KT Corporation (SEC Filing Page | XBRL Cloud Viewer | XBRL Instance)

Line	Label	Object Class	Period Type	Balance	Report ElementName
1	1001 - Document - Document and Entity Information	Network	*	*	http://www.kt.com/taxonomy/role/DocumentandEntityInformation
2	Implied Table	Table	*	*	implied:Table
3	Document and entity information [abstract]	Abstract			kt: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	Trading Symbol	Concept (Text/String)	For Period		dei:TradingSymbol
10	Entity Registrant Name	Concept (Text/String)	For Period		dei:EntityRegistrantName
11	Entity Central Index Key	Concept (CIK Number)	For Period		dei:EntityCentralIndexKey
12	Current Fiscal Year End Date	Concept (Month/Day)	For Period		dei:CurrentFiscalYearEndDate
13	Entity Well-known Seasoned Issuer	Concept (Yes/No)	For Period		dei:EntityWellKnownSeasonedIssuer
14	Entity Current Reporting Status	Concept (Yes/No)	For Period		dei:EntityCurrentReportingStatus
15	Entity Filer Category	Concept (Filer Category)	For Period		dei:EntityFilerCategory
16	Entity Emerging Growth Company	Concept (Yes/No)	For Period		dei:EntityEmergingGrowthCompany
17	Entity Shell Company	Concept (Yes/No)	For Period		dei:EntityShellCompany
18	Entity Ex Transition Period	Concept (Yes/No)	For Period		dei:EntityExTransitionPeriod
19	Entity Common Stock, Shares Outstanding	Concept (Shares)	As Of		dei:EntityCommonStockSharesOutstanding
20	1003 - Statement - Consolidated Statements of Financial Position	Network	*	*	http://www.kt.com/taxonomy/role/StatementOfFinancialPositionCurrentNonCurrent-210000
21	Implied Table	Table	*	*	implied:Table
22	Statement of financial position [abstract]	Abstract			ifrs-full:StatementOfFinancialPositionAbstract
23	Assets	Abstract			ifrs-full:AssetsAbstract
24	Current assets	Abstract			ifrs-full:CurrentAssetsAbstract
25	Cash and cash equivalents	Concept (Monetary)	As Of	Debit	ifrs-full:CashAndCashEquivalents
26	Trade and other receivables, net	Concept (Monetary)	As Of	Debit	ifrs-full:TradeAndOtherCurrentReceivables
27	Other financial assets	Concept (Monetary)	As Of	Debit	ifrs-full:OtherCurrentFinancialAssets
28	Current income tax assets	Concept (Monetary)	As Of	Debit	ifrs-full:CurrentTaxAssetsCurrent
29	Inventories, net	Concept (Monetary)	As Of	Debit	ifrs-full:Inventories
30	Current assets held for sale	Concept (Monetary)	As Of	Debit	ifrs-full:CurrentFinancialAssetsAtFairValueThroughProfitOrLossClassifiedAsHeldForTrading
31	Other current assets	Concept (Monetary)	As Of	Debit	ifrs-full:OtherCurrentAssets
32	Current assets	Concept (Monetary)	As Of	Debit	ifrs-full:CurrentAssets
33	Non-current assets	Abstract			ifrs-full:NoncurrentAssetsAbstract
34	Trade and other receivables, net	Concept (Monetary)	As Of	Debit	ifrs-full:NoncurrentReceivables
35	Other financial assets	Concept (Monetary)	As Of	Debit	ifrs-full:OtherNoncurrentFinancialAssets
36	Property and equipment, net	Concept (Monetary)	As Of	Debit	ifrs-full:PropertyPlantAndEquipment
37	Investment properties, net	Concept (Monetary)	As Of	Debit	kt:InvestmentPropertyNet
38	Intangible assets, net	Concept (Monetary)	As Of	Debit	ifrs-full:IntangibleAssetsAndGoodwill
39	Investments in associates and joint ventures	Concept (Monetary)	As Of	Debit	ifrs-full:InvestmentAccountedForUsingEquityMethod
40	Deferred income tax assets	Concept (Monetary)	As Of	Debit	ifrs-full:DeferredTaxAssets
41	Other non-current assets	Concept (Monetary)	As Of	Debit	ifrs-full:OtherNoncurrentNonfinancialAssets
42	Non-current assets	Concept (Monetary)	As Of	Debit	ifrs-full:NoncurrentAssets
43	Total assets	Concept (Monetary)	As Of	Debit	ifrs-full:Assets
44	Liabilities	Abstract			ifrs-full:LiabilitiesAbstract
45	Current liabilities	Abstract			ifrs-full:CurrentLiabilitiesAbstract
46	Trade and other payables	Concept (Monetary)	As Of	Credit	ifrs-full:TradeAndOtherCurrentPayables
47	Borrowings	Concept (Monetary)	As Of	Credit	ifrs-full:CurrentBorrowingsAndCurrentPortionOfNoncurrentBorrowings
48	Other financial liabilities	Concept (Monetary)	As Of	Credit	ifrs-full:OtherCurrentFinancialLiabilities
49	Current income tax liabilities	Concept (Monetary)	As Of	Credit	ifrs-full:CurrentTaxLiabilitiesCurrent
50	Provisions	Concept (Monetary)	As Of	Credit	ifrs-full:OtherShorttermProvisions
51	Deferred revenue	Concept (Monetary)	As Of	Credit	ifrs-full:DeferredIncomeClassifiedAsCurrent
52	Other current liabilities	Concept (Monetary)	As Of	Credit	ifrs-full:OtherCurrentNonfinancialLiabilities
53	Current liabilities	Concept (Monetary)	As Of	Credit	ifrs-full:CurrentLiabilities
54	Non-current liabilities	Abstract			ifrs-full:NoncurrentLiabilitiesAbstract
55	Trade and other payables	Concept (Monetary)	As Of	Credit	ifrs-full:NoncurrentPayables
56	Borrowings	Concept (Monetary)	As Of	Credit	ifrs-full:LongtermBorrowings
57	Other financial liabilities	Concept (Monetary)	As Of	Credit	ifrs-full:OtherNoncurrentFinancialLiabilities
58	Defined benefit liabilities, net	Concept (Monetary)	As Of	Credit	ifrs-full:NoncurrentRecognisedLiabilitiesDefinedBenefitPlan
59	Provisions	Concept (Monetary)	As Of	Credit	ifrs-full:OtherLongtermProvisions
60	Deferred revenue	Concept (Monetary)	As Of	Credit	ifrs-full:DeferredIncomeClassifiedAsNoncurrent
61	Deferred income tax liabilities	Concept (Monetary)	As Of	Credit	ifrs-full:DeferredTaxLiabilities
62	Other non-current liabilities	Concept (Monetary)	As Of	Credit	ifrs-full:OtherNoncurrentNonfinancialLiabilities
63	Non-current liabilities	Concept (Monetary)	As Of	Credit	ifrs-full:NoncurrentLiabilities
64	Total liabilities	Concept (Monetary)	As Of	Credit	ifrs-full:Liabilities
65	Equity	Abstract			ifrs-full:EquityAbstract
66	Share capital	Concept (Monetary)	As Of	Credit	ifrs-full:IssuedCapital
67	Share premium	Concept (Monetary)	As Of	Credit	ifrs-full:SharePremium
68	Retained earnings	Concept (Monetary)	As Of	Credit	ifrs-full:RetainedEarnings
69	Accumulated other comprehensive income	Concept (Monetary)	As Of	Credit	ifrs-full:AccumulatedOtherComprehensiveIncome
70	Other components of equity	Concept (Monetary)	As Of	Credit	ifrs-full:OtherEquityInterest
71	Equity attributable to owners of the Controlling Company	Concept (Monetary)	As Of	Credit	ifrs-full:EquityAttributableToOwnersOfParent
72	Non-controlling interest	Concept (Monetary)	As Of	Credit	ifrs-full:NoncontrollingInterests
73	Total equity	Concept (Monetary)	As Of	Credit	ifrs-full:Equity
74	Total liabilities and equity	Concept (Monetary)	As Of	Credit	ifrs-full:EquityAndLiabilities
75	1004 - Statement - Consolidated Statements of Operations	Network	*	*	http://www.kt.com/taxonomy/role/StatementOfComprehensiveIncomeProfitOrLossByFunctionOfExpense-310000
76	Implied Table	Table	*	*	implied:Table
77	Profit or loss [abstract]	Abstract			ifrs-full:IncomeStatementAbstract
78	Operating revenue	Concept (Monetary)	For Period	Credit	ifrs-full:Revenue
79	Revenue	Concept (Monetary)	For Period	Credit	kt:RevenueFromProductsAndServices
80	Others	Concept (Monetary)	For Period	Credit	ifrs-full:OtherRevenue
81	Operating expenses	Concept (Monetary)	For Period	Debit	ifrs-full:OperatingExpense
82	Operating profit	Concept (Monetary)	For Period	Credit	ifrs-full:ProfitLossFromOperatingActivities
83	Finance income	Concept (Monetary)	For Period	Credit	ifrs-full:FinanceIncome
84	Finance costs	Concept (Monetary)	For Period	Debit	ifrs-full:FinanceCosts
85	Share of net profit (losses) of associates and joint venture	Concept (Monetary)	For Period	Credit	ifrs-full:ShareOfProfitLossOfAssociatesAndJointVenturesAccountedForUsingEquityMethod
86	Profit before income tax	Concept (Monetary)	For Period	Credit	ifrs-full:ProfitLossBeforeTax
87	Income tax expense	Concept (Monetary)	For Period	Debit	ifrs-full:IncomeTaxExpenseContinuingOperations
88	Profit for the year	Concept (Monetary)	For Period	Credit	ifrs-full:ProfitLoss
89	Profit for the year attributable to:	Abstract			ifrs-full:ProfitLossAttributableToAbstract
90	Profit (loss) for the year attributable to Owners of the Controlling Company	Concept (Monetary)	For Period	Credit	ifrs-full:ProfitLossAttributableToOwnersOfParent
91	Profit (loss) for the year attributable to Non-controlling interest	Concept (Monetary)	For Period	Credit	ifrs-full:ProfitLossAttributableToNoncontrollingInterests
92	Earnings per share attributable to the equity holders of the Controlling Company during the year (in Korean won):	Abstract			ifrs-full:EarningsPerShareAbstract
93	Basic earnings per share	Concept (Share)	For Period		ifrs-full:BasicEarningsLossPerShare
94	Diluted earnings per share	Concept (Share)	For Period		ifrs-full:DilutedEarningsLossPerShare
95	1005 - Statement - Consolidated Statements of Comprehensive Income	Network	*	*	http://www.kt.com/taxonomy/role/StatementOfComprehensiveIncomeOCIComponentsPresentedNetOfTax-410000
96	Implied Table	Table	*	*	implied:Table
97	Statement of comprehensive income [abstract]	Abstract			ifrs-full:StatementOfComprehensiveIncomeAbstract
98	Profit for the year	Concept (Monetary)	For Period	Credit	ifrs-full:ProfitLoss
99	Other comprehensive income Items that will not be reclassified to profit or loss:	Abstract			ifrs-full:ComponentsOfOtherComprehensiveIncomeThatWillNotBeReclassifiedToProfitOrLossNetOfTaxAbstract
100	Remeasurements of the net defined benefit liability	Concept (Monetary)	For Period	Credit	ifrs-full:OtherComprehensiveIncomeNetOfTaxGainsLossesOnRemeasurementsOfDefinedBenefitPlans
101	Shares of remeasurement gain (loss) of associates and joint ventures	Concept (Monetary)	For Period	Credit	ifrs-full:ShareOfOtherComprehensiveIncomeOfAssociatesAndJointVenturesAccountedForUsingEquityMethodThatWillNotBeReclassifiedToProfitOrLossNetOfTax
102	Gain on valuation of equity instruments at fair value through other comprehensive income	Concept (Monetary)	For Period	Credit	ifrs-full:OtherComprehensiveIncomeNetOfTaxGainsLossesFromInvestmentsInEquityInstruments
103	Other comprehensive income, Items that may be subsequently reclassified to profit or loss:	Abstract			ifrs-full:ComponentsOfOtherComprehensiveIncomeThatWillBeReclassifiedToProfitOrLossNetOfTaxAbstract
104	Gain on valuation of debt instruments at fair value through other comprehensive income	Concept (Monetary)	For Period	Credit	kt:GainsLossesOnOtherFinancialAssetsMeasuredAtFairValueThroughOtherComprehensiveIncomeNetOfTax
105	Changes in value of available-for-sale financial assets	Concept (Monetary)	For Period	Credit	ifrs-full:GainsLossesOnRemeasuringAvailableforsaleFinancialAssetsNetOfTax
106	Other comprehensive income from available-for sale financial assets reclassified to loss	Concept (Monetary)	For Period	Debit	ifrs-full:ReclassificationAdjustmentsOnAvailableforsaleFinancialAssetsNetOfTax
107	Valuation gain (loss) on cash flow hedge	Concept (Monetary)	For Period	Credit	ifrs-full:GainsLossesOnCashFlowHedgesNetOfTax
108	Other comprehensive income (loss) from cash flow hedges reclassified to profit (loss)	Concept (Monetary)	For Period	Debit	ifrs-full:ReclassificationAdjustmentsOnCashFlowHedgesNetOfTax
109	Share of other comprehensive income (loss) from associates and joint ventures	Concept (Monetary)	For Period	Credit	ifrs-full:ShareOfOtherComprehensiveIncomeOfAssociatesAndJointVenturesAccountedForUsingEquityMethodThatWillBeReclassifiedToProfitOrLossNetOfTax
110	Exchange differences on translation of foreign operations	Concept (Monetary)	For Period	Credit	ifrs-full:OtherComprehensiveIncomeNetOfTaxExchangeDifferencesOnTranslation
111	Total other comprehensive loss	Concept (Monetary)	For Period	Credit	ifrs-full:OtherComprehensiveIncome
112	Total comprehensive income for the year	Concept (Monetary)	For Period	Credit	ifrs-full:ComprehensiveIncome
113	Total comprehensive income for the year attributable to:	Abstract			ifrs-full:ComprehensiveIncomeAttributableToAbstract
114	Owners of the Controlling Company	Concept (Monetary)	For Period	Credit	ifrs-full:ComprehensiveIncomeAttributableToOwnersOfParent
115	Non-controlling interest	Concept (Monetary)	For Period	Credit	ifrs-full:ComprehensiveIncomeAttributableToNoncontrollingInterests
116	Total comprehensive income for the year	Concept (Monetary)	For Period	Credit	ifrs-full:ComprehensiveIncome
117	1006 - Statement - Consolidated Statements of Changes in Equity	Network	*	*	http://www.kt.com/taxonomy/role/StatementOfChangesInEquity-610000
118	Statement of changes in equity [table]	Table	*	*	ifrs-full:StatementOfChangesInEquityTable
119	Components of equity [axis]	Axis			ifrs-full:ComponentsOfEquityAxis
120	Equity [member]	Member			ifrs-full:EquityMember
121	Share capital [member]	Member			ifrs-full:IssuedCapitalMember
122	Share premium [member]	Member			ifrs-full:SharePremiumMember
123	Retained earnings [member]	Member			ifrs-full:RetainedEarningsMember
124	Accumulated other comprehensive income [member]	Member			ifrs-full:AccumulatedOtherComprehensiveIncomeMember
125	Other components of equity [member]	Member			ifrs-full:OtherEquityInterestMember
126	Total attributable to owners of the Controlling Company [member]	Member			ifrs-full:EquityAttributableToOwnersOfParentMember
127	Non-controlling interest [member]	Member			ifrs-full:NoncontrollingInterestsMember
128	Retrospective application and retrospective restatement [axis]	Axis			ifrs-full:RetrospectiveApplicationAndRetrospectiveRestatementAxis
129	Currently stated [member]	Member			ifrs-full:RestatedMember
130	As previously reported [member]	Member			ifrs-full:PreviouslyStatedMember
131	Adjusted [member]	Member			kt:AdjustedMember
132	Increase (decrease) due to changes in accounting policy required by IFRSs [member]	Member			ifrs-full:IncreaseDecreaseDueToChangesInAccountingPolicyRequiredByIFRSsMember
133	Statement of changes in equity [line items]	LineItems			ifrs-full:StatementOfChangesInEquityLineItems
134	Beginning balance	Concept (Monetary)	As Of	Credit	ifrs-full:Equity
135	Comprehensive income	Abstract			ifrs-full:ComprehensiveIncomeAbstract
136	Profit for the year	Concept (Monetary)	For Period	Credit	ifrs-full:ProfitLoss
137	Changes in value of available-for-sale financial assets	Concept (Monetary)	For Period	Credit	ifrs-full:OtherComprehensiveIncomeNetOfTaxAvailableforsaleFinancialAssets
138	Remeasurements of net defined benefit liability	Concept (Monetary)	For Period	Credit	ifrs-full:OtherComprehensiveIncomeNetOfTaxGainsLossesOnRemeasurementsOfDefinedBenefitPlans
139	Shares of remeasurement gain (loss) of associates and joint ventures	Concept (Monetary)	For Period	Credit	ifrs-full:ShareOfOtherComprehensiveIncomeOfAssociatesAndJointVenturesAccountedForUsingEquityMethodThatWillNotBeReclassifiedToProfitOrLossNetOfTax
140	Shares of other comprehensive income (losses) of joint ventures and associates	Concept (Monetary)	For Period	Credit	ifrs-full:ShareOfOtherComprehensiveIncomeOfAssociatesAndJointVenturesAccountedForUsingEquityMethodThatWillBeReclassifiedToProfitOrLossNetOfTax
141	Valuation gains (losses) on cashflow hedge	Concept (Monetary)	For Period	Credit	ifrs-full:OtherComprehensiveIncomeNetOfTaxCashFlowHedges
142	Gain(loss) on disposal of equity instruments at fair value through other comprehensive income	Concept (Monetary)	For Period	Credit	ifrs-full:CumulativeGainLossOnDisposalOfInvestmentsInEquityInstrumentsDesignatedAsMeasuredAtFairValueThroughOtherComprehensiveIncome
143	Gain on valuation of financial instruments at fair value through other comprehensive income	Concept (Monetary)	For Period	Credit	ifrs-full:OtherComprehensiveIncomeNetOfTaxFinancialAssetsMeasuredAtFairValueThroughOtherComprehensiveIncome
144	Exchange differences on translation of foreign operations	Concept (Monetary)	For Period	Credit	ifrs-full:OtherComprehensiveIncomeNetOfTaxExchangeDifferencesOnTranslation
145	Total comprehensive income for the year	Concept (Monetary)	For Period	Credit	ifrs-full:ComprehensiveIncome
146	Transactions with equity holders	Abstract			kt:TransactionsWithOwnersAbstract
147	Dividends paid by the Controlling Company	Concept (Monetary)	For Period	Debit	ifrs-full:DividendsRecognisedAsDistributionsToOwnersOfParent
148	Dividends paid to non-controlling interest of subsidiaries	Concept (Monetary)	For Period	Debit	ifrs-full:DividendsRecognisedAsDistributionsToNoncontrollingInterests
149	Changes in consolidation scope	Concept (Monetary)	For Period	Credit	ifrs-full:IncreaseDecreaseThroughChangeInEquityOfSubsidiaries
150	Change in ownership interest in subsidiaries	Concept (Monetary)	For Period	Credit	ifrs-full:IncreaseDecreaseThroughChangesInOwnershipInterestsInSubsidiariesThatDoNotResultInLossOfControl
151	Appropriation of loss on disposal of treasury stock	Concept (Monetary)	For Period	Credit	ifrs-full:IncreaseDecreaseThroughTreasuryShareTransactions
152	Disposal of treasury stock	Concept (Monetary)	For Period	Credit	ifrs-full:CancellationOfTreasuryShares
153	Others	Concept (Monetary)	For Period	Credit	ifrs-full:IncreaseDecreaseThroughTransfersAndOtherChangesEquity
154	Subtotal	Concept (Monetary)	For Period	Credit	kt:TransactionsWithOwners
155	Ending balance	Concept (Monetary)	As Of	Credit	ifrs-full:Equity
156	1007 - Statement - Consolidated Statements of Cash Flows	Network	*	*	http://www.kt.com/taxonomy/role/StatementOfCashFlowsIndirectMethod-520000
157	Implied Table	Table	*	*	implied:Table
158	Statement of cash flows [abstract]	Abstract			ifrs-full:StatementOfCashFlowsAbstract
159	Cash flows from operating activities	Abstract			ifrs-full:CashFlowsFromUsedInOperatingActivitiesAbstract
160	Cash generated from operations	Concept (Monetary)	For Period		ifrs-full:CashFlowsFromUsedInOperations
161	Interest paid	Concept (Monetary)	For Period	Credit	ifrs-full:InterestPaidClassifiedAsOperatingActivities
162	Interest received	Concept (Monetary)	For Period	Debit	ifrs-full:InterestReceivedClassifiedAsOperatingActivities
163	Dividends received	Concept (Monetary)	For Period	Debit	ifrs-full:DividendsReceivedClassifiedAsOperatingActivities
164	Income tax paid	Concept (Monetary)	For Period	Credit	ifrs-full:IncomeTaxesPaidClassifiedAsOperatingActivities
165	Net cash inflow from operating activities	Concept (Monetary)	For Period		ifrs-full:CashFlowsFromUsedInOperatingActivities
166	Cash flows from investing activities	Abstract			ifrs-full:CashFlowsFromUsedInInvestingActivitiesAbstract
167	Collection of loans	Concept (Monetary)	For Period	Debit	ifrs-full:CashReceiptsFromRepaymentOfAdvancesAndLoansMadeToOtherPartiesClassifiedAsInvestingActivities
168	Loans granted	Concept (Monetary)	For Period	Credit	ifrs-full:CashAdvancesAndLoansMadeToOtherPartiesClassifiedAsInvestingActivities
169	Disposal of financial assets at fair value through profit or loss	Concept (Monetary)	For Period	Debit	kt:ProceedsFromDisposalOfFinancialAssetsAtFairValueThroughProfitOrLoss
170	Disposal of financial assets at amortized cost	Concept (Monetary)	For Period	Debit	kt:ProceedsFromDisposalOfFinancialAssetsAtAmortizedCost
171	Disposal of financial assets at fair value through other comprehensive income	Concept (Monetary)	For Period	Debit	kt:ProceedsFromDisposalOfFinancialAssetsAtFairValueThroughOtherComprehensiveIncome
172	Disposal of assets held-for-sale	Concept (Monetary)	For Period	Debit	ifrs-full:ProceedsFromDisposalOfNoncurrentAssetsOrDisposalGroupsClassifiedAsHeldForSaleAndDiscontinuedOperations
173	Disposal of available-for-sale financial assets	Concept (Monetary)	For Period	Debit	ifrs-full:ProceedsFromDisposalOrMaturityOfAvailableforsaleFinancialAssets
174	Acquisition of available-for-sale financial assets	Concept (Monetary)	For Period	Credit	ifrs-full:PurchaseOfAvailableforsaleFinancialAssets
175	Disposal of investments in associates and joint ventures	Concept (Monetary)	For Period	Debit	ifrs-full:ProceedsFromSalesOfInvestmentsAccountedForUsingEquityMethod
176	Acquisition of investments in associates and joint ventures	Concept (Monetary)	For Period	Credit	ifrs-full:PurchaseOfInterestsInInvestmentsAccountedForUsingEquityMethod
177	Disposal of current and non-current financial instruments	Concept (Monetary)	For Period	Debit	ifrs-full:ProceedsFromSalesOrMaturityOfFinancialInstrumentsClassifiedAsInvestingActivities
178	Acquisition of current and non-current financial instruments	Concept (Monetary)	For Period	Credit	ifrs-full:PurchaseOfFinancialInstrumentsClassifiedAsInvestingActivities
179	Disposal of property and equipment, and investment properties	Concept (Monetary)	For Period	Debit	ifrs-full:ProceedsFromDisposalsOfPropertyPlantAndEquipmentIntangibleAssetsOtherThanGoodwillInvestmentPropertyAndOtherNoncurrentAssets
180	Acquisition of property and equipment, and investment properties	Concept (Monetary)	For Period	Credit	ifrs-full:PurchaseOfPropertyPlantAndEquipmentIntangibleAssetsOtherThanGoodwillInvestmentPropertyAndOtherNoncurrentAssets
181	Acquisition of financial assets at fair value through profit or loss	Concept (Monetary)	For Period	Credit	kt:PurchaseOfFinancialAssetsAtFairValueThroughProfitOrLoss
182	Acquisition of financial assets at amortized cost	Concept (Monetary)	For Period	Credit	kt:PurchaseOfFinancialAssetsAtAmortizedCost
183	Acquisition of financial assets at fair value through other comprehensive income	Concept (Monetary)	For Period	Credit	kt:PurchaseOfFinancialAssetsAtFairValueThroughOtherComprehensiveIncome
184	Disposal of intangible assets	Concept (Monetary)	For Period	Debit	ifrs-full:ProceedsFromSalesOfIntangibleAssetsClassifiedAsInvestingActivities
185	Acquisition of intangible assets	Concept (Monetary)	For Period	Credit	ifrs-full:PurchaseOfIntangibleAssetsClassifiedAsInvestingActivities
186	Decrease in cash due to business combination, etc.	Concept (Monetary)	For Period	Debit	ifrs-full:CashAndCashEquivalentsInSubsidiaryOrBusinessesAcquiredOrDisposed2013
187	Net cash outflow from investing activities	Concept (Monetary)	For Period	Debit	ifrs-full:CashFlowsFromUsedInInvestingActivities
188	Cash flows from financing activities	Abstract			ifrs-full:CashFlowsFromUsedInFinancingActivitiesAbstract
189	Proceeds from borrowings and debentures	Concept (Monetary)	For Period	Debit	ifrs-full:ProceedsFromBorrowingsClassifiedAsFinancingActivities
190	Repayments of borrowings and debentures	Concept (Monetary)	For Period	Credit	ifrs-full:RepaymentsOfBorrowingsClassifiedAsFinancingActivities
191	Settlement of derivative assets and liabilities, net	Concept (Monetary)	For Period	Debit	kt:ProceedsFromPaymentsForSettlementOfDerivativeAssetsAndLiabilities
192	Cash inflow from consolidated capital transactions	Concept (Monetary)	For Period	Debit	ifrs-full:ProceedsFromContributionsOfNoncontrollingInterests
193	Cash outflow from consolidated capital transactions	Concept (Monetary)	For Period	Credit	ifrs-full:PaymentsOfOtherEquityInstruments
194	Cash inflow from other financing activities	Concept (Monetary)	For Period	Debit	ifrs-full:OtherInflowsOutflowsOfCashClassifiedAsFinancingActivities
195	Dividends paid to shareholders	Concept (Monetary)	For Period	Credit	ifrs-full:DividendsPaidClassifiedAsFinancingActivities
196	Acquisition of treasury stock	Concept (Monetary)	For Period	Debit	ifrs-full:PurchaseOfTreasuryShares
197	Decrease in finance leases liabilities	Concept (Monetary)	For Period	Credit	ifrs-full:PaymentsOfFinanceLeaseLiabilitiesClassifiedAsFinancingActivities
198	Net cash outflow from financing activities	Concept (Monetary)	For Period	Debit	ifrs-full:CashFlowsFromUsedInFinancingActivities
199	Effect of exchange rate change on cash and equivalents	Concept (Monetary)	For Period	Debit	ifrs-full:EffectOfExchangeRateChangesOnCashAndCashEquivalents
200	Net increase (decrease) in cash and cash equivalents	Concept (Monetary)	For Period	Debit	ifrs-full:IncreaseDecreaseInCashAndCashEquivalents
201	Cash and cash equivalents at beginning of year	Concept (Monetary)	As Of	Debit	ifrs-full:CashAndCashEquivalents
202	Cash and cash equivalents at end of year	Concept (Monetary)	As Of	Debit	ifrs-full:CashAndCashEquivalents
203	1008 - Disclosure - General Information	Network	*	*	http://www.kt.com/taxonomy/role/NotesToFinancialStatementsDisclosureOfGeneralInformationAboutFinancialStatementsExplanatory
204	Implied Table	Table	*	*	implied:Table
205	Text block [abstract]	Abstract			kt:TextBlockAbstract
206	General Information	Concept (Text Block (HTML))	For Period		ifrs-full:DisclosureOfGeneralInformationAboutFinancialStatementsExplanatory
207	1009 - Disclosure - Significant Accounting Policies	Network	*	*	http://www.kt.com/taxonomy/role/NotesToFinancialStatementsDisclosureOfSummaryOfSignificantAccountingPoliciesExplanatory
208	Implied Table	Table	*	*	implied:Table
209	Text block [abstract]	Abstract			kt:TextBlockAbstract
210	Significant Accounting Policies	Concept (Text Block (HTML))	For Period		ifrs-full:DisclosureOfSummaryOfSignificantAccountingPoliciesExplanatory
211	1010 - Disclosure - Critical Accounting Estimates and Assumptions	Network	*	*	http://www.kt.com/taxonomy/role/NotesToFinancialStatementsDisclosureOfAccountingJudgementsAndEstimatesExplanatory
212	Implied Table	Table	*	*	implied:Table
213	Text block [abstract]	Abstract			kt:TextBlockAbstract
214	Critical Accounting Estimates and Assumptions	Concept (Text Block (HTML))	For Period		ifrs-full:DisclosureOfAccountingJudgementsAndEstimatesExplanatory
215	1011 - Disclosure - Financial Instruments by Category	Network	*	*	http://www.kt.com/taxonomy/role/NotesToFinancialStatementsDisclosureOfFinancialInstrumentsExplanatory
216	Implied Table	Table	*	*	implied:Table
217	Text block [abstract]	Abstract			kt:TextBlockAbstract
218	Financial Instruments by Category	Concept (Text Block (HTML))	For Period		ifrs-full:DisclosureOfFinancialInstrumentsExplanatory
219	1012 - Disclosure - Cash and Cash Equivalents	Network	*	*	http://www.kt.com/taxonomy/role/NotesToFinancialStatementsDisclosureOfRestrictedCashAndCashEquivalentsExplanatory
220	Implied Table	Table	*	*	implied:Table
221	Text block [abstract]	Abstract			kt:TextBlockAbstract
222	Cash and Cash Equivalents	Concept (Text Block (HTML))	For Period		ifrs-full:DisclosureOfRestrictedCashAndCashEquivalentsExplanatory
223	1013 - Disclosure - Trade and Other Receivables	Network	*	*	http://www.kt.com/taxonomy/role/NotesToFinancialStatementsDisclosureOfTradeAndOtherReceivablesExplanatory
224	Implied Table	Table	*	*	implied:Table
225	Text block [abstract]	Abstract			kt:TextBlockAbstract
226	Trade and Other Receivables	Concept (Text Block (HTML))	For Period		ifrs-full:DisclosureOfTradeAndOtherReceivablesExplanatory
227	1014 - Disclosure - Other Financial Assets and Liabilities	Network	*	*	http://www.kt.com/taxonomy/role/NotesToFinancialStatementsDisclosureOfOtherFinancialAssetsAndLiabilitiesExplanatory
228	Implied Table	Table	*	*	implied:Table
229	Text block [abstract]	Abstract			kt:TextBlockAbstract
230	Other Financial Assets and Liabilities	Concept (Text Block (HTML))	For Period		kt:DisclosureOfOtherFinancialAssetsAndLiabilitiesExplanatory
231	1015 - Disclosure - Inventories	Network	*	*	http://www.kt.com/taxonomy/role/NotesToFinancialStatementsDisclosureOfInventoriesExplanatory
232	Implied Table	Table	*	*	implied:Table
233	Text block [abstract]	Abstract			kt:TextBlockAbstract
234	Inventories	Concept (Text Block (HTML))	For Period		ifrs-full:DisclosureOfInventoriesExplanatory
235	1016 - Disclosure - Other Assets and Liabilities	Network	*	*	http://www.kt.com/taxonomy/role/NotesToFinancialStatementsDisclosureOfOtherAssetsAndLiabilitiesExplanatory
236	Implied Table	Table	*	*	implied:Table
237	Text block [abstract]	Abstract			kt:TextBlockAbstract
238	Other Assets and Liabilities	Concept (Text Block (HTML))	For Period		kt:DisclosureOfOtherAssetsAndLiabilitiesExplanatory
239	1017 - Disclosure - Assets Held for Sale	Network	*	*	http://www.kt.com/taxonomy/role/NotesToFinancialStatementsDisclosureOfAssetsHeldForSaleExplanatory
240	Implied Table	Table	*	*	implied:Table
241	Text block [abstract]	Abstract			kt:TextBlockAbstract
242	Assets Held for Sale	Concept (Text Block (HTML))	For Period		kt:DisclosureOfAssetsHeldForSaleExplanatory
243	1018 - Disclosure - Property and Equipment	Network	*	*	http://www.kt.com/taxonomy/role/NotesToFinancialStatementsDisclosureOfPropertyPlantAndEquipmentExplanatory
244	Implied Table	Table	*	*	implied:Table
245	Text block [abstract]	Abstract			kt:TextBlockAbstract
246	Property and Equipment	Concept (Text Block (HTML))	For Period		ifrs-full:DisclosureOfPropertyPlantAndEquipmentExplanatory
247	1019 - Disclosure - Investment Properties	Network	*	*	http://www.kt.com/taxonomy/role/NotesToFinancialStatementsDisclosureOfInvestmentPropertyExplanatory
248	Implied Table	Table	*	*	implied:Table
249	Text block [abstract]	Abstract			kt:TextBlockAbstract
250	Investment Properties	Concept (Text Block (HTML))	For Period		ifrs-full:DisclosureOfInvestmentPropertyExplanatory
251	1020 - Disclosure - Intangible Assets	Network	*	*	http://www.kt.com/taxonomy/role/NotesToFinancialStatementsDisclosureOfIntangibleAssetsAndGoodwillExplanatory
252	Implied Table	Table	*	*	implied:Table
253	Text block [abstract]	Abstract			kt:TextBlockAbstract
254	Intangible Assets	Concept (Text Block (HTML))	For Period		ifrs-full:DisclosureOfIntangibleAssetsAndGoodwillExplanatory
255	1021 - Disclosure - Investments in Associates and Joint Ventures	Network	*	*	http://www.kt.com/taxonomy/role/NotesToFinancialStatementsDisclosureOfInvestmentsAccountedForUsingEquityMethodExplanatory
256	Implied Table	Table	*	*	implied:Table
257	Text block [abstract]	Abstract			kt:TextBlockAbstract
258	Investments in Associates and Joint Ventures	Concept (Text Block (HTML))	For Period		ifrs-full:DisclosureOfInvestmentsAccountedForUsingEquityMethodExplanatory
259	1022 - Disclosure - Trade and Other Payables	Network	*	*	http://www.kt.com/taxonomy/role/NotesToFinancialStatementsDisclosureOfTradeAndOtherPayablesExplanatory
260	Implied Table	Table	*	*	implied:Table
261	Text block [abstract]	Abstract			kt:TextBlockAbstract
262	Trade and Other Payables	Concept (Text Block (HTML))	For Period		ifrs-full:DisclosureOfTradeAndOtherPayablesExplanatory
263	1023 - Disclosure - Borrowings	Network	*	*	http://www.kt.com/taxonomy/role/NotesToFinancialStatementsDisclosureOfBorrowingsExplanatory
264	Implied Table	Table	*	*	implied:Table
265	Text block [abstract]	Abstract			kt:TextBlockAbstract
266	Borrowings	Concept (Text Block (HTML))	For Period		ifrs-full:DisclosureOfBorrowingsExplanatory
267	1024 - Disclosure - Provisions	Network	*	*	http://www.kt.com/taxonomy/role/NotesToFinancialStatementsDisclosureOfProvisionsExplanatory
268	Implied Table	Table	*	*	implied:Table
269	Text block [abstract]	Abstract			kt:TextBlockAbstract
270	Provisions	Concept (Text Block (HTML))	For Period		ifrs-full:DisclosureOfProvisionsExplanatory
271	1025 - Disclosure - Net Defined Benefit Liabilities	Network	*	*	http://www.kt.com/taxonomy/role/NotesToFinancialStatementsDisclosureOfEmployeeBenefitsExplanatory
272	Implied Table	Table	*	*	implied:Table
