NUCANA PLC (SEC Filing Page | XBRL Cloud Viewer | XBRL Instance)

Line Label Object Class Period Type Balance Report ElementName
1 100000 - Document - Document and Entity Information Network

*

*

 http://www.nucana.com/20181231/taxonomy/role/DocumentDocumentAndEntityInformation
2 Implied Table Table

*

*

 implied:Table
3 Document And Entity Information [Abstract] Abstract ncna: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 Voluntary Filers Concept (Yes/No) For Period dei:EntityVoluntaryFilers
16 Entity Filer Category Concept (Filer Category) For Period dei:EntityFilerCategory
17 Entity Common Stock, Shares Outstanding Concept (Shares) As Of dei:EntityCommonStockSharesOutstanding
18 100010 - Statement - Consolidated Statements of Operations Network

*

*

 http://www.nucana.com/20181231/taxonomy/role/StatementConsolidatedStatementsOfOperations
19 Implied Table Table

*

*

 implied:Table
20 Income Statement [Abstract] Abstract ifrs-full:IncomeStatementAbstract
21 Research and development expenses Concept (Monetary) For Period Debit ifrs-full:ResearchAndDevelopmentExpense
22 Administrative expenses Concept (Monetary) For Period Debit ifrs-full:AdministrativeExpense
23 Initial public offering related expenses Concept (Monetary) For Period Debit ifrs-full:FinanceCosts
24 Net foreign exchange gains (losses) Concept (Monetary) For Period Credit ifrs-full:GainsLossesOnExchangeDifferencesOnTranslationBeforeTax
25 Operating loss Concept (Monetary) For Period Credit ifrs-full:ProfitLossFromOperatingActivities
26 Finance income Concept (Monetary) For Period Credit ifrs-full:FinanceIncome
27 Loss before tax Concept (Monetary) For Period Credit ifrs-full:ProfitLossBeforeTax
28 Income tax credit Concept (Monetary) For Period Debit ifrs-full:IncomeTaxExpenseContinuingOperations
29 Loss for the year attributable to equity holders of the Company Concept (Monetary) For Period Credit ifrs-full:ProfitLoss
30 Basic and diluted loss per share Concept (Share) For Period ifrs-full:BasicAndDilutedEarningsLossPerShare
31 100020 - Statement - Consolidated Statements of Comprehensive Loss Network

*

*

 http://www.nucana.com/20181231/taxonomy/role/StatementConsolidatedStatementsOfComprehensiveLoss
32 Implied Table Table

*

*

 implied:Table
33 Statement Of Comprehensive Income [Abstract] Abstract ifrs-full:StatementOfComprehensiveIncomeAbstract
34 Loss for the year Concept (Monetary) For Period Credit ifrs-full:ProfitLoss
35 Other comprehensive income (expense): Abstract ifrs-full:OtherComprehensiveIncomeAbstract
36 Items that may be reclassified subsequently to profit or loss: Abstract ifrs-full:ComponentsOfOtherComprehensiveIncomeThatWillBeReclassifiedToProfitOrLossNetOfTaxAbstract
37 Exchange differences on translation of foreign operations Concept (Monetary) For Period Credit ifrs-full:OtherComprehensiveIncomeNetOfTaxExchangeDifferencesOnTranslation
38 Other comprehensive income (expense) for the year Concept (Monetary) For Period Credit ifrs-full:OtherComprehensiveIncome
39 Total comprehensive loss for the year Concept (Monetary) For Period Credit ifrs-full:ComprehensiveIncome
40 Attributable to: Abstract ifrs-full:ComprehensiveIncomeAttributableToAbstract
41 Equity holders of the Company Concept (Monetary) For Period Credit ifrs-full:ComprehensiveIncomeAttributableToOwnersOfParent
42 100030 - Statement - Consolidated Statements of Financial Position Network

*

*

 http://www.nucana.com/20181231/taxonomy/role/StatementConsolidatedStatementsOfFinancialPosition
43 Implied Table Table

