	Axis			srt:ConsolidatedEntitiesAxis
5623	Consolidated Entities [Domain]	Member			srt:ConsolidatedEntitiesDomain
5624	Barclays Bank Group [member]	Member			c070:BarclaysBankGroupMember
5625	Disclosure of contingent liabilities [line items]	LineItems			ifrs-full:DisclosureOfContingentLiabilitiesLineItems
5626	Contingent liabilities	Concept (Monetary)	As Of		ifrs-full:EstimatedFinancialEffectOfContingentLiabilities
5627	Documentary credits and other short-term trade related transactions	Concept (Monetary)	As Of	Credit	c070:DocumentaryCreditsAndOtherShortTermTradeRelatedTransactions
5628	Standby facilities, credit lines and other commitments	Concept (Monetary)	As Of	Credit	c070:StandbyFacilitiesCreditLinesAndOtherCommitments
5629	Total off-balance sheet	Concept (Monetary)	As Of	Credit	c070:CommitmentsGiven
5630	044764 - Disclosure - Other disclosures - Risk Management and Principal Risks - Capital resources (audited) (Details)	Network	*	*	http://www.barclays.co.uk/role/OtherDisclosuresRiskManagementAndPrincipalRisksCapitalResourcesauditedDetails
5631	Disclosure of objectives, policies and processes for managing capital [table]	Table	*	*	ifrs-full:DisclosureOfObjectivesPoliciesAndProcessesForManagingCapitalTable
5632	Capital requirements [axis]	Axis			ifrs-full:CapitalRequirementsAxis
5633	Capital requirements [member]	Member			ifrs-full:CapitalRequirementsMember
5634	CET1 Capital [member]	Member			c070:FullyLoadedCommonEquityTierOneCapitalMember
5635	T1 capital [member]	Member			c070:PraTransitionalTierOneCapitalMember
5636	Total regulatory capital [member]	Member			c070:TierTwoCapitalInstrumentsMember
5637	Consolidated Entities [Axis]	Axis			srt:ConsolidatedEntitiesAxis
5638	Consolidated Entities [Domain]	Member			srt:ConsolidatedEntitiesDomain
5639	Barclays Bank PLC [member]	Member			c070:BarclaysBankPlcMember
5640	Disclosure of objectives, policies and processes for managing capital [line items]	LineItems			ifrs-full:DisclosureOfObjectivesPoliciesAndProcessesForManagingCapitalLineItems
5641	PRA transitional regulatory capital	Concept (Monetary)	As Of	Credit	c070:PraTransitionalRegulatoryCapital
5642	044765 - Disclosure - Other disclosures - Risk Management and Principal Risks - Functional currency of operations (audited) (Details)	Network	*	*	http://www.barclays.co.uk/role/OtherDisclosuresRiskManagementAndPrincipalRisksFunctionalCurrencyOfOperationsauditedDetails
5643	Disclosure of risk management strategy related to hedge accounting [table]	Table	*	*	ifrs-full:DisclosureOfRiskManagementStrategyRelatedToHedgeAccountingTable
5644	Types of risks [axis]	Axis			ifrs-full:TypesOfRisksAxis
5645	Risks [member]	Member			ifrs-full:TypesOfRisksMember
5646	Foreign exchange risk [member]	Member			ifrs-full:CurrencyRiskMember
5647	USD [Member]	Member			currency:USD
5648	EUR [Member]	Member			currency:EUR
5649	ZAR [Member]	Member			currency:ZAR
5650	JPY [Member]	Member			currency:JPY
5651	Other [member]	Member			c070:OtherCurrencyMember
5652	Consolidated Entities [Axis]	Axis			srt:ConsolidatedEntitiesAxis
5653	Consolidated Entities [Domain]	Member			srt:ConsolidatedEntitiesDomain
5654	Barclays Bank Group [member]	Member			c070:BarclaysBankGroupMember
5655	Disclosure of risk management strategy related to hedge accounting [line items]	LineItems			ifrs-full:DisclosureOfRiskManagementStrategyRelatedToHedgeAccountingLineItems
5656	Foreign currency net investments, hedged item	Concept (Monetary)	As Of	Debit	c070:ForeignCurrencyNetInvestmentsHedgedItem
5657	Borrowings which hedge net investments	Concept (Monetary)	As Of	Credit	c070:BorrowingsWhichHedgeNetInvestmentsHedges
5658	Derivatives which hedge the net investments	Concept (Monetary)	As Of	Credit	c070:DerivativesWhichHedgeTheNetInvestmentsHedges
5659	Structural currency exposures pre-economic hedges	Concept (Monetary)	As Of	Debit	c070:StructuralCurrencyExposuresBeforeHedgingInstruments
5660	Economic hedges	Concept (Monetary)	As Of		ifrs-full:FinancialInstrumentsDesignatedAsHedgingInstrumentsAtFairValue
5661	Remaining structural currency exposures	Concept (Monetary)	As Of	Debit	c070:StructuralCurrencyExposuresNetOfHedgingInstruments
5662	044766 - Disclosure - Other disclosures - Risk Management and Principal Risks - Functional currency of operations (audited) (Narrative) (Details)	Network	*	*	http://www.barclays.co.uk/role/OtherDisclosuresRiskManagementAndPrincipalRisksFunctionalCurrencyOfOperationsauditedNarrativeDetails
5663	Disclosure of risk management strategy related to hedge accounting [table]	Table	*	*	ifrs-full:DisclosureOfRiskManagementStrategyRelatedToHedgeAccountingTable