273	Text block [abstract]	Abstract			kt:TextBlockAbstract
274	Net Defined Benefit Liabilities	Concept (Text Block (HTML))	For Period		ifrs-full:DisclosureOfEmployeeBenefitsExplanatory
275	1026 - Disclosure - Defined Contribution Plan	Network	*	*	http://www.kt.com/taxonomy/role/NotesToFinancialStatementsDisclosureOfDefinedContributionPlansExplanatory
276	Implied Table	Table	*	*	implied:Table
277	Text block [abstract]	Abstract			kt:TextBlockAbstract
278	Defined Contribution Plan	Concept (Text Block (HTML))	For Period		kt:DisclosureOfDefinedContributionPlansExplanatory
279	1027 - Disclosure - Commitments and Contingencies	Network	*	*	http://www.kt.com/taxonomy/role/NotesToFinancialStatementsDisclosureOfCommitmentsAndContingentLiabilitiesExplanatory
280	Implied Table	Table	*	*	implied:Table
281	Text block [abstract]	Abstract			kt:TextBlockAbstract
282	Commitments and Contingencies	Concept (Text Block (HTML))	For Period		ifrs-full:DisclosureOfCommitmentsAndContingentLiabilitiesExplanatory
283	1028 - Disclosure - Lease	Network	*	*	http://www.kt.com/taxonomy/role/NotesToFinancialStatementsDisclosureOfLeasesExplanatory
284	Implied Table	Table	*	*	implied:Table
285	Text block [abstract]	Abstract			kt:TextBlockAbstract
286	Lease	Concept (Text Block (HTML))	For Period		ifrs-full:DisclosureOfLeasesExplanatory
287	1029 - Disclosure - Share Capital	Network	*	*	http://www.kt.com/taxonomy/role/NotesToFinancialStatementsDisclosureOfIssuedCapitalExplanatory
288	Implied Table	Table	*	*	implied:Table
289	Text block [abstract]	Abstract			kt:TextBlockAbstract
290	Share Capital	Concept (Text Block (HTML))	For Period		ifrs-full:DisclosureOfIssuedCapitalExplanatory
291	1030 - Disclosure - Retained Earnings	Network	*	*	http://www.kt.com/taxonomy/role/NotesToFinancialStatementsDisclosureOfRetainedEarningsExplanatory
292	Implied Table	Table	*	*	implied:Table
293	Text block [abstract]	Abstract			kt:TextBlockAbstract
294	Retained Earnings	Concept (Text Block (HTML))	For Period		kt:DisclosureOfRetainedEarningsExplanatory
295	1031 - Disclosure - Accumulated Other Comprehensive Income and Other Components of Equity	Network	*	*	http://www.kt.com/taxonomy/role/NotesToFinancialStatementsDisclosureOfReservesAndOtherEquityInterestExplanatory
296	Implied Table	Table	*	*	implied:Table
297	Text block [abstract]	Abstract			kt:TextBlockAbstract
298	Accumulated Other Comprehensive Income and Other Components of Equity	Concept (Text Block (HTML))	For Period		ifrs-full:DisclosureOfReservesAndOtherEquityInterestExplanatory
299	1032 - Disclosure - Share-based Payments	Network	*	*	http://www.kt.com/taxonomy/role/NotesToFinancialStatementsDisclosureOfSharebasedPaymentArrangementsExplanatory
300	Implied Table	Table	*	*	implied:Table
301	Text block [abstract]	Abstract			kt:TextBlockAbstract
302	Share-based Payments	Concept (Text Block (HTML))	For Period		ifrs-full:DisclosureOfSharebasedPaymentArrangementsExplanatory
303	1033 - Disclosure - Revenue from Contracts with Customers and Relevant Contract Assets and Liabilities	Network	*	*	http://www.kt.com/taxonomy/role/NotesToFinancialStatementsDisclosureOfRevenueFromContractsWithCustomersAndRelevantContractAssetsAndLiabilitiesExplanatory
304	Implied Table	Table	*	*	implied:Table
305	Text block [abstract]	Abstract			kt:TextBlockAbstract
306	Revenue from Contracts with Customers and Relevant Contract Assets and Liabilities	Concept (Text Block (HTML))	For Period		kt:DisclosureOfRevenueFromContractsWithCustomersAndRelevantContractAssetsAndLiabilitiesExplanatory
307	1034 - Disclosure - Operating Expenses	Network	*	*	http://www.kt.com/taxonomy/role/NotesToFinancialStatementsDisclosureOfExpensesExplanatory
308	Implied Table	Table	*	*	implied:Table
309	Text block [abstract]	Abstract			kt:TextBlockAbstract
310	Operating Expenses	Concept (Text Block (HTML))	For Period		ifrs-full:DisclosureOfExpensesExplanatory
311	1035 - Disclosure - Financial Income and Costs	Network	*	*	http://www.kt.com/taxonomy/role/NotesToFinancialStatementsDisclosureOfFinanceIncomeExpenseExplanatory
312	Implied Table	Table	*	*	implied:Table
313	Text block [abstract]	Abstract			kt:TextBlockAbstract
314	Financial Income and Costs	Concept (Text Block (HTML))	For Period		ifrs-full:DisclosureOfFinanceIncomeExpenseExplanatory
315	1036 - Disclosure - Deferred Income Tax and income Tax Expense	Network	*	*	http://www.kt.com/taxonomy/role/NotesToFinancialStatementsDisclosureOfDeferredTaxesExplanatory
316	Implied Table	Table	*	*	implied:Table
317	Text block [abstract]	Abstract			kt:TextBlockAbstract
318	Deferred Income Tax and income Tax Expense	Concept (Text Block (HTML))	For Period		ifrs-full:DisclosureOfDeferredTaxesExplanatory
319	1037 - Disclosure - Earnings per Share	Network	*	*	http://www.kt.com/taxonomy/role/NotesToFinancialStatementsDisclosureOfEarningsPerShareExplanatory
320	Implied Table	Table	*	*	implied:Table
321	Text block [abstract]	Abstract			kt:TextBlockAbstract
322	Earnings per Share	Concept (Text Block (HTML))	For Period		ifrs-full:DisclosureOfEarningsPerShareExplanatory
323	1038 - Disclosure - Dividend	Network	*	*	http://www.kt.com/taxonomy/role/NotesToFinancialStatementsDisclosureOfDividendsExplanatory
324	Implied Table	Table	*	*	implied:Table
325	Text block [abstract]	Abstract			kt:TextBlockAbstract
326	Dividend	Concept (Text Block (HTML))	For Period		ifrs-full:DisclosureOfDividendsExplanatory
327	1039 - Disclosure - Cash Generated from Operations	Network	*	*	http://www.kt.com/taxonomy/role/NotesToFinancialStatementsDisclosureOfCashGeneratedFromOperationsExplanatory
328	Implied Table	Table	*	*	implied:Table
329	Text block [abstract]	Abstract			kt:TextBlockAbstract
330	Cash Generated from Operations	Concept (Text Block (HTML))	For Period		kt:DisclosureOfCashGeneratedFromOperationsExplanatory
331	1040 - Disclosure - Changes in Liabilities Arising from Financing Activities	Network	*	*	http://www.kt.com/taxonomy/role/NotesToFinancialStatementsDisclosureOfReconciliationOfLiabilitiesArisingFromFinancingActivitiesExplanatory
332	Implied Table	Table	*	*	implied:Table
333	Text block [abstract]	Abstract			kt:TextBlockAbstract
334	Changes in Liabilities Arising from Financing Activities	Concept (Text Block (HTML))	For Period		ifrs-full:DisclosureOfReconciliationOfLiabilitiesArisingFromFinancingActivitiesExplanatory
335	1041 - Disclosure - Segment Information	Network	*	*	http://www.kt.com/taxonomy/role/NotesToFinancialStatementsDisclosureOfEntitysReportableSegmentsExplanatory
336	Implied Table	Table	*	*	implied:Table
337	Text block [abstract]	Abstract			kt:TextBlockAbstract
338	Segment Information	Concept (Text Block (HTML))	For Period		ifrs-full:DisclosureOfEntitysReportableSegmentsExplanatory
339	1042 - Disclosure - Related Party Transactions	Network	*	*	http://www.kt.com/taxonomy/role/NotesToFinancialStatementsDisclosureOfRelatedPartyExplanatory
340	Implied Table	Table	*	*	implied:Table
341	Text block [abstract]	Abstract			kt:TextBlockAbstract
342	Related Party Transactions	Concept (Text Block (HTML))	For Period		ifrs-full:DisclosureOfRelatedPartyExplanatory
343	1043 - Disclosure - Financial Risk Management	Network	*	*	http://www.kt.com/taxonomy/role/NotesToFinancialStatementsDisclosureOfFinancialRiskManagementExplanatory
344	Implied Table	Table	*	*	implied:Table
345	Text block [abstract]	Abstract			kt:TextBlockAbstract
346	Financial Risk Management	Concept (Text Block (HTML))	For Period		ifrs-full:DisclosureOfFinancialRiskManagementExplanatory
347	1044 - Disclosure - Fair Value	Network	*	*	http://www.kt.com/taxonomy/role/NotesToFinancialStatementsDisclosureOfFairValueMeasurementExplanatory
348	Implied Table	Table	*	*	implied:Table
349	Text block [abstract]	Abstract			kt:TextBlockAbstract
350	Fair Value	Concept (Text Block (HTML))	For Period		ifrs-full:DisclosureOfFairValueMeasurementExplanatory
351	1045 - Disclosure - Interests in Unconsolidated Structured Entities	Network	*	*	http://www.kt.com/taxonomy/role/NotesToFinancialStatementsDisclosureOfInterestsInUnconsolidatedStructuredEntitiesExplanatory
352	Implied Table	Table	*	*	implied:Table
353	Investments accounted for using equity method [abstract]	Abstract			ifrs-full:InvestmentsAccountedForUsingEquityMethodAbstract
354	Interests in Unconsolidated Structured Entities	Concept (Text Block (HTML))	For Period		ifrs-full:DisclosureOfInterestsInUnconsolidatedStructuredEntitiesExplanatory
355	1046 - Disclosure - Information About Non-controlling Interests	Network	*	*	http://www.kt.com/taxonomy/role/NotesToFinancialStatementsDisclosureOfNoncontrollingInterestsExplanatory
356	Implied Table	Table	*	*	implied:Table
357	Text block [abstract]	Abstract			kt:TextBlockAbstract
358	Information About Non-controlling Interests	Concept (Text Block (HTML))	For Period		ifrs-full:DisclosureOfNoncontrollingInterestsExplanatory
359	1047 - Disclosure - Business Combination	Network	*	*	http://www.kt.com/taxonomy/role/NotesToFinancialStatementsDisclosureOfBusinessCombinationsExplanatory
360	Implied Table	Table	*	*	implied:Table
361	Text block [abstract]	Abstract			kt:TextBlockAbstract
362	Business Combination	Concept (Text Block (HTML))	For Period		ifrs-full:DisclosureOfBusinessCombinationsExplanatory
363	1048 - Disclosure - Changes in Accounting Policies	Network	*	*	http://www.kt.com/taxonomy/role/NotesToFinancialStatementsDisclosureOfChangesInAccountingPoliciesAccountingEstimatesAndErrorsExplanatory
364	Implied Table	Table	*	*	implied:Table
365	Text block [abstract]	Abstract			kt:TextBlockAbstract
366	Changes in Accounting Policies	Concept (Text Block (HTML))	For Period		ifrs-full:DisclosureOfChangesInAccountingPoliciesAccountingEstimatesAndErrorsExplanatory
367	1049 - Disclosure - Events after Reporting Period	Network	*	*	http://www.kt.com/taxonomy/role/NotesToFinancialStatementsDisclosureOfEventsAfterReportingPeriodExplanatory
368	Implied Table	Table	*	*	implied:Table
369	Text block [abstract]	Abstract			kt:TextBlockAbstract
370	Events after Reporting Period	Concept (Text Block (HTML))	For Period		ifrs-full:DisclosureOfEventsAfterReportingPeriodExplanatory
371	1050 - Disclosure - Revision of prior financial statements	Network	*	*	http://www.kt.com/taxonomy/role/NotesToFinancialStatementsDisclosureOfRevisionOfPriorPeriodFinancialStatementsExplanatory
372	Implied Table	Table	*	*	implied:Table
373	Text block [abstract]	Abstract			kt:TextBlockAbstract
374	Revision of prior financial statements	Concept (Text Block (HTML))	For Period		kt:DisclosureOfRevisionOfPriorPeriodFinancialStatementsExplanatory
375	1051 - Disclosure - Significant Accounting Policies (Policies)	Network	*	*	http://www.kt.com/taxonomy/role/NotesToFinancialStatementsDisclosureOfSummaryOfSignificantAccountingPoliciesExplanatoryPolicies
376	Implied Table	Table	*	*	implied:Table
377	Text block [abstract]	Abstract			kt:TextBlockAbstract
378	Basis of Preparation	Concept (Text Block (HTML))	For Period		ifrs-full:DisclosureOfBasisOfPreparationOfFinancialStatementsExplanatory
379	Changes in Accounting Policy and Disclosures	Concept (Text Block (HTML))	For Period		ifrs-full:DescriptionOfExpectedImpactOfInitialApplicationOfNewStandardsOrInterpretations
380	Consolidation	Concept (Text Block (HTML))	For Period		ifrs-full:DisclosureOfBasisOfConsolidationExplanatory
381	Segment Reporting	Concept (Text Block (HTML))	For Period		ifrs-full:DescriptionOfAccountingPolicyForSegmentReportingExplanatory
382	Foreign Currency Translation	Concept (Text Block (HTML))	For Period		ifrs-full:DescriptionOfAccountingPolicyForForeignCurrencyTranslationExplanatory
383	Cash and Cash Equivalents	Concept (Text Block (HTML))	For Period		ifrs-full:DescriptionOfAccountingPolicyToDetermineComponentsOfCashAndCashEquivalents
384	Financial Assets	Concept (Text Block (HTML))	For Period		ifrs-full:DescriptionOfAccountingPolicyForFinancialAssetsExplanatory
385	Derivative Instruments	Concept (Text Block (HTML))	For Period		ifrs-full:DescriptionOfAccountingPolicyForDerivativeFinancialInstrumentsExplanatory
386	Trade Receivables	Concept (Text Block (HTML))	For Period		ifrs-full:DescriptionOfAccountingPolicyForTradeAndOtherReceivablesExplanatory
387	Inventories	Concept (Text Block (HTML))	For Period		ifrs-full:DescriptionOfAccountingPolicyForMeasuringInventories
388	Non-current Assets (or Disposal Group) Held-for-sale	Concept (Text Block (HTML))	For Period		ifrs-full:DescriptionOfAccountingPolicyForNoncurrentAssetsOrDisposalGroupsClassifiedAsHeldForSaleExplanatory
389	Property and Equipment	Concept (Text Block (HTML))	For Period		ifrs-full:DescriptionOfAccountingPolicyForPropertyPlantAndEquipmentExplanatory
390	Investment Property	Concept (Text Block (HTML))	For Period		ifrs-full:DescriptionOfAccountingPolicyForInvestmentPropertyExplanatory
391	Intangible Assets	Concept (Text Block (HTML))	For Period		ifrs-full:DescriptionOfAccountingPolicyForIntangibleAssetsAndGoodwillExplanatory
392	Borrowing Costs	Concept (Text Block (HTML))	For Period		ifrs-full:DescriptionOfAccountingPolicyForBorrowingCostsExplanatory
393	Government Grants	Concept (Text Block (HTML))	For Period		ifrs-full:DescriptionOfAccountingPolicyForGovernmentGrants
394	Impairment of Non-Financial Assets	Concept (Text Block (HTML))	For Period		ifrs-full:DescriptionOfAccountingPolicyForImpairmentOfNonfinancialAssetsExplanatory
395	Trade and other payables	Concept (Text Block (HTML))	For Period		ifrs-full:DescriptionOfAccountingPolicyForTradeAndOtherPayablesExplanatory
396	Financial Liabilities	Concept (Text Block (HTML))	For Period		ifrs-full:DescriptionOfAccountingPolicyForFinancialLiabilitiesExplanatory
397	Financial Guarantee Contracts	Concept (Text Block (HTML))	For Period		ifrs-full:DescriptionOfAccountingPolicyForFinancialGuaranteesExplanatory
398	Employee Benefits	Concept (Text Block (HTML))	For Period		ifrs-full:DescriptionOfAccountingPolicyForEmployeeBenefitsExplanatory
399	Share-based payments	Concept (Text Block (HTML))	For Period		ifrs-full:DescriptionOfAccountingPolicyForSharebasedPaymentTransactionsExplanatory
400	Provisions	Concept (Text Block (HTML))	For Period		ifrs-full:DescriptionOfAccountingPolicyForProvisionsExplanatory
401	Leases	Concept (Text Block (HTML))	For Period		ifrs-full:DescriptionOfAccountingPolicyForLeasesExplanatory
402	Share Capital	Concept (Text Block (HTML))	For Period		ifrs-full:DescriptionOfAccountingPolicyForIssuedCapitalExplanatory
403	Revenue Recognition	Concept (Text Block (HTML))	For Period		ifrs-full:DescriptionOfAccountingPolicyForRecognitionOfRevenue
404	Current and Deferred Income Tax	Concept (Text Block (HTML))	For Period		ifrs-full:DescriptionOfAccountingPolicyForIncomeTaxExplanatory
405	Dividend	Concept (Text Block (HTML))	For Period		ifrs-full:DescriptionOfAccountingPolicyForDividendsExplanatory
406	Approval of the Financial Statements	Concept (Text Block (HTML))	For Period		ifrs-full:DisclosureOfAuthorisationOfFinancialStatementsExplanatory
407	1052 - Disclosure - General Information (Tables)	Network	*	*	http://www.kt.com/taxonomy/role/NotesToFinancialStatementsDisclosureOfGeneralInformationAboutFinancialStatementsExplanatoryTables
408	Implied Table	Table	*	*	implied:Table
409	Text block [abstract]	Abstract			kt:TextBlockAbstract
410	Summary of Consolidated Subsidiaries	Concept (Text Block (HTML))	For Period		ifrs-full:DisclosureOfSignificantInvestmentsInSubsidiariesExplanatory
411	1053 - Disclosure - Significant Accounting Policies (Tables)	Network	*	*	http://www.kt.com/taxonomy/role/NotesToFinancialStatementsDisclosureOfSummaryOfSignificantAccountingPoliciesExplanatoryTables
412	Implied Table	Table	*	*	implied:Table
413	Text block [abstract]	Abstract			kt:TextBlockAbstract
414	Summary of Estimated Useful Lives of Property, Plant and Equipment	Concept (Text Block (HTML))	For Period		kt:DisclosureOfPropertyPlantAndEquipmentEstimatedUsefulLifeExplanatory
415	Summary of Amortization of Intangible Assets With Limited Useful Life	Concept (Text Block (HTML))	For Period		kt:DisclosureOfDetailedInformationAboutUsefulLivesOfIntangibleAssetsExplanatory
416	1054 - Disclosure - Financial Instruments by Category (Tables)	Network	*	*	http://www.kt.com/taxonomy/role/NotesToFinancialStatementsDisclosureOfFinancialInstrumentsExplanatoryTables
417	Implied Table	Table	*	*	implied:Table
418	Text block [abstract]	Abstract			kt:TextBlockAbstract
419	Summary of Financial Instruments by Category	Concept (Text Block (HTML))	For Period		kt:DisclosureOfInstrumentsByCategoryExplanatory
420	Summary of Gains or Losses Arising From Financial Instruments by Category	Concept (Text Block (HTML))	For Period		kt:DisclosureOfGainLossOnFinancialInstrumentsExplanatory
421	1055 - Disclosure - Cash and Cash Equivalents (Tables)	Network	*	*	http://www.kt.com/taxonomy/role/NotesToFinancialStatementsDisclosureOfRestrictedCashAndCashEquivalentsExplanatoryTables
422	Implied Table	Table	*	*	implied:Table
423	Text block [abstract]	Abstract			kt:TextBlockAbstract
424	Summary of Restricted Cash and Cash Equivalents	Concept (Text Block (HTML))	For Period		kt:DisclosureOfDetailsOfRestrictedCashAndCashEquivalentsExplanatory
425	1056 - Disclosure - Trade and Other Receivables (Tables)	Network	*	*	http://www.kt.com/taxonomy/role/NotesToFinancialStatementsDisclosureOfTradeAndOtherReceivablesExplanatoryTables
426	Implied Table	Table	*	*	implied:Table
427	Text block [abstract]	Abstract			kt:TextBlockAbstract
428	Summary of Trade and Other Receivables	Concept (Text Block (HTML))	For Period		kt:DisclosureOfDetailedInformationAboutTradeAndOtherReceivablesExplanatory
429	Summary of Changes in Allowance for Doubtful Accounts	Concept (Text Block (HTML))	For Period		kt:DisclosureOfChangesInAllowanceForDoubtfulAccountsExplanatory
430	Summary of Other Receivables	Concept (Text Block (HTML))	For Period		kt:DisclosureOfOtherReceivablesExplanatory
431	1057 - Disclosure - Other Financial Assets and Liabilities (Tables)	Network	*	*	http://www.kt.com/taxonomy/role/NotesToFinancialStatementsDisclosureOfOtherFinancialAssetsAndLiabilitiesExplanatoryTables
432	Implied Table	Table	*	*	implied:Table
433	Text block [abstract]	Abstract			kt:TextBlockAbstract
434	Summary of Other Financial Assets and Liabilities	Concept (Text Block (HTML))	For Period		kt:DisclosureOfDetailsOfOtherFinancialAssetsAndLiabilitiesExplanatory
435	Summary of Financial Assets at Fair Value Through Profit or Loss	Concept (Text Block (HTML))	For Period		ifrs-full:DisclosureOfFinancialAssetsExplanatory
436	Summary of Financial Assets at Fair Value Through Other Comprehensive Income	Concept (Text Block (HTML))	For Period		kt:DisclosureOfDetailedInformationAboutFinancialAssetsAtFairValueThroughOtherComprehensiveIncomeExplanatory
437	Summary of Derivative Financial Assets and Liabilities	Concept (Text Block (HTML))	For Period		ifrs-full:DisclosureOfDerivativeFinancialInstrumentsExplanatory
438	Summary of Valuation Gains and Losses on Derivatives Contracts	Concept (Text Block (HTML))	For Period		kt:DisclosureOfValuationGainsAndLossesOnTheDerivativesContractsExplanatory
439	Summary of Financial Liabilities at Fair Value Through Profit or Loss	Concept (Text Block (HTML))	For Period		ifrs-full:DisclosureOfFinancialLiabilitiesExplanatory
440	Summary of Valuation Gain and Loss on Financial Liabilities at Fair Value Through Profit or Loss	Concept (Text Block (HTML))	For Period		kt:DisclosureOfValuationGainsAndLossesOnFinancialLiabilitiesAtFairValueThroughProfitOrLossExpalanatory
441	1058 - Disclosure - Inventories (Tables)	Network	*	*	http://www.kt.com/taxonomy/role/NotesToFinancialStatementsDisclosureOfInventoriesExplanatoryTables
442	Implied Table	Table	*	*	implied:Table
443	Text block [abstract]	Abstract			kt:TextBlockAbstract
444	Summary of Inventories Net	Concept (Text Block (HTML))	For Period		kt:DisclosureOfInventoriesNetExplanatory
445	1059 - Disclosure - Other Assets and Liabilities (Tables)	Network	*	*	http://www.kt.com/taxonomy/role/NotesToFinancialStatementsDisclosureOfOtherAssetsAndLiabilitiesExplanatoryTables
446	Implied Table	Table	*	*	implied:Table
447	Text block [abstract]	Abstract			kt:TextBlockAbstract
448	Summary of Other Assets and Liabilities	Concept (Text Block (HTML))	For Period		kt:DisclosureOfDetailedInformationOfOtherAssetsAndLiabilitiesExplanatory
449	1060 - Disclosure - Property and Equipment (Tables)	Network	*	*	http://www.kt.com/taxonomy/role/NotesToFinancialStatementsDisclosureOfPropertyPlantAndEquipmentExplanatoryTables
450	Implied Table	Table	*	*	implied:Table
451	Text block [abstract]	Abstract			kt:TextBlockAbstract
452	Summary of Changes in Property and Equipment	Concept (Text Block (HTML))	For Period		ifrs-full:DisclosureOfDetailedInformationAboutPropertyPlantAndEquipmentExplanatory
453	Summary of the Details of Property and Equipment Provided	Concept (Text Block (HTML))	For Period		kt:DisclosureOfPropertyPlantAndEquipmentCollateralExplanatory
454	1061 - Disclosure - Investment Properties (Tables)	Network	*	*	http://www.kt.com/taxonomy/role/NotesToFinancialStatementsDisclosureOfInvestmentPropertyExplanatoryTables
455	Implied Table	Table	*	*	implied:Table
456	Text block [abstract]	Abstract			kt:TextBlockAbstract
457	Summary of Investment Properties	Concept (Text Block (HTML))	For Period		ifrs-full:DisclosureOfDetailedInformationAboutInvestmentPropertyExplanatory
458	Summary of Investment Properties Provided as Collateral	Concept (Text Block (HTML))	For Period		kt:DisclosureOfDetailedInformationAboutInvestmentPropertyAsCollateralExplanatory
459	1062 - Disclosure - Intangible Assets (Tables)	Network	*	*	http://www.kt.com/taxonomy/role/NotesToFinancialStatementsDisclosureOfIntangibleAssetsAndGoodwillExplanatoryTables
460	Implied Table	Table	*	*	implied:Table
461	Text block [abstract]	Abstract			kt:TextBlockAbstract
462	Summary of Intangible Assets	Concept (Text Block (HTML))	For Period		ifrs-full:DisclosureOfDetailedInformationAboutIntangibleAssetsExplanatory
463	Summary of Goodwill Allocated to Each Cash-Generation Unit	Concept (Text Block (HTML))	For Period		ifrs-full:DisclosureOfInformationForIndividualAssetOrCashgeneratingUnitWithSignificantAmountOfGoodwillOrIntangibleAssetsWithIndefiniteUsefulLivesExplanatory
464	1063 - Disclosure - Investments in Associates and Joint Ventures (Tables)	Network	*	*	http://www.kt.com/taxonomy/role/NotesToFinancialStatementsDisclosureOfInvestmentsAccountedForUsingEquityMethodExplanatoryTables
465	Implied Table	Table	*	*	implied:Table
466	Text block [abstract]	Abstract			kt:TextBlockAbstract
467	Summary of Details of Associates	Concept (Text Block (HTML))	For Period		ifrs-full:DisclosureOfSignificantInvestmentsInAssociatesExplanatory
468	Summary of Changes in Investments in Associates and Joint Ventures	Concept (Text Block (HTML))	For Period		kt:DisclosureOfChangeInInvestmentsInAssociatesAndJointVenturesExplanatory
469	Summary of Financial Information of Associates and Joint Ventures	Concept (Text Block (HTML))	For Period		kt:DisclosureOfFinancialInformationAboutAssociatesAndJointVenturesExplanatory
470	Summary of Reconciliation of Carrying Amount of Interests in the Associates and Joint Ventures	Concept (Text Block (HTML))	For Period		ifrs-full:DisclosureOfReconciliationBetweenInvestmentDerecognisedAndAssetsAndLiabilitiesRecognisedTransitionFromEquityMethodToAccountingForAssetsAndLiabilitiesExplanatory
471	1064 - Disclosure - Trade and Other Payables (Tables)	Network	*	*	http://www.kt.com/taxonomy/role/NotesToFinancialStatementsDisclosureOfTradeAndOtherPayablesExplanatoryTables
472	Implied Table	Table	*	*	implied:Table
473	Text block [abstract]	Abstract			kt:TextBlockAbstract
474	Summary of Trade and Other Payables	Concept (Text Block (HTML))	For Period		kt:DisclosureOfDetailedInformationAboutTradeAndOtherPayablesExplanatory
475	Summary of Other Payables	Concept (Text Block (HTML))	For Period		kt:DisclosureOfOtherPayablesExplanatory
476	1065 - Disclosure - Borrowings (Tables)	Network	*	*	http://www.kt.com/taxonomy/role/NotesToFinancialStatementsDisclosureOfBorrowingsExplanatoryTables
477	Implied Table	Table	*	*	implied:Table
478	Text block [abstract]	Abstract			kt:TextBlockAbstract
479	Summary of Borrowings	Concept (Text Block (HTML))	For Period		ifrs-full:DisclosureOfDetailedInformationAboutBorrowingsExplanatory
480	Summary of Short-term Borrowings	Concept (Text Block (HTML))	For Period		kt:DisclosureOfShortTermBorrowingsExplanatory
481	Summary of Long-term Borrowings	Concept (Text Block (HTML))	For Period		kt:DisclosureOfLongTermBorrowingsExplanatory
482	Summary of Repayment of Borrowings Including the Current Liabilities	Concept (Text Block (HTML))	For Period		kt:DisclosureOfRepaymentScheduleOfBorrowingsExplanatory
483	1066 - Disclosure - Provisions (Tables)	Network	*	*	http://www.kt.com/taxonomy/role/NotesToFinancialStatementsDisclosureOfProvisionsExplanatoryTables
484	Implied Table	Table	*	*	implied:Table
485	Text block [abstract]	Abstract			kt:TextBlockAbstract
486	Summary of Changes in Provisions	Concept (Text Block (HTML))	For Period		ifrs-full:DisclosureOfOtherProvisionsExplanatory
487	1067 - Disclosure - Net Defined Benefit Liabilities (Tables)	Network	*	*	http://www.kt.com/taxonomy/role/NotesToFinancialStatementsDisclosureOfEmployeeBenefitsExplanatoryTables
488	Statement [table]	Table	*	*	kt:StatementTable
489	Net defined benefit liability (asset) [axis]	Axis			ifrs-full:NetDefinedBenefitLiabilityAssetAxis
490	Net defined benefit liability (asset) [member]	Member			ifrs-full:NetDefinedBenefitLiabilityAssetMember
491	Defined benefit obligations [member]	Member			kt:DefinedBenefitObligationsMember
492	Statement [LineItems]	LineItems			kt:StatementLineItems
493	Summary of Amount Recognized in the Statements of Financial Position	Concept (Text Block (HTML))	For Period		kt:DisclosureOfAmountsRecognizedInTheStatementOfFinancialPositionExplanatory
494	Summary of Changes in the Defined Benefit Obligations	Concept (Text Block (HTML))	For Period		kt:DisclosureOfChangesInDefinedBenefitObligationsExplanatory
495	Summary of Amounts Recognized in the Statement of Profit or Loss	Concept (Text Block (HTML))	For Period		kt:DisclosureOfAmountsRecognizedInTheStatementOfOperationsExplanatory
496	Summary of Principal Actuarial Assumptions	Concept (Text Block (HTML))	For Period		ifrs-full:DisclosureOfSensitivityAnalysisForActuarialAssumptionsExplanatory
497	Summary of Sensitivity of the Defined Benefit Obligations	Concept (Text Block (HTML))	For Period		kt:DisclosureOfSensitivityAnalysisForDefinedBenifitObligationsExplanatory
498	Summary of Expected Maturity Analysis of Undiscounted Pension Benefits	Concept (Text Block (HTML))	For Period		kt:DisclosureOfExpectedMaturityAnalysisOfUndiscountedPensionBenefitsExplanatory
499	1068 - Disclosure - Commitments and Contingencies (Tables)	Network	*	*	http://www.kt.com/taxonomy/role/NotesToFinancialStatementsDisclosureOfCommitmentsAndContingentLiabilitiesExplanatoryTables
500	Implied Table	Table	*	*	implied:Table
501	Text block [abstract]	Abstract			kt:TextBlockAbstract
502	Summary Of Major Commitments With Local Financial Institutions	Concept (Text Block (HTML))	For Period		ifrs-full:DisclosureOfCommitmentsExplanatory
503	Summary of Guarantees Received from Financial Institutions	Concept (Text Block (HTML))	For Period		kt:DisclosureOfGuaranteesReceivedFromFinancialInstitutionsExplanatory
504	Summary Of Guarantees Provided By The Group For Third Parties	Concept (Text Block (HTML))	For Period		kt:DisclosureOfFinancialGuaranteesExplanatory
505	1069 - Disclosure - Lease (Tables)	Network	*	*	http://www.kt.com/taxonomy/role/NotesToFinancialStatementsDisclosureOfLeasesExplanatoryTables
506	Implied Table	Table	*	*	implied:Table
507	Text block [abstract]	Abstract			kt:TextBlockAbstract
508	Summary Of Details Of Finance Lease Assets	Concept (Text Block (HTML))	For Period		ifrs-full:DisclosureOfRecognisedFinanceLeaseAsAssetsByLesseeExplanatory
509	Summary Of Details Of Future Minimum Lease Payments Under Finance Lease Contracts	Concept (Text Block (HTML))	For Period		kt:DisclosureOfFinanceLeaseByLesseeExplanatory
510	Summary Of Details Of future Minimum Lease Payments Under Operating Lease Contracts	Concept (Text Block (HTML))	For Period		kt:DisclosureOfOperatingLeaseByLesseeExplanatory
511	1070 - Disclosure - Share Capital (Tables)	Network	*	*	http://www.kt.com/taxonomy/role/NotesToFinancialStatementsDisclosureOfIssuedCapitalExplanatoryTables
512	Implied Table	Table	*	*	implied:Table
513	Text block [abstract]	Abstract			kt:TextBlockAbstract
514	Summary of Share Capital	Concept (Text Block (HTML))	For Period		ifrs-full:DisclosureOfClassesOfShareCapitalExplanatory
515	1071 - Disclosure - Retained Earnings (Tables)	Network	*	*	http://www.kt.com/taxonomy/role/NotesToFinancialStatementsDisclosureOfRetainedEarningsExplanatoryTables
516	Implied Table	Table	*	*	implied:Table
517	Text block [abstract]	Abstract			kt:TextBlockAbstract
518	Summary of Retained Earnings	Concept (Text Block (HTML))	For Period		kt:DisclosureDetailedInformationAboutRetainedEarningsExplanatory
519	1072 - Disclosure - Accumulated Other Comprehensive Income and Other Components of Equity (Tables)	Network	*	*	http://www.kt.com/taxonomy/role/NotesToFinancialStatementsDisclosureOfReservesAndOtherEquityInterestExplanatoryTables
520	Implied Table	Table	*	*	implied:Table
521	Text block [abstract]	Abstract			kt:TextBlockAbstract
522	Summary of Accumulated Other Comprehensive Income	Concept (Text Block (HTML))	For Period		kt:DisclosureOfAccumulatedOtherComprehensiveIncomeExplanatory
523	Summary of Changes in Accumulated Other Comprehensive Income	Concept (Text Block (HTML))	For Period		kt:DisclosureOfChangesInAccumulatedOtherComprehensiveIncomeLossExplanatory
524	Summary of Other Components of Equity	Concept (Text Block (HTML))	For Period		kt:DisclosureOfOtherComponentsOfEquityExplanatory
525	Summary of Treasury Stock	Concept (Text Block (HTML))	For Period		ifrs-full:DisclosureOfTreasurySharesExplanatory
526	1073 - Disclosure - Share-based Payments (Tables)	Network	*	*	http://www.kt.com/taxonomy/role/NotesToFinancialStatementsDisclosureOfSharebasedPaymentArrangementsExplanatoryTables
527	Implied Table	Table	*	*	implied:Table
528	Text block [abstract]	Abstract			kt:TextBlockAbstract
529	Summary of Details of Share-Based Payments	Concept (Text Block (HTML))	For Period		ifrs-full:DisclosureOfTermsAndConditionsOfSharebasedPaymentArrangementExplanatory
530	Summary of Changes in the Number of Stock Options and the Weighted-Average Exercise Price	Concept (Text Block (HTML))	For Period		ifrs-full:DisclosureOfNumberAndWeightedAverageExercisePricesOfShareOptionsExplanatory
531	1074 - Disclosure - Revenue from Contracts with Customers and Relevant Contract Assets and Liabilities (Tables)	Network	*	*	http://www.kt.com/taxonomy/role/NotesToFinancialStatementsDisclosureOfRevenueFromContractsWithCustomersAndRelevantContractAssetsAndLiabilitiesExplanatoryTables