*

*

 implied:Table
44 Statement Of Financial Position [Abstract] Abstract ifrs-full:StatementOfFinancialPositionAbstract
45 ASSETS Abstract ifrs-full:AssetsAbstract
46 Non-current assets Abstract ifrs-full:NoncurrentAssetsAbstract
47 Intangible assets Concept (Monetary) As Of Debit ifrs-full:IntangibleAssetsOtherThanGoodwill
48 Property, plant and equipment Concept (Monetary) As Of Debit ifrs-full:PropertyPlantAndEquipment
49 Deferred tax asset Concept (Monetary) As Of Debit ifrs-full:DeferredTaxAssets
50 Total non-current assets Concept (Monetary) As Of Debit ifrs-full:NoncurrentAssets
51 Current assets Abstract ifrs-full:CurrentAssetsAbstract
52 Prepayments, accrued income and other receivables Concept (Monetary) As Of Debit ifrs-full:TradeAndOtherCurrentReceivables
53 Current income tax receivable Concept (Monetary) As Of Debit ifrs-full:CurrentTaxAssetsCurrent
54 Cash and cash equivalents Concept (Monetary) As Of Debit ifrs-full:CashAndCashEquivalents
55 Total current assets Concept (Monetary) As Of Debit ifrs-full:CurrentAssets
56 Total assets Concept (Monetary) As Of Debit ifrs-full:Assets
57 EQUITY AND LIABILITIES Abstract ifrs-full:EquityAndLiabilitiesAbstract
58 Capital and reserves Abstract ifrs-full:EquityAbstract
59 Share capital and share premium Concept (Monetary) As Of Credit ncna:ShareCapitalAndSharePremium
60 Other reserves Concept (Monetary) As Of Credit ifrs-full:OtherReserves
61 Accumulated deficit Concept (Monetary) As Of Credit ifrs-full:RetainedEarnings
62 Total equity attributable to equity holders of the Company Concept (Monetary) As Of Credit ifrs-full:Equity
63 Non-current liabilities Abstract ifrs-full:NoncurrentLiabilitiesAbstract
64 Provisions Concept (Monetary) As Of Credit ifrs-full:NoncurrentProvisions
65 Current liabilities Abstract ifrs-full:CurrentLiabilitiesAbstract
66 Trade payables Concept (Monetary) As Of Credit ifrs-full:TradeAndOtherCurrentPayablesToTradeSuppliers
67 Payroll taxes and social security Concept (Monetary) As Of Credit ifrs-full:CurrentProvisionsForEmployeeBenefits
68 Accrued expenditure Concept (Monetary) As Of Credit ifrs-full:AccrualsClassifiedAsCurrent
69 Total current liabilities Concept (Monetary) As Of Credit ifrs-full:CurrentLiabilities
70 Total liabilities Concept (Monetary) As Of Credit ifrs-full:Liabilities
71 Total equity and liabilities Concept (Monetary) As Of Credit ifrs-full:EquityAndLiabilities
72 100040 - Statement - Consolidated Statements Of Changes In Equity Network

*

*

 http://www.nucana.com/20181231/taxonomy/role/StatementConsolidatedStatementsOfChangesInEquity
73 Statement Of Changes In Equity [Table] Table