5664	Types of risks [axis]	Axis			ifrs-full:TypesOfRisksAxis
5665	Risks [member]	Member			ifrs-full:TypesOfRisksMember
5666	Foreign exchange risk [member]	Member			ifrs-full:CurrencyRiskMember
5667	Consolidated Entities [Axis]	Axis			srt:ConsolidatedEntitiesAxis
5668	Consolidated Entities [Domain]	Member			srt:ConsolidatedEntitiesDomain
5669	Barclays Bank Group [member]	Member			c070:BarclaysBankGroupMember
5670	Disclosure of risk management strategy related to hedge accounting [line items]	LineItems			ifrs-full:DisclosureOfRiskManagementStrategyRelatedToHedgeAccountingLineItems
5671	Decrease in structural currency exposures, net of hedging instruments	Concept (Monetary)	For Period	Credit	c070:IncreaseDecreaseInStructuralCurrencyExposuresNetOfHedgingInstruments
5672	Structural currency exposures, net of hedging instruments	Concept (Monetary)	As Of	Debit	c070:StructuralCurrencyExposuresNetOfHedgingInstruments
5673	Decrease in foreign currency net investments, hedged item	Concept (Monetary)	For Period	Debit	c070:IncreaseDecreaseInForeignCurrencyNetInvestmentsHedgedItem
5674	Foreign currency net investments, hedged item	Concept (Monetary)	As Of	Debit	c070:ForeignCurrencyNetInvestmentsHedgedItem
5675	Financial instruments which hedge net investments, Hedges	Concept (Monetary)	As Of	Credit	c070:FinancialInstrumentsWhichHedgeTheNetInvestmentsHedges
5676	Decrease in financial instruments which hedge net investments, Hedges	Concept (Monetary)	For Period	Credit	c070:IncreaseDecreaseInFinancialInstrumentsWhichHedgeNetInvestmentsHedges
5677	044776 - Disclosure - Other disclosures - Risk Management and Principal Risks - Analysis of equity sensitivity (audited) (Details)	Network	*	*	http://www.barclays.co.uk/role/OtherDisclosuresRiskManagementAndPrincipalRisksAnalysisOfEquitySensitivityauditedDetails
5678	Disclosure of sensitivity analysis to changes in risk exposures that arise from contracts within scope of IFRS 17 [table]	Table	*	*	ifrs-full:DisclosureOfSensitivityAnalysisToChangesInRiskExposuresThatAriseFromContractsWithinScopeOfIFRS17Table
5679	Types of risks [axis]	Axis			ifrs-full:TypesOfRisksAxis
5680	Risks [member]	Member			ifrs-full:TypesOfRisksMember
5681	Interest rate risk [member]	Member			ifrs-full:InterestRateRiskMember
5682	Risk exposures [axis]	Axis			ifrs-full:RiskExposuresAxis
5683	Risk exposures [member]	Member			ifrs-full:RiskExposuresMember
5684	+/- 25bps [member]	Member			c070:TwentyFiveBasisPointsSensitivityAnalysisMember
5685	Components of equity [axis]	Axis			ifrs-full:ComponentsOfEquityAxis
5686	Equity [member]	Member			ifrs-full:EquityMember
5687	Retained earnings [member]	Member			ifrs-full:RetainedEarningsMember
5688	Taxation effects on the above [member]	Member			c070:TaxExpenseIncomeMember
5689	Reserve of gains and losses on remeasuring available-for-sale financial assets [member]	Member			ifrs-full:ReserveOfGainsAndLossesOnRemeasuringAvailableforsaleFinancialAssetsMember
5690	Reserve of cash flow hedges [member]	Member			ifrs-full:ReserveOfCashFlowHedgesMember
5691	Equity attributable to owners of parent [member]	Member			ifrs-full:EquityAttributableToOwnersOfParentMember
5692	Disclosure of sensitivity analysis to changes in risk exposures that arise from contracts within scope of IFRS 17 [line items]	LineItems			ifrs-full:DisclosureOfSensitivityAnalysisToChangesInRiskExposuresThatAriseFromContractsWithinScopeOfIFRS17LineItems
5693	Effect on profit for the year, increase	Concept (Monetary)	For Period	Credit	ifrs-full:IncreaseDecreaseInProfitLossDueToReasonablyPossibleIncreaseInRiskExposureThatArisesFromContractsWithinScopeOfIFRS17
5694	Effect on profit for the year, decrease	Concept (Monetary)	For Period	Credit	ifrs-full:IncreaseDecreaseInProfitLossDueToReasonablyPossibleDecreaseInRiskExposureThatArisesFromContractsWithinScopeOfIFRS17
5695	As percentage, increase	Concept (Percent)	As Of		ifrs-full:PercentageOfReasonablyPossibleIncreaseInRiskExposureThatArisesFromContractsWithinScopeOfIFRS17
5696	As percentage, decrease	Concept (Percent)	As Of		ifrs-full:PercentageOfReasonablyPossibleDecreaseInRiskExposureThatArisesFromContractsWithinScopeOfIFRS17
5697	Effect on equity, increase	Concept (Monetary)	As Of	Credit	ifrs-full:IncreaseDecreaseInEquityDueToReasonablyPossibleIncreaseInRiskExposureThatArisesFromContractsWithinScopeOfIFRS17
5698	Effect on equity, decrease	Concept (Monetary)	As Of	Credit	ifrs-full:IncreaseDecreaseInEquityDueToReasonablyPossibleDecreaseInRiskExposureThatArisesFromContractsWithinScopeOfIFRS17