532	Implied Table	Table	*	*	implied:Table
533	Text block [abstract]	Abstract			kt:TextBlockAbstract
534	Detail Explanation of Revenue in Statement of Profit or Loss	Concept (Text Block (HTML))	For Period		kt:DisclosureOfRevenueFromContractWithCustomersDetailsExplanatory
535	Detail Explanation of Operating Revenue	Concept (Text Block (HTML))	For Period		kt:DisclosureOfOperatingRevenueExplanatory
536	Detail Analysis of Contract with Customer Assets and Liabilities	Concept (Text Block (HTML))	For Period		ifrs-full:ExplanationOfSignificantChangesInContractAssetsAndContractLiabilitiesExplanatory
537	Detail Analysis of Contract Costs Recognized as Assets	Concept (Text Block (HTML))	For Period		kt:DisclosureOfContractCostsRecognizedAsAssetsExplanatory
538	Detail of Revenue Arising from Carried-Forward Contract Liabilities	Concept (Text Block (HTML))	For Period		kt:DisclosureOfRevenueRecognizedRelatedToContractLiabilitiesTextBlock
539	1075 - Disclosure - Operating Expenses (Tables)	Network	*	*	http://www.kt.com/taxonomy/role/NotesToFinancialStatementsDisclosureOfExpensesExplanatoryTables
540	Implied Table	Table	*	*	implied:Table
541	Text block [abstract]	Abstract			kt:TextBlockAbstract
542	Summary of Operating Expenses	Concept (Text Block (HTML))	For Period		kt:DisclosureOfDetailedInformationAboutOperatingCostsExplanatory
543	Summary of Details of Employee Benefits	Concept (Text Block (HTML))	For Period		kt:DisclosureOfShortTermEmployeeBenefitsExpenseExplanatory
544	1076 - Disclosure - Financial Income and Costs (Tables)	Network	*	*	http://www.kt.com/taxonomy/role/NotesToFinancialStatementsDisclosureOfFinanceIncomeExpenseExplanatoryTables
545	Implied Table	Table	*	*	implied:Table
546	Text block [abstract]	Abstract			kt:TextBlockAbstract
547	Summary of Details of Financial Income	Concept (Text Block (HTML))	For Period		ifrs-full:DisclosureOfFinanceIncomeExplanatory
548	Summary of Details of Financial Costs	Concept (Text Block (HTML))	For Period		ifrs-full:DisclosureOfFinanceCostExplanatory
549	1077 - Disclosure - Deferred Income Tax and income Tax Expense (Tables)	Network	*	*	http://www.kt.com/taxonomy/role/NotesToFinancialStatementsDisclosureOfDeferredTaxesExplanatoryTables
550	Implied Table	Table	*	*	implied:Table
551	Text block [abstract]	Abstract			kt:TextBlockAbstract
552	Summary of Analysis of Deferred Tax Assets and Deferred Tax Liabilities	Concept (Text Block (HTML))	For Period		kt:DisclosureOfDeferredTaxLiabilityAssetExplanatory
553	Summary of Gross Movements on the Deferred Income Tax Account	Concept (Text Block (HTML))	For Period		ifrs-full:DisclosureOfTemporaryDifferenceUnusedTaxLossesAndUnusedTaxCreditsExplanatory
554	Summary of Movement in Deferred Income Tax Assets and Liabilities	Concept (Text Block (HTML))	For Period		kt:DisclosureOfMovementInDeferredTaxAssetsAndLiabilitiesWithoutOffsettingExplanatory
555	Summary of Tax Impacts Recognized Directly To Equity	Concept (Text Block (HTML))	For Period		kt:DisclosureOfIncomeTaxRecognizedDirectlyInEquityExplanatory
556	Summary of Details of Income Tax Expense	Concept (Text Block (HTML))	For Period		kt:DisclosureOfIncomeTaxExpenseBenefitsExplanatory
557	Summary of Tax on the Group's Profit Before Tax	Concept (Text Block (HTML))	For Period		kt:DisclosureOfReconciliationOfAccountingProfitMultipliedByApplicableTaxRatesExplanatory
558	1078 - Disclosure - Earnings per Share (Tables)	Network	*	*	http://www.kt.com/taxonomy/role/NotesToFinancialStatementsDisclosureOfEarningsPerShareExplanatoryTables
559	Implied Table	Table	*	*	implied:Table
560	Text block [abstract]	Abstract			kt:TextBlockAbstract
561	Summary of Basic and Diluted Earnings per Share From Operations	Concept (Text Block (HTML))	For Period		ifrs-full:EarningsPerShareExplanatory
562	1079 - Disclosure - Cash Generated from Operations (Tables)	Network	*	*	http://www.kt.com/taxonomy/role/NotesToFinancialStatementsDisclosureOfCashGeneratedFromOperationsExplanatoryTables
563	Implied Table	Table	*	*	implied:Table
564	Text block [abstract]	Abstract			kt:TextBlockAbstract
565	Summary of Cash Flows from Operating Activities	Concept (Text Block (HTML))	For Period		kt:DisclosureOfDetailedInformationAboutCashFlowsFromOperatingActivitiesExplanatory
566	Summary of Significant Transactions not Affecting Cash Flows	Concept (Text Block (HTML))	For Period		kt:DisclosureOfSignificantTransactionsNotAffectingCashFlowsExplanatory
567	1080 - Disclosure - Changes in Liabilities Arising from Financing Activities (Tables)	Network	*	*	http://www.kt.com/taxonomy/role/NotesToFinancialStatementsDisclosureOfReconciliationOfLiabilitiesArisingFromFinancingActivitiesExplanatoryTables
568	Implied Table	Table	*	*	implied:Table
569	Text block [abstract]	Abstract			kt:TextBlockAbstract
570	Summary of Changes in Liabilities Arising from Financial Activities	Concept (Text Block (HTML))	For Period		kt:DisclosureOfDetailedInformationAboutReconciliationOfLiabilitiesArisingFromFinancingActivitiesExplanatory
571	1081 - Disclosure - Segment Information (Tables)	Network	*	*	http://www.kt.com/taxonomy/role/NotesToFinancialStatementsDisclosureOfEntitysReportableSegmentsExplanatoryTables
572	Implied Table	Table	*	*	implied:Table
573	Text block [abstract]	Abstract			kt:TextBlockAbstract
574	Summary of Segment Information	Concept (Text Block (HTML))	For Period		ifrs-full:DisclosureOfOperatingSegmentsExplanatory
575	Summary of Operating Revenues and Non Current Assets by Geographical Regions	Concept (Text Block (HTML))	For Period		ifrs-full:DisclosureOfGeographicalAreasExplanatory
576	1082 - Disclosure - Related Party Transactions (Tables)	Network	*	*	http://www.kt.com/taxonomy/role/NotesToFinancialStatementsDisclosureOfRelatedPartyExplanatoryTables
577	Implied Table	Table	*	*	implied:Table
578	Text block [abstract]	Abstract			kt:TextBlockAbstract
579	Summary of Related Parties Outstanding Balances of Receivables and Payables	Concept (Text Block (HTML))	For Period		kt:DisclosureOfTransactionsBetweenRelatedPartiesOutstandingReceivablesAndPayablesExplanatory
580	Summary of Significant Transactions With Related Parties	Concept (Text Block (HTML))	For Period		ifrs-full:DisclosureOfTransactionsBetweenRelatedPartiesExplanatory
581	Summary of Key Management Compensation	Concept (Text Block (HTML))	For Period		ifrs-full:DisclosureOfInformationAboutKeyManagementPersonnelExplanatory
582	Summary of Fund Transactions With Related Parties	Concept (Text Block (HTML))	For Period		kt:DisclosureOfAssociatesAndJointVenturesExplanatory
583	1083 - Disclosure - Financial Risk Management (Tables)	Network	*	*	http://www.kt.com/taxonomy/role/NotesToFinancialStatementsDisclosureOfFinancialRiskManagementExplanatoryTables
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585	Types of risks [axis]	Axis			ifrs-full:TypesOfRisksAxis
586	Risks [member]	Member			ifrs-full:TypesOfRisksMember
587	Currency risk [Member]	Member			ifrs-full:CurrencyRiskMember
588	Equity price risk [Member]	Member			ifrs-full:EquityPriceRiskMember
589	Interest rate risk [Member]	Member			ifrs-full:InterestRateRiskMember
590	Statement [LineItems]	LineItems			kt:StatementLineItems
591	Summary of Exposures to Risks, Effects on Profit before Income Tax and Shareholders' Equity	Concept (Text Block (HTML))	For Period		ifrs-full:SensitivityAnalysisForEachTypeOfMarketRisk
592	Summary of Details of Financial Assets and Liabilities in Foreign Currencies	Concept (Text Block (HTML))	For Period		kt:DisclosureOfFinancialAssetsAndFinancialLiabilitiesExplanatory
593	Summary of Maximum Exposure to Credit Risk	Concept (Text Block (HTML))	For Period		ifrs-full:DisclosureOfCreditRiskExposureExplanatory
594	Summary of Contractual Undiscounted Cash Flows	Concept (Text Block (HTML))	For Period		kt:DisclosureOfMaturityAnalysisForNonderivativeAndDerivativeFinancialLiabilitiesExplanatory
595	Summary of Cash Outflow and Inflow of Derivatives Settled Gross or Net are Undiscounted Contractual Cash Flow	Concept (Text Block (HTML))	For Period		ifrs-full:MaturityAnalysisForDerivativeFinancialLiabilities
596	Summary of Debt-to-equity Ratios	Concept (Text Block (HTML))	For Period		kt:DisclosureOfDebtEquityRatioExplanatory
597	Summary of Gearing Ratios	Concept (Text Block (HTML))	For Period		kt:DisclosureOfDetailInformationAboutGearingRatioExplanatory
598	Summary of Group's Recognized Financial Assets Subject to Enforceable Master Netting Arrangements or Similar Agreements	Concept (Text Block (HTML))	For Period		ifrs-full:DisclosureOfReconciliationOfFinancialAssetsSubjectToOffsettingEnforceableMasterNettingArrangementsOrSimilarAgreementsToIndividualLineItemsInStatementOfFinancialPositionExplanatory
599	Summary of Group's Recognized Financial Liabilities Subject to Enforceable Master Netting Arrangements or Similar Agreements	Concept (Text Block (HTML))	For Period		ifrs-full:DisclosureOfReconciliationOfFinancialLiabilitiesSubjectToOffsettingEnforceableMasterNettingArrangementsOrSimilarAgreementsToIndividualLineItemsInStatementOfFinancialPositionExplanatory
600	1084 - Disclosure - Fair Value (Tables)	Network	*	*	http://www.kt.com/taxonomy/role/NotesToFinancialStatementsDisclosureOfFairValueMeasurementExplanatoryTables
601	Implied Table	Table	*	*	implied:Table
602	Text block [abstract]	Abstract			kt:TextBlockAbstract
603	Summary of Carrying Amount and Fair Value of Financial Instruments by Category	Concept (Text Block (HTML))	For Period		kt:DisclosureOfDetailedInformationAboutFairValueOfFinancialInstrumentsExplanatory
604	Summary of Fair Value Hierarchy Classifications of Financial Assets and Financial Liabilities That are Measured at Fair Value	Concept (Text Block (HTML))	For Period		kt:DisclosureOfFairValueMeasurementOfAssetsAndLiabilitiesExplanatory
605	Summary of Fair Value Non of Financial Instruments	Concept (Text Block (HTML))	For Period		kt:DisclosureOfDetailedInformationAboutFairValueOfNonFinancialInstrumentsExplanatory
606	Summary of Changes in Level 3 of Fair Value Hierarchy for Recurring Fair Value Measurements	Concept (Text Block (HTML))	For Period		kt:DisclosureOfReconciliationOfChangesInFairValueMeasurementAssetsLiabilitiesExplanatory
607	Summary of Valuation Techniques and Inputs	Concept (Text Block (HTML))	For Period		kt:DisclosureOfValuationAndInputUsedInFairValueOfFinancialInstrumentsExplanatory
608	Summary of Details and Changes of Total Deferred Difference	Concept (Text Block (HTML))	For Period		kt:DisclosureOfReconciliationOfChangesInFinancialInstrumentExplanatory
609	1085 - Disclosure - Interests in Unconsolidated Structured Entities (Tables)	Network	*	*	http://www.kt.com/taxonomy/role/NotesToFinancialStatementsDisclosureOfInterestsInUnconsolidatedStructuredEntitiesExplanatoryTables
610	Implied Table	Table	*	*	implied:Table
611	Investments accounted for using equity method [abstract]	Abstract			ifrs-full:InvestmentsAccountedForUsingEquityMethodAbstract
612	Summary of Unconsolidated Structured Entities and Nature of Risks	Concept (Text Block (HTML))	For Period		ifrs-full:DisclosureOfUnconsolidatedStructuredEntitiesExplanatory
613	1086 - Disclosure - Information About Non-controlling Interests (Tables)	Network	*	*	http://www.kt.com/taxonomy/role/NotesToFinancialStatementsDisclosureOfNoncontrollingInterestsExplanatoryTables
614	Implied Table	Table	*	*	implied:Table
615	Text block [abstract]	Abstract			kt:TextBlockAbstract
616	Summary of Changes in Accumulated Non-controlling Interests	Concept (Text Block (HTML))	For Period		kt:DisclosureOfChangesInAccumulatedNoncontrollingInterestsExplanatory
617	Summary of Financial Information on Subsidiaries	Concept (Text Block (HTML))	For Period		kt:DisclosureOfSummarizedFinancialInformationOnSubsidiariesExplanatory
618	Summary of Changes in Ownership Interest on the Equity Attributable to Owners	Concept (Text Block (HTML))	For Period		ifrs-full:DisclosureOfEffectsOfChangesInParentsOwnershipInterestInSubsidiaryThatDoNotResultInLossOfControlOnEquityAttributableToOwnersOfParentExplanatory
619	1087 - Disclosure - Business Combination (Tables)	Network	*	*	http://www.kt.com/taxonomy/role/NotesToFinancialStatementsDisclosureOfBusinessCombinationsExplanatoryTables
620	Implied Table	Table	*	*	implied:Table
621	Text block [abstract]	Abstract			kt:TextBlockAbstract
622	Summary of Business Combination	Concept (Text Block (HTML))	For Period		ifrs-full:DisclosureOfDetailedInformationAboutBusinessCombinationsExplanatory
623	Schedule of Fair Value of Assets and Liabilities Recognized as a Result of Acquisition at Acquisition Date	Concept (Text Block (HTML))	For Period		kt:DisclosureOfFairValueOfAssetsAndLiabilitiesRecognizedAtAcquisitionDateExplanatory
624	Schedule of Recognized Goodwill as a Result of Business Combination	Concept (Text Block (HTML))	For Period		kt:DisclosureOfDetailedInformationAboutGoodwillRecognizedOnBusinessCombinationExplanatory
625	Schedule of Cash Outflows as a Result of Acquisition	Concept (Text Block (HTML))	For Period		kt:DisclosureOfCashFlowsAsResultOfTheAcquisitionAtTheAcquisitionDateExplanatory
626	1088 - Disclosure - Changes in Accounting Policies (Tables)	Network	*	*	http://www.kt.com/taxonomy/role/NotesToFinancialStatementsDisclosureOfChangesInAccountingPoliciesAccountingEstimatesAndErrorsExplanatoryTables
627	Implied Table	Table	*	*	implied:Table
628	Text block [abstract]	Abstract			kt:TextBlockAbstract
629	Summary of Impact on Financial Statements Due to Application of IFRS 15 at the Date of Initial Application	Concept (Text Block (HTML))	For Period		ifrs-full:DescriptionOfInitialApplicationOfStandardsOrInterpretations
630	Summary of Beginning Balance of Retained Earnings after Adjustment Due to Application of IFRS 9	Concept (Text Block (HTML))	For Period		kt:DisclosureOfImpactOfTransitionToIFRS9OnRetainedEarningsExplanatory
631	Summary of Effects Resulting from Classification and Measurement of Financial Instruments	Concept (Text Block (HTML))	For Period		ifrs-full:DisclosureOfReclassificationOfFinancialInstrumentsExplanatory
632	Summary of Impact on Changes in Equity	Concept (Text Block (HTML))	For Period		kt:DisclosureOfImpactOnChangesOnEquityExplanatory
633	1089 - Disclosure - Events after Reporting Period (Tables)	Network	*	*	http://www.kt.com/taxonomy/role/NotesToFinancialStatementsDisclosureOfEventsAfterReportingPeriodExplanatoryTables
634	Implied Table	Table	*	*	implied:Table
635	Text block [abstract]	Abstract			kt:TextBlockAbstract
636	Summary of Public Bonds Issued After Reporting Period	Concept (Text Block (HTML))	For Period		ifrs-full:DisclosureOfDebtSecuritiesExplanatory
637	1090 - Disclosure - Revision of prior financial statements (Tables)	Network	*	*	http://www.kt.com/taxonomy/role/NotesToFinancialStatementsDisclosureOfRevisionOfPriorPeriodFinancialStatementsExplanatoryTables
638	Implied Table	Table	*	*	implied:Table
639	Text block [abstract]	Abstract			kt:TextBlockAbstract
640	Summary of Revision of Prior Period Financial Statements	Concept (Text Block (HTML))	For Period		kt:DisclosureOfChangesInConsolidatedFinancialStatementsToCorrectionOfErrorsExplanatory
641	1091 - Disclosure - General Information - Additional Information (Detail)	Network	*	*	http://www.kt.com/taxonomy/role/DisclosureGeneralInformationAdditionalInformation
642	Disclosure of General Information [table]	Table	*	*	kt:DisclosureOfGeneralInformationTable
643	Classes of share capital [axis]	Axis			ifrs-full:ClassesOfShareCapitalAxis
644	Share capital [member]	Member			ifrs-full:ClassesOfShareCapitalMember
645	Government Owned shares [member]	Member			kt:GovernmentOwnedSharesMember
646	Disclosure of general information [line items]	LineItems			kt:DisclosureOfGeneralInformationLineItems
647	Number of additional shares issued	Concept (Shares)	For Period		ifrs-full:IncreaseDecreaseInNumberOfOrdinarySharesIssued
648	1092 - Disclosure - General Information - Summary of Consolidated Subsidiaries (Detail)	Network	*	*	http://www.kt.com/taxonomy/role/DisclosureGeneralInformationSummaryOfConsolidatedSubsidiaries
649	Disclosure of subsidiaries [table]	Table	*	*	ifrs-full:DisclosureOfSignificantInvestmentsInSubsidiariesTable
650	Subsidiaries [axis]	Axis			ifrs-full:SignificantInvestmentsInSubsidiariesAxis
651	Entity's total for subsidiaries [member]	Member			ifrs-full:EntitysTotalForSubsidiariesMember
652	KT Powertel Co., Ltd. [member]	Member			kt:KTPowertelCoLtdMember
653	KT Linkus Co., Ltd. [member]	Member			kt:KTLinkusCoLtdMember
654	KT Submarine Co., Ltd. [member]	Member			kt:KTSubmarineCoLtdMember
655	KT Telecop Co., Ltd. [member]	Member			kt:KTTelecopCoLtdMember
656	KT Hitel Co., Ltd. [member]	Member			kt:KTHitelCoLtdMember
657	KT service bukbu Co., Ltd. [member]	Member			kt:KTServiceBukbuCoLtdMember
658	KT service nambu Co., Ltd. [member]	Member			kt:KTServiceNambuCoLtdMember
659	KT Commerce Inc. [Member]	Member			kt:KTCommerceIncMember
660	KT Strategic Investment Fund No.1 [Member]	Member			kt:KTStrategicInvestmentFundNumberOneMember
661	KT Strategic Investment Fund No.2 [Member]	Member			kt:KTStrategicInvestmentFundNumberTwoMember
662	KT Strategic Investment Fund No.3 [Member]	Member			kt:KTStrategicInvestmentFundNumberThreeMember
663	KT strategic investment fund number four [member]	Member			kt:KtStrategicInvestmentFundNumberFourMember
664	BCVP Strategic Investment Fund Number One [member]	Member			kt:BCVPStrategicInvestmentFundNumberOneMember
665	BC Card Co., Ltd. [member]	Member			kt:BCCardCoLtdMember
666	VP Inc. [Member]	Member			kt:VPIncMember
667	H&C Network [member]	Member			kt:HAndCNetworkMember
668	BC Card China Co., Ltd. [Member]	Member			kt:BCCardChinaCoLtdMember
669	INITECH Co., Ltd. [Member]	Member			kt:INITECHCoLtdMember
670	Smartro Co., Ltd. [Member]	Member			kt:SmartroCoLtdMember
671	KTDS Co., Ltd. [member]	Member			kt:KTDSCoLtdMember
672	KT M Hows Co., Ltd. [member]	Member			kt:KTMHowsCoLtdMember
673	KT M&S Co., Ltd. [member]	Member			kt:KTMAndSCoLtdMember
674	GENIE Music Corporation K T Music Corporation [member]	Member			kt:GENIEMusicCorporationMusicKTCorporationMember
675	KT MOS Bukbu Co.,Ltd. [member]	Member			kt:KtMosBukbuCoLtdMember
676	KTMOS Nambu Co.,Ltd. [member]	Member			kt:KTMOSNambuCoLtdMember
677	KT Skylife Co., Ltd. [member]	Member			kt:KTSkylifeCoLtdMember
678	Skylife TV Co., Ltd. [Member]	Member			kt:SkylifeTVCoLtdMember
679	KT Estate Inc. [member]	Member			kt:KTEstateIncMember
680	KT AMC Co., Ltd. [Member]	Member			kt:KTAMCCoLtdMember
681	NEXR Co., Ltd. [Member]	Member			kt:NEXRCoLtdMember
682	KTSB Data service [member]	Member			kt:KTSBDataServiceMember
683	KT Sat Co., Ltd. [member]	Member			kt:KTSatCoLtdMember
684	Nasmedia Co Ltd [member]	Member			kt:NasmediaCoLtdMember
685	KT sports [member]	Member			kt:KTSportsMember
686	KT music contents fund no.1 [member]	Member			kt:KTMusicContentsFundNumberOneMember
687	K T Music Contents Fund No.2 [member]	Member			kt:KTMusicContentsFundNo2Member
688	KT-Michigan global content fund [member]	Member			kt:KTMichiganGlobalContentFundMember
689	Autopion Co., Ltd. [member]	Member			kt:AutopionCoLtdMember
690	KTCS Corporation [member]	Member			kt:KTCSCorporationMember
691	KTIS Corporation [member]	Member			kt:KTISCorporationMember
692	KT M mobile [member]	Member			kt:KTMMobileMember
693	KT Investment Co., Ltd. [member]	Member			kt:KTInvestmentCoLtdMember
694	Whowho&Company Co., Ltd. [Member]	Member			kt:WhowhoAndCompanyCoLtdMember
695	PlayD Co., Ltd. (N Search Marketing Co., Ltd.) [member]	Member			kt:PlayDCoLtdNSearchMarketingCoLtdMember
696	Next Connect PFV [member]	Member			kt:NextConnectPFVMember
697	KT Rwanda Networks Ltd. [member]	Member			kt:KTRwandaNetworksLtdMember
698	AOS Ltd. [member]	Member			kt:AOSLtdMember
699	KT Belgium [member]	Member			kt:KTBelgiumMember
700	KT ORS Belgium [member]	Member			kt:KTORSBelgiumMember
701	Korea Telecom Japan Co., Ltd. [member]	Member			kt:KoreaTelecomJapanCoLtdMember
702	KBTO sp.zo.o. [member]	Member			kt:KBTOspzooMember
703	Korea Telecom China Co., Ltd. [member]	Member			kt:KoreaTelecomChinaCoLtdMember
704	KT Dutch B.V. [member]	Member			kt:KTDutchBVMember
705	Super iMax LLC [member]	Member			kt:SuperIMaxLLCMember
706	East Telecom LLC [member]	Member			kt:EastTelecomLLCMember
707	Korea Telecom America, Inc. [member]	Member			kt:KoreaTelecomAmericaIncMember
708	PT. KT Indonesia [member]	Member			kt:PTKTIndonesiaMember
709	PT BC card Asia Pacific [member]	Member			kt:PTBCCardAsiaPacificMember
710	KT Hongkong Telecommunications Co., Ltd. [member]	Member			kt:KTHongkongTelecommunicationsCoLtdMember
711	KT Hong kong Limited [member]	Member			kt:KtHongKongLimitedMember
712	Korea Telecom Singapore Pte.Ltd. [member]	Member			kt:KoreaTelecomSingaporePteLtdMember
713	Texnoprosistem LLP [member]	Member			kt:TexnoprosistemLlpMember
714	Nasmedia Thailand Company Limited [member]	Member			kt:NasmediaThailandCompanyLimitedMember
715	GENIE Music Corporation(KT Music Corporation) [member]	Member			kt:GenieMusicCorporationKtMusicCorporationMember
716	KT Sports Co Ltd [member]	Member			kt:KTSportsCoLtdMember
717	KT music contents fund number two [member]	Member			kt:KtMusicContentsFundNumberTwoMember
718	KT Innoedu Co., Ltd. [Member]	Member			kt:KTInnoeduCoLtdMember
719	NgeneBio [member]	Member			kt:NgeneBioMember
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730	1093 - Disclosure - Significant Accounting Policies - Additional Information (Detail)	Network	*	*	http://www.kt.com/taxonomy/role/DisclosureSignificantAccountingPoliciesAdditionalInformation
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735	Disclosure of significant accounting policies [line items]	LineItems			kt:DisclosureOfSignificantAccountingPoliciesLineItems
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737	Description of assets which are not low value	Concept (Text/String)	For Period		kt:StatementThatLesseeAccountsForLeasesOfNotLowvalueAssetsUsingRecognitionExemption
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740	1094 - Disclosure - Significant Accounting Policies - Summary of Estimated Useful Lives of Property, Plant and Equipment (Detail)	Network	*	*	http://www.kt.com/taxonomy/role/DisclosureSignificantAccountingPoliciesSummaryOfEstimatedUsefulLivesOfPropertyPlantAndEquipment
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747	Vehicles [member]	Member			ifrs-full:VehiclesMember
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753	Disclosure of detailed information about intangible assets [table]	Table	*	*	ifrs-full:DisclosureOfIntangibleAssetsTable
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756	Development costs [member]	Member			ifrs-full:IntangibleAssetsUnderDevelopmentMember
757	Software [member]	Member			ifrs-full:ComputerSoftwareMember
758	Industrial property rights [Member]	Member			kt:IndustrialPropertyRightsMember
759	Frequency usage rights [member]	Member			kt:FrequencyUsageRightsMember
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761	Disclosure of detailed information about intangible assets [line items]	LineItems			ifrs-full:DisclosureOfIntangibleAssetsLineItems
762	Estimated Useful Life	Concept (Text/String)	For Period		ifrs-full:UsefulLivesOrAmortisationRatesIntangibleAssetsOtherThanGoodwill
763	1096 - Disclosure - Critical Accounting Estimates and Assumptions - Additional Information (Detail)	Network	*	*	http://www.kt.com/taxonomy/role/DisclosureCriticalAccountingEstimatesAndAssumptionsAdditionalInformation
764	Disclosure of changes in accounting estimates [table]	Table	*	*	ifrs-full:DisclosureOfChangesInAccountingEstimatesTable
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767	Bottom of range [member]	Member			ifrs-full:BottomOfRangeMember
768	Top of range [member]	Member			ifrs-full:TopOfRangeMember
769	Disclosure of changes in accounting estimates [line items]	LineItems			ifrs-full:DisclosureOfChangesInAccountingEstimatesLineItems
770	Amortization term of contract assets and contract liabilities	Concept (xbrli:durationItemType)	For Period		kt:AmortizationTermOfContractAssetsAndContractLiabilities
771	1097 - Disclosure - Financial Instruments by Category - Summary of Financial Instruments by Category (Detail)	Network	*	*	http://www.kt.com/taxonomy/role/DisclosureFinancialInstrumentsByCategorySummaryOfFinancialInstrumentsByCategory
772	Disclosure of detailed information about financial instruments [table]	Table	*	*	ifrs-full:DisclosureOfFinancialInstrumentsTable
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776	Financial assets at fair value through profit or loss [member]	Member			ifrs-full:FinancialAssetsAtFairValueThroughProfitOrLossCategoryMember
777	Derivative used for hedge [member]	Member			ifrs-full:DerivativesMember
778	Available-for-sale [member]	Member			ifrs-full:FinancialAssetsAvailableforsaleCategoryMember
779	Held-to-maturity financial assets [member]	Member			ifrs-full:HeldtomaturityInvestmentsCategoryMember
780	Financial liabilities designated as at fair value through profit or loss [member]	Member			ifrs-full:FinancialLiabilitiesAtFairValueThroughProfitOrLossCategoryMember
781	Financial liabilities at amortized cost [member]	Member			ifrs-full:FinancialLiabilitiesAtAmortisedCostCategoryMember
782	Financial assets at fair value through other comprehensive income [member]	Member			ifrs-full:FinancialAssetsAtFairValueThroughOtherComprehensiveIncomeCategoryMember
783	Disclosure of detailed information about financial instruments [line items]	LineItems			ifrs-full:DisclosureOfFinancialInstrumentsLineItems
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785	Borrowings	Concept (Monetary)	As Of	Credit	ifrs-full:Borrowings
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787	Cash and cash equivalents	Concept (Monetary)	As Of	Debit	ifrs-full:CashAndCashEquivalents
788	Trade and other receivables	Concept (Monetary)	As Of	Debit	ifrs-full:TradeAndOtherReceivables
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790	1098 - Disclosure - Financial Instruments by Category - Summary of Gains or Losses Arising From Financial Instruments by Category (Detail)	Network	*	*	http://www.kt.com/taxonomy/role/DisclosureFinancialInstrumentsByCategorySummaryOfGainsOrLossesArisingFromFinancialInstrumentsByCategory
791	Disclosure of detailed information about financial instruments [table]	Table	*	*	ifrs-full:DisclosureOfFinancialInstrumentsTable
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795	Financial assets at fair value through profit or loss [member]	Member			ifrs-full:FinancialAssetsAtFairValueThroughProfitOrLossCategoryMember
796	Financial assets at fair value through other comprehensive income [member]	Member			ifrs-full:FinancialAssetsAtFairValueThroughOtherComprehensiveIncomeCategoryMember
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803	Financial liabilities designated as at fair value through profit or loss [member]	Member			ifrs-full:FinancialLiabilitiesAtFairValueThroughProfitOrLossCategoryMember
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805	Financial liabilities at amortized cost [member]	Member			ifrs-full:FinancialLiabilitiesAtAmortisedCostCategoryMember
806	Disclosure of detailed information about financial instruments [line items]	LineItems			ifrs-full:DisclosureOfFinancialInstrumentsLineItems
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809	Interest expense	Concept (Monetary)	For Period	Debit	ifrs-full:InterestExpense
810	Dividend income	Concept (Monetary)	For Period	Credit	ifrs-full:RevenueFromDividends
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812	Gain (loss) foreign currency transaction	Concept (Monetary)	For Period	Credit	kt:GainLossOnForeignCurrencyTransaction
813	Gain (loss) on foreign currency translation	Concept (Monetary)	For Period	Credit	kt:GainOnForeignCurrencyTranslations
814	Gain(loss) foreign currency translation	Concept (Monetary)	For Period	Credit	kt:GainLossOnForeignCurrencyTranslations
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816	Gain (loss) on disposal	Concept (Monetary)	For Period	Credit	kt:GainsLossesOnDisposal
817	Impairment loss	Concept (Monetary)	For Period	Debit	ifrs-full:ImpairmentLoss
818	Gain (loss) on valuation	Concept (Monetary)	For Period	Credit	kt:GainLossOnValuation
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820	Reclassified to profit or loss from other comprehensive income for the year	Concept (Monetary)	For Period	Credit	ifrs-full:OtherComprehensiveIncomeThatWillBeReclassifiedToProfitOrLossBeforeTax
821	1099 - Disclosure - Financial Instruments by Category - Summary of Gains or Losses Arising From Financial Instruments by Category (Parenthetical) (Detail)	Network	*	*	http://www.kt.com/taxonomy/role/DisclosureFinancialInstrumentsByCategorySummaryOfGainsOrLossesArisingFromFinancialInstrumentsByCategoryParenthetical
822	Disclosure of detailed information about financial instruments [table]	Table	*	*	ifrs-full:DisclosureOfFinancialInstrumentsTable
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825	BC Card Co., Ltd. [member]	Member			kt:BCCardCoLtdMember
826	Disclosure of detailed information about financial instruments [line items]	LineItems			ifrs-full:DisclosureOfFinancialInstrumentsLineItems
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828	Profit and loss from foreign currency transaction	Concept (Monetary)	For Period	Credit	ifrs-full:NetForeignExchangeGain
829	1100 - Disclosure - Cash and Cash Equivalents to Restricted Cash - Summary of Restricted Cash and Cash Equivalents (Detail)	Network	*	*	http://www.kt.com/taxonomy/role/DisclosureCashAndCashEquivalentsToRestrictedCashSummaryOfRestrictedCashAndCashEquivalents
830	Implied Table	Table	*	*	implied:Table
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832	Deposit restricted for governmental project and others	Concept (Monetary)	As Of	Debit	ifrs-full:RestrictedCashAndCashEquivalents
833	1101 - Disclosure - Trade and Other Receivables - Summary of Trade and Other Receivables (Detail)	Network	*	*	http://www.kt.com/taxonomy/role/DisclosureTradeAndOtherReceivablesSummaryOfTradeAndOtherReceivables
834	Disclosure of financial assets [table]	Table	*	*	ifrs-full:DisclosureOfFinancialAssetsTable
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836	Carrying amount [member]	Member			ifrs-full:CarryingAmountMember
837	Gross carrying amount [member]	Member			ifrs-full:GrossCarryingAmountMember
838	Allowance for doubtful accounts [member]	Member			ifrs-full:AllowanceForCreditLossesMember
839	Expected credit losses [member]	Member			kt:ExpectedCreditLossesMember
840	Present value discount [member]	Member			kt:PresentValueDiscountMember
841	Disclosure of financial assets [line items]	LineItems			ifrs-full:DisclosureOfFinancialAssetsLineItems