*

*

 ifrs-full:StatementOfChangesInEquityTable
74 Components of equity [axis] Axis ifrs-full:ComponentsOfEquityAxis
75 Equity [member] Member ifrs-full:EquityMember
76 Share Capital Member ifrs-full:IssuedCapitalMember
77 Share Premium Member ifrs-full:SharePremiumMember
78 Own Share Reserve Member ifrs-full:CapitalRedemptionReserveMember
79 Share Option Reserve Member ifrs-full:ReserveOfChangeInValueOfTimeValueOfOptionsMember
80 Foreign Currency Translation Reserve Member ifrs-full:ReserveOfExchangeDifferencesOnTranslationMember
81 Capital Reserve Member ifrs-full:CapitalReserveMember
82 Accumulated Deficit Member ifrs-full:RetainedEarningsMember
83 Classes of share capital [axis] Axis ifrs-full:ClassesOfShareCapitalAxis
84 Share capital [member] Member ifrs-full:ClassesOfShareCapitalMember
85 Series B Shareholders Member ncna:ClassesOfSeriesBSharesMember
86 Statement Of Changes In Equity [Line Items] LineItems ifrs-full:StatementOfChangesInEquityLineItems
87 Beginning balance Concept (Monetary) As Of Credit ifrs-full:Equity
88 Loss for the year Concept (Monetary) For Period Credit ifrs-full:ProfitLoss
89 Other comprehensive expense for the year Concept (Monetary) For Period Credit ifrs-full:OtherComprehensiveIncome
90 Total comprehensive loss for the year Concept (Monetary) For Period Credit ifrs-full:ComprehensiveIncome
91 Share-based payments Concept (Monetary) For Period Credit ifrs-full:IncreaseDecreaseThroughSharebasedPaymentTransactions
92 Exercise of share options Concept (Monetary) For Period Credit ifrs-full:IncreaseDecreaseThroughExerciseOfOptions
93 Ending balance Concept (Monetary) As Of Credit ifrs-full:Equity
94 Reduction in share premium Concept (Monetary) For Period Debit ncna:AdjustmentOnReductionOfSharePremium
95 Forfeiture of share options Concept (Monetary) For Period Credit ncna:IncreaseDecreaseThroughForfeitOfOptionsEquity
96 Lapse of share options Concept (Monetary) For Period Credit ncna:LapseOfShareOptions
97 Bonus issue to series B shareholders Concept (Monetary) For Period Credit ncna:BonusSharesIssued
98 Issue of share capital Concept (Monetary) For Period Credit ifrs-full:IssueOfEquity
99 Initial public offering related expenses Concept (Monetary) For Period Debit ifrs-full:ShareIssueRelatedCost
100 100050 - Statement - Consolidated Statements of Cash Flows Network

*

*

 http://www.nucana.com/20181231/taxonomy/role/StatementConsolidatedStatementsOfCashFlows
101 Implied Table Table

*

*

 implied:Table
102 Statement Of Cash Flows [Abstract] Abstract ifrs-full:StatementOfCashFlowsAbstract
103 Cash flows from operating activities Abstract ifrs-full:CashFlowsFromUsedInOperatingActivitiesAbstract
104 Loss for the year Concept (Monetary) For Period Credit ifrs-full:ProfitLoss
105 Adjustments for: Abstract ifrs-full:AdjustmentsForReconcileProfitLossAbstract
106 Income tax credit Concept (Monetary) For Period Debit ifrs-full:AdjustmentsForIncomeTaxExpense
107 Amortization and depreciation Concept (Monetary) For Period Debit ifrs-full:AdjustmentsForDepreciationAndAmortisationExpense
108 Finance income Concept (Monetary) For Period Credit ifrs-full:AdjustmentsForFinanceIncome
109 Share-based payments Concept (Monetary) For Period Debit ifrs-full:AdjustmentsForSharebasedPayments
110 Initial public offering (IPO) related expenses Concept (Monetary) For Period Debit ncna:AdjustmentsForShareIssueRelatedCost
111 Net foreign exchange (gains) losses Concept (Monetary) For Period Debit ifrs-full:AdjustmentsForUnrealisedForeignExchangeLossesGains
112 Cash flows from (used in) operations before changes in working capital Concept (Monetary) For Period ifrs-full:CashFlowsFromUsedInOperationsBeforeChangesInWorkingCapital
113 Movements in working capital: Abstract ncna:ChangesInWorkingCapitalAbstract
114 Decrease (increase) in prepayments, accrued income and other receivables Concept (Monetary) For Period Debit ifrs-full:AdjustmentsForDecreaseIncreaseInTradeAndOtherReceivables
115 Increase in trade payables Concept (Monetary) For Period Debit ifrs-full:AdjustmentsForIncreaseDecreaseInTradeAccountPayable
116 Increase in payroll taxes, social security and accrued expenditure Concept (Monetary) For Period Debit ifrs-full:AdjustmentsForIncreaseDecreaseInEmployeeBenefitLiabilities
117 Movements in working capital Concept (Monetary) For Period Credit ifrs-full:IncreaseDecreaseInWorkingCapital
118 Cash used in operations Concept (Monetary) For Period ifrs-full:CashFlowsFromUsedInOperations
119 Net income tax credit Concept (Monetary) For Period Credit ifrs-full:IncomeTaxesPaidRefundClassifiedAsOperatingActivities
120 Net cash used in operating activities Concept (Monetary) For Period ifrs-full:CashFlowsFromUsedInOperatingActivities
121 Cash flows from investing activities Abstract ifrs-full:CashFlowsFromUsedInInvestingActivitiesAbstract
122 Interest received Concept (Monetary) For Period Debit ifrs-full:InterestReceivedClassifiedAsOperatingActivities
123 Payments for property, plant and equipment Concept (Monetary) For Period Credit ifrs-full:PurchaseOfPropertyPlantAndEquipmentClassifiedAsInvestingActivities
124 Payments for intangible assets Concept (Monetary) For Period Credit ifrs-full:PurchaseOfIntangibleAssetsClassifiedAsInvestingActivities
125 Proceeds from short-term deposits Concept (Monetary) For Period Debit ifrs-full:CashFlowsFromUsedInDecreaseIncreaseInShorttermDepositsAndInvestments
126 Net cash (used in) provided by investing activities Concept (Monetary) For Period Debit ifrs-full:CashFlowsFromUsedInInvestingActivities
127 Cash flows from financing activities Abstract ifrs-full:CashFlowsFromUsedInFinancingActivitiesAbstract
128 Proceeds from issue of share capital Concept (Monetary) For Period Debit ifrs-full:ProceedsFromIssuingShares
129 IPO related expenses from issue of share capital - included in share premium Concept (Monetary) For Period Credit ncna:PaymentOfTransactionCostsOnIssueOfShareCapitalIncludedInSharePremium
130 IPO related expenses included in statement of operations Concept (Monetary) For Period Credit ncna:PaymentOfTransactionCostsOnIssueOfShareCapitalIncludedInInitialPublicOffering
131 Proceeds from issue of share capital - exercise of share options Concept (Monetary) For Period Debit ifrs-full:ProceedsFromExerciseOfOptions
132 Net cash from financing activities Concept (Monetary) For Period Debit ifrs-full:CashFlowsFromUsedInFinancingActivities
133 Net (decrease) increase in cash and cash equivalents Concept (Monetary) For Period Debit ifrs-full:IncreaseDecreaseInCashAndCashEquivalentsBeforeEffectOfExchangeRateChanges
134 Cash and cash equivalents at beginning of year Concept (Monetary) As Of Debit ifrs-full:CashAndCashEquivalents
135 Foreign currency translation differences Concept (Monetary) For Period Debit ifrs-full:EffectOfExchangeRateChangesOnCashAndCashEquivalents
136 Cash and cash equivalents at end of year Concept (Monetary) As Of Debit ifrs-full:CashAndCashEquivalents
137 100060 - Disclosure - General Information Network

*

*

 http://www.nucana.com/20181231/taxonomy/role/DisclosureGeneralInformation
138 Implied Table Table

*

*

 implied:Table
139 Disclosure Of General Information About Financial Statements [Abstract] Abstract ncna:DisclosureOfGeneralInformationAboutFinancialStatementsAbstract
140 General information Concept (Text Block (HTML)) For Period ifrs-full:DisclosureOfNotesAndOtherExplanatoryInformationExplanatory
141 100070 - Disclosure - Significant Accounting Policies Network

*

*

 http://www.nucana.com/20181231/taxonomy/role/DisclosureSignificantAccountingPolicies
142 Implied Table Table

*

*

 implied:Table
143 Disclosure Of Summary Of Significant Accounting Policies [Abstract] Abstract ncna:DisclosureOfSummaryOfSignificantAccountingPoliciesAbstract
144 Significant accounting policies Concept (Text Block (HTML)) For Period ifrs-full:DisclosureOfSummaryOfSignificantAccountingPoliciesExplanatory
145 100080 - Disclosure - Staff Costs Network

*

*

 http://www.nucana.com/20181231/taxonomy/role/DisclosureStaffCosts
146 Implied Table Table