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848	1102 - Disclosure - Trade and Other Receivables - Summary of Changes in Allowance for Doubtful Accounts (Detail)	Network	*	*	http://www.kt.com/taxonomy/role/DisclosureTradeAndOtherReceivablesSummaryOfChangesInAllowanceForDoubtfulAccounts
849	Disclosure of financial assets [table]	Table	*	*	ifrs-full:DisclosureOfFinancialAssetsTable
850	Classes of financial assets [axis]	Axis			ifrs-full:ClassesOfFinancialAssetsAxis
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852	Trade receivables [member]	Member			ifrs-full:TradeReceivablesMember
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861	1103 - Disclosure - Trade and Other Receivables - Summary of Other Receivables (Detail)	Network	*	*	http://www.kt.com/taxonomy/role/DisclosureTradeAndOtherReceivablesSummaryOfOtherReceivables
862	Disclosure of financial assets [table]	Table	*	*	ifrs-full:DisclosureOfFinancialAssetsTable
863	Classes of financial assets [axis]	Axis			ifrs-full:ClassesOfFinancialAssetsAxis
864	Financial assets, class [member]	Member			ifrs-full:FinancialAssetsMember
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866	Disclosure of financial assets [line items]	LineItems			ifrs-full:DisclosureOfFinancialAssetsLineItems
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870	Refundable deposits	Concept (Monetary)	As Of	Debit	kt:RefundableDeposits
871	Loans receivable	Concept (Monetary)	As Of	Debit	ifrs-full:LoansAndAdvancesToCustomers
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876	1104 - Disclosure - Trade and Other Receivables - Summary of Other Receivables (Parenthetical) (Detail)	Network	*	*	http://www.kt.com/taxonomy/role/DisclosureTradeAndOtherReceivablesSummaryOfOtherReceivablesParenthetical
877	Disclosure of financial assets [table]	Table	*	*	ifrs-full:DisclosureOfFinancialAssetsTable
878	Subsidiaries [axis]	Axis			ifrs-full:SignificantInvestmentsInSubsidiariesAxis
879	Entity's total for subsidiaries [member]	Member			ifrs-full:EntitysTotalForSubsidiariesMember
880	BC Card Co., Ltd. [member]	Member			kt:BCCardCoLtdMember
881	Disclosure of financial assets [line items]	LineItems			ifrs-full:DisclosureOfFinancialAssetsLineItems
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883	1105 - Disclosure - Other Financial Assets and Liabilities - Summary of Other Financial Assets and Liabilities (Detail)	Network	*	*	http://www.kt.com/taxonomy/role/DisclosureOtherFinancialAssetsAndLiabilitiesSummaryOfOtherFinancialAssetsAndLiabilities
884	Implied Table	Table	*	*	implied:Table
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900	1106 - Disclosure - Other Financial Assets and Liabilities - Summary of Other Financial Assets and Liabilities (Parenthetical) (Detail)	Network	*	*	http://www.kt.com/taxonomy/role/DisclosureOtherFinancialAssetsAndLiabilitiesSummaryOfOtherFinancialAssetsAndLiabilitiesParenthetical
901	Disclosure of detailed information about financial instruments [table]	Table	*	*	ifrs-full:DisclosureOfFinancialInstrumentsTable
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911	1107 - Disclosure - Other Financial Assets and Liabilities - Summary of Financial Assets at Fair Value Through Profit or Loss (Detail)	Network	*	*	http://www.kt.com/taxonomy/role/DisclosureOtherFinancialAssetsAndLiabilitiesSummaryOfFinancialAssetsAtFairValueThroughProfitOrLoss
912	Disclosure of financial assets [table]	Table	*	*	ifrs-full:DisclosureOfFinancialAssetsTable
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916	Equity Instruments Unlisted [member]	Member			kt:EquityInstrumentsUnlistedMember
917	Debt securities [member]	Member			ifrs-full:DebtSecuritiesMember
918	Disclosure of financial assets [line items]	LineItems			ifrs-full:DisclosureOfFinancialAssetsLineItems
919	Equity Instruments	Concept (Monetary)	As Of	Debit	ifrs-full:FinancialAssetsAtFairValueThroughProfitOrLoss
920	Less: non-current	Concept (Monetary)	As Of	Debit	ifrs-full:NoncurrentFinancialAssetsAtFairValueThroughProfitOrLoss
921	Current	Concept (Monetary)	As Of	Debit	ifrs-full:CurrentFinancialAssetsAtFairValueThroughProfitOrLoss
922	1108 - Disclosure - Other Financial Assets and Liabilities - Additional Information (Detail)	Network	*	*	http://www.kt.com/taxonomy/role/DisclosureOtherFinancialAssetsAndLiabilitiesAdditionalInformation
923	Disclosure of detailed information about financial instruments [table]	Table	*	*	ifrs-full:DisclosureOfFinancialInstrumentsTable
924	Associates [axis]	Axis			ifrs-full:SignificantInvestmentsInAssociatesAxis
925	Entity's total for associates [member]	Member			ifrs-full:EntitysTotalForAssociatesMember
926	Korea software financial cooperative [member]	Member			kt:KoreaSoftwareFinancialCooperativeMember
927	Disclosure of detailed information about financial instruments [line items]	LineItems			ifrs-full:DisclosureOfFinancialInstrumentsLineItems
928	Available-for-sale financial assets investment amount	Concept (Monetary)	As Of	Debit	ifrs-full:FinancialAssetsPledgedAsCollateralForLiabilitiesOrContingentLiabilities
929	Available-for-sales financial assets at fair value through profit or loss	Concept (Monetary)	As Of	Debit	ifrs-full:CurrentFinancialAssetsAvailableforsale
930	Available-for-sales classified as financial assets at fair value through other comprehensive income	Concept (Monetary)	As Of	Debit	kt:AvailableforsalesClassifiedAsFinancialAssetsAtFairValueThroughOtherComprehensiveIncome
931	Ineffective portion recognized in profit or loss cash flow hedge valuation gain	Concept (Monetary)	For Period	Credit	ifrs-full:GainsLossesOnIneffectivenessOfCashFlowHedgesRecognisedInProfitOrLoss
932	1109 - Disclosure - Other Financial Assets and Liabilities - Summary of Financial Assets at Fair Value Through Other Comprehensive Income (Detail)	Network	*	*	http://www.kt.com/taxonomy/role/DisclosureOtherFinancialAssetsAndLiabilitiesSummaryOfFinancialAssetsAtFairValueThroughOtherComprehensiveIncome
933	Financial assets at fair value through other comprehensive income [table]	Table	*	*	kt:FinancialAssetsAtFairValueThroughOtherComprehensiveIncomeTable
934	Classes of financial assets [axis]	Axis			ifrs-full:ClassesOfFinancialAssetsAxis
935	Financial assets, class [member]	Member			ifrs-full:FinancialAssetsMember
936	Equity Instruments Listed [member]	Member			kt:EquityInstrumentsListedMember
937	Equity Instruments Unlisted [member]	Member			kt:EquityInstrumentsUnlistedMember
938	Debt securities [member]	Member			ifrs-full:DebtSecuritiesMember
939	Financial assets at fair value through other comprehensive income [line items]	LineItems			kt:FinancialAssetsAtFairValueThroughOtherComprehensiveIncomeLineItems
940	Equity Instruments	Concept (Monetary)	As Of	Debit	ifrs-full:FinancialAssetsAtFairValueThroughOtherComprehensiveIncome
941	Less: non-current	Concept (Monetary)	As Of	Debit	ifrs-full:NoncurrentFinancialAssetsAtFairValueThroughOtherComprehensiveIncome
942	Current	Concept (Monetary)	As Of	Debit	ifrs-full:CurrentFinancialAssetsAtFairValueThroughOtherComprehensiveIncome
943	1110 - Disclosure - Other Financial Assets and Liabilities - Summary of Derivative Financial Assets and Liabilities (Detail)	Network	*	*	http://www.kt.com/taxonomy/role/DisclosureOtherFinancialAssetsAndLiabilitiesSummaryOfDerivativeFinancialAssetsAndLiabilities
944	Disclosure of detailed information about financial instruments [table]	Table	*	*	ifrs-full:DisclosureOfFinancialInstrumentsTable
945	Classes of financial assets [axis]	Axis			ifrs-full:ClassesOfFinancialAssetsAxis
946	Financial assets, class [member]	Member			ifrs-full:FinancialAssetsMember
947	Interest rate swap [member]	Member			ifrs-full:InterestRateSwapContractMember
948	Currency swap [member]	Member			ifrs-full:CurrencySwapContractMember
949	Currency forwards [member]	Member			ifrs-full:ForwardContractMember
950	Disclosure of detailed information about financial instruments [line items]	LineItems			ifrs-full:DisclosureOfFinancialInstrumentsLineItems
951	Assets, Total	Concept (Monetary)	As Of	Debit	ifrs-full:DerivativeFinancialAssets
952	Less: Assets, non-current	Concept (Monetary)	As Of	Debit	ifrs-full:NoncurrentDerivativeFinancialAssets
953	Assets, Current	Concept (Monetary)	As Of	Debit	ifrs-full:CurrentDerivativeFinancialAssets
954	Liabilities, Total	Concept (Monetary)	As Of	Credit	ifrs-full:DerivativeFinancialLiabilities
955	Less: Liabilities, non-current	Concept (Monetary)	As Of	Credit	ifrs-full:NoncurrentDerivativeFinancialLiabilities
956	Liabilities, Current	Concept (Monetary)	As Of	Credit	ifrs-full:CurrentDerivativeFinancialLiabilities
957	1111 - Disclosure - Other Financial Assets and Liabilities - Summary of Valuation Gains and Losses on Derivatives Contracts (Detail)	Network	*	*	http://www.kt.com/taxonomy/role/DisclosureOtherFinancialAssetsAndLiabilitiesSummaryOfValuationGainsAndLossesOnDerivativesContracts
958	Disclosure of detailed information about financial instruments [table]	Table	*	*	ifrs-full:DisclosureOfFinancialInstrumentsTable
959	Classes of financial instruments [axis]	Axis			ifrs-full:ClassesOfFinancialInstrumentsAxis
960	Financial instruments, class [member]	Member			ifrs-full:ClassesOfFinancialInstrumentsMember
961	Interest rate swap [member]	Member			ifrs-full:InterestRateSwapContractMember
962	Currency swap [member]	Member			ifrs-full:CurrencySwapContractMember
963	Currency forwards [member]	Member			ifrs-full:ForwardContractMember
964	Disclosure of detailed information about financial instruments [line items]	LineItems			ifrs-full:DisclosureOfFinancialInstrumentsLineItems
965	Valuation gain	Concept (Monetary)	For Period	Credit	kt:GainOnValuationOfDerivatives
966	Valuation loss	Concept (Monetary)	For Period	Debit	kt:LossOnValuationOfDerivatives
967	Other comprehensive income	Concept (Monetary)	For Period	Credit	ifrs-full:GainsLossesOnCashFlowHedgesBeforeTax
968	1112 - Disclosure - Other Financial Assets and Liabilities - Summary of Financial Liabilities at Fair Value Through Profit or Loss (Detail)	Network	*	*	http://www.kt.com/taxonomy/role/DisclosureOtherFinancialAssetsAndLiabilitiesSummaryOfFinancialLiabilitiesAtFairValueThroughProfitOrLoss
969	Implied Table	Table	*	*	implied:Table
970	Disclosure of financial liabilities [abstract]	Abstract			ifrs-full:DisclosureOfFinancialLiabilitiesAbstract
971	Financial liabilities at fair value through profit or loss	Abstract			ifrs-full:FinancialLiabilitiesAtFairValueThroughProfitOrLossAbstract
972	Derivative liabilities held for trading	Concept (Monetary)	As Of	Credit	ifrs-full:DerivativeFinancialLiabilitiesHeldForTrading
973	1113 - Disclosure - Other Financial Assets and Liabilities - Summary of Valuation Gain and Loss on Financial Liabilities at Fair Value Through Profit or Loss (Detail)	Network	*	*	http://www.kt.com/taxonomy/role/DisclosureOtherFinancialAssetsAndLiabilitiesSummaryOfValuationGainAndLossOnFinancialLiabilitiesAtFairValueThroughProfitOrLoss
974	Disclosure of financial liabilities [table]	Table	*	*	ifrs-full:DisclosureOfFinancialLiabilitiesTable
975	Categories of financial liabilities [axis]	Axis			ifrs-full:CategoriesOfFinancialLiabilitiesAxis
976	Other liabilities [Member]	Member			ifrs-full:FinancialLiabilitiesCategoryMember
977	Valuation loss on financial liabilities [member]	Member			kt:ValuationLossOnFinancialLiabilitiesMember
978	Disclosure of financial liabilities [line items]	LineItems			ifrs-full:DisclosureOfFinancialLiabilitiesLineItems
979	Derivative liabilities held for trading	Concept (Monetary)	As Of	Credit	ifrs-full:DerivativeFinancialLiabilitiesHeldForTrading
980	1114 - Disclosure - Inventories - Summary of Inventories Net (Detail)	Network	*	*	http://www.kt.com/taxonomy/role/DisclosureInventoriesSummaryOfInventoriesNet
981	Disclosure of inventories [table]	Table	*	*	kt:DisclosureOfInventoriesTable
982	Carrying amount, accumulated depreciation, amortisation and impairment and gross carrying amount [axis]	Axis			ifrs-full:CarryingAmountAccumulatedDepreciationAmortisationAndImpairmentAndGrossCarryingAmountAxis
983	Carrying amount [member]	Member			ifrs-full:CarryingAmountMember
984	Gross carrying amount [member]	Member			ifrs-full:GrossCarryingAmountMember
985	Valuation allowance [member]	Member			ifrs-full:AccumulatedImpairmentMember
986	Classes of assets [axis]	Axis			ifrs-full:ClassesOfAssetsAxis
987	Assets [member]	Member			ifrs-full:ClassesOfAssetsMember
988	Merchandise [member]	Member			kt:MerchandiseMember
989	Others [member]	Member			kt:OthersMember
990	Disclosure of inventories [line items]	LineItems			kt:DisclosureOfInventoriesLineItems
991	Inventories	Concept (Monetary)	As Of	Debit	ifrs-full:Inventories
992	1115 - Disclosure - Inventories - Additional Information (Detail)	Network	*	*	http://www.kt.com/taxonomy/role/DisclosureInventoriesAdditionalInformation
993	Implied Table	Table	*	*	implied:Table
994	Classes of current inventories [abstract]	Abstract			ifrs-full:ClassesOfInventoriesAbstract
995	Inventories recognised as expense	Concept (Monetary)	For Period	Debit	ifrs-full:CostOfInventoriesRecognisedAsExpenseDuringPeriod
996	Valuation loss and reversal of valuation loss	Concept (Monetary)	For Period	Debit	ifrs-full:WritedownsReversalsOfInventories
997	1116 - Disclosure - Other Assets and Liabilities - Summary of Other Assets and Liabilities (Detail)	Network	*	*	http://www.kt.com/taxonomy/role/DisclosureOtherAssetsAndLiabilitiesSummaryOfOtherAssetsAndLiabilities
998	Implied Table	Table	*	*	implied:Table
999	Subclassifications of assets, liabilities and equities [abstract]	Abstract			ifrs-full:SubclassificationsOfAssetsLiabilitiesAndEquitiesAbstract
1000	Other assets	Abstract			ifrs-full:MiscellaneousAssetsAbstract
1001	Advance payments	Concept (Monetary)	As Of	Debit	kt:OtherAdvancePayments
1002	Prepaid expenses	Concept (Monetary)	As Of	Debit	ifrs-full:Prepayments
1003	Contract assets	Concept (Monetary)	As Of	Debit	ifrs-full:CurrentContractAssets
1004	Others	Concept (Monetary)	As Of	Debit	ifrs-full:OtherAssets
1005	Less: Non-current	Concept (Monetary)	As Of	Debit	ifrs-full:OtherNoncurrentNonfinancialAssets
1006	Current	Concept (Monetary)	As Of	Debit	ifrs-full:OtherCurrentAssets
1007	Other liabilities	Abstract			ifrs-full:MiscellaneousLiabilitiesAbstract
1008	Advances received	Concept (Monetary)	As Of	Credit	ifrs-full:Advances
1009	Withholdings	Concept (Monetary)	As Of	Credit	kt:CurrentWithholdings
1010	Unearned revenue	Concept (Monetary)	As Of	Credit	ifrs-full:DeferredIncome
1011	Contract liabilities	Concept (Monetary)	As Of	Credit	ifrs-full:CurrentContractLiabilities
1012	Others	Concept (Monetary)	As Of	Credit	ifrs-full:OtherLiabilities
1013	Less: Non-current	Concept (Monetary)	As Of	Credit	ifrs-full:OtherNoncurrentNonfinancialLiabilities
1014	Current	Concept (Monetary)	As Of	Credit	ifrs-full:OtherCurrentNonfinancialLiabilities
1015	1117 - Disclosure - Assets Held for Sale - Additional Information (Detail)	Network	*	*	http://www.kt.com/taxonomy/role/DisclosureAssetsHeldForSaleAdditionalInformation
1016	Implied Table	Table	*	*	implied:Table
1017	Disclosure Of Assets Held For Sale [abstract]	Abstract			kt:DisclosureOfAssetsHeldForSaleAbstract
1018	Assets held for sale	Concept (Monetary)	As Of	Debit	ifrs-full:NoncurrentAssetsOrDisposalGroupsClassifiedAsHeldForSale
1019	1118 - Disclosure - Property and Equipment - Summary of Changes in Property and Equipment (Detail)	Network	*	*	http://www.kt.com/taxonomy/role/DisclosurePropertyAndEquipmentSummaryOfChangesInPropertyAndEquipment
1020	Disclosure of detailed information about property, plant and equipment [table]	Table	*	*	ifrs-full:DisclosureOfPropertyPlantAndEquipmentTable
1021	Classes of property, plant and equipment [axis]	Axis			ifrs-full:ClassesOfPropertyPlantAndEquipmentAxis
1022	Property, plant and equipment [member]	Member			ifrs-full:PropertyPlantAndEquipmentMember
1023	Land [member]	Member			ifrs-full:LandMember
1024	Buildings [member]	Member			ifrs-full:BuildingsMember
1025	Machinery and equipment1 [member]	Member			kt:MachineryAndEquipment1Member
1026	Others [member]	Member			ifrs-full:OtherPropertyPlantAndEquipmentMember
1027	Construction-in-progress [member]	Member			ifrs-full:ConstructionInProgressMember
1028	Carrying amount, accumulated depreciation, amortisation and impairment and gross carrying amount [axis]	Axis			ifrs-full:CarryingAmountAccumulatedDepreciationAmortisationAndImpairmentAndGrossCarryingAmountAxis
1029	Carrying amount [member]	Member			ifrs-full:CarryingAmountMember
1030	Gross carrying amount [member]	Member			ifrs-full:GrossCarryingAmountMember
1031	Accumulated depreciation, amortisation and impairment [member]	Member			ifrs-full:AccumulatedDepreciationAmortisationAndImpairmentMember
1032	Disclosure of detailed information about property, plant and equipment [line items]	LineItems			ifrs-full:DisclosureOfPropertyPlantAndEquipmentLineItems
1033	Beginning, net	Concept (Monetary)	As Of	Debit	ifrs-full:PropertyPlantAndEquipment
1034	Acquisition and capital expenditure	Concept (Monetary)	For Period	Debit	ifrs-full:AdditionsOtherThanThroughBusinessCombinationsPropertyPlantAndEquipment
1035	Disposal and termination	Concept (Monetary)	For Period	Credit	ifrs-full:DisposalsAndRetirementsPropertyPlantAndEquipment
1036	Depreciation	Concept (Monetary)	For Period		ifrs-full:DepreciationPropertyPlantAndEquipment
1037	Impairment	Concept (Monetary)	For Period		ifrs-full:ImpairmentLossRecognisedInProfitOrLossPropertyPlantAndEquipment
1038	Transfer in (out)	Concept (Monetary)	For Period	Debit	ifrs-full:IncreaseDecreaseThroughTransfersAndOtherChangesPropertyPlantAndEquipment
1039	Inclusion in scope of consolidation	Concept (Monetary)	For Period	Credit	kt:InclusionFromScopeOfConsolidation
1040	Exclusion from scope of consolidation	Concept (Monetary)	For Period	Credit	kt:ExclusionFromScopeOfConsolidation
1041	Transfer from(to) investment properties	Concept (Monetary)	For Period	Debit	ifrs-full:IncreaseDecreaseThroughTransfersPropertyPlantAndEquipment
1042	Others	Concept (Monetary)	For Period	Debit	ifrs-full:IncreaseDecreaseThroughOtherChangesPropertyPlantAndEquipment
1043	Ending, net	Concept (Monetary)	As Of	Debit	ifrs-full:PropertyPlantAndEquipment
1044	1119 - Disclosure - Property and Equipment - Summary of the Details of Property and Equipment Provided (Detail)	Network	*	*	http://www.kt.com/taxonomy/role/DisclosurePropertyAndEquipmentSummaryOfTheDetailsOfPropertyAndEquipmentProvided
1045	Disclosure of detailed information about property, plant and equipment [table]	Table	*	*	ifrs-full:DisclosureOfPropertyPlantAndEquipmentTable
1046	Classes of property, plant and equipment [axis]	Axis			ifrs-full:ClassesOfPropertyPlantAndEquipmentAxis
1047	Property, plant and equipment [member]	Member			ifrs-full:PropertyPlantAndEquipmentMember
1048	Land and buildings [member]	Member			ifrs-full:LandAndBuildingsMember
1049	Others [member]	Member			ifrs-full:OtherPropertyPlantAndEquipmentMember
1050	Disclosure of detailed information about property, plant and equipment [line items]	LineItems			ifrs-full:DisclosureOfPropertyPlantAndEquipmentLineItems
1051	Carrying amount	Concept (Monetary)	As Of	Debit	ifrs-full:PropertyPlantAndEquipmentPledgedAsSecurity
1052	Secured amount	Concept (Monetary)	For Period	Credit	kt:SecuredAmountInPropertyPlantAndEquipment
1053	Related line item	Concept (Text/String)	For Period		kt:RelatedAmountDescriptionInPropertyPlantAndEquipment
1054	Related amount	Concept (Monetary)	As Of	Credit	ifrs-full:Borrowings
1055	Secured party	Concept (Text/String)	For Period		kt:SecuredParty
1056	1120 - Disclosure - Property and Equipment - Additional Information (Detail)	Network	*	*	http://www.kt.com/taxonomy/role/DisclosurePropertyAndEquipmentAdditionalInformation
1057	Disclosure of detailed information about property, plant and equipment [table]	Table	*	*	ifrs-full:DisclosureOfPropertyPlantAndEquipmentTable
1058	Range [axis]	Axis			ifrs-full:RangeAxis
1059	Ranges [member]	Member			ifrs-full:RangesMember
1060	Bottom of range [member]	Member			ifrs-full:BottomOfRangeMember
1061	Top of range [member]	Member			ifrs-full:TopOfRangeMember
1062	Disclosure of detailed information about property, plant and equipment [line items]	LineItems			ifrs-full:DisclosureOfPropertyPlantAndEquipmentLineItems
1063	Borrowing cost capitalized	Concept (Monetary)	For Period		ifrs-full:BorrowingCostsCapitalised
1064	Interest rate of capitalized borrowing cost	Concept (Percent)	For Period		ifrs-full:CapitalisationRateOfBorrowingCostsEligibleForCapitalisation
1065	1121 - Disclosure - Investment Properties - Summary of Investment Properties (Detail)	Network	*	*	http://www.kt.com/taxonomy/role/DisclosureInvestmentPropertiesSummaryOfInvestmentProperties
1066	Disclosure of detailed information about investment property [table]	Table	*	*	ifrs-full:DisclosureOfInvestmentPropertyTable
1067	Types of investment property [axis]	Axis			ifrs-full:TypesOfInvestmentPropertyAxis
1068	Investment property [member]	Member			ifrs-full:InvestmentPropertyMember
1069	Land [member]	Member			ifrs-full:LandMember
1070	Buildings [member]	Member			ifrs-full:BuildingsMember
1071	Investment property, construction-in-progress [Member]	Member			ifrs-full:InvestmentPropertyUnderConstructionOrDevelopmentMember
1072	Carrying amount, accumulated depreciation, amortisation and impairment and gross carrying amount [axis]	Axis			ifrs-full:CarryingAmountAccumulatedDepreciationAmortisationAndImpairmentAndGrossCarryingAmountAxis
1073	Carrying amount [member]	Member			ifrs-full:CarryingAmountMember
1074	Gross carrying amount [member]	Member			ifrs-full:GrossCarryingAmountMember
1075	Accumulated depreciation and amortisation [member]	Member			ifrs-full:AccumulatedDepreciationAndAmortisationMember
1076	Disclosure of detailed information about investment property [line items]	LineItems			ifrs-full:DisclosureOfInvestmentPropertyLineItems
1077	Beginning balance	Concept (Monetary)	As Of	Debit	ifrs-full:InvestmentProperty
1078	Acquisition	Concept (Monetary)	For Period	Credit	ifrs-full:PurchaseOfInvestmentProperty
1079	Disposal and termination	Concept (Monetary)	For Period	Credit	ifrs-full:DisposalsInvestmentProperty
1080	Depreciation	Concept (Monetary)	For Period		ifrs-full:DepreciationInvestmentProperty
1081	Transfer from(to) property and equipment	Concept (Monetary)	For Period	Debit	ifrs-full:IncreaseDecreaseThroughTransfersPropertyPlantAndEquipment
1082	Transfer and others	Concept (Monetary)	For Period	Debit	kt:TransferFromInvestmentPropertyUnderConstructionOrDevelopmentInvestmentPropertyAndOther
1083	Ending balance	Concept (Monetary)	As Of	Debit	ifrs-full:InvestmentProperty
1084	1122 - Disclosure - Investment Properties - Additional Information (Detail)	Network	*	*	http://www.kt.com/taxonomy/role/DisclosureInvestmentPropertiesAdditionalInformation
1085	Implied Table	Table	*	*	implied:Table
1086	Disclosure of detailed information about investment property [abstract]	Abstract			ifrs-full:DisclosureOfInvestmentPropertyAbstract
1087	Fair value of investment properties	Concept (Monetary)	As Of	Debit	ifrs-full:InvestmentPropertyFairValueUsedAsDeemedCost
1088	Rental income from investment properties	Concept (Monetary)	For Period	Credit	ifrs-full:RentalIncomeFromInvestmentProperty
1089	1123 - Disclosure - Investment Properties - Summary of Investment Properties Provided as Collateral (Detail)	Network	*	*	http://www.kt.com/taxonomy/role/DisclosureInvestmentPropertiesSummaryOfInvestmentPropertiesProvidedAsCollateral
1090	Disclosure of detailed information about investment property [table]	Table	*	*	ifrs-full:DisclosureOfInvestmentPropertyTable
1091	Classes of financial instruments [axis]	Axis			ifrs-full:ClassesOfFinancialInstrumentsAxis
1092	Financial instruments, class [member]	Member			ifrs-full:ClassesOfFinancialInstrumentsMember
1093	Deposits 1 [member]	Member			kt:Deposits1Member
1094	Borrowings [member]	Member			kt:Borrowings1Member
1095	Types of investment property [axis]	Axis			ifrs-full:TypesOfInvestmentPropertyAxis
1096	Investment property [member]	Member			ifrs-full:InvestmentPropertyMember
1097	Land and buildings [member]	Member			ifrs-full:LandAndBuildingsMember
1098	Disclosure of detailed information about investment property [line items]	LineItems			ifrs-full:DisclosureOfInvestmentPropertyLineItems
1099	Carrying amount	Concept (Monetary)	As Of	Debit	kt:InvestmentPropertyPledgedAsSecurity
1100	Secured amount	Concept (Monetary)	As Of	Debit	kt:SecuredAmountInInvestmentProperty
1101	Related account	Concept (Text/String)	For Period		kt:RelatedAmountDescriptionInInvestmentProperty
1102	Related amount	Concept (Monetary)	As Of	Credit	kt:DepositsAndBorrowings
1103	1124 - Disclosure - Intangible Assets - Summary of Intangible Assets (Detail)	Network	*	*	http://www.kt.com/taxonomy/role/DisclosureIntangibleAssetsSummaryOfIntangibleAssets
1104	Disclosure of detailed information about intangible assets [table]	Table	*	*	ifrs-full:DisclosureOfIntangibleAssetsTable
1105	Classes of intangible assets and goodwill [axis]	Axis			ifrs-full:ClassesOfIntangibleAssetsAndGoodwillAxis
1106	Intangible assets and goodwill [member]	Member			ifrs-full:IntangibleAssetsAndGoodwillMember
1107	Goodwill [member]	Member			ifrs-full:GoodwillMember
1108	Development costs [member]	Member			ifrs-full:IntangibleAssetsUnderDevelopmentMember
1109	Software [member]	Member			ifrs-full:ComputerSoftwareMember
1110	Frequency usage rights [member]	Member			kt:FrequencyUsageRightsMember
1111	Others [member]	Member			ifrs-full:OtherIntangibleAssetsMember
1112	Carrying amount, accumulated depreciation, amortisation and impairment and gross carrying amount [axis]	Axis			ifrs-full:CarryingAmountAccumulatedDepreciationAmortisationAndImpairmentAndGrossCarryingAmountAxis
1113	Carrying amount [member]	Member			ifrs-full:CarryingAmountMember
1114	Gross carrying amount [member]	Member			ifrs-full:GrossCarryingAmountMember
1115	Accumulated depreciation and amortisation [member]	Member			ifrs-full:AccumulatedDepreciationAndAmortisationMember
1116	Disclosure of detailed information about intangible assets [line items]	LineItems			ifrs-full:DisclosureOfIntangibleAssetsLineItems
1117	Beginning, net	Concept (Monetary)	As Of	Debit	ifrs-full:IntangibleAssetsAndGoodwill
1118	Acquisition and capital expenditure	Concept (Monetary)	For Period	Debit	ifrs-full:AcquisitionsThroughBusinessCombinationsIntangibleAssetsAndGoodwill
1119	Disposal and termination	Concept (Monetary)	For Period	Credit	ifrs-full:DisposalsAndRetirementsIntangibleAssetsAndGoodwill
1120	Amortization	Concept (Monetary)	For Period		ifrs-full:AmortisationIntangibleAssetsOtherThanGoodwill
1121	Impairment	Concept (Monetary)	For Period		ifrs-full:ImpairmentLossRecognisedInProfitOrLossIntangibleAssetsAndGoodwill
1122	Inclusion in scope of consolidation	Concept (Monetary)	For Period	Credit	kt:InclusionOfIntangibleAssetsAndGoodwillInScopeOfConsolidation
1123	Exclusion in scope of consolidation	Concept (Monetary)	For Period	Credit	kt:ExclusionOfIntangibleAssetsAndGoodwillInScopeOfConsolidation
1124	Others	Concept (Monetary)	For Period	Debit	ifrs-full:IncreaseDecreaseThroughOtherChangesIntangibleAssetsAndGoodwill
1125	Ending, net	Concept (Monetary)	As Of	Debit	ifrs-full:IntangibleAssetsAndGoodwill
1126	1125 - Disclosure - Intangible Assets - Additional Information (Detail)	Network	*	*	http://www.kt.com/taxonomy/role/DisclosureIntangibleAssetsAdditionalInformation
1127	Disclosure of detailed information about intangible assets [table]	Table	*	*	ifrs-full:DisclosureOfIntangibleAssetsTable
1128	Classes of intangible assets other than goodwill [axis]	Axis			ifrs-full:ClassesOfIntangibleAssetsOtherThanGoodwillAxis
1129	Intangible assets other than goodwill [member]	Member			ifrs-full:IntangibleAssetsOtherThanGoodwillMember
1130	Frequency usage rights for 3.5GHz band [member]	Member			kt:FrequencyUsageRightsForThreePointFiveGHzBandMember
1131	Frequency usage rights for twenty 28GHz band [member]	Member			kt:FrequencyUsageRightsForTwentyEightGhzBandMember
1132	Business combinations [axis]	Axis			ifrs-full:BusinessCombinationsAxis
1133	Entity's total for business combinations [member]	Member			ifrs-full:EntitysTotalForBusinessCombinationsMember
1134	Assignment of radio frequencies [member]	Member			kt:AssignmentOfRadioFrequenciesMember
1135	Individual assets or cash-generating units [axis]	Axis			ifrs-full:IndividualAssetsOrCashgeneratingUnitsAxis
1136	Entity's total for individual assets or cash-generating units [member]	Member			ifrs-full:EntitysTotalForIndividualAssetsOrCashgeneratingUnitsMember
1137	Satellite TV segment [member]	Member			kt:SatelliteTvSegmentMember
1138	Disclosure of detailed information about intangible assets [line items]	LineItems			ifrs-full:DisclosureOfIntangibleAssetsLineItems
1139	Indefinite useful life	Concept (Monetary)	As Of	Debit	ifrs-full:IntangibleAssetsWithIndefiniteUsefulLife
1140	Purchase consideration	Concept (Monetary)	As Of	Credit	ifrs-full:AcquisitiondateFairValueOfTotalConsiderationTransferred
1141	Consideration payment period	Concept (xbrli:durationItemType)	For Period		kt:ConsiderationPaymentPeriod
1142	Annual growth rate	Concept (Percent)	For Period		kt:AnnualGrowthRate
1143	Expected revenue growth rate	Concept (Percent)	As Of		kt:RevenueGrowthRates
1144	Discount rate	Concept (Percent)	For Period		kt:DiscountRate
1145	Description of calculation of recoverable amount	Concept (Text/String)	For Period		ifrs-full:DescriptionOfBasisOnWhichUnitsRecoverableAmountHasBeenDetermined
1146	Impairment loss on goodwill	Concept (Monetary)	For Period		ifrs-full:ImpairmentLossRecognisedInProfitOrLossGoodwill
1147	Impairment loss on indefinite-lived intangible assets	Concept (Monetary)	For Period		ifrs-full:ImpairmentLossRecognisedInProfitOrLossIntangibleAssetsOtherThanGoodwill
1148	1126 - Disclosure - Intangible Assets - Summary of Goodwill Allocated to Each Cash-Generation Unit (Detail)	Network	*	*	http://www.kt.com/taxonomy/role/DisclosureIntangibleAssetsSummaryOfGoodwillAllocatedToEachCashGenerationUnit
1149	Disclosure of detailed information about intangible assets [table]	Table	*	*	ifrs-full:DisclosureOfIntangibleAssetsTable
1150	Subsidiaries [axis]	Axis			ifrs-full:SignificantInvestmentsInSubsidiariesAxis
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1201	Disclosure of associates [line items]	LineItems			ifrs-full:DisclosureOfSignificantInvestmentsInAssociatesLineItems
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1230	Disclosure of information about unconsolidated structured entities controlled by investment entity [table]	Table	*	*	ifrs-full:DisclosureOfInformationAboutUnconsolidatedStructuredEntitiesControlledByInvestmentEntityTable
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1452	Borrowings by name [axis]	Axis			ifrs-full:BorrowingsByNameAxis
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1478	1146 - Disclosure - Net Defined Benefit Liabilities - Summary of Amount Recognized in the Statements of Financial Position (Detail)	Network	*	*	http://www.kt.com/taxonomy/role/DisclosureNetDefinedBenefitLiabilitiesSummaryOfAmountRecognizedInTheStatementsOfFinancialPosition
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1485	1147 - Disclosure - Net Defined Benefit Liabilities - Summary of Changes in the Defined Benefit Obligations (Detail)	Network	*	*	http://www.kt.com/taxonomy/role/DisclosureNetDefinedBenefitLiabilitiesSummaryOfChangesInTheDefinedBenefitObligations
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1502	1148 - Disclosure - Net Defined Benefit Liabilities - Summary of Changes in the Fair Value of Plan Assets (Detail)	Network	*	*	http://www.kt.com/taxonomy/role/DisclosureNetDefinedBenefitLiabilitiesSummaryOfChangesInTheFairValueOfPlanAssets
1503	Disclosure of net defined benefit liability (asset) [table]	Table	*	*	ifrs-full:DisclosureOfNetDefinedBenefitLiabilityAssetTable
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1507	Disclosure of net defined benefit liability (asset) [Line Items]	LineItems			ifrs-full:DisclosureOfNetDefinedBenefitLiabilityAssetLineItems
1508	Beginning	Concept (Monetary)	As Of	Credit	ifrs-full:LiabilityAssetOfDefinedBenefitPlans
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1528	Future salary increase	Concept (Percent)	As Of		ifrs-full:ActuarialAssumptionOfExpectedRatesOfSalaryIncreases
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1544	Disclosure of net defined benefit liability (asset) [Line Items]	LineItems			ifrs-full:DisclosureOfNetDefinedBenefitLiabilityAssetLineItems
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1548	Disclosure of net defined benefit liability (asset) [table]	Table	*	*	ifrs-full:DisclosureOfNetDefinedBenefitLiabilityAssetTable
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1550	Aggregated time bands [member]	Member			ifrs-full:AggregatedTimeBandsMember
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1555	Disclosure of net defined benefit liability (asset) [Line Items]	LineItems			ifrs-full:DisclosureOfNetDefinedBenefitLiabilityAssetLineItems
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1561	1155 - Disclosure - Commitments and Contingencies - Summary of Major Commitments with Local Financial Institutions (Detail)	Network	*	*	http://www.kt.com/taxonomy/role/DisclosureCommitmentsAndContingenciesSummaryOfMajorCommitmentsWithLocalFinancialInstitutions
1562	Disclosure of detailed information about borrowings [table]	Table	*	*	ifrs-full:DisclosureOfDetailedInformationAboutBorrowingsTable
1563	Classes of financial instruments [axis]	Axis			ifrs-full:ClassesOfFinancialInstrumentsAxis
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1567	Inter-Korean Cooperation Fund [member]	Member			kt:InterKoreanCooperationFundMember
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1571	Facility loans [member]	Member			kt:FacilityLoansMember
1572	Facility loans on ships [member]	Member			kt:FacilityLoansOnShipsMember
1573	Export L C [member]	Member			kt:ExportLCMember
1574	Derivatives transaction limit [member]	Member			kt:DerivativesTransactionLimitMember
1575	FX forward trading commitment [member]	Member			kt:FXForwardTradingCommitmentMember
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1579	NH Investment & Security Co., Ltd. [member]	Member			kt:NHInvestmentAndSecurityCoLtdMember
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1616	1157 - Disclosure - Commitments and Contingencies - Summary of Guarantees Provided by the Group for Third Parties (Detail)	Network	*	*	http://www.kt.com/taxonomy/role/DisclosureCommitmentsAndContingenciesSummaryOfGuaranteesProvidedByTheGroupForThirdParties
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1622	Subsidiaries [axis]	Axis			ifrs-full:SignificantInvestmentsInSubsidiariesAxis
1623	Entity's total for subsidiaries [member]	Member			ifrs-full:EntitysTotalForSubsidiariesMember
1624	KT Estate Inc. [member]	Member			kt:KTEstateIncMember
1625	KT Hitel Co., Ltd. [member]	Member			kt:KTHitelCoLtdMember
1626	PT BC card Asia Pacific [member]	Member			kt:PTBCCardAsiaPacificMember
1627	Counterparties [axis]	Axis			ifrs-full:CounterpartiesAxis
1628	Counterparties [member]	Member			ifrs-full:CounterpartiesMember
1629	Shinhan Bank [member]	Member			kt:ShinhanBankMember
1630	Cash payers [member]	Member			kt:CashPayersMember
1631	Yonsei University and others [member]	Member			kt:YonseiUniversityAndOthersMember
1632	Shinhan Bank Indonesia [member]	Member			kt:ShinhanBankIndonesiaMember
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1645	Number of lawsuits	Concept (Integer)	For Period		kt:NumberOfLawsuitsFaced
1646	Litigation settlement claim amount	Concept (Monetary)	As Of	Credit	kt:LitigationSettlementsClaimAmount
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1651	1159 - Disclosure - Lease - Summary of Details of Finance Lease Assets (Detail)	Network	*	*	http://www.kt.com/taxonomy/role/DisclosureLeaseSummaryOfDetailsOfFinanceLeaseAssets
1652	Disclosure of recognised finance lease as assets by lessee [table]	Table	*	*	ifrs-full:DisclosureOfRecognisedFinanceLeaseAsAssetsByLesseeTable
1653	Carrying amount, accumulated depreciation, amortisation and impairment and gross carrying amount [axis]	Axis			ifrs-full:CarryingAmountAccumulatedDepreciationAmortisationAndImpairmentAndGrossCarryingAmountAxis
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1655	Gross carrying amount [member]	Member			ifrs-full:GrossCarryingAmountMember
1656	Accumulated depreciation and amortisation [member]	Member			ifrs-full:AccumulatedDepreciationAndAmortisationMember
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1658	Finance lease assets	Concept (Monetary)	As Of	Debit	ifrs-full:RecognisedFinanceLeaseAsAssets
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1660	Implied Table	Table	*	*	implied:Table
1661	Disclosure of detailed information about arrangements involving legal form of lease [abstract]	Abstract			ifrs-full:DisclosureOfArrangementsInvolvingLegalFormOfLeaseAbstract
1662	Depreciation property plant and equipment	Concept (Monetary)	For Period	Debit	kt:DepreciationRecognisedFinanceLeaseAsOtherPropertyPlantAndEquipment
1663	Operating lease expenses incurred	Concept (Monetary)	For Period	Debit	ifrs-full:MinimumOperatingLeasePayments
1664	1161 - Disclosure - Lease - Summary of Details of Future Minimum Lease Payments under Finance Lease Contracts (Detail)	Network	*	*	http://www.kt.com/taxonomy/role/DisclosureLeaseSummaryOfDetailsOfFutureMinimumLeasePaymentsUnderFinanceLeaseContracts
1665	Disclosure of finance lease and operating lease by lessee [table]	Table	*	*	ifrs-full:DisclosureOfFinanceLeaseAndOperatingLeaseByLesseeTable
1666	Maturity [axis]	Axis			ifrs-full:MaturityAxis
1667	Aggregated time bands [member]	Member			ifrs-full:AggregatedTimeBandsMember
1668	Less than 1 year [member]	Member			ifrs-full:NotLaterThanOneYearMember
1669	1-5 years [member]	Member			ifrs-full:LaterThanOneYearAndNotLaterThanFiveYearsMember
1670	More than 5 years [member]	Member			ifrs-full:LaterThanFiveYearsMember
1671	Disclosure of finance lease and operating lease by lessee [Line Items]	LineItems			ifrs-full:DisclosureOfFinanceLeaseAndOperatingLeaseByLesseeLineItems
1672	Total amount of minimum lease payments	Concept (Monetary)	As Of	Credit	ifrs-full:MinimumFinanceLeasePaymentsPayable
1673	Unrealized interest expense	Concept (Monetary)	As Of	Credit	ifrs-full:FutureFinanceChargeOnFinanceLease
1674	Net amount of minimum lease payments	Concept (Monetary)	As Of	Credit	ifrs-full:MinimumFinanceLeasePaymentsPayableAtPresentValue
1675	1162 - Disclosure - Lease - Summary of Details of Future Minimum Lease Payments under Operating Lease Contracts (Detail)	Network	*	*	http://www.kt.com/taxonomy/role/DisclosureLeaseSummaryOfDetailsOfFutureMinimumLeasePaymentsUnderOperatingLeaseContracts
1676	Disclosure of finance lease and operating lease by lessee [table]	Table	*	*	ifrs-full:DisclosureOfFinanceLeaseAndOperatingLeaseByLesseeTable
1677	Maturity [axis]	Axis			ifrs-full:MaturityAxis
1678	Aggregated time bands [member]	Member			ifrs-full:AggregatedTimeBandsMember
1679	Less than 1 year [member]	Member			ifrs-full:NotLaterThanOneYearMember
1680	1-5 years [member]	Member			ifrs-full:LaterThanOneYearAndNotLaterThanFiveYearsMember
1681	More than 5 years [member]	Member			ifrs-full:LaterThanFiveYearsMember
1682	Disclosure of finance lease and operating lease by lessee [Line Items]	LineItems			ifrs-full:DisclosureOfFinanceLeaseAndOperatingLeaseByLesseeLineItems
1683	Net amount of minimum lease payments	Concept (Monetary)	As Of	Credit	ifrs-full:MinimumLeasePaymentsPayableUnderNoncancellableOperatingLease
1684	1163 - Disclosure - Share Capital - Additional Information (Detail)	Network	*	*	http://www.kt.com/taxonomy/role/DisclosureShareCapitalAdditionalInformation
1685	Implied Table	Table	*	*	implied:Table
1686	Disclosure of classes of share capital [abstract]	Abstract			ifrs-full:DisclosureOfClassesOfShareCapitalAbstract
1687	Number of authorized shares	Concept (Shares)	As Of		ifrs-full:NumberOfSharesAuthorised
1688	1164 - Disclosure - Share Capital - Summary of Share Capital (Detail)	Network	*	*	http://www.kt.com/taxonomy/role/DisclosureShareCapitalSummaryOfShareCapital
1689	Disclosure of classes of share capital [table]	Table	*	*	ifrs-full:DisclosureOfClassesOfShareCapitalTable
1690	Classes of share capital [axis]	Axis			ifrs-full:ClassesOfShareCapitalAxis
1691	Share capital [member]	Member			ifrs-full:ClassesOfShareCapitalMember
1692	Ordinary shares [member]	Member			ifrs-full:OrdinarySharesMember
1693	Disclosure of classes of share capital [Line Items]	LineItems			ifrs-full:DisclosureOfClassesOfShareCapitalLineItems
1694	Number of outstanding shares	Concept (Shares)	As Of		ifrs-full:NumberOfSharesOutstanding
1695	Par value per share	Concept (Share)	As Of		ifrs-full:ParValuePerShare
1696	Ordinary Shares	Concept (Monetary)	As Of	Credit	ifrs-full:IssuedCapital
1697	1165 - Disclosure - Share Capital - Summary of Share Capital (Parenthetical) (Detail)	Network	*	*	http://www.kt.com/taxonomy/role/DisclosureShareCapitalSummaryOfShareCapitalParenthetical
1698	Implied Table	Table	*	*	implied:Table
1699	Disclosure of classes of share capital [abstract]	Abstract			ifrs-full:DisclosureOfClassesOfShareCapitalAbstract
1700	Treasury shares	Concept (Shares)	As Of		kt:NumberOfTreasurySharesRetiredAgainstRetainedEarnings
1701	1166 - Disclosure - Retained Earnings - Summary of Retained Earnings (Detail)	Network	*	*	http://www.kt.com/taxonomy/role/DisclosureRetainedEarningsSummaryOfRetainedEarnings
1702	Implied Table	Table	*	*	implied:Table
1703	Miscellaneous equity [abstract]	Abstract			ifrs-full:MiscellaneousEquityAbstract
1704	Legal reserve	Concept (Monetary)	As Of	Credit	kt:RetainedEarningsTransferredToLegalReserves
1705	Voluntary reserves	Concept (Monetary)	As Of	Credit	kt:VoluntaryReserves
1706	Unappropriated retained earnings	Concept (Monetary)	As Of	Credit	kt:UnappropriatedRetainedEarnings
1707	Total	Concept (Monetary)	As Of	Credit	ifrs-full:RetainedEarnings
1708	1167 - Disclosure - Retained Earnings - Summary of Retained Earnings (Parenthetical) (Detail)	Network	*	*	http://www.kt.com/taxonomy/role/DisclosureRetainedEarningsSummaryOfRetainedEarningsParenthetical
1709	Implied Table	Table	*	*	implied:Table
1710	Miscellaneous equity [abstract]	Abstract			ifrs-full:MiscellaneousEquityAbstract
1711	Minimum percentage of cash dividend declared appropriation to legal reserve	Concept (Percent)	For Period		kt:MinimumPercentageOfCashDividendDeclaredAppropriationToLegalReserve
1712	Percentage of legal reserve equal to capital stock issued	Concept (Percent)	For Period		kt:PercentageOfLegalReservesEqualToCapitalStock
1713	1168 - Disclosure - Accumulated Other Comprehensive Income and Other Components of Equity - Summary of Accumulated Other Comprehensive Income (Detail)	Network	*	*	http://www.kt.com/taxonomy/role/DisclosureAccumulatedOtherComprehensiveIncomeAndOtherComponentsOfEquitySummaryOfAccumulatedOtherComprehensiveIncome
1714	Statement of changes in equity [table]	Table	*	*	ifrs-full:StatementOfChangesInEquityTable
1715	Components of equity [axis]	Axis			ifrs-full:ComponentsOfEquityAxis
1716	Equity [member]	Member			ifrs-full:EquityMember
1717	Changes in investments in associates and joint ventures [member]	Member			kt:ChangesinInvestmentsInAssociatesandJointVenturesMember
1718	Loss on derivatives valuation [member]	Member			kt:LossOnDerivativesValuationMember
1719	Gain on valuation of financial assets at fair value through other comprehensive income [member]	Member			kt:GainOnValuationOfFinancialAssetsAtFairValueThroughOtherComprehensiveIncomeMember
1720	Gain of valuation on available for sale [member]	Member			kt:GainOfValuationOnAvailableForSaleMember
1721	Exchange differences on translation for foreign operations [member]	Member			kt:ExchangeDifferencesOnTranslationForForeignOperationsMember
1722	Statement of changes in equity [line items]	LineItems			ifrs-full:StatementOfChangesInEquityLineItems
1723	Total accumulated other comprehensive income	Concept (Monetary)	As Of	Credit	ifrs-full:AccumulatedOtherComprehensiveIncome
1724	1169 - Disclosure - Accumulated Other Comprehensive Income and Other Components of Equity - Summary of Changes in Accumulated Other Comprehensive Income (Detail)	Network	*	*	http://www.kt.com/taxonomy/role/DisclosureAccumulatedOtherComprehensiveIncomeAndOtherComponentsOfEquitySummaryOfChangesInAccumulatedOtherComprehensiveIncome
1725	Statement of changes in equity [table]	Table	*	*	ifrs-full:StatementOfChangesInEquityTable
1726	Components of equity [axis]	Axis			ifrs-full:ComponentsOfEquityAxis
1727	Equity [member]	Member			ifrs-full:EquityMember
1728	Changes in investments in associates and joint ventures [member]	Member			kt:ChangesinInvestmentsInAssociatesandJointVenturesMember
1729	Loss on derivatives valuation [member]	Member			kt:LossOnDerivativesValuationMember
1730	Gain on valuation of financial assets at fair value through other comprehensive income [member]	Member			kt:GainOnValuationOfFinancialAssetsAtFairValueThroughOtherComprehensiveIncomeMember
1731	Gain of valuation on available for sale [member]	Member			kt:GainOfValuationOnAvailableForSaleMember
1732	Exchange differences on translation for foreign operations [member]	Member			kt:ExchangeDifferencesOnTranslationForForeignOperationsMember
1733	Statement of changes in equity [line items]	LineItems			ifrs-full:StatementOfChangesInEquityLineItems
1734	Beginning	Concept (Monetary)	As Of	Credit	ifrs-full:AccumulatedOtherComprehensiveIncome
1735	Changes in accounting policy	Concept (Monetary)	For Period	Credit	kt:ChangesInAccountingPoliciesAdjustments
1736	Increase /decrease	Concept (Monetary)	For Period	Credit	kt:IncreaseDecreaseInOtherComprehensiveIncome
1737	Reclassified to gain or loss	Concept (Monetary)	For Period	Credit	ifrs-full:OtherComprehensiveIncomeThatWillBeReclassifiedToProfitOrLossBeforeTax
1738	Ending	Concept (Monetary)	As Of	Credit	ifrs-full:AccumulatedOtherComprehensiveIncome
1739	1170 - Disclosure - Accumulated Other Comprehensive Income and Other Components of Equity - Summary of Other Components of Equity (Detail)	Network	*	*	http://www.kt.com/taxonomy/role/DisclosureAccumulatedOtherComprehensiveIncomeAndOtherComponentsOfEquitySummaryOfOtherComponentsOfEquity
1740	Implied Table	Table	*	*	implied:Table
1741	Miscellaneous equity [abstract]	Abstract			ifrs-full:MiscellaneousEquityAbstract
1742	Treasury stock	Concept (Monetary)	As Of	Debit	ifrs-full:TreasuryShares
1743	Gain or loss on disposal of treasury stock	Concept (Monetary)	For Period	Debit	kt:GainLossOnDisposalOfTreasuryStock
1744	Share-based payments	Concept (Monetary)	For Period	Debit	ifrs-full:ExpenseFromSharebasedPaymentTransactionsWithEmployees
1745	Others	Concept (Monetary)	As Of	Credit	kt:OtherEquityInstruments
1746	Total	Concept (Monetary)	As Of	Credit	ifrs-full:OtherEquityInterest
1747	1171 - Disclosure - Accumulated Other Comprehensive Income and Other Components of Equity - Summary of Other Components of Equity (Parenthetical) (Detail)	Network	*	*	http://www.kt.com/taxonomy/role/DisclosureAccumulatedOtherComprehensiveIncomeAndOtherComponentsOfEquitySummaryOfOtherComponentsOfEquityParenthetical
1748	Implied Table	Table	*	*	implied:Table
1749	Miscellaneous equity [abstract]	Abstract			ifrs-full:MiscellaneousEquityAbstract
1750	Number of treasury shares acquired	Concept (Shares)	For Period		kt:NumberOfTreasurySharesAcquired
1751	Number of treasury shares disposed	Concept (Shares)	For Period		kt:NumberOfTreasurySharesDisposed
1752	Treasury shares, Amount directly reflected in equity	Concept (Monetary)	For Period	Debit	kt:TreasurySharesAmountDirectlyReflectedInEquity
1753	1172 - Disclosure - Accumulated Other Comprehensive Income and Other Components of Equity - Summary of Treasury Stock (Detail)	Network	*	*	http://www.kt.com/taxonomy/role/DisclosureAccumulatedOtherComprehensiveIncomeAndOtherComponentsOfEquitySummaryOfTreasuryStock
1754	Implied Table	Table	*	*	implied:Table
1755	Miscellaneous equity [abstract]	Abstract			ifrs-full:MiscellaneousEquityAbstract
1756	Number of shares (in shares)	Concept (Shares)	As Of		kt:NumberOfTreasuryShares
1757	Amounts (In millions of Korean won)	Concept (Monetary)	As Of	Debit	ifrs-full:TreasuryShares
1758	1173 - Disclosure - Share-based Payments - Summary of Details of Share-based Payments (Detail)	Network	*	*	http://www.kt.com/taxonomy/role/DisclosureSharebasedPaymentsSummaryOfDetailsOfSharebasedPayments
1759	Implied Table	Table	*	*	implied:Table
1760	Disclosure of terms and conditions of share-based payment arrangement [abstract]	Abstract			ifrs-full:DisclosureOfTermsAndConditionsOfSharebasedPaymentArrangementAbstract
1761	Grant date	Concept (Text/String)	For Period		ifrs-full:DateOfGrantOfSharebasedPaymentArrangement
1762	Vesting conditions	Concept (Text/String)	For Period		ifrs-full:DescriptionOfVestingRequirementsForSharebasedPaymentArrangement
1763	Fair value per option	Concept (Monetary)	For Period		ifrs-full:WeightedAverageSharePriceShareOptionsGranted
1764	Total compensation costs	Concept (Monetary)	For Period	Debit	ifrs-full:ExpenseFromSharebasedPaymentTransactionsWithEmployees
1765	1174 - Disclosure - Share-based Payments - Summary of Changes in the Number of Stock Options and the Weighted-Average Exercise Price (Detail)	Network	*	*	http://www.kt.com/taxonomy/role/DisclosureSharebasedPaymentsSummaryOfChangesInTheNumberOfStockOptionsAndTheWeightedAverageExercisePrice
1766	Disclosure of terms and conditions of share-based payment arrangement [table]	Table	*	*	ifrs-full:DisclosureOfTermsAndConditionsOfSharebasedPaymentArrangementTable
1767	Types of share-based payment arrangements [axis]	Axis			ifrs-full:TypesOfSharebasedPaymentArrangementsAxis
1768	Share-based payment arrangements [member]	Member			ifrs-full:SharebasedPaymentArrangementsMember
1769	10th Grant [member]	Member			kt:TenthGrantMember
1770	11th grant [member]	Member			kt:EleventhGrantMember
1771	12th grant [member]	Member			kt:TwelvethGrantMember
1772	Disclosure of terms and conditions of share-based payment arrangement [Line Items]	LineItems			ifrs-full:DisclosureOfTermsAndConditionsOfSharebasedPaymentArrangementLineItems
1773	Beginning	Concept (Decimal)	As Of		ifrs-full:NumberOfOutstandingShareOptions
1774	Granted	Concept (Decimal)	For Period		ifrs-full:NumberOfShareOptionsGrantedInSharebasedPaymentArrangement
1775	Expired	Concept (Decimal)	For Period		ifrs-full:NumberOfShareOptionsExpiredInSharebasedPaymentArrangement
1776	Exercised	Concept (Decimal)	For Period		ifrs-full:NumberOfShareOptionsExercisedInSharebasedPaymentArrangement
1777	Ending	Concept (Decimal)	As Of		ifrs-full:NumberOfOutstandingShareOptions
1778	Number of shares exercisable	Concept (Decimal)	As Of		ifrs-full:NumberOfShareOptionsExercisableInSharebasedPaymentArrangement
1779	1175 - Disclosure - Share-based Payments - Summary of Changes in the Number of Stock Options and the Weighted-Average Exercise Price (Parenthetical) (Detail)	Network	*	*	http://www.kt.com/taxonomy/role/DisclosureSharebasedPaymentsSummaryOfChangesInTheNumberOfStockOptionsAndTheWeightedAverageExercisePriceParenthetical
1780	Implied Table	Table	*	*	implied:Table
1781	Disclosure of terms and conditions of share-based payment arrangement [abstract]	Abstract			ifrs-full:DisclosureOfTermsAndConditionsOfSharebasedPaymentArrangementAbstract
1782	Closing price of ordinary shares	Concept (Monetary)	For Period		ifrs-full:WeightedAverageExercisePriceOfShareOptionsExercisedInSharebasedPaymentArrangement
1783	1176 - Disclosure - Revenue from Contracts with Customers and Relevant Contract Assets and Liabilities - Detail Explanation of Revenue in Statement of Profit or Loss (Detail)	Network	*	*	http://www.kt.com/taxonomy/role/DisclosureRevenueFromContractsWithCustomersAndRelevantContractAssetsAndLiabilitiesDetailExplanationOfRevenueInStatementOfProfitOrLoss
1784	Implied Table	Table	*	*	implied:Table
1785	Disclosure of disaggregation of revenue from contracts with customers [abstract]	Abstract			ifrs-full:DisclosureOfDisaggregationOfRevenueFromContractsWithCustomersAbstract
1786	Revenue from contracts with customers	Concept (Monetary)	For Period	Credit	ifrs-full:RevenueFromContractsWithCustomers
1787	Revenue from other sources	Concept (Monetary)	For Period	Credit	kt:RevenueFromOtherSources
1788	Operating revenue	Concept (Monetary)	For Period	Credit	ifrs-full:Revenue
1789	1177 - Disclosure - Revenue from Contracts with Customers and Relevant Contract Assets and Liabilities - Detail explanation of Operating revenue (Detail)	Network	*	*	http://www.kt.com/taxonomy/role/DisclosureRevenueFromContractsWithCustomersAndRelevantContractAssetsAndLiabilitiesDetailExplanationOfOperatingRevenue
1790	Implied Table	Table	*	*	implied:Table
1791	Disclosure of disaggregation of revenue from contracts with customers [abstract]	Abstract			ifrs-full:DisclosureOfDisaggregationOfRevenueFromContractsWithCustomersAbstract
1792	Mobile services	Concept (Monetary)	For Period	Credit	ifrs-full:RevenueFromRenderingOfMobileTelephoneServices
1793	Fixed-line services:	Concept (Monetary)	For Period	Credit	ifrs-full:RevenueFromRenderingOfLandLineTelephoneServices
1794	Fixed-line and VoIP telephone services	Concept (Monetary)	For Period	Credit	ifrs-full:RevenueFromRenderingOfTelecommunicationServices
1795	Broadband Internet access services	Concept (Monetary)	For Period	Credit	ifrs-full:RevenueFromRenderingOfInternetServices
1796	Data communication services	Concept (Monetary)	For Period	Credit	ifrs-full:RevenueFromRenderingOfDataServices
1797	Media and content	Concept (Monetary)	For Period	Credit	kt:RevenueFromRenderingOfMediaAndContent
1798	Financial services	Concept (Monetary)	For Period	Credit	kt:RevenueFromRenderingOfFinancialServices
1799	Sale of goods	Concept (Monetary)	For Period	Credit	ifrs-full:RevenueFromSaleOfGoods
1800	Others	Concept (Monetary)	For Period	Credit	kt:RevenueFromRenderingOfOtherServices
1801	Operating revenue	Concept (Monetary)	For Period	Credit	ifrs-full:Revenue
1802	1178 - Disclosure - Revenue from Contracts with Customers and Relevant Contract Assets and Liabilities - Detail Analysis of Contract with Customer Assets and Liabilities (Detail)	Network	*	*	http://www.kt.com/taxonomy/role/DisclosureRevenueFromContractsWithCustomersAndRelevantContractAssetsAndLiabilitiesDetailAnalysisOfContractWithCustomerAssetsAndLiabilities
1803	Disclosure of revenue from contracts with customers [table]	Table	*	*	kt:DisclosureOfRevenueFromContractsWithCustomersTable
1804	Types of contracts [axis]	Axis			ifrs-full:TypesOfContractsAxis
1805	Types of contracts [member]	Member			ifrs-full:TypesOfContractsMember
1806	Revenue from contracts with customers [member]	Member			kt:RevenueFromContractsWithCustomersMember
1807	Disclosure of revenue from contracts with customers [line items]	LineItems			kt:DisclosureOfRevenueFromContractsWithCustomersLineItems
1808	Contract assets	Concept (Monetary)	As Of	Debit	ifrs-full:ContractAssets
1809	Contract liabilities	Concept (Monetary)	As Of	Credit	ifrs-full:ContractLiabilities
1810	Deferred revenue	Concept (Monetary)	As Of	Credit	ifrs-full:DeferredIncome
1811	1179 - Disclosure - Revenue from Contracts with Customers and Relevant Contract Assets and Liabilities - Detail Analysis of Contract Costs Recognized as Assets (Detail)	Network	*	*	http://www.kt.com/taxonomy/role/DisclosureRevenueFromContractsWithCustomersAndRelevantContractAssetsAndLiabilitiesDetailAnalysisOfContractCostsRecognizedAsAssets
1812	Implied Table	Table	*	*	implied:Table
1813	Disclosure of disaggregation of revenue from contracts with customers [abstract]	Abstract			ifrs-full:DisclosureOfDisaggregationOfRevenueFromContractsWithCustomersAbstract
1814	Contract costs recognized as assets	Concept (Monetary)	As Of	Debit	ifrs-full:AssetsRecognisedFromCostsToObtainOrFulfilContractsWithCustomers
1815	1180 - Disclosure - Revenue from Contracts with Customers and Relevant Contract Assets and Liabilities - Additional Information (Detail)	Network	*	*	http://www.kt.com/taxonomy/role/DisclosureRevenueFromContractsWithCustomersAndRelevantContractAssetsAndLiabilitiesAdditionalInformation
1816	Implied Table	Table	*	*	implied:Table
1817	Disclosure of disaggregation of revenue from contracts with customers [abstract]	Abstract			ifrs-full:DisclosureOfDisaggregationOfRevenueFromContractsWithCustomersAbstract
1818	Operating expenses	Concept (Monetary)	For Period	Debit	kt:OperatingExpensesRelatedToContractCostAssets
1819	1181 - Disclosure - Revenue from Contracts with Customers and Relevant Contract Assets and Liabilities - Detail of Revenue Arising from Carried-Forward Contract Liabilities (Detail)	Network	*	*	http://www.kt.com/taxonomy/role/DisclosureRevenueFromContractsWithCustomersAndRelevantContractAssetsAndLiabilitiesDetailOfRevenueArisingFromCarriedForwardContractLiabilities
1820	Implied Table	Table	*	*	implied:Table
1821	Disclosure of disaggregation of revenue from contracts with customers [abstract]	Abstract			ifrs-full:DisclosureOfDisaggregationOfRevenueFromContractsWithCustomersAbstract
1822	Allocation of the transaction price	Concept (Monetary)	As Of	Credit	ifrs-full:TransactionPriceAllocatedToRemainingPerformanceObligations
1823	Deferred revenue of joining/installment fee	Concept (Monetary)	For Period	Credit	kt:DeferredRevenueRelatedToContractLiabilities
1824	Others	Concept (Monetary)	For Period	Credit	kt:RevenueRecognizedRelatedToContractLiabilitiesOthers
1825	Total	Concept (Monetary)	For Period	Credit	kt:RevenueRecognizedRelatedToContractLiabilities
1826	1182 - Disclosure - Operating Expenses - Summary of Operating Expenses (Detail)	Network	*	*	http://www.kt.com/taxonomy/role/DisclosureOperatingExpensesSummaryOfOperatingExpenses
1827	Implied Table	Table	*	*	implied:Table
1828	Profit (loss) [abstract]	Abstract			ifrs-full:ProfitLossAbstract
1829	Salaries and wages	Concept (Monetary)	For Period	Debit	ifrs-full:WagesAndSalaries
1830	Depreciation	Concept (Monetary)	For Period	Debit	ifrs-full:DepreciationExpense
1831	Amortization of intangible assets	Concept (Monetary)	For Period	Debit	ifrs-full:AmortisationExpense
1832	Commissions	Concept (Monetary)	For Period	Debit	ifrs-full:FeeAndCommissionExpense
1833	Interconnection charges	Concept (Monetary)	For Period	Debit	kt:InterconnectionCharges
1834	International interconnection fee	Concept (Monetary)	For Period	Debit	kt:InternationalInterconnectionFee
1835	Purchase of inventories	Concept (Monetary)	For Period	Debit	kt:PurchaseOfInventories
1836	Changes of inventories	Concept (Monetary)	For Period	Debit	kt:ChangesOfInventories
1837	Sales commission	Concept (Monetary)	For Period	Debit	kt:SalesCommission
1838	Service cost	Concept (Monetary)	For Period	Debit	ifrs-full:ServicesExpense
1839	Utilities	Concept (Monetary)	For Period	Debit	ifrs-full:UtilitiesExpense
1840	Taxes and dues	Concept (Monetary)	For Period	Debit	kt:TaxesAndDues
1841	Rent	Concept (Monetary)	For Period	Debit	ifrs-full:RentalExpense
1842	Insurance premium	Concept (Monetary)	For Period	Debit	ifrs-full:InsuranceExpense
1843	Installation fee	Concept (Monetary)	For Period	Debit	kt:InstallationFee
1844	Advertising expenses	Concept (Monetary)	For Period	Debit	kt:AdvertisingExpense1
1845	Research and development expenses	Concept (Monetary)	For Period	Debit	ifrs-full:ResearchAndDevelopmentExpense
1846	Card service cost	Concept (Monetary)	For Period	Debit	kt:CardServiceCost
1847	Others	Concept (Monetary)	For Period	Debit	ifrs-full:MiscellaneousOtherOperatingExpense
1848	Total	Concept (Monetary)	For Period	Debit	ifrs-full:OperatingExpense
1849	1183 - Disclosure - Operating Expenses - Summary of Details of Employee Benefits (Detail)	Network	*	*	http://www.kt.com/taxonomy/role/DisclosureOperatingExpensesSummaryOfDetailsOfEmployeeBenefits
1850	Implied Table	Table	*	*	implied:Table
1851	Profit (loss) [abstract]	Abstract			ifrs-full:ProfitLossAbstract
1852	Short-term employee benefits	Concept (Monetary)	For Period	Debit	ifrs-full:ShorttermEmployeeBenefitsExpense
1853	Post-employment benefits(Defined benefit plan)	Concept (Monetary)	For Period	Debit	ifrs-full:PostemploymentBenefitExpenseDefinedBenefitPlans
1854	Post-employment benefits(Defined contribution plan)	Concept (Monetary)	For Period	Debit	ifrs-full:PostemploymentBenefitExpenseDefinedContributionPlans
1855	Post-employment benefits(Others)	Concept (Monetary)	For Period	Debit	kt:OtherPostemploymentBenefitExpenseRetirementBonus
1856	Share-based payment	Concept (Monetary)	For Period	Debit	kt:PostemploymentBenefitExpenseShareBasedPayment
1857	Total	Concept (Monetary)	For Period	Debit	ifrs-full:EmployeeBenefitsExpense
1858	1184 - Disclosure - Financial Income and Costs - Summary of Details of Financial Income (Detail)	Network	*	*	http://www.kt.com/taxonomy/role/DisclosureFinancialIncomeAndCostsSummaryOfDetailsOfFinancialIncome
1859	Implied Table	Table	*	*	implied:Table
1860	Profit (loss) [abstract]	Abstract			ifrs-full:ProfitLossAbstract
1861	Interest income	Concept (Monetary)	For Period	Credit	ifrs-full:RevenueFromInterest
1862	Gain on foreign currency transactions	Concept (Monetary)	For Period	Credit	ifrs-full:NetForeignExchangeGain
1863	Gain on foreign currency translation	Concept (Monetary)	For Period	Credit	kt:GainOnForeignCurrencyTranslation
1864	Gain on settlement of derivatives	Concept (Monetary)	For Period	Credit	kt:GainOnSettlementOfDerivatives
1865	Gain on valuation of derivatives	Concept (Monetary)	For Period	Credit	ifrs-full:GainsOnChangeInFairValueOfDerivatives
1866	Others	Concept (Monetary)	For Period	Credit	ifrs-full:OtherFinanceIncome