*

*

 implied:Table
147 Classes Of Employee Benefits Expense [Abstract] Abstract ifrs-full:ClassesOfEmployeeBenefitsExpenseAbstract
148 Staff Costs Explanatory Concept (Text Block (HTML)) For Period ifrs-full:DisclosureOfEmployeeBenefitsExplanatory
149 100090 - Disclosure - Basic and Diluted Loss Per Share Network

*

*

 http://www.nucana.com/20181231/taxonomy/role/DisclosureBasicAndDilutedLossPerShare
150 Implied Table Table

*

*

 implied:Table
151 Earnings Per Share [Abstract] Abstract ifrs-full:EarningsPerShareAbstract
152 Basic and diluted loss per share Concept (Text Block (HTML)) For Period ifrs-full:DisclosureOfEarningsPerShareExplanatory
153 100100 - Disclosure - Loss Before Tax Network

*

*

 http://www.nucana.com/20181231/taxonomy/role/DisclosureLossBeforeTax
154 Implied Table Table

*

*

 implied:Table
155 Material Income And Expense [Abstract] Abstract ifrs-full:MaterialIncomeAndExpenseAbstract
156 Loss Before Tax Concept (Text Block (HTML)) For Period ncna:DisclosureOfLossBeforeTaxExplanatory
157 100110 - Disclosure - Capital Commitments and Contingencies Network

*

*

 http://www.nucana.com/20181231/taxonomy/role/DisclosureCapitalCommitmentsAndContingencies
158 Implied Table Table

*

*

 implied:Table
159 Disclosure Of Capital Commitments And Contingencies [Abstract] Abstract ncna:DisclosureOfCapitalCommitmentsAndContingenciesAbstract
160 Capital commitments and contingencies Concept (Text Block (HTML)) For Period ifrs-full:DisclosureOfCommitmentsAndContingentLiabilitiesExplanatory
161 100120 - Disclosure - Income Tax Credit Network

*

*

 http://www.nucana.com/20181231/taxonomy/role/DisclosureIncomeTaxCredit
162 Implied Table Table

*

*

 implied:Table
163 Major Components Of Tax Expense Income [Abstract] Abstract ifrs-full:MajorComponentsOfTaxExpenseIncomeAbstract
164 Income tax credit Concept (Text Block (HTML)) For Period ifrs-full:DisclosureOfIncomeTaxExplanatory
165 100130 - Disclosure - Intangible Assets Network

*

*

 http://www.nucana.com/20181231/taxonomy/role/DisclosureIntangibleAssets
166 Implied Table Table

*

*

 implied:Table
167 Disclosure Of Intangible Assets [Abstract] Abstract ifrs-full:DisclosureOfIntangibleAssetsAbstract
168 Intangible Assets Concept (Text Block (HTML)) For Period ifrs-full:DisclosureOfIntangibleAssetsExplanatory
169 100140 - Disclosure - Property, Plant and Equipment Network

*

*

 http://www.nucana.com/20181231/taxonomy/role/DisclosurePropertyPlantAndEquipment
170 Implied Table Table

*

*

 implied:Table
171 Disclosure Of Property Plant And Equipment [Abstract] Abstract ifrs-full:DisclosureOfPropertyPlantAndEquipmentAbstract
172 Property, Plant and Equipment Concept (Text Block (HTML)) For Period ifrs-full:DisclosureOfPropertyPlantAndEquipmentExplanatory
173 100150 - Disclosure - Prepayments, Accrued Income and Other Receivables Network

*

*

 http://www.nucana.com/20181231/taxonomy/role/DisclosurePrepaymentsAccruedIncomeAndOtherReceivables
174 Implied Table Table

*

*

 implied:Table
175 Prepayments Accrued Income And Other Receivables [Abstract] Abstract ncna:PrepaymentsAccruedIncomeAndOtherReceivablesAbstract
176 Prepayments, accrued income and other receivables Concept (Text Block (HTML)) For Period ncna:PrepaymentsAccruedIncomeAndOtherReceivablesExplanatory
177 100160 - Disclosure - Share Capital and Share Premium Network

*

*

 http://www.nucana.com/20181231/taxonomy/role/DisclosureShareCapitalAndSharePremium
178 Implied Table Table