1867	Total	Concept (Monetary)	For Period	Credit	ifrs-full:FinanceIncome
1868	1185 - Disclosure - Financial Income and Costs - Summary of Details of Financial Expense (Detail)	Network	*	*	http://www.kt.com/taxonomy/role/DisclosureFinancialIncomeAndCostsSummaryOfDetailsOfFinancialExpense
1869	Disclosure Of Finance Income [table]	Table	*	*	kt:DisclosureOfFinanceIncomeTable
1870	Categories of financial assets [axis]	Axis			ifrs-full:CategoriesOfFinancialAssetsAxis
1871	Financial assets, category [member]	Member			ifrs-full:FinancialAssetsCategoryMember
1872	Loans and receivables [member]	Member			ifrs-full:LoansAndReceivablesCategoryMember
1873	Available-for-sale [member]	Member			ifrs-full:FinancialAssetsAvailableforsaleCategoryMember
1874	Disclosure Of Finance Income [line items]	LineItems			kt:DisclosureOfFinanceIncomeLineItems
1875	Interest expenses	Concept (Monetary)	For Period	Debit	ifrs-full:InterestExpense
1876	Loss on foreign currency transactions	Concept (Monetary)	For Period	Debit	ifrs-full:NetForeignExchangeLoss
1877	Loss on foreign currency translation	Concept (Monetary)	For Period	Debit	kt:LossOnForeignCurrencyTranslations
1878	Loss on settlement of derivatives	Concept (Monetary)	For Period	Debit	kt:LossOnSettlementOfDerivatives
1879	Loss on valuation of derivatives	Concept (Monetary)	For Period	Debit	ifrs-full:LossesOnChangeInFairValueOfDerivatives
1880	Loss on disposal of trade receivables	Concept (Monetary)	For Period	Credit	ifrs-full:GainsLossesOnLoansAndReceivables
1881	Impairment loss on available-for-sale financial assets	Concept (Monetary)	For Period	Debit	ifrs-full:ImpairmentLossOnFinancialAssets
1882	Others	Concept (Monetary)	For Period	Debit	ifrs-full:OtherFinanceCost
1883	Total	Concept (Monetary)	For Period	Debit	ifrs-full:FinanceCosts
1884	1186 - Disclosure - Deferred Income Tax and Income Tax Expense - Summary of Analysis of Deferred Tax Assets and Deferred Tax Liabilities (Detail)	Network	*	*	http://www.kt.com/taxonomy/role/DisclosureDeferredIncomeTaxAndIncomeTaxExpenseSummaryOfAnalysisOfDeferredTaxAssetsAndDeferredTaxLiabilities
1885	Disclosure of temporary difference, unused tax losses and unused tax credits [table]	Table	*	*	ifrs-full:DisclosureOfTemporaryDifferenceUnusedTaxLossesAndUnusedTaxCreditsTable
1886	Carrying amount, accumulated depreciation, amortisation and impairment and gross carrying amount [axis]	Axis			ifrs-full:CarryingAmountAccumulatedDepreciationAmortisationAndImpairmentAndGrossCarryingAmountAxis
1887	Carrying amount [member]	Member			ifrs-full:CarryingAmountMember
1888	Gross carrying amount [member]	Member			ifrs-full:GrossCarryingAmountMember
1889	Maturity [axis]	Axis			ifrs-full:MaturityAxis
1890	Aggregated time bands [member]	Member			ifrs-full:AggregatedTimeBandsMember
1891	Less than 1 year [member]	Member			ifrs-full:NotLaterThanOneYearMember
1892	Over 12 months [member]	Member			ifrs-full:LaterThanOneYearMember
1893	Disclosure of temporary difference, unused tax losses and unused tax credits [Line Items]	LineItems			ifrs-full:DisclosureOfTemporaryDifferenceUnusedTaxLossesAndUnusedTaxCreditsLineItems
1894	Deferred income tax assets	Concept (Monetary)	As Of	Debit	ifrs-full:DeferredTaxAssets
1895	Deferred income tax liabilities	Concept (Monetary)	As Of	Credit	ifrs-full:DeferredTaxLiabilities
1896	1187 - Disclosure - Deferred Income Tax and Income Tax Expense - Summary of Gross Movements on the Deferred Income Tax Account (Detail)	Network	*	*	http://www.kt.com/taxonomy/role/DisclosureDeferredIncomeTaxAndIncomeTaxExpenseSummaryOfGrossMovementsOnTheDeferredIncomeTaxAccount
1897	Implied Table	Table	*	*	implied:Table
1898	Deferred tax assets and liabilities [abstract]	Abstract			ifrs-full:DeferredTaxAssetsAndLiabilitiesAbstract
1899	Beginning	Concept (Monetary)	As Of	Credit	ifrs-full:DeferredTaxLiabilityAsset
1900	Changes in accounting policy	Concept (Monetary)	For Period	Debit	kt:EffectOfChangeInAccountingPolicy
1901	Credited to the statement of profit or loss	Concept (Monetary)	For Period		ifrs-full:DeferredTaxExpenseIncomeRecognisedInProfitOrLoss
1902	Charged to other comprehensive income	Concept (Monetary)	For Period		ifrs-full:IncomeTaxRelatingToComponentsOfOtherComprehensiveIncome
1903	Ending	Concept (Monetary)	As Of	Credit	ifrs-full:DeferredTaxLiabilityAsset
1904	1188 - Disclosure - Deferred Income Tax and Income Tax Expense - Summary of Movement in Deferred Income Tax Assets and Liabilities (Detail)	Network	*	*	http://www.kt.com/taxonomy/role/DisclosureDeferredIncomeTaxAndIncomeTaxExpenseSummaryOfMovementInDeferredIncomeTaxAssetsAndLiabilities
1905	Disclosure of temporary difference, unused tax losses and unused tax credits [table]	Table	*	*	ifrs-full:DisclosureOfTemporaryDifferenceUnusedTaxLossesAndUnusedTaxCreditsTable
1906	Temporary difference, unused tax losses and unused tax credits [axis]	Axis			ifrs-full:TemporaryDifferenceUnusedTaxLossesAndUnusedTaxCreditsAxis
1907	Temporary difference, unused tax losses and unused tax credits [member]	Member			ifrs-full:TemporaryDifferenceUnusedTaxLossesAndUnusedTaxCreditsMember
1908	Deferred tax derivative liabilities [member]	Member			kt:DeferredTaxDerivativeLiabilitiesMember
1909	Deferred tax liabilities available for sale financial assets [member]	Member			kt:DeferredTaxLiabilitiesAvailableForSaleFinancialAssetsMember
1910	Deferred tax liabilities investment in subsidiaries associates and joint ventures [member]	Member			kt:DeferredTaxLiabilitiesInvestmentInSubsidiariesAssociatesAndJointVenturesMember
1911	Deferred tax liabilities depreciation [member]	Member			kt:DeferredTaxLiabilitiesDepreciationMember
1912	Deferred tax liabilities advanced depreciation provision [member]	Member			kt:DeferredTaxLiabilitiesAdvancedDepreciationProvisionMember
1913	Deferred tax liabilities deposits for severance benefits [member]	Member			kt:DeferredTaxLiabilitiesDepositsForSeveranceBenefitsMember
1914	Deferred tax liabilities accrued income [member]	Member			kt:DeferredTaxLiabilitiesAccruedIncomeMember
1915	Deferred tax liabilities reserve for technology and human resource development [member]	Member			kt:DeferredTaxLiabilitiesReserveForTechnologyAndHumanResourceDevelopmentMember
1916	Other deferred tax liabilities [member]	Member			kt:OtherDeferredTaxLiabilitiesMember
1917	Deferred tax liabilities prepaid expenses [member]	Member			kt:DeferredTaxLiabilitiesPrepaidExpensesMember
1918	Deferred tax derivative assets [member]	Member			kt:DeferredTaxDerivativeAssetsMember
1919	Deferred tax assets provision for impairment or trade receivables [member]	Member			kt:DeferredTaxAssetsProvisionForImpairmentOrTradeReceivablesMember
1920	Deferred tax assets inventory valuation [member]	Member			kt:DeferredTaxAssetsInventoryValuationMember
1921	Deferred tax assets contribution for construction [member]	Member			kt:DeferredTaxAssetsContributionForConstructionMember
1922	Deferred tax assets accrued expenses [member]	Member			kt:DeferredTaxAssetsAccruedExpensesMember
1923	Deferred Tax Assets Provisions [member]	Member			kt:DeferredTaxAssetsProvisionsMember
1924	Deferred tax assets property, plant and equipment [member]	Member			kt:DeferredTaxAssetsPropertyPlantAndEquipmentMember
1925	Deferred Tax assets assets retirement obligation [member]	Member			kt:DeferredTaxAssetsAssetsRetirementObligationMember
1926	Deferred tax assets withholding of facilities expenses [member]	Member			kt:DeferredTaxAssetsWithholdingOfFacilitiesExpensesMember
1927	Deferred tax assets accrued payroll expenses [member]	Member			kt:DeferredTaxAssetsAccruedPayrollExpensesMember
1928	Deferred tax assets deduction of installment receivables [member]	Member			kt:DeferredTaxAssetsDeductionOfInstallmentReceivablesMember
1929	Deferred tax assets property and equipment [member]	Member			kt:DeferredTaxAssetsPropertyAndEquipmentMember
1930	Deferred tax assets gain or loss foreign currency translation [member]	Member			kt:DeferredTaxAssetsGainOrLossForeignCurrencyTranslationMember
1931	Deferred tax assets deferred revenue [member]	Member			kt:DeferredTaxAssetsDeferredRevenueMember
1932	Deferred tax assets real-estate sales [member]	Member			kt:DeferredTaxAssetsReal-EstateSalesMember
1933	Deferred tax assets tax loss carryforward [member]	Member			kt:DeferredTaxAssetsTaxLossCarryforwardMember
1934	Other deferred tax assets [member]	Member			kt:OtherDeferredTaxAssetsMember
1935	Deferred tax assets [member]	Member			kt:DeferredTaxAssetsMember
1936	Deferred tax assets defined benefit liabilities [member]	Member			kt:DeferredTaxAssetsDefinedBenefitLiabilitiesMember
1937	Deferred tax assets tax credit carry forwards [member]	Member			kt:DeferredTaxAssetsTaxCreditCarryforwardsMember
1938	Deferred tax liabilities contract assets [member]	Member			kt:DeferredTaxLiabilitiesContractAssetsMember
1939	Deferred tax liabilities financial assets at fair value through profit or loss [member]	Member			kt:DeferredTaxLiabilitiesFinancialAssetsAtFairValueThroughProfitOrLossMember
1940	Deferred tax liabilities Financial assets at fair value through other comprehensive income [member]	Member			kt:DeferredTaxLiabilitiesFinancialAssetsAtFairValueThroughOtherComprehensiveIncomeMember
1941	Deferred tax assets unsettled expenses [member]	Member			kt:DeferredTaxAssetsUnsettledExpensesMember
1942	Deferred tax assets trade receivables [member]	Member			kt:DeferredTaxAssetsTradeReceivablesMember
1943	Temporary differences [member]	Member			ifrs-full:TemporaryDifferenceMember
1944	Deferred tax liabilities [member]	Member			kt:DeferredTaxLiabilitiesMember
1945	Disclosure of temporary difference, unused tax losses and unused tax credits [Line Items]	LineItems			ifrs-full:DisclosureOfTemporaryDifferenceUnusedTaxLossesAndUnusedTaxCreditsLineItems
1946	Beginning	Concept (Monetary)	As Of	Credit	ifrs-full:DeferredTaxLiabilityAsset
1947	Changes in accounting policy	Concept (Monetary)	For Period	Debit	kt:EffectOfChangeInAccountingPolicy
1948	Statement of operations	Concept (Monetary)	For Period		ifrs-full:DeferredTaxExpenseIncomeRecognisedInProfitOrLoss
1949	Other comprehensive income	Concept (Monetary)	For Period		kt:DeferredTaxExpenseIncomeRecognisedInOtherComprehensiveIncome
1950	Ending	Concept (Monetary)	As Of	Credit	ifrs-full:DeferredTaxLiabilityAsset
1951	1189 - Disclosure - Deferred Income Tax and Income Tax Expense - Summary of Tax Impacts Recognized Directly To Equity (Detail)	Network	*	*	http://www.kt.com/taxonomy/role/DisclosureDeferredIncomeTaxAndIncomeTaxExpenseSummaryOfTaxImpactsRecognizedDirectlyToEquity
1952	Implied Table	Table	*	*	implied:Table
1953	Deferred tax assets and liabilities [abstract]	Abstract			ifrs-full:DeferredTaxAssetsAndLiabilitiesAbstract
1954	Loss on valuation of available-for-sale securities, Before recognition	Concept (Monetary)	For Period	Credit	ifrs-full:OtherComprehensiveIncomeBeforeTaxAvailableforsaleFinancialAssets
1955	Gain on valuation of financial assets at fair value through other comprehensive income, Before recognition	Concept (Monetary)	For Period	Credit	ifrs-full:GainsLossesOnFinancialAssetsMeasuredAtFairValueThroughOtherComprehensiveIncomeBeforeTax
1956	Gain (loss) on valuation of hedge instruments (loss)liabilities, Before recognition	Concept (Monetary)	For Period	Credit	ifrs-full:OtherComprehensiveIncomeBeforeTaxCashFlowHedges
1957	Remeasurements of net defined benefit liabilities, Before recognition	Concept (Monetary)	For Period	Credit	ifrs-full:OtherComprehensiveIncomeBeforeTaxGainsLossesOnRemeasurementsOfDefinedBenefitPlans
1958	Share of Gain (loss) of associates and joint ventures, and others, Before recognition	Concept (Monetary)	For Period	Credit	ifrs-full:ShareOfOtherComprehensiveIncomeOfAssociatesAndJointVenturesAccountedForUsingEquityMethodThatWillNotBeReclassifiedToProfitOrLossBeforeTax
1959	Exchange differences on translation for foreign operations, Before recognition	Concept (Monetary)	For Period	Credit	ifrs-full:OtherComprehensiveIncomeBeforeTaxExchangeDifferencesOnTranslation
1960	Total, Before recognition	Concept (Monetary)	For Period	Credit	ifrs-full:OtherComprehensiveIncomeBeforeTax
1961	Loss on valuation of available-for-sale securities, Tax effect	Concept (Monetary)	For Period	Debit	ifrs-full:IncomeTaxRelatingToAvailableforsaleFinancialAssetsOfOtherComprehensiveIncome
1962	Gain on valuation of financial assets at fair value through other comprehensive income, Tax effect	Concept (Monetary)	For Period	Debit	ifrs-full:IncomeTaxRelatingToFinancialAssetsMeasuredAtFairValueThroughOtherComprehensiveIncome
1963	Gain (loss) on valuation of hedge instruments (loss)liabilities, Tax effect	Concept (Monetary)	For Period	Debit	ifrs-full:IncomeTaxRelatingToCashFlowHedgesOfOtherComprehensiveIncome
1964	Remeasurements of net defined benefit liabilities, Tax effect	Concept (Monetary)	For Period	Debit	ifrs-full:IncomeTaxRelatingToRemeasurementsOfDefinedBenefitPlansOfOtherComprehensiveIncome
1965	Share of Gain (loss) of associates and joint ventures, and others, Tax effect	Concept (Monetary)	For Period	Debit	ifrs-full:IncomeTaxRelatingToShareOfOtherComprehensiveIncomeOfAssociatesAndJointVenturesAccountedForUsingEquityMethodThatWillBeReclassifiedToProfitOrLoss
1966	Exchange differences on translation for foreign operations, Tax effect	Concept (Monetary)	For Period	Debit	ifrs-full:IncomeTaxRelatingToExchangeDifferencesOnTranslationOfOtherComprehensiveIncome
1967	Total, Tax effect	Concept (Monetary)	For Period		ifrs-full:IncomeTaxRelatingToComponentsOfOtherComprehensiveIncome
1968	Loss on valuation of available-for-sale securities, After recognition	Concept (Monetary)	For Period	Credit	ifrs-full:OtherComprehensiveIncomeNetOfTaxAvailableforsaleFinancialAssets
1969	Gain on valuation of financial assets at fair value through other comprehensive income, After recognition	Concept (Monetary)	For Period	Credit	ifrs-full:GainsLossesOnFinancialAssetsMeasuredAtFairValueThroughOtherComprehensiveIncomeNetOfTax
1970	Gain (loss) on valuation of hedge instruments (loss)liabilities, After recognition	Concept (Monetary)	For Period	Credit	ifrs-full:OtherComprehensiveIncomeNetOfTaxCashFlowHedges
1971	Remeasurements of net defined benefit liabilities, After recognition	Concept (Monetary)	For Period	Credit	ifrs-full:OtherComprehensiveIncomeNetOfTaxGainsLossesOnRemeasurementsOfDefinedBenefitPlans
1972	Share of Gain (loss) of associates and joint ventures, and others, After recognition	Concept (Monetary)	For Period	Credit	kt:ShareOfProfitLossAndOtherComprehensiveIncomeOfAssociatesAndJointVenturesAccountedForUsingEquityMethod
1973	Exchange differences on translation for foreign operations, After recognition	Concept (Monetary)	For Period	Credit	ifrs-full:OtherComprehensiveIncomeNetOfTaxExchangeDifferencesOnTranslation
1974	Total other comprehensive loss	Concept (Monetary)	For Period	Credit	ifrs-full:OtherComprehensiveIncome
1975	1190 - Disclosure - Deferred Income Tax and Income Tax Expense - Summary of Details of Income Tax Expense (Detail)	Network	*	*	http://www.kt.com/taxonomy/role/DisclosureDeferredIncomeTaxAndIncomeTaxExpenseSummaryOfDetailsOfIncomeTaxExpense
1976	Implied Table	Table	*	*	implied:Table
1977	Deferred tax assets and liabilities [abstract]	Abstract			ifrs-full:DeferredTaxAssetsAndLiabilitiesAbstract
1978	Current income tax expense	Concept (Monetary)	For Period	Debit	ifrs-full:CurrentTaxExpenseIncome
1979	Impact of change in deferred taxes	Concept (Monetary)	For Period		ifrs-full:DeferredTaxExpenseIncomeRecognisedInProfitOrLoss
1980	Income tax expense	Concept (Monetary)	For Period	Debit	ifrs-full:IncomeTaxExpenseContinuingOperations
1981	1191 - Disclosure - Deferred Income Tax and Income Tax Expense - Summary of Tax on the Group's Profit Before Tax (Detail)	Network	*	*	http://www.kt.com/taxonomy/role/DisclosureDeferredIncomeTaxAndIncomeTaxExpenseSummaryOfTaxOnTheGroupsProfitBeforeTax
1982	Implied Table	Table	*	*	implied:Table
1983	Deferred tax assets and liabilities [abstract]	Abstract			ifrs-full:DeferredTaxAssetsAndLiabilitiesAbstract
1984	Profit before income tax expense	Concept (Monetary)	For Period	Credit	ifrs-full:AccountingProfit
1985	Statutory income tax expense	Concept (Monetary)	For Period	Debit	ifrs-full:TaxExpenseIncomeAtApplicableTaxRate
1986	Tax effect	Abstract			ifrs-full:ReconciliationOfAccountingProfitMultipliedByApplicableTaxRatesAbstract
1987	Income not taxable for taxation purposes	Concept (Monetary)	For Period	Credit	ifrs-full:TaxEffectOfRevenuesExemptFromTaxation2011
1988	Non-deductible expenses	Concept (Monetary)	For Period	Debit	ifrs-full:TaxEffectOfExpenseNotDeductibleInDeterminingTaxableProfitTaxLoss
1989	Tax credit	Concept (Monetary)	For Period	Credit	kt:TaxEffectOfTaxCredit
1990	Additional payment of income taxes	Concept (Monetary)	For Period	Credit	kt:TaxEffectOfAdditionalIncomeTaxPayment
1991	Tax effect and adjustment on consolidation	Abstract			kt:TaxEffectAndAdjustmentOnConsolidationAbstract
1992	Goodwill impairment	Concept (Monetary)	For Period	Debit	ifrs-full:TaxEffectOfImpairmentOfGoodwill
1993	Eliminated dividend income form subsidiaries	Concept (Monetary)	For Period	Credit	kt:TaxEffectOfEliminatedDividendIncomeFormSubsidiaries
1994	Changes of out-side tax effect	Concept (Monetary)	For Period	Credit	kt:IncreaseDecreaseInOutSideTaxEffect
1995	Tax effect of investment in kind	Concept (Monetary)	For Period	Debit	kt:TaxEffectOfInvestmentInKind
1996	Others	Concept (Monetary)	For Period	Debit	ifrs-full:OtherTaxEffectsForReconciliationBetweenAccountingProfitAndTaxExpenseIncome
1997	Income tax expense	Concept (Monetary)	For Period	Debit	ifrs-full:IncomeTaxExpenseContinuingOperations
1998	1192 - Disclosure - Earnings per Share - Summary of Basic and Diluted Earnings per Share from Operations (Detail)	Network	*	*	http://www.kt.com/taxonomy/role/DisclosureEarningsPerShareSummaryOfBasicAndDilutedEarningsPerShareFromOperations
1999	Implied Table	Table	*	*	implied:Table
2000	Basic earnings per share [abstract]	Abstract			ifrs-full:BasicEarningsPerShareAbstract
2001	Profit (loss) attributable to ordinary shares	Concept (Monetary)	For Period	Credit	ifrs-full:ProfitLossAttributableToOrdinaryEquityHoldersOfParentEntity
2002	Weighted average number of ordinary shares outstanding	Concept (Shares)	For Period		kt:WeightedAverageNumberOfSharesBasic
2003	Basic earnings per share (In Korean won)	Concept (Share)	For Period		ifrs-full:BasicEarningsLossPerShare
2004	Profit attributable to ordinary shares (In millions of Korean won)	Concept (Monetary)	For Period	Credit	ifrs-full:ProfitLossAttributableToOrdinaryEquityHoldersOfParentEntity
2005	Adjusted net income attributable to ordinary shares (In millions of Korean won)	Concept (Monetary)	For Period	Credit	kt:AdjustedNetIncomeAttributableToOrdinaryShares
2006	Diluted profit attributable to ordinary shares (In millions of Korean won)	Concept (Monetary)	For Period	Credit	ifrs-full:ProfitLossAttributableToOrdinaryEquityHoldersOfParentEntityIncludingDilutiveEffects
2007	Number of dilutive potential ordinary shares outstanding	Concept (Shares)	For Period		ifrs-full:AdjustedWeightedAverageShares
2008	Weighted average number of ordinary shares outstanding	Concept (Shares)	For Period		kt:WeightedAverageNumberOfSharesDilutive
2009	Diluted earnings per share (In Korean won)	Concept (Share)	For Period		ifrs-full:DilutedEarningsLossPerShare
2010	1193 - Disclosure - Dividend - Additional Information (Detail)	Network	*	*	http://www.kt.com/taxonomy/role/DisclosureDividendAdditionalInformation
2011	Implied Table	Table	*	*	implied:Table
2012	Disclosure of Dividends [abstract]	Abstract			kt:DisclosureOfDividendsAbstract
2013	Dividends paid	Concept (Monetary)	For Period	Debit	ifrs-full:DividendsPaidOrdinaryShares
2014	Dividends paid per share	Concept (Share)	For Period		ifrs-full:DividendsPaidOrdinarySharesPerShare
2015	Dividends declared	Concept (Monetary)	For Period		ifrs-full:DividendsProposedOrDeclaredBeforeFinancialStatementsAuthorisedForIssueButNotRecognisedAsDistributionToOwners
2016	Dividends declared per share	Concept (Share)	For Period		ifrs-full:DividendsProposedOrDeclaredBeforeFinancialStatementsAuthorisedForIssueButNotRecognisedAsDistributionToOwnersPerShare
2017	1194 - Disclosure - Cash Generated from Operations - Summary of Cash Flows from Operating Activities (Detail)	Network	*	*	http://www.kt.com/taxonomy/role/DisclosureCashGeneratedFromOperationsSummaryOfCashFlowsFromOperatingActivities
2018	Implied Table	Table	*	*	implied:Table
2019	Cash flows from (used in) operating activities [abstract]	Abstract			ifrs-full:CashFlowsFromUsedInOperatingActivitiesAbstract
2020	Profit for the year	Concept (Monetary)	For Period	Credit	ifrs-full:ProfitLoss
2021	Adjustments to reconcile net income	Abstract			ifrs-full:AdjustmentsForReconcileProfitLossAbstract
2022	Income tax expense	Concept (Monetary)	For Period	Debit	ifrs-full:AdjustmentsForIncomeTaxExpense
2023	Interest income	Concept (Monetary)	For Period	Credit	ifrs-full:AdjustmentsForInterestIncome
2024	Interest expense	Concept (Monetary)	For Period	Debit	ifrs-full:AdjustmentsForInterestExpense
2025	Dividends income	Concept (Monetary)	For Period	Credit	ifrs-full:AdjustmentsForDividendIncome
2026	Depreciation	Concept (Monetary)	For Period	Debit	ifrs-full:AdjustmentsForDepreciationExpense
2027	Amortization of intangible assets	Concept (Monetary)	For Period		ifrs-full:AmortisationIntangibleAssetsOtherThanGoodwill
2028	Provision for severance benefits	Concept (Monetary)	For Period	Debit	kt:AdjustmentsForProvisionForSeveranceBenefits
2029	Impairment losses on trade receivables	Concept (Monetary)	For Period	Debit	ifrs-full:AdjustmentsForImpairmentLossReversalOfImpairmentLossRecognisedInProfitOrLossTradeAndOtherReceivables
2030	Share of net profit or loss of associates and joint ventures	Concept (Monetary)	For Period	Debit	kt:AdjustmentsForShareOfNetProfitOfAssociatesAndJointVentures
2031	Loss (gain) on disposal of associates and joint ventures	Concept (Monetary)	For Period	Credit	ifrs-full:AdjustmentsForGainLossOnDisposalOfInvestmentsInSubsidiariesJointVenturesAndAssociates
2032	Impairment loss of associates and joint ventures	Concept (Monetary)	For Period	Debit	kt:AdjustmentsForImpairmentOfInvestmentsInAssociatesAndJointVentures
2033	Loss on disposal of property and equipment and investment in properties	Concept (Monetary)	For Period	Credit	ifrs-full:AdjustmentsForGainLossOnDisposalsPropertyPlantAndEquipment
2034	Loss (gain) on disposal of intangible assets	Concept (Monetary)	For Period	Debit	kt:AdjustmentsForLossOnDisposalOfIntangibleAssets
2035	Loss on impairment of intangible assets	Concept (Monetary)	For Period		ifrs-full:ImpairmentLossRecognisedInProfitOrLossIntangibleAssetsOtherThanGoodwill
2036	Loss on foreign currency translation	Concept (Monetary)	For Period	Debit	kt:AdjustmentsForLossOnForeignCurrencyTranslation
2037	Loss(gain) on valuation and settlement of derivatives, net	Concept (Monetary)	For Period	Credit	kt:AdjustmentsForGainsLossOnValuationAndSettlementOfDerivatives
2038	Gain on disposal of financial assets at fair value through profit or loss	Concept (Monetary)	For Period	Debit	kt:AdjustmentsForGainOnDisposalOfAvailableForSaleFairValueThroughProfitOrLoss
2039	Gain on valuation of financial assets at fair value through profit or loss	Concept (Monetary)	For Period	Debit	kt:GainLossValuationOfFinancialAssetsFairValueOfProfitOrLoss
2040	Gain on disposal of financial assets at amortized cost	Concept (Monetary)	For Period	Credit	ifrs-full:GainLossArisingFromDerecognitionOfFinancialAssetsMeasuredAtAmortisedCost
2041	Impairment losses on available-for-sale financial assets	Concept (Monetary)	For Period	Debit	kt:AdjustmentsForImpairmentOfAvailableForSaleFinancialAssets
2042	Gain on disposal of available-for-sale financial assets	Concept (Monetary)	For Period	Debit	kt:AdjustmentsForGainOnDisposalOfAvailableforsaleFinancialAssets
2043	Others	Concept (Monetary)	For Period	Debit	ifrs-full:OtherAdjustmentsToReconcileProfitLoss
2044	Changes in operating assets and liabilities	Abstract			kt:ChangeInOperatingAssetsAndLiabilitiesAbstract
2045	Decrease(increase) in trade receivables	Concept (Monetary)	For Period	Debit	ifrs-full:AdjustmentsForDecreaseIncreaseInTradeAccountReceivable
2046	Decrease(increase) in other receivables	Concept (Monetary)	For Period	Debit	kt:AdjustmentsForDecreaseIncreaseInOtherReceivable
2047	Decrease(increase) in other current assets	Concept (Monetary)	For Period	Debit	ifrs-full:AdjustmentsForDecreaseIncreaseInOtherCurrentAssets
2048	Decrease(increase) in other non-current assets	Concept (Monetary)	For Period	Debit	kt:AdjustmentForIncreaseDecreaseInOtherNoncurrentAssets
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2183	MOS GB Co., Ltd. [member]	Member			kt:MosGbCompanyLimitedMember
2184	MOS BS Co., Ltd. [member]	Member			kt:MosBsCompanyLimitedMember
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2277	Gearing ratio	Concept (Percent)	For Period		kt:GearingRatio
2278	1211 - Disclosure - Financial Risk Management - Summary of Group's Recognized Financial Assets Subject to Enforceable Master Netting Arrangements or Similar Agreements (Detail)	Network	*	*	http://www.kt.com/taxonomy/role/DisclosureFinancialRiskManagementSummaryOfGroupsRecognizedFinancialAssetsSubjectToEnforceableMasterNettingArrangementsOrSimilarAgreements
2279	Disclosure of offsetting of financial assets [table]	Table	*	*	ifrs-full:DisclosureOfOffsettingOfFinancialAssetsTable
2280	Categories of financial assets [axis]	Axis			ifrs-full:CategoriesOfFinancialAssetsAxis
2281	Financial assets, category [member]	Member			ifrs-full:FinancialAssetsCategoryMember
2282	Derivative used for hedge [member]	Member			ifrs-full:DerivativesMember
2283	Trade receivables [member]	Member			ifrs-full:TradeReceivablesMember
2284	Other Financial Assets1 [member]	Member			kt:OtherFinancialAssets1Member
2285	Disclosure of offsetting of financial assets [line items]	LineItems			ifrs-full:DisclosureOfOffsettingOfFinancialAssetsLineItems
2286	Gross assets	Concept (Monetary)	As Of	Debit	ifrs-full:GrossFinancialAssetsSubjectToOffsettingEnforceableMasterNettingArrangementsOrSimilarAgreements
2287	Gross liabilities offset	Concept (Monetary)	As Of	Credit	ifrs-full:GrossFinancialLiabilitiesSetOffAgainstFinancialAssetsSubjectToOffsettingEnforceableMasterNettingArrangementsOrSimilarAgreements
2288	Net amounts presented in the statement of financial position	Concept (Monetary)	As Of	Debit	ifrs-full:NetFinancialAssetsSubjectToOffsettingEnforceableMasterNettingArrangementsOrSimilarAgreementsInStatementOfFinancialPosition
2289	Amounts not offset, Financial instruments	Concept (Monetary)	As Of	Credit	ifrs-full:FinancialInstrumentsSubjectToEnforceableMasterNettingArrangementOrSimilarAgreementNotSetOffAgainstFinancialAssets
2290	Amounts not offset, Cash collateral	Concept (Monetary)	As Of	Credit	ifrs-full:CashCollateralReceivedSubjectToEnforceableMasterNettingArrangementOrSimilarAgreementNotSetOffAgainstFinancialAssets
2291	Net amount	Concept (Monetary)	As Of	Debit	ifrs-full:NetFinancialAssetsSubjectToOffsettingEnforceableMasterNettingArrangementsOrSimilarAgreements
2292	1212 - Disclosure - Financial Risk Management - Summary of Group's Recognized Financial Liabilities Subject to Enforceable Master Netting Arrangements or Similar Agreements (Detail)	Network	*	*	http://www.kt.com/taxonomy/role/DisclosureFinancialRiskManagementSummaryOfGroupsRecognizedFinancialLiabilitiesSubjectToEnforceableMasterNettingArrangementsOrSimilarAgreements
2293	Disclosure of offsetting of financial liabilities [table]	Table	*	*	ifrs-full:DisclosureOfOffsettingOfFinancialLiabilitiesTable
2294	Categories of financial liabilities [axis]	Axis			ifrs-full:CategoriesOfFinancialLiabilitiesAxis
2295	Other liabilities [Member]	Member			ifrs-full:FinancialLiabilitiesCategoryMember
2296	Derivative used for hedge [member]	Member			ifrs-full:DerivativesMember
2297	Trade payables [member]	Member			kt:TradePayablesMember
2298	Other [member]	Member			kt:OtherFinancialLiabilitiyMember
2299	Disclosure of offsetting of financial liabilities [Line Items]	LineItems			ifrs-full:DisclosureOfOffsettingOfFinancialLiabilitiesLineItems
2300	Gross liabilities	Concept (Monetary)	As Of	Credit	ifrs-full:GrossFinancialLiabilitiesSubjectToOffsettingEnforceableMasterNettingArrangementsOrSimilarAgreements
2301	Gross assets offset	Concept (Monetary)	As Of	Debit	ifrs-full:GrossFinancialAssetsSetOffAgainstFinancialLiabilitiesSubjectToOffsettingEnforceableMasterNettingArrangementsOrSimilarAgreements
2302	Net amounts presented in the statement of financial position	Concept (Monetary)	As Of	Credit	ifrs-full:NetFinancialLiabilitiesSubjectToOffsettingEnforceableMasterNettingArrangementsOrSimilarAgreementsInStatementOfFinancialPosition
2303	Amounts not offset, Financial instruments	Concept (Monetary)	As Of	Debit	ifrs-full:FinancialInstrumentsSubjectToEnforceableMasterNettingArrangementOrSimilarAgreementNotSetOffAgainstFinancialLiabilities
2304	Amounts not offset, Cash collateral	Concept (Monetary)	As Of	Debit	ifrs-full:CashCollateralPledgedSubjectToEnforceableMasterNettingArrangementOrSimilarAgreementNotSetOffAgainstFinancialLiabilities
2305	Net amount	Concept (Monetary)	As Of	Credit	ifrs-full:NetFinancialLiabilitiesSubjectToOffsettingEnforceableMasterNettingArrangementsOrSimilarAgreements
2306	1213 - Disclosure - Fair Value - Summary of Carrying Amount and Fair Value of Financial Instruments by Category (Detail)	Network	*	*	http://www.kt.com/taxonomy/role/DisclosureFairValueSummaryOfCarryingAmountAndFairValueOfFinancialInstrumentsByCategory
2307	Disclosure of detailed information about financial instruments [table]	Table	*	*	ifrs-full:DisclosureOfFinancialInstrumentsTable
2308	Measurement [axis]	Axis			ifrs-full:MeasurementAxis
2309	Aggregated measurement [member]	Member			ifrs-full:AggregatedMeasurementMember
2310	Fair value [member]	Member			ifrs-full:AtFairValueMember
2311	Categories of financial assets [axis]	Axis			ifrs-full:CategoriesOfFinancialAssetsAxis
2312	Financial assets, category [member]	Member			ifrs-full:FinancialAssetsCategoryMember
2313	Cash and cash equivalents [member]	Member			kt:CashAndCashEquivalentMember
2314	Financial assets at amortized costs [member]	Member			ifrs-full:FinancialAssetsAtAmortisedCostMember
2315	Financial assets at fair value through other comprehensive income [member]	Member			kt:FinancialAssetsAtFairValueThroughOtherComprehensiveIncomeMember
2316	Other financial assets at amortized costs [member]	Member			kt:OtherFinancialAssetsAtAmortizedCostsMember
2317	Financial assets at fair value through profit or loss [member]	Member			ifrs-full:FinancialAssetsAtFairValueThroughProfitOrLossCategoryMember
2318	Other financial assets at fair value through other comprehensive income [member]	Member			kt:OtherFinancialAssetsAtFairValueThroughOtherComprehensiveIncomeMember
2319	Available-for-sale [member]	Member			ifrs-full:FinancialAssetsAvailableforsaleCategoryMember
2320	Derivatives financial assets for hedging [member]	Member			kt:DerivativesFinancialAssetsForHedgingMember
2321	Categories of financial liabilities [axis]	Axis			ifrs-full:CategoriesOfFinancialLiabilitiesAxis
2322	Other liabilities [Member]	Member			ifrs-full:FinancialLiabilitiesCategoryMember
2323	Trade and other payables [member]	Member			kt:TradeAndOtherPayableMember
2324	Borrowings [member]	Member			kt:Borrowings1Member
2325	Financial Liabilities At Amortized Costs [member]	Member			ifrs-full:FinancialLiabilitiesAtAmortisedCostMember
2326	Financial liabilities designated as at fair value through profit or loss [member]	Member			ifrs-full:FinancialLiabilitiesAtFairValueThroughProfitOrLossCategoryMember
2327	Derivative financial liabilities for hedging [member]	Member			kt:DerivativesFinancialLiabilitiesForHedgingMember
2328	Disclosure of detailed information about financial instruments [line items]	LineItems			ifrs-full:DisclosureOfFinancialInstrumentsLineItems
2329	Financial assets	Concept (Monetary)	As Of	Debit	ifrs-full:FinancialAssets
2330	Financial liabilities	Concept (Monetary)	As Of	Credit	ifrs-full:FinancialLiabilities
2331	1214 - Disclosure - Fair Value - Summary of Fair Value Hierarchy Classifications of Financial Assets and Financial Liabilities That are Measured at Fair Value (Detail)	Network	*	*	http://www.kt.com/taxonomy/role/DisclosureFairValueSummaryOfFairValueHierarchyClassificationsOfFinancialAssetsAndFinancialLiabilitiesThatAreMeasuredAtFairValue
2332	Disclosure of detailed information about financial instruments [table]	Table	*	*	ifrs-full:DisclosureOfFinancialInstrumentsTable
2333	Levels of fair value hierarchy [axis]	Axis			ifrs-full:LevelsOfFairValueHierarchyAxis
2334	All levels of fair value hierarchy [member]	Member			ifrs-full:AllLevelsOfFairValueHierarchyMember
2335	Level 1 [Member]	Member			ifrs-full:Level1OfFairValueHierarchyMember
2336	Level 2 [Member]	Member			ifrs-full:Level2OfFairValueHierarchyMember
2337	Level 3 [Member]	Member			ifrs-full:Level3OfFairValueHierarchyMember
2338	Measurement [axis]	Axis			ifrs-full:MeasurementAxis
2339	Aggregated measurement [member]	Member			ifrs-full:AggregatedMeasurementMember
2340	Recurring fair value measurement [Member]	Member			ifrs-full:RecurringFairValueMeasurementMember
2341	Not measured at fair value in statement of financial position but for which fair value is disclosed [Member]	Member			ifrs-full:NotMeasuredAtFairValueInStatementOfFinancialPositionButForWhichFairValueIsDisclosedMember
2342	Disclosure of detailed information about financial instruments [line items]	LineItems			ifrs-full:DisclosureOfFinancialInstrumentsLineItems
2343	Financial assets at fair value through profit or loss	Concept (Monetary)	As Of	Debit	ifrs-full:FinancialAssetsAtFairValueThroughProfitOrLoss
2344	Derivative financial assets for hedging	Concept (Monetary)	As Of	Debit	ifrs-full:DerivativeFinancialAssets
2345	Available-for-sale financial assets	Concept (Monetary)	As Of	Debit	ifrs-full:FinancialAssetsAvailableforsale
2346	Investment properties	Concept (Monetary)	As Of	Debit	ifrs-full:InvestmentProperty
2347	Financial assets, at fair value	Concept (Monetary)	As Of	Debit	ifrs-full:FinancialAssetsAtFairValue
2348	Financial liabilities at fair value through profit or loss	Concept (Monetary)	As Of	Credit	ifrs-full:FinancialLiabilitiesAtFairValueThroughProfitOrLoss
2349	Derivative financial liabilities for hedging	Concept (Monetary)	As Of	Credit	ifrs-full:DerivativeFinancialLiabilities
2350	Financial liabilities, at fair value	Concept (Monetary)	As Of	Credit	ifrs-full:FinancialLiabilitiesAtFairValue
2351	1215 - Disclosure - Fair Value - Summary of Fair Value Non of Financial Instruments (Detail)	Network	*	*	http://www.kt.com/taxonomy/role/DisclosureFairValueSummaryOfFairValueNonOfFinancialInstruments
2352	Disclosure of detailed information about financial instruments [table]	Table	*	*	ifrs-full:DisclosureOfFinancialInstrumentsTable
2353	Classes of financial instruments [axis]	Axis			ifrs-full:ClassesOfFinancialInstrumentsAxis
2354	Financial instruments, class [member]	Member			ifrs-full:ClassesOfFinancialInstrumentsMember
2355	Financial assets at fair value through other comprehensive income [member]	Member			kt:FinancialAssetsAtFairValueThroughOtherComprehensiveIncomeMember
2356	Financial assets at fair value through profit or loss [member]	Member			kt:OtherFinancialAssetsAtFairValueThroughProfitOrLossMember
2357	Other financial assets at fair value through other comprehensive income [member]	Member			kt:OtherFinancialAssetsAtFairValueThroughOtherComprehensiveIncomeMember
2358	Derivative financial assets for hedging [member]	Member			kt:OtherDerivativeFinancialAssetsForHedgingMember
2359	Investment Properties [member]	Member			kt:InvestmentPropertiesMember
2360	Other financial liabilities at fair value through profit or loss [member]	Member			kt:OtherFinancialLiabilitiesAtFairValueThroughProfitOrLossMember
2361	Derivative financial liabilities for hedging [member]	Member			kt:OtherDerivativeFinancialLiabilitiesForHedgingMember
2362	Levels of fair value hierarchy [axis]	Axis			ifrs-full:LevelsOfFairValueHierarchyAxis
2363	All levels of fair value hierarchy [member]	Member			ifrs-full:AllLevelsOfFairValueHierarchyMember
2364	Level 1 [Member]	Member			ifrs-full:Level1OfFairValueHierarchyMember
2365	Level 2 [Member]	Member			ifrs-full:Level2OfFairValueHierarchyMember
2366	Level 3 [Member]	Member			ifrs-full:Level3OfFairValueHierarchyMember
2367	Disclosure of detailed information about financial instruments [line items]	LineItems			ifrs-full:DisclosureOfFinancialInstrumentsLineItems
2368	Non financial assets	Concept (Monetary)	As Of	Debit	kt:NonFinancialAssets
2369	Non financial liabilities	Concept (Monetary)	As Of	Credit	kt:NonFinancialLiabilities
2370	1216 - Disclosure - Fair Value - Summary of Changes in Level 3 of Fair Value Hierarchy for Recurring Fair Value Measurements (Detail)	Network	*	*	http://www.kt.com/taxonomy/role/DisclosureFairValueSummaryOfChangesInLevel3OfFairValueHierarchyForRecurringFairValueMeasurements
2371	Disclosure of detailed information about financial instruments [table]	Table	*	*	ifrs-full:DisclosureOfFinancialInstrumentsTable
2372	Measurement [axis]	Axis			ifrs-full:MeasurementAxis
2373	Aggregated measurement [member]	Member			ifrs-full:AggregatedMeasurementMember
2374	Recurring fair value measurement [Member]	Member			ifrs-full:RecurringFairValueMeasurementMember
2375	Levels of fair value hierarchy [axis]	Axis			ifrs-full:LevelsOfFairValueHierarchyAxis
2376	All levels of fair value hierarchy [member]	Member			ifrs-full:AllLevelsOfFairValueHierarchyMember
2377	Level 3 [Member]	Member			ifrs-full:Level3OfFairValueHierarchyMember
2378	Categories of financial assets [axis]	Axis			ifrs-full:CategoriesOfFinancialAssetsAxis
2379	Financial assets, category [member]	Member			ifrs-full:FinancialAssetsCategoryMember
2380	Financial assets at fair value through profit or loss [member]	Member			ifrs-full:FinancialAssetsAtFairValueThroughProfitOrLossCategoryMember
2381	Financial assets at fair value through other comprehensive income [member]	Member			ifrs-full:FinancialAssetsAtFairValueThroughOtherComprehensiveIncomeCategoryMember
2382	Classes of financial liabilities [axis]	Axis			ifrs-full:ClassesOfFinancialLiabilitiesAxis
2383	Financial liabilities, class [member]	Member			ifrs-full:FinancialLiabilitiesMember
2384	Other derivative liabilities [Member]	Member			kt:OtherDerivativeFinancialLiabilitiesMember
2385	Derivative financial liabilities [member]	Member			kt:DerivativeFinancialLiabilitiesMember
2386	Financial liabilities designated as at fair value through profit or loss [member]	Member			ifrs-full:FinancialLiabilitiesAtFairValueThroughProfitOrLossCategoryMember
2387	Classes of financial instruments [axis]	Axis			ifrs-full:ClassesOfFinancialInstrumentsAxis
2388	Financial instruments, class [member]	Member			ifrs-full:ClassesOfFinancialInstrumentsMember
2389	Financial assets at fair value through profit or loss [member]	Member			ifrs-full:FinancialAssetsAtFairValueThroughProfitOrLossCategoryMember
2390	Available-for-sale [member]	Member			ifrs-full:FinancialAssetsAvailableforsaleCategoryMember
2391	Disclosure of detailed information about financial instruments [line items]	LineItems			ifrs-full:DisclosureOfFinancialInstrumentsLineItems
2392	Beginning balance	Concept (Monetary)	As Of	Debit	ifrs-full:FinancialAssets
2393	Changes in accounting policy	Concept (Monetary)	For Period	Debit	kt:EffectOfChangesInAccountingPolicyFairValueMeasurementAssets
2394	Purchases	Concept (Monetary)	For Period	Debit	ifrs-full:PurchasesFairValueMeasurementAssets
2395	Reclassification	Concept (Monetary)	For Period	Debit	kt:ReclassificationFairValueMeasurementAssets
2396	Changes in scope of consolidation	Concept (Monetary)	For Period	Debit	kt:ChangesInScopeOfConsolidationFairValueMeasurementAssets
2397	Sales	Concept (Monetary)	For Period	Credit	ifrs-full:SalesFairValueMeasurementAssets
2398	Amount recognized in profit or loss	Concept (Monetary)	For Period		ifrs-full:GainsLossesRecognisedInProfitOrLossFairValueMeasurementAssets
2399	Amount recognized in other comprehensive income	Concept (Monetary)	For Period		ifrs-full:GainsLossesRecognisedInOtherComprehensiveIncomeFairValueMeasurementAssets
2400	Ending balance	Concept (Monetary)	As Of	Debit	ifrs-full:FinancialAssets
2401	Beginning balance	Concept (Monetary)	As Of	Credit	ifrs-full:FinancialLiabilities
2402	Changes in accounting policy	Concept (Monetary)	For Period	Credit	kt:EffectOfChangesInAccountingPolicyFairValueMeasurementLiabilities
2403	Purchases	Concept (Monetary)	For Period	Credit	ifrs-full:PurchasesFairValueMeasurementLiabilities
2404	Reclassification	Concept (Monetary)	For Period	Credit	kt:ReclassificationFairValueMeasurementLiabilities
2405	Changes in scope of consolidation	Concept (Monetary)	For Period	Credit	kt:ChangesInScopeOfConsolidationFairValueMeasurementLiabilities
2406	Sales	Concept (Monetary)	For Period	Debit	ifrs-full:SalesFairValueMeasurementLiabilities
2407	Amount recognized in profit or loss	Concept (Monetary)	For Period		ifrs-full:GainsLossesRecognisedInProfitOrLossFairValueMeasurementLiabilities
2408	Amount recognized in other comprehensive income	Concept (Monetary)	For Period		ifrs-full:GainsLossesRecognisedInOtherComprehensiveIncomeFairValueMeasurementLiabilities
2409	Ending balance	Concept (Monetary)	As Of	Credit	ifrs-full:FinancialLiabilities
2410	1217 - Disclosure - Fair Value - Summary of Valuation Techniques and Inputs (Detail)	Network	*	*	http://www.kt.com/taxonomy/role/DisclosureFairValueSummaryOfValuationTechniquesAndInputs
2411	Disclosure of detailed information about financial instruments [table]	Table	*	*	ifrs-full:DisclosureOfFinancialInstrumentsTable
2412	Levels of fair value hierarchy [axis]	Axis			ifrs-full:LevelsOfFairValueHierarchyAxis
2413	All levels of fair value hierarchy [member]	Member			ifrs-full:AllLevelsOfFairValueHierarchyMember
2414	Level 2 [Member]	Member			ifrs-full:Level2OfFairValueHierarchyMember
2415	Level 2, 3 [Member]	Member			ifrs-full:Level2And3OfFairValueHierarchyMember
2416	Level 3 [Member]	Member			ifrs-full:Level3OfFairValueHierarchyMember
2417	Categories of financial assets [axis]	Axis			ifrs-full:CategoriesOfFinancialAssetsAxis
2418	Financial assets, category [member]	Member			ifrs-full:FinancialAssetsCategoryMember
2419	Financial assets at fair value through profit or loss [member]	Member			ifrs-full:FinancialAssetsAtFairValueThroughProfitOrLossCategoryMember
2420	Financial assets at fair value through other comprehensive income [member]	Member			ifrs-full:FinancialAssetsAtFairValueThroughOtherComprehensiveIncomeCategoryMember
2421	Classes of assets [axis]	Axis			ifrs-full:ClassesOfAssetsAxis
2422	Assets [member]	Member			ifrs-full:ClassesOfAssetsMember
2423	Trades and other receivables [member]	Member			kt:TradesAndOtherReceivablesMember
2424	Disclosure of detailed information about financial instruments [line items]	LineItems			ifrs-full:DisclosureOfFinancialInstrumentsLineItems
2425	Assets	Abstract			ifrs-full:AssetsAbstract
2426	Financial assets at fair value through other comprehensive income	Concept (Monetary)	As Of	Debit	ifrs-full:FinancialAssetsAtFairValueThroughOtherComprehensiveIncome
2427	Other financial assets	Abstract			kt:OtherFinancialAssetsAbstract
2428	Available-for-sale financial assets	Concept (Monetary)	As Of	Debit	ifrs-full:FinancialAssetsAvailableforsale
2429	Financial assets at fair value through profit or loss	Concept (Monetary)	As Of	Debit	ifrs-full:FinancialAssetsAtFairValueThroughProfitOrLoss
2430	Financial assets at fair value through other comprehensive income	Concept (Monetary)	As Of	Debit	ifrs-full:FinancialAssetsAtFairValueThroughOtherComprehensiveIncome
2431	Derivative financial assets for hedging	Concept (Monetary)	As Of	Debit	ifrs-full:DerivativeFinancialAssets
2432	Investment properties	Concept (Monetary)	As Of	Debit	ifrs-full:InvestmentProperty
2433	Liabilities	Abstract			ifrs-full:LiabilitiesAbstract
2434	Other financial liabilities	Abstract			kt:OtherFinancialLiabilitiesAbstract
2435	Other derivative financial liabilities	Concept (Monetary)	As Of	Credit	kt:OtherDerivativeFinancialLiabilities
2436	Financial liabilities at fair value through profit or loss	Concept (Monetary)	As Of	Credit	ifrs-full:FinancialLiabilitiesAtFairValueThroughProfitOrLoss
2437	Derivative financial liabilities for hedging	Concept (Monetary)	As Of	Credit	ifrs-full:DerivativeFinancialLiabilities
2438	Valuation techniques	Concept (Text/String)	For Period		ifrs-full:DescriptionOfValuationTechniquesUsedInFairValueMeasurementAssets
2439	Valuation techniques	Concept (Text/String)	For Period		ifrs-full:DescriptionOfValuationTechniquesUsedInFairValueMeasurementLiabilities
2440	1218 - Disclosure - Fair Value - Summary of Details and Changes of Total Deferred Difference (Detail)	Network	*	*	http://www.kt.com/taxonomy/role/DisclosureFairValueSummaryOfDetailsAndChangesOfTotalDeferredDifference
2441	Disclosure of detailed information about financial instruments [table]	Table	*	*	ifrs-full:DisclosureOfFinancialInstrumentsTable
2442	Classes of financial instruments [axis]	Axis			ifrs-full:ClassesOfFinancialInstrumentsAxis
2443	Financial instruments, class [member]	Member			ifrs-full:ClassesOfFinancialInstrumentsMember
2444	Derivatives held for trading [member]	Member			kt:DerivativesHeldForTradingMember
2445	Derivatives used for hedging [member]	Member			kt:DerivativesUsedForHedgingMember
2446	Disclosure of detailed information about financial instruments [line items]	LineItems			ifrs-full:DisclosureOfFinancialInstrumentsLineItems
2447	Beginning balance	Concept (Monetary)	As Of	Debit	ifrs-full:FinancialAssets
2448	New transactions	Concept (Monetary)	For Period	Debit	ifrs-full:IncreaseThroughOriginationOrPurchaseFinancialAssets
2449	Recognized at fair value through profit or loss	Concept (Monetary)	As Of	Debit	ifrs-full:FinancialAssetsAtFairValueThroughProfitOrLoss
2450	Ending balance	Concept (Monetary)	As Of	Debit	ifrs-full:FinancialAssets
2451	Beginning balance	Concept (Monetary)	As Of	Credit	ifrs-full:FinancialLiabilities
2452	New transactions	Concept (Monetary)	For Period	Credit	kt:IncreaseThroughOriginationOrPurchaseFinancialLiabilities
2453	Recognized at fair value through profit or loss	Concept (Monetary)	As Of	Credit	ifrs-full:FinancialLiabilitiesAtFairValueThroughProfitOrLoss
2454	Ending balance	Concept (Monetary)	As Of	Credit	ifrs-full:FinancialLiabilities
2455	1219 - Disclosure - Interests in Unconsolidated Structured Entities - Summary of Unconsolidated Structured Entities and Nature of Risks (Detail)	Network	*	*	http://www.kt.com/taxonomy/role/DisclosureInterestsInUnconsolidatedStructuredEntitiesSummaryOfUnconsolidatedStructuredEntitiesAndNatureOfRisks
2456	Disclosure of unconsolidated structured entities [table]	Table	*	*	ifrs-full:DisclosureOfUnconsolidatedStructuredEntitiesTable
2457	Unconsolidated structured entities [axis]	Axis			ifrs-full:UnconsolidatedStructuredEntitiesAxis
2458	Entity's total for unconsolidated structured entities [member]	Member			ifrs-full:EntitysTotalForUnconsolidatedStructuredEntitiesMember
2459	Real Estate Finance [member]	Member			kt:RealEstateFinanceMember
2460	PEF &Investment Fund [member]	Member			ifrs-full:InvestmentFundsMember
2461	Asset Securitization [member]	Member			ifrs-full:AssetbackedFinancingsMember
2462	Unconsolidated structured entities [member]	Member			ifrs-full:UnconsolidatedStructuredEntitiesMember
2463	Disclosure of unconsolidated structured entities [line items]	LineItems			ifrs-full:DisclosureOfUnconsolidatedStructuredEntitiesLineItems
2464	Total assets of unconsolidated structured entities	Concept (Monetary)	As Of		ifrs-full:RiskExposureAssociatedWithInstrumentsSharingCharacteristic
2465	Other financial assets	Concept (Monetary)	As Of	Debit	ifrs-full:OtherFinancialAssets
2466	Joint ventures and associates	Concept (Monetary)	As Of	Debit	ifrs-full:InvestmentAccountedForUsingEquityMethod
2467	Total	Concept (Monetary)	As Of	Debit	ifrs-full:AssetsRecognisedInEntitysFinancialStatementsInRelationToStructuredEntities
2468	Maximum loss exposure Investment assets	Concept (Monetary)	As Of		ifrs-full:MaximumExposureToLossFromInterestsInStructuredEntities
2469	1220 - Disclosure - Information About Non-controlling Interests - Summary of Changes in Accumulated Non-controlling Interests (Detail)	Network	*	*	http://www.kt.com/taxonomy/role/DisclosureInformationAboutNoncontrollingInterestsSummaryOfChangesInAccumulatedNoncontrollingInterests
2470	Disclosure of subsidiaries [table]	Table	*	*	ifrs-full:DisclosureOfSignificantInvestmentsInSubsidiariesTable
2471	Subsidiaries [axis]	Axis			ifrs-full:SignificantInvestmentsInSubsidiariesAxis
2472	Entity's total for subsidiaries [member]	Member			ifrs-full:EntitysTotalForSubsidiariesMember
2473	KT Skylife Co., Ltd. [member]	Member			kt:KTSkylifeCoLtdMember
2474	BC Card Co., Ltd. [member]	Member			kt:BCCardCoLtdMember
2475	KT Powertel Co., Ltd. [member]	Member			kt:KTPowertelCoLtdMember
2476	KT Hitel Co., Ltd. [member]	Member			kt:KTHitelCoLtdMember
2477	KT Telecop Co., Ltd. [member]	Member			kt:KTTelecopCoLtdMember
2478	Disclosure of subsidiaries [line items]	LineItems			ifrs-full:DisclosureOfSignificantInvestmentsInSubsidiariesLineItems
2479	Non-controlling Interests rate(%)	Concept (Percent)	For Period		ifrs-full:ProportionOfOwnershipInterestsHeldByNoncontrollingInterests
2480	Accumulated non-controlling interests at the beginning of the year	Concept (Monetary)	As Of	Credit	ifrs-full:NoncontrollingInterests
2481	Profit or loss allocated to non-controlling interests	Concept (Monetary)	For Period	Credit	ifrs-full:ProfitLossAttributableToNoncontrollingInterests
2482	Dividend paid to non-controlling interests	Concept (Monetary)	For Period	Credit	ifrs-full:DividendsPaidToNoncontrollingInterests
2483	Others	Concept (Monetary)	For Period	Credit	kt:OtherChangesInAccumulatedNonControllingInterests
2484	Accumulated non-controlling interests at the end of the year	Concept (Monetary)	As Of	Credit	ifrs-full:NoncontrollingInterests
2485	1221 - Disclosure - Information About Non-controlling Interests - Summary of Financial Information on Subsidiaries (Detail)	Network	*	*	http://www.kt.com/taxonomy/role/DisclosureInformationAboutNoncontrollingInterestsSummaryOfFinancialInformationOnSubsidiaries
2486	Disclosure of subsidiaries [table]	Table	*	*	ifrs-full:DisclosureOfSignificantInvestmentsInSubsidiariesTable
2487	Subsidiaries [axis]	Axis			ifrs-full:SignificantInvestmentsInSubsidiariesAxis
2488	Entity's total for subsidiaries [member]	Member			ifrs-full:EntitysTotalForSubsidiariesMember
2489	KT Skylife Co., Ltd. [member]	Member			kt:KTSkylifeCoLtdMember
2490	BC Card Co., Ltd. [member]	Member			kt:BCCardCoLtdMember
2491	KT Powertel Co., Ltd. [member]	Member			kt:KTPowertelCoLtdMember
2492	KT Hitel Co., Ltd. [member]	Member			kt:KTHitelCoLtdMember
2493	KT Telecop Co., Ltd. [member]	Member			kt:KTTelecopCoLtdMember
2494	Disclosure of subsidiaries [line items]	LineItems			ifrs-full:DisclosureOfSignificantInvestmentsInSubsidiariesLineItems
2495	Non-controlling Interests rate (%)	Concept (Percent)	For Period		ifrs-full:ProportionOfOwnershipInterestsHeldByNoncontrollingInterests
2496	Current assets	Concept (Monetary)	As Of	Debit	ifrs-full:CurrentAssets
2497	Non-current assets	Concept (Monetary)	As Of	Debit	ifrs-full:NoncurrentAssets
2498	Current liabilities	Concept (Monetary)	As Of	Credit	ifrs-full:CurrentLiabilities
2499	Non-current liabilities	Concept (Monetary)	As Of	Credit	ifrs-full:NoncurrentLiabilities
2500	Equity	Concept (Monetary)	As Of	Credit	ifrs-full:Equity
2501	Operating revenue	Concept (Monetary)	For Period	Credit	ifrs-full:Revenue
2502	Profit or loss for the year	Concept (Monetary)	For Period	Credit	ifrs-full:ProfitLoss
2503	Total comprehensive income	Concept (Monetary)	For Period	Credit	ifrs-full:ComprehensiveIncome
2504	Cash flows from operating activities	Concept (Monetary)	For Period		ifrs-full:CashFlowsFromUsedInOperatingActivities
2505	Cash flows from investing activities	Concept (Monetary)	For Period	Debit	ifrs-full:CashFlowsFromUsedInInvestingActivities
2506	Cash flows from financing activities	Concept (Monetary)	For Period	Debit	ifrs-full:CashFlowsFromUsedInFinancingActivities
2507	Cash flows from financing activities before dividend paid to non-controlling interests	Concept (Monetary)	For Period	Debit	kt:CashFlowsFromFinancingActivitiesBeforeDividendPaidToNoncontrollingInterests
2508	Dividend paid to non-controlling interests	Concept (Monetary)	For Period	Credit	ifrs-full:DividendsPaidToNoncontrollingInterests
2509	Gain or loss foreign currency translation	Concept (Monetary)	For Period	Credit	ifrs-full:GainsLossesOnExchangeDifferencesOnTranslationRecognisedInProfitOrLoss
2510	Net (decrease)/increase in cash and cash equivalents	Concept (Monetary)	For Period	Debit	ifrs-full:IncreaseDecreaseInCashAndCashEquivalents
2511	Cash and cash equivalents at beginning of year	Concept (Monetary)	As Of	Debit	ifrs-full:CashAndCashEquivalents
2512	Exchange differences	Concept (Monetary)	For Period	Debit	ifrs-full:EffectOfExchangeRateChangesOnCashAndCashEquivalents
2513	Cash and cash equivalents at end of year	Concept (Monetary)	As Of	Debit	ifrs-full:CashAndCashEquivalents
2514	1222 - Disclosure - Information About Non-controlling Interests - Summary of Changes in Ownership Interest on the Equity Attributable to Owners (Detail)	Network	*	*	http://www.kt.com/taxonomy/role/DisclosureInformationAboutNoncontrollingInterestsSummaryOfChangesInOwnershipInterestOnTheEquityAttributableToOwners
2515	Implied Table	Table	*	*	implied:Table
2516	Disclosure of subsidiaries [abstract]	Abstract			ifrs-full:DisclosureOfSignificantInvestmentsInSubsidiariesAbstract
2517	Carrying amount of non-controlling interests acquired	Concept (Monetary)	As Of	Credit	ifrs-full:NoncontrollingInterestInAcquireeRecognisedAtAcquisitionDate
2518	Consideration paid to non-controlling interests	Concept (Monetary)	For Period	Debit	kt:ConsiderationPaidToNoncontrollingInterests
2519	Excess of consideration paid recognized in parent's equity	Concept (Monetary)	For Period	Credit	kt:ExcessOfConsiderationPaidRecognizedInParentEquity
2520	1223 - Disclosure - Business Combination - Additional Information (Detail)	Network	*	*	http://www.kt.com/taxonomy/role/DisclosureBusinessCombinationAdditionalInformation
2521	Disclosure of detailed information about business combination [table]	Table	*	*	ifrs-full:DisclosureOfBusinessCombinationsTable
2522	Subsidiaries [axis]	Axis			ifrs-full:SignificantInvestmentsInSubsidiariesAxis
2523	Entity's total for subsidiaries [member]	Member			ifrs-full:EntitysTotalForSubsidiariesMember
2524	GENIE Music Corporation K T Music Corporation [member]	Member			kt:GENIEMusicCorporationMusicKTCorporationMember
2525	Business combinations [axis]	Axis			ifrs-full:BusinessCombinationsAxis
2526	Entity's total for business combinations [member]	Member			ifrs-full:EntitysTotalForBusinessCombinationsMember
2527	SG Safety Corporation [member]	Member			kt:SGSafetyCorporationMember
2528	MOS GB Co.,Ltd and MOS Chungcheong Co., Ltd., [member]	Member			kt:MosGbCompanyLimitedAndMosChungcheongCompanyLimitedMember
2529	CJ Digital Music Co., Ltd. [member]	Member			kt:CjDigitalMusicCoLtdMember
2530	Categories of related parties [axis]	Axis			ifrs-full:CategoriesOfRelatedPartiesAxis
2531	Entity's total for related parties [member]	Member			ifrs-full:EntitysTotalForRelatedPartiesMember
2532	CJ ENM CO., Ltd [member]	Member			kt:CjEnmCoLtdMember
2533	Disclosure of detailed information about business combination [Line Items]	LineItems			ifrs-full:DisclosureOfBusinessCombinationsLineItems
2534	Consideration	Concept (Monetary)	As Of	Credit	ifrs-full:AcquisitiondateFairValueOfTotalConsiderationTransferred
2535	Number of shares issued	Concept (Decimal)	As Of		ifrs-full:NumberOfInstrumentsOrInterestsIssuedOrIssuable
2536	Percentage of ownership interest	Concept (Percent)	For Period		ifrs-full:ProportionOfOwnershipInterestInSubsidiary
2537	Number of shares acquired	Concept (Shares)	As Of		kt:NumberOfSharesAcquired
2538	1224 - Disclosure - Business Combination - Summary of Business Combination (Detail)	Network	*	*	http://www.kt.com/taxonomy/role/DisclosureBusinessCombinationSummaryOfBusinessCombination
2539	Disclosure of detailed information about business combination [table]	Table	*	*	ifrs-full:DisclosureOfBusinessCombinationsTable
2540	Business combinations [axis]	Axis			ifrs-full:BusinessCombinationsAxis
2541	Entity's total for business combinations [member]	Member			ifrs-full:EntitysTotalForBusinessCombinationsMember
2542	SG Safety Corporation [member]	Member			kt:SGSafetyCorporationMember
2543	KT MOS Bukbu Co.,Ltd. [member]	Member			kt:KtMosBukbuCoLtdMember
2544	KTMOS Nambu Co.,Ltd. [member]	Member			kt:KTMOSNambuCoLtdMember
2545	CJ Digital Music Co., Ltd. [member]	Member			kt:CjDigitalMusicCoLtdMember
2546	Disclosure of detailed information about business combination [Line Items]	LineItems			ifrs-full:DisclosureOfBusinessCombinationsLineItems
2547	Date	Concept (Date)	For Period		ifrs-full:DateOfAcquisition2013
2548	Purchase consideration	Concept (Monetary)	As Of	Credit	ifrs-full:AcquisitiondateFairValueOfTotalConsiderationTransferred
2549	1225 - Disclosure - Business Combination - Schedule of Fair Value of Purchase Consideration from Business Combination (Detail)	Network	*	*	http://www.kt.com/taxonomy/role/DisclosureBusinessCombinationScheduleOfFairValueOfPurchaseConsiderationFromBusinessCombination
2550	Disclosure of detailed information about business combination [table]	Table	*	*	ifrs-full:DisclosureOfBusinessCombinationsTable
2551	Business combinations [axis]	Axis			ifrs-full:BusinessCombinationsAxis
2552	Entity's total for business combinations [member]	Member			ifrs-full:EntitysTotalForBusinessCombinationsMember
2553	SG Safety Corporation [member]	Member			kt:SGSafetyCorporationMember
2554	KT MOS Bukbu Co.,Ltd. [member]	Member			kt:KtMosBukbuCoLtdMember
2555	KTMOS Nambu Co.,Ltd. [member]	Member			kt:KTMOSNambuCoLtdMember
2556	CJ Digital Music Co., Ltd. [member]	Member			kt:CjDigitalMusicCoLtdMember
2557	Disclosure of detailed information about business combination [Line Items]	LineItems			ifrs-full:DisclosureOfBusinessCombinationsLineItems
2558	Cash and cash equivalents	Concept (Monetary)	As Of	Credit	ifrs-full:CashTransferred
2559	Settled receivables	Concept (Monetary)	As Of	Debit	ifrs-full:FairValueOfAcquiredReceivables
2560	Fair value of equity instruments previously held	Concept (Monetary)	As Of	Debit	kt:AcquisitionDateFairValueOfEquityInstrumentsPreviouslyHeld
2561	Fair value of equity instruments newly issued	Concept (Monetary)	As Of	Debit	kt:AcquisitionDateFairValueOfEquityInstrumentsNewlyIssued
2562	Total	Concept (Monetary)	As Of	Credit	ifrs-full:AcquisitiondateFairValueOfTotalConsiderationTransferred
2563	1226 - Disclosure - Business Combination - Schedule of Fair Value of Purchase Consideration from Business Combination (Parenthetical) (Detail)	Network	*	*	http://www.kt.com/taxonomy/role/DisclosureBusinessCombinationScheduleOfFairValueOfPurchaseConsiderationFromBusinessCombinationParenthetical
2564	Disclosure of detailed information about business combination [table]	Table	*	*	ifrs-full:DisclosureOfBusinessCombinationsTable
2565	Business combinations [axis]	Axis			ifrs-full:BusinessCombinationsAxis
2566	Entity's total for business combinations [member]	Member			ifrs-full:EntitysTotalForBusinessCombinationsMember
2567	KT MOS Bukbu Co.,Ltd. [member]	Member			kt:KtMosBukbuCoLtdMember
2568	KTMOS Nambu Co.,Ltd. [member]	Member			kt:KTMOSNambuCoLtdMember
2569	GENIE Music Corporation K T Music Corporation [member]	Member			kt:GENIEMusicCorporationMusicKTCorporationMember
2570	Disclosure of detailed information about business combination [Line Items]	LineItems			ifrs-full:DisclosureOfBusinessCombinationsLineItems
2571	Number of ordinary shares previously held	Concept (Shares)	For Period		kt:NumberOfOrdinarySharesPreviouslyHeld
2572	Fair value of equity instruments newly issued	Concept (Monetary)	As Of	Debit	kt:AcquisitionDateFairValueOfEquityInstrumentsNewlyIssued
2573	Number of ordinary shares issued	Concept (Decimal)	As Of		ifrs-full:NumberOfInstrumentsOrInterestsIssuedOrIssuable
2574	Share issuance cost	Concept (Monetary)	For Period	Debit	ifrs-full:ShareIssueRelatedCost
2575	1227 - Disclosure - Business Combination - Schedule of Fair Value of Assets and Liabilities Recognized as a Result of Acquisition at Acquisition Date (Detail)	Network	*	*	http://www.kt.com/taxonomy/role/DisclosureBusinessCombinationScheduleOfFairValueOfAssetsAndLiabilitiesRecognizedAsAResultOfAcquisitionAtAcquisitionDate
2576	Disclosure of detailed information about business combination [table]	Table	*	*	ifrs-full:DisclosureOfBusinessCombinationsTable
2577	Business combinations [axis]	Axis			ifrs-full:BusinessCombinationsAxis
2578	Entity's total for business combinations [member]	Member			ifrs-full:EntitysTotalForBusinessCombinationsMember
2579	SG Safety Corporation [member]	Member			kt:SGSafetyCorporationMember
2580	KT MOS Bukbu Co.,Ltd. [member]	Member			kt:KtMosBukbuCoLtdMember
2581	KTMOS Nambu Co.,Ltd. [member]	Member			kt:KTMOSNambuCoLtdMember
2582	CJ Digital Music Co., Ltd. [member]	Member			kt:CjDigitalMusicCoLtdMember
2583	Disclosure of detailed information about business combination [Line Items]	LineItems			ifrs-full:DisclosureOfBusinessCombinationsLineItems
2584	Recognized amounts of identifiable assets acquired	Concept (Monetary)	As Of	Debit	kt:IdentifiableAssetsAcquiredAsOfAcquistionDate
2585	Cash and cash equivalents	Concept (Monetary)	As Of	Debit	ifrs-full:CashAndCashEquivalentsRecognisedAsOfAcquisitionDate
2586	Trade and other receivables	Concept (Monetary)	As Of	Debit	kt:TradeAndOtherReceivablesRecognisedAsOfAcquisitionDate
2587	Other current assets	Concept (Monetary)	As Of	Debit	ifrs-full:CurrentAssetsRecognisedAsOfAcquisitionDate
2588	Inventories	Concept (Monetary)	As Of	Debit	ifrs-full:InventoryRecognisedAsOfAcquisitionDate
2589	Current income tax assets	Concept (Monetary)	As Of	Debit	kt:CurrentIncomeTaxAssetsRecognizedAsOfAcquisitionDate
2590	Property and equipment	Concept (Monetary)	As Of	Debit	ifrs-full:PropertyPlantAndEquipmentRecognisedAsOfAcquisitionDate
2591	Intangible assets	Concept (Monetary)	As Of	Debit	ifrs-full:IdentifiableIntangibleAssetsRecognisedAsOfAcquisitionDate
2592	Distribution agency contract (included in intangibles)	Concept (Monetary)	As Of	Debit	kt:AgencyRelatedIntangibleAssetsRecognisedAsOfAcquisitionDate
2593	Contractual customer relationship (included in intangibles)	Concept (Monetary)	As Of	Debit	ifrs-full:CustomerrelatedIntangibleAssetsRecognisedAsOfAcquisitionDate
2594	Deferred income tax assets	Concept (Monetary)	As Of	Debit	ifrs-full:DeferredTaxAssetsRecognisedAsOfAcquisitionDate
2595	Other non-currentassets	Concept (Monetary)	As Of	Debit	ifrs-full:NoncurrentAssetsRecognisedAsOfAcquisitionDate
2596	Other non-current financial assets	Concept (Monetary)	As Of	Debit	kt:OtherNonCurrentFinancialAssetsRecognisedAsOfAcquisitionDate
2597	Recognized amounts of identifiable liabilities assumed	Concept (Monetary)	As Of	Credit	kt:IdentifiableLiabilitiesAssumedAsOfAcquistionDate
2598	Trade and other payables	Concept (Monetary)	As Of	Credit	ifrs-full:TradeAndOtherPayablesRecognisedAsOfAcquisitionDate
2599	Borrowings	Concept (Monetary)	As Of	Credit	ifrs-full:BorrowingsRecognisedAsOfAcquisitionDate
2600	Other current liabilities	Concept (Monetary)	As Of	Credit	ifrs-full:CurrentLiabilitiesRecognisedAsOfAcquisitionDate
2601	Current income tax liabilities	Concept (Monetary)	As Of	Credit	kt:CurrentIncomeTaxLiabilitiesRecognizedAsOfAcquisitionDate
2602	Post-employment benefit obligations	Concept (Monetary)	As Of	Credit	kt:PostemploymentBenefitObligationsRecognizedAsOfAcquisitionDate
2603	Deferred income tax liabilities	Concept (Monetary)	As Of	Credit	ifrs-full:DeferredTaxLiabilitiesRecognisedAsOfAcquisitionDate
2604	Other non-currentliabilities	Concept (Monetary)	As Of	Credit	ifrs-full:NoncurrentLiabilitiesRecognisedAsOfAcquisitionDate
2605	Total	Concept (Monetary)	As Of	Debit	ifrs-full:IdentifiableAssetsAcquiredLiabilitiesAssumed
2606	1228 - Disclosure - Business Combination - Schedule of Recognized Goodwill as a Result of Business Combination (Detail)	Network	*	*	http://www.kt.com/taxonomy/role/DisclosureBusinessCombinationScheduleOfRecognizedGoodwillAsAResultOfBusinessCombination
2607	Disclosure of detailed information about business combination [table]	Table	*	*	ifrs-full:DisclosureOfBusinessCombinationsTable
2608	Business combinations [axis]	Axis			ifrs-full:BusinessCombinationsAxis
2609	Entity's total for business combinations [member]	Member			ifrs-full:EntitysTotalForBusinessCombinationsMember
2610	SG Safety Corporation [member]	Member			kt:SGSafetyCorporationMember
2611	KT MOS Bukbu Co.,Ltd. [member]	Member			kt:KtMosBukbuCoLtdMember
2612	KTMOS Nambu Co.,Ltd. [member]	Member			kt:KTMOSNambuCoLtdMember
2613	CJ Digital Music Co., Ltd. [member]	Member			kt:CjDigitalMusicCoLtdMember
2614	Disclosure of detailed information about business combination [Line Items]	LineItems			ifrs-full:DisclosureOfBusinessCombinationsLineItems
2615	Purchase consideration	Concept (Monetary)	As Of	Credit	ifrs-full:AcquisitiondateFairValueOfTotalConsiderationTransferred
2616	Add: Non-controllinginterests	Concept (Monetary)	As Of	Credit	ifrs-full:NoncontrollingInterestInAcquireeRecognisedAtAcquisitionDate
2617	Less: Fair value of identifiable net assets	Concept (Monetary)	As Of	Debit	ifrs-full:IdentifiableAssetsAcquiredLiabilitiesAssumed
2618	Goodwill	Concept (Monetary)	As Of	Debit	ifrs-full:GoodwillRecognisedAsOfAcquisitionDate
2619	1229 - Disclosure - Business Combination - Schedule of Cash Outflows as a Result of Acquisition (Detail)	Network	*	*	http://www.kt.com/taxonomy/role/DisclosureBusinessCombinationScheduleOfCashOutflowsAsAResultOfAcquisition
2620	Disclosure of detailed information about business combination [table]	Table	*	*	ifrs-full:DisclosureOfBusinessCombinationsTable
2621	Business combinations [axis]	Axis			ifrs-full:BusinessCombinationsAxis
2622	Entity's total for business combinations [member]	Member			ifrs-full:EntitysTotalForBusinessCombinationsMember
2623	SG Safety Corporation [member]	Member			kt:SGSafetyCorporationMember
2624	KT MOS Bukbu Co.,Ltd. [member]	Member			kt:KtMosBukbuCoLtdMember
2625	KTMOS Nambu Co.,Ltd. [member]	Member			kt:KTMOSNambuCoLtdMember
2626	CJ Digital Music Co., Ltd. [member]	Member			kt:CjDigitalMusicCoLtdMember
2627	Disclosure of detailed information about business combination [Line Items]	LineItems			ifrs-full:DisclosureOfBusinessCombinationsLineItems
2628	Purchase consideration Cash	Concept (Monetary)	As Of	Credit	ifrs-full:CashTransferred
2629	Less : Recognized amounts of cash and cash equivalents	Concept (Monetary)	As Of	Debit	ifrs-full:CashAndCashEquivalentsRecognisedAsOfAcquisitionDate
2630	Total	Concept (Monetary)	As Of	Credit	kt:CashConsiderationNetOfCashAcquired
2631	1230 - Disclosure - Business Combination - Schedule of Cash Outflows as a Result of Acquisition (Parenthetical) (Detail)	Network	*	*	http://www.kt.com/taxonomy/role/DisclosureBusinessCombinationScheduleOfCashOutflowsAsAResultOfAcquisitionParenthetical
2632	Disclosure of detailed information about business combination [table]	Table	*	*	ifrs-full:DisclosureOfBusinessCombinationsTable
2633	Business combinations [axis]	Axis			ifrs-full:BusinessCombinationsAxis
2634	Entity's total for business combinations [member]	Member			ifrs-full:EntitysTotalForBusinessCombinationsMember
2635	SG Safety Corporation [member]	Member			kt:SGSafetyCorporationMember
2636	Disclosure of detailed information about business combination [Line Items]	LineItems			ifrs-full:DisclosureOfBusinessCombinationsLineItems
2637	Purchase considerations	Concept (Monetary)	As Of	Credit	ifrs-full:AcquisitiondateFairValueOfTotalConsiderationTransferred
2638	1231 - Disclosure - Changes in Accounting Policies - Summary of Impact on Financial Statements Due to Application of IFRS 15 at the Date of Initial Application (Detail)	Network	*	*	http://www.kt.com/taxonomy/role/DisclosureChangesInAccountingPoliciesSummaryOfImpactOnFinancialStatementsDueToApplicationOfIFRS15AtTheDateOfInitialApplication
2639	Disclosure of expected impact of initial application of new standards or interpretations [table]	Table	*	*	ifrs-full:DescriptionOfExpectedImpactOfInitialApplicationOfNewStandardsOrInterpretationsTable
2640	Retrospective application and retrospective restatement [axis]	Axis			ifrs-full:RetrospectiveApplicationAndRetrospectiveRestatementAxis
2641	Currently stated [member]	Member			ifrs-full:RestatedMember
2642	As previously reported [member]	Member			ifrs-full:PreviouslyStatedMember
2643	Increase (decrease) due to application of IFRS 15 [member]	Member			ifrs-full:IncreaseDecreaseDueToApplicationOfIFRS15Member
2644	Adjusted [member]	Member			kt:AdjustedMember
2645	Disclosure of expected impact of initial application of new standards or interpretations [line items]	LineItems			ifrs-full:DescriptionOfExpectedImpactOfInitialApplicationOfNewStandardsOrInterpretationsLineItems
2646	Current assets	Concept (Monetary)	As Of	Debit	ifrs-full:CurrentAssets
2647	Trade and other receivables	Concept (Monetary)	As Of	Debit	ifrs-full:TradeAndOtherCurrentReceivables
2648	Inventories	Concept (Monetary)	As Of	Debit	ifrs-full:Inventories
2649	Other current assets	Concept (Monetary)	As Of	Debit	ifrs-full:OtherCurrentAssets
2650	Others	Concept (Monetary)	As Of	Debit	kt:OtherCurrentAssetsOther
2651	Non-current assets	Concept (Monetary)	As Of	Debit	ifrs-full:NoncurrentAssets
2652	Trade and other receivables	Concept (Monetary)	As Of	Debit	ifrs-full:NoncurrentReceivables
2653	Deferred income tax assets	Concept (Monetary)	As Of	Debit	ifrs-full:DeferredTaxAssets
2654	Other non-current assets	Concept (Monetary)	As Of	Debit	ifrs-full:OtherNoncurrentNonfinancialAssets
2655	Others	Concept (Monetary)	As Of	Debit	kt:OtherNonCurrentAssetsOther
2656	Total assets	Concept (Monetary)	As Of	Debit	ifrs-full:Assets
2657	Current liabilities	Concept (Monetary)	As Of	Credit	ifrs-full:CurrentLiabilities
2658	Trade and other payables	Concept (Monetary)	As Of	Credit	ifrs-full:TradeAndOtherCurrentPayables
2659	Deferred revenue	Concept (Monetary)	As Of	Credit	ifrs-full:DeferredIncomeClassifiedAsCurrent
2660	Provisions	Concept (Monetary)	As Of	Credit	ifrs-full:OtherShorttermProvisions
2661	Other current liabilities	Concept (Monetary)	As Of	Credit	ifrs-full:OtherCurrentNonfinancialLiabilities
2662	Others	Concept (Monetary)	As Of	Credit	kt:OtherCurrentLiabilitiesOther
2663	Non-current liabilities	Concept (Monetary)	As Of	Credit	ifrs-full:NoncurrentLiabilities
2664	Deferred revenue	Concept (Monetary)	As Of	Credit	ifrs-full:DeferredIncomeClassifiedAsNoncurrent
2665	Deferred income tax liabilities	Concept (Monetary)	As Of	Credit	ifrs-full:DeferredTaxLiabilities
2666	Other non-current liabilities	Concept (Monetary)	As Of	Credit	ifrs-full:OtherNoncurrentNonfinancialLiabilities
2667	Others	Concept (Monetary)	As Of	Credit	kt:OtherNoncurrentLiabilitiesOther
2668	Total liabilities	Concept (Monetary)	As Of	Credit	ifrs-full:Liabilities
2669	Equity attribute to owners of the Controlling Company	Concept (Monetary)	As Of	Credit	ifrs-full:EquityAttributableToOwnersOfParent
2670	Non-controllinginterest	Concept (Monetary)	As Of	Credit	ifrs-full:NoncontrollingInterests
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2673	Operating expenses	Concept (Monetary)	For Period	Debit	ifrs-full:OperatingExpense
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2675	Financial income	Concept (Monetary)	For Period	Credit	ifrs-full:FinanceIncome
2676	Financial costs	Concept (Monetary)	For Period	Debit	ifrs-full:FinanceCosts
2677	Share of net losses of associates and joint venture	Concept (Monetary)	For Period	Credit	ifrs-full:ShareOfProfitLossOfAssociatesAndJointVenturesAccountedForUsingEquityMethod
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2679	Income tax expense	Concept (Monetary)	For Period	Debit	ifrs-full:IncomeTaxExpenseContinuingOperations
2680	Profit for the year	Concept (Monetary)	For Period	Credit	ifrs-full:ProfitLoss
2681	1232 - Disclosure - Changes in Accounting Policies - Additional Information (Detail)	Network	*	*	http://www.kt.com/taxonomy/role/DisclosureChangesInAccountingPoliciesAdditionalInformation
2682	Disclosure of expected impact of initial application of new standards or interpretations [table]	Table	*	*	ifrs-full:DescriptionOfExpectedImpactOfInitialApplicationOfNewStandardsOrInterpretationsTable
2683	Retrospective application and retrospective restatement [axis]	Axis			ifrs-full:RetrospectiveApplicationAndRetrospectiveRestatementAxis
2684	Currently stated [member]	Member			ifrs-full:RestatedMember
2685	Increase (decrease) due to application of IFRS 15 [member]	Member			ifrs-full:IncreaseDecreaseDueToApplicationOfIFRS15Member
2686	Disclosure of expected impact of initial application of new standards or interpretations [line items]	LineItems			ifrs-full:DescriptionOfExpectedImpactOfInitialApplicationOfNewStandardsOrInterpretationsLineItems
2687	Increase (decrease) in contract assets	Concept (Monetary)	For Period	Debit	ifrs-full:IncreaseDecreaseThroughCumulativeCatchupAdjustmentsToRevenueContractAssets
2688	Increase (decrease) in contract liabilities	Concept (Monetary)	For Period	Credit	ifrs-full:IncreaseDecreaseThroughCumulativeCatchupAdjustmentsToRevenueContractLiabilities
2689	Description of practical expedients used for incremental cost of obtaining contract	Concept (Text/String)	For Period		ifrs-full:DescriptionOfPracticalExpedientsUsedWhenApplyingIFRS15Retrospectively
2690	Increase (decrease) in prepaid expenses	Concept (Monetary)	For Period		kt:IncreaseDecreaseInPrepaidExpenses
2691	1233 - Disclosure - Changes in Accounting Policies - Summary of Beginning Balance of Retained Earnings after Adjustment Due to Application of IFRS 9 (Detail)	Network	*	*	http://www.kt.com/taxonomy/role/DisclosureChangesInAccountingPoliciesSummaryOfBeginningBalanceOfRetainedEarningsAfterAdjustmentDueToApplicationOfIFRS9
2692	Disclosure of expected impact of initial application of new standards or interpretations [table]	Table	*	*	ifrs-full:DescriptionOfExpectedImpactOfInitialApplicationOfNewStandardsOrInterpretationsTable
2693	Retrospective application and retrospective restatement [axis]	Axis			ifrs-full:RetrospectiveApplicationAndRetrospectiveRestatementAxis
2694	Currently stated [member]	Member			ifrs-full:RestatedMember
2695	IAS 39 [member]	Member			kt:IAS39Member
2696	IFRS9 [member]	Member			kt:IFRS9Member
2697	IFRS 15 [member]	Member			kt:IFRS15Member
2698	Disclosure of expected impact of initial application of new standards or interpretations [line items]	LineItems			ifrs-full:DescriptionOfExpectedImpactOfInitialApplicationOfNewStandardsOrInterpretationsLineItems
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2702	Increase in provision with unused limit	Concept (Monetary)	For Period	Debit	kt:IncreaseDecreaseInProvisionWithUnusedLimit
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2704	Adjustments of non-controlled interests	Concept (Monetary)	For Period	Credit	kt:IncreaseDecreaseInNoncontrollingInterests
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2706	Beginning balance - IAS 39	Concept (Monetary)	As Of	Credit	ifrs-full:RetainedEarnings
2707	Beginning balance of retained earnings after adjustment	Concept (Monetary)	As Of	Credit	kt:CumulativeEffectAdjustmentOfChangesRecognizedInBeginningOfRetainedEarningsUnderModifiedRetrospectiveMethod
2708	1234 - Disclosure - Changes in Accounting Policies - Summary of Effects Resulting from Classification and Measurement of Financial Instruments (Detail)	Network	*	*	http://www.kt.com/taxonomy/role/DisclosureChangesInAccountingPoliciesSummaryOfEffectsResultingFromClassificationAndMeasurementOfFinancialInstruments
2709	Disclosure of expected impact of initial application of new standards or interpretations [table]	Table	*	*	ifrs-full:DescriptionOfExpectedImpactOfInitialApplicationOfNewStandardsOrInterpretationsTable
2710	Effect of overlay approach reclassification [axis]	Axis			ifrs-full:EffectOfOverlayApproachReclassificationAxis
2711	In accordance with IFRS 9 [member]	Member			ifrs-full:InAccordanceWithIFRS9Member
2712	IAS 39 [member]	Member			kt:IAS39Member
2713	IFRS9 [member]	Member			kt:IFRS9Member
2714	Classes of financial instruments [axis]	Axis			ifrs-full:ClassesOfFinancialInstrumentsAxis
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2716	Loans and receivables under IAS 39 reclassified to financial assets measured at amortized cost under IFRS 9 [member]	Member			kt:LoansAndReceivablesUnderIAS39ReclassifiedToFinancialAssetsMeasuredAtAmortizedCostUnderIFRS9Member
2717	Loans and receivables under IAS 39 reclassified to financial assets at fair value through other comprehensive income under IFRS 9 [member]	Member			kt:LoansAndReceivablesUnderIAS39ReclassifiedToFinancialAssetsAtFairValueThroughOtherComprehensiveIncomeUnderIFRS9Member
2718	Loans and receivables under IAS 39 reclassified to financial assets at fair value through profit or loss under IFRS 9 [member]	Member			kt:LoansAndReceivablesUnderIAS39ReclassifiedToFinancialAssetsAtFairValueThroughProfitOrLossUnderIFRS9Member
2719	Financial assets at fair value through profit or loss under IAS 39 reclassified to Financial assets at fair value through profit or loss under IFRS 9 [member]	Member			kt:FinancialAssetsAtFairValueThroughProfitOrLossUnderIAS39ReclassifiedToFinancialAssetsAtFairValueThroughProfitOrLossUnderIFRS9Member
2720	Derivative financial assets for hedging purpose under IAS 39 reclassified to Derivative financial assets for hedging purpose under IFRS 9 [member]	Member			kt:DerivativeFinancialAssetsForHedgingPurposeUnderIAS39ReclassifiedToDerivativeFinancialAssetsForHedgingPurposeUnderIFRS9Member
2721	Financial assets available -for- sale under IAS 39 reclassified to financial assets measured at amortized cost under IFRS 9 [member]	Member			kt:FinancialAssetsAvailableForSaleUnderIAS39ReclassifiedToFinancialAssetsMeasuredAtAmortizedCostUnderIFRS9Member
2722	Financial assets available -for- sale under IAS 39 reclassified to financial assets at fair value through profit or loss under IFRS 9 [member]	Member			kt:FinancialAssetsAvailableForSaleUnderIAS39ReclassifiedToFinancialAssetsAtFairValueThroughProfitOrLossUnderIFRS9Member
2723	Financial assets available -for- sale under IAS 39 reclassified to financial assets at fair value through other comprehensive income under IFRS 9 [member]	Member			kt:FinancialAssetsAvailableForSaleUnderIAS39ReclassifiedToFinancialAssetsAtFairValueThroughOtherComprehensiveIncomeUnderIFRS9Member
2724	Financial assets held to maturity under IAS 39 reclassified to Financial assets measured at amortized cost under IFRS 9 [member]	Member			kt:FinancialAssetsHeldToMaturityUnderIAS39ReclassifiedToFinancialAssetsMeasuredAtAmortizedCostUnderIFRS9Member
2725	Financial assets held to maturity under IAS 39 reclassified to Financial assets at fair value through profit or loss under IFRS 9 [member]	Member			kt:FinancialAssetsHeldToMaturityUnderIAS39ReclassifiedToFinancialAssetsAtFairValueThroughProfitOrLossUnderIFRS9Member
2726	Other financial liabilities measured at amortized cost under IAS 39 reclassified to financial assets measured at amortized cost under IFRS 9 [member]	Member			kt:OtherFinancialLiabilitiesMeasuredAtAmortizedCostUnderIAS39ReclassifiedToFinancialAssetsMeasuredAtAmortizedCostUnderIFRS9Member
2727	Financial liabilities at fair value through profit or loss under IAS 39 reclassified to financial liabilities at fair value through profit or loss under IFRS 9 [member]	Member			kt:FinancialLiabilitiesAtFairValueThroughProfitOrLossUnderIAS39ReclassifiedToFinancialLiabilitiesAtFairValueThroughProfitOrLossUnderIFRS9Member
2728	Derivative financial liabilities for hedging purpose under IAS 39 reclassified to derivative financial liabilities for hedging purpose under IFRS 9 [member]	Member			kt:DerivativeFinancialLiabilitiesForHedgingPurposeUnderIAS39ReclassifiedToDerivativeFinancialLiabilitiesForHedgingPurposeUnderIFRS9Member
2729	Disclosure of expected impact of initial application of new standards or interpretations [line items]	LineItems			ifrs-full:DescriptionOfExpectedImpactOfInitialApplicationOfNewStandardsOrInterpretationsLineItems
2730	Cash and cash equivalent	Concept (Monetary)	As Of	Debit	ifrs-full:CashAndCashEquivalents
2731	Trade and other receivables	Concept (Monetary)	As Of	Debit	ifrs-full:TradeAndOtherReceivables
2732	Other financial assets	Concept (Monetary)	As Of	Debit	ifrs-full:OtherFinancialAssets
2733	Trade payables and payables	Concept (Monetary)	As Of	Credit	ifrs-full:TradeAndOtherPayables
2734	Borrowing	Concept (Monetary)	As Of	Credit	ifrs-full:Borrowings
2735	Other financial liabilities	Concept (Monetary)	As Of	Credit	ifrs-full:OtherFinancialLiabilities
2736	1235 - Disclosure - Changes in Accounting Policies - Summary of Impact on Changes in Equity (Detail)	Network	*	*	http://www.kt.com/taxonomy/role/DisclosureChangesInAccountingPoliciesSummaryOfImpactOnChangesInEquity
2737	Disclosure of expected impact of initial application of new standards or interpretations [table]	Table	*	*	ifrs-full:DescriptionOfExpectedImpactOfInitialApplicationOfNewStandardsOrInterpretationsTable
2738	Components of equity [axis]	Axis			ifrs-full:ComponentsOfEquityAxis
2739	Equity [member]	Member			ifrs-full:EquityMember
2740	Accumulated other comprehensive income [member]	Member			ifrs-full:AccumulatedOtherComprehensiveIncomeMember
2741	Retained earnings [member]	Member			ifrs-full:RetainedEarningsMember
2742	Retrospective application and retrospective restatement [axis]	Axis			ifrs-full:RetrospectiveApplicationAndRetrospectiveRestatementAxis
2743	Currently stated [member]	Member			ifrs-full:RestatedMember
2744	Increase (decrease) due to changes in accounting policy required by IFRSs [member]	Member			ifrs-full:IncreaseDecreaseDueToChangesInAccountingPolicyRequiredByIFRSsMember
2745	Disclosure of expected impact of initial application of new standards or interpretations [line items]	LineItems			ifrs-full:DescriptionOfExpectedImpactOfInitialApplicationOfNewStandardsOrInterpretationsLineItems
2746	Reclassification from loans and receivables to financial assets at fair value through other comprehensive income, and fair value assessment	Concept (Monetary)	For Period		kt:ReclassificationFromLoansAndReceivablesToFinancialAssetsAtFairValueThroughOtherComprehensiveIncome
2747	Reclassification from available-for-sale financial assets to financial assets at fair value through profit or loss, and fair value assessment	Concept (Monetary)	As Of	Credit	kt:ReclassificationFromAvailableForSaleFinancialAssetsToFinancialAssetsAtFairValueThroughProfitOrLoss
2748	Reclassification from available-for-sale financial assets to financial assets at fair value through other comprehensive income	Concept (Monetary)	As Of	Credit	kt:ReclassificationFromAvailableForSaleFinancialAssetsToFinancialAssetsAtFairValueThroughOtherComprehensiveIncome
2749	Increase in provision for impairment of financial assets at amortized cost	Concept (Monetary)	For Period	Debit	kt:IncreaseDecreaseInProvisionForImpairmentOfFinancialAssetsAtAmortizedCost
2750	Increase in provision with unused limit	Concept (Monetary)	For Period	Debit	kt:IncreaseDecreaseInProvisionWithUnusedLimit
2751	Income tax effect	Concept (Monetary)	For Period	Debit	kt:IncreaseDecreaseInDeferredTaxAssets
2752	Adjustments of non-controlled interests	Concept (Monetary)	For Period	Credit	kt:IncreaseDecreaseInNoncontrollingInterests
2753	Total adjustments from application of IFRS 9	Concept (Monetary)	For Period	Credit	ifrs-full:ChangesInEquity
2754	1236 - Disclosure - Events after Reporting Period - Summary of Public Bonds Issued After Reporting Period (Detail)	Network	*	*	http://www.kt.com/taxonomy/role/DisclosureEventsAfterReportingPeriodSummaryOfPublicBondsIssuedAfterReportingPeriod
2755	Disclosure of non-adjusting events after reporting period [table]	Table	*	*	ifrs-full:DisclosureOfNonadjustingEventsAfterReportingPeriodTable
2756	Carrying amount, accumulated depreciation, amortisation and impairment and gross carrying amount [axis]	Axis			ifrs-full:CarryingAmountAccumulatedDepreciationAmortisationAndImpairmentAndGrossCarryingAmountAxis
2757	Carrying amount [member]	Member			ifrs-full:CarryingAmountMember
2758	Gross carrying amount [member]	Member			ifrs-full:GrossCarryingAmountMember
2759	Borrowings by name [axis]	Axis			ifrs-full:BorrowingsByNameAxis
2760	Borrowings by name [member]	Member			ifrs-full:BorrowingsByNameMember
2761	The 191-1st Public bond, January fourteen, twenty twenty two [member]	Member			kt:The1911stPublicBondJanuaryFourteenTwentyTwentyTwoMember
2762	The 191-2nd Public bond, January fifteen, twenty twenty four [member]	Member			kt:The1912ndPublicBondJanuaryFifteenTwentyTwentyFourMember
2763	The191-3rd Public bond, January fifteen, twenty twenty nine [member]	Member			kt:The1913rdPublicBondJanuaryFifteenTwentyTwentyNineMember
2764	The191-4th Public bond, January fourteen, twenty thirty nine [member]	Member			kt:The1914thPublicBondJanuaryFourteenTwentyThirtyNineMember
2765	Disclosure of non-adjusting events after reporting period [line items]	LineItems			ifrs-full:DisclosureOfNonadjustingEventsAfterReportingPeriodLineItems
2766	Issue date	Concept (Text/String)	For Period		kt:PublicBondIssueDate
2767	Carrying amount	Concept (Monetary)	As Of	Credit	ifrs-full:BondsIssued
2768	Interest rate	Concept (Percent)	As Of		ifrs-full:BorrowingsInterestRate
2769	Redemption date	Concept (Text/String)	For Period		ifrs-full:BorrowingsMaturity
2770	1237 - Disclosure - Revision of Prior Financial Statements - Summary of Consolidated Statements of Financial Position (Detail)	Network	*	*	http://www.kt.com/taxonomy/role/DisclosureRevisionOfPriorFinancialStatementsSummaryOfConsolidatedStatementsOfFinancialPosition
2771	Disclosure of changes in accounting policies, accounting estimates and errors [table]	Table	*	*	kt:DisclosureOfChangesInAccountingPoliciesAccountingEstimatesAndErrorsTable
2772	Retrospective application and retrospective restatement [axis]	Axis			ifrs-full:RetrospectiveApplicationAndRetrospectiveRestatementAxis
2773	Currently stated [member]	Member			ifrs-full:RestatedMember
2774	As previously reported [member]	Member			ifrs-full:PreviouslyStatedMember
2775	Adjustments [member]	Member			ifrs-full:FinancialEffectOfCorrectionsOfAccountingErrorsMember
2776	Disclosure of changes in accounting policies, accounting estimates and errors [line items]	LineItems			kt:DisclosureOfChangesInAccountingPoliciesAccountingEstimatesAndErrorsLineItems
2777	Current assets	Concept (Monetary)	As Of	Debit	ifrs-full:CurrentAssets
2778	Trade and other receivables	Concept (Monetary)	As Of	Debit	ifrs-full:TradeAndOtherCurrentReceivables
2779	Total assets	Concept (Monetary)	As Of	Debit	ifrs-full:Assets
2780	Current liabilities	Concept (Monetary)	As Of	Credit	ifrs-full:CurrentLiabilities
2781	Trade and other payables	Concept (Monetary)	As Of	Credit	ifrs-full:TradeAndOtherCurrentPayables
2782	Current income tax liabilities	Concept (Monetary)	As Of	Credit	ifrs-full:CurrentTaxLiabilitiesCurrent
2783	Total liabilities	Concept (Monetary)	As Of	Credit	ifrs-full:Liabilities
2784	Equity attribute to owners of the Controlling Company	Concept (Monetary)	As Of	Credit	ifrs-full:EquityAttributableToOwnersOfParent
2785	Retained earnings	Concept (Monetary)	As Of	Credit	ifrs-full:RetainedEarnings
2786	Total equity	Concept (Monetary)	As Of	Credit	ifrs-full:Equity
2787	Total liabilities and equity	Concept (Monetary)	As Of	Credit	ifrs-full:EquityAndLiabilities
2788	1238 - Disclosure - Revision of Prior Financial Statements - Summary of Consolidated Statement of Operations & Comprehensive Income (Detail)	Network	*	*	http://www.kt.com/taxonomy/role/DisclosureRevisionOfPriorFinancialStatementsSummaryOfConsolidatedStatementOfOperationsComprehensiveIncome
2789	Disclosure of changes in accounting policies, accounting estimates and errors [table]	Table	*	*	kt:DisclosureOfChangesInAccountingPoliciesAccountingEstimatesAndErrorsTable
2790	Retrospective application and retrospective restatement [axis]	Axis			ifrs-full:RetrospectiveApplicationAndRetrospectiveRestatementAxis
2791	Currently stated [member]	Member			ifrs-full:RestatedMember
2792	As previously reported [member]	Member			ifrs-full:PreviouslyStatedMember
2793	Adjustments [member]	Member			ifrs-full:FinancialEffectOfCorrectionsOfAccountingErrorsMember
2794	Disclosure of changes in accounting policies, accounting estimates and errors [line items]	LineItems			kt:DisclosureOfChangesInAccountingPoliciesAccountingEstimatesAndErrorsLineItems
2795	Operating revenue	Concept (Monetary)	For Period	Credit	ifrs-full:Revenue
2796	Operating profit	Concept (Monetary)	For Period	Credit	ifrs-full:ProfitLossFromOperatingActivities
2797	Profit before income tax	Concept (Monetary)	For Period	Credit	ifrs-full:ProfitLossBeforeTax
2798	Income tax expense	Concept (Monetary)	For Period	Debit	ifrs-full:IncomeTaxExpenseContinuingOperations
2799	Profit for the year	Concept (Monetary)	For Period	Credit	ifrs-full:ProfitLoss
2800	Profit for the year attributable to the equity holders of the Controlling Company	Concept (Monetary)	For Period	Credit	ifrs-full:ProfitLossAttributableToOwnersOfParent
2801	Total comprehensive income for the year	Concept (Monetary)	For Period	Credit	ifrs-full:ComprehensiveIncome
2802	Total comprehensive income for the year attributable to the equity holders of the Controlling Company	Concept (Monetary)	For Period	Credit	ifrs-full:ComprehensiveIncomeAttributableToOwnersOfParent
2803	1239 - Disclosure - Revision of Prior Financial Statements - Summary of Consolidated Statements of Changes in Equity (Detail)	Network	*	*	http://www.kt.com/taxonomy/role/DisclosureRevisionOfPriorFinancialStatementsSummaryOfConsolidatedStatementsOfChangesInEquity
2804	Disclosure of changes in accounting policies, accounting estimates and errors [table]	Table	*	*	kt:DisclosureOfChangesInAccountingPoliciesAccountingEstimatesAndErrorsTable
2805	Retrospective application and retrospective restatement [axis]	Axis			ifrs-full:RetrospectiveApplicationAndRetrospectiveRestatementAxis
2806	Currently stated [member]	Member			ifrs-full:RestatedMember
2807	As previously reported [member]	Member			ifrs-full:PreviouslyStatedMember
2808	Adjustments [member]	Member			ifrs-full:FinancialEffectOfCorrectionsOfAccountingErrorsMember
2809	Disclosure of changes in accounting policies, accounting estimates and errors [line items]	LineItems			kt:DisclosureOfChangesInAccountingPoliciesAccountingEstimatesAndErrorsLineItems
2810	Retained earnings	Concept (Monetary)	As Of	Credit	ifrs-full:RetainedEarnings
2811	Owners of the Controlling Company	Concept (Monetary)	As Of	Credit	ifrs-full:EquityAttributableToOwnersOfParent
2812	1241 - Disclosure - Revision of Prior Financial Statements - Summary of Effects from Adjustments of Financial Statements before 2016 (Parenthetical) (Detail)	Network	*	*	http://www.kt.com/taxonomy/role/DisclosureRevisionOfPriorFinancialStatementsSummaryOfEffectsFromAdjustmentsOfFinancialStatementsBefore2016Parenthetical
2813	Disclosure of changes in accounting policies, accounting estimates and errors [table]	Table	*	*	kt:DisclosureOfChangesInAccountingPoliciesAccountingEstimatesAndErrorsTable
2814	Retrospective application and retrospective restatement [axis]	Axis			ifrs-full:RetrospectiveApplicationAndRetrospectiveRestatementAxis
2815	Currently stated [member]	Member			ifrs-full:RestatedMember
2816	Adjustments [member]	Member			ifrs-full:FinancialEffectOfCorrectionsOfAccountingErrorsMember
2817	Disclosure of changes in accounting policies, accounting estimates and errors [line items]	LineItems			kt:DisclosureOfChangesInAccountingPoliciesAccountingEstimatesAndErrorsLineItems
2818	Retained earnings	Concept (Monetary)	As Of	Credit	ifrs-full:RetainedEarnings