*

*

 implied:Table
179 Disclosure Of Classes Of Share Capital [Abstract] Abstract ifrs-full:DisclosureOfClassesOfShareCapitalAbstract
180 Share capital and share Premium Concept (Text Block (HTML)) For Period ifrs-full:DisclosureOfShareCapitalReservesAndOtherEquityInterestExplanatory
181 100170 - Disclosure - Other Reserves Network

*

*

 http://www.nucana.com/20181231/taxonomy/role/DisclosureOtherReserves
182 Implied Table Table

*

*

 implied:Table
183 Disclosure Of Other Reserves [Abstract] Abstract ncna:DisclosureOfOtherReservesAbstract
184 Other reserves Concept (Text Block (HTML)) For Period ncna:DisclosureOfOtherReservesExplanatory
185 100180 - Disclosure - Share-based payments Network

*

*

 http://www.nucana.com/20181231/taxonomy/role/DisclosureShareBasedPayments
186 Implied Table Table

*

*

 implied:Table
187 Disclosure Of Terms And Conditions Of Sharebased Payment Arrangement [Abstract] Abstract ifrs-full:DisclosureOfTermsAndConditionsOfSharebasedPaymentArrangementAbstract
188 Share-based payments Concept (Text Block (HTML)) For Period ifrs-full:DisclosureOfSharebasedPaymentArrangementsExplanatory
189 100190 - Disclosure - Related party disclosures Network

*

*

 http://www.nucana.com/20181231/taxonomy/role/DisclosureRelatedPartyDisclosures
190 Implied Table Table

*

*

 implied:Table
191 Related Party Transactions [Abstract] Abstract ifrs-full:RelatedPartyTransactionsAbstract
192 Related party disclosures Concept (Text Block (HTML)) For Period ifrs-full:DisclosureOfRelatedPartyExplanatory
193 100200 - Disclosure - Cash And Cash Equivalents Network

*

*

 http://www.nucana.com/20181231/taxonomy/role/DisclosureCashAndCashEquivalents
194 Implied Table Table

*

*

 implied:Table
195 Cash And Cash Equivalents [Abstract] Abstract ifrs-full:CashAndCashEquivalentsAbstract
196 Cash and cash equivalents Concept (Text Block (HTML)) For Period ifrs-full:DisclosureOfCashAndCashEquivalentsExplanatory
197 100210 - Disclosure - Financial Instruments Risk Management Network

*

*

 http://www.nucana.com/20181231/taxonomy/role/DisclosureFinancialInstrumentsRiskManagement
198 Implied Table Table

*

*

 implied:Table
199 Disclosure Of Financial Instruments [Abstract] Abstract ifrs-full:DisclosureOfFinancialInstrumentsAbstract
200 Financial instruments risk management Concept (Text Block (HTML)) For Period ifrs-full:DisclosureOfFinancialInstrumentsExplanatory
201 100220 - Disclosure - Events After the Reporting Period Network

*

*

 http://www.nucana.com/20181231/taxonomy/role/DisclosureEventsAfterReportingPeriod
202 Implied Table Table

*

*

 implied:Table
203 Events After Reporting Period [Abstract] Abstract ncna:EventsAfterReportingPeriodAbstract
204 Events After the Reporting Period Concept (Text Block (HTML)) For Period ifrs-full:DisclosureOfEventsAfterReportingPeriodExplanatory
205 100230 - Disclosure - Significant Accounting Policies (Policies) Network

*

*

 http://www.nucana.com/20181231/taxonomy/role/DisclosureSignificantAccountingPoliciesPolicies
206 Implied Table Table

*

*

 implied:Table
207 Disclosure Of Summary Of Significant Accounting Policies [Abstract] Abstract ncna:DisclosureOfSummaryOfSignificantAccountingPoliciesAbstract
208 Basis of preparation Concept (Text Block (HTML)) For Period ifrs-full:DisclosureOfBasisOfPreparationOfFinancialStatementsExplanatory
209 Going concern Concept (Text Block (HTML)) For Period ifrs-full:DisclosureOfGoingConcernExplanatory
210 Judgements and estimates Concept (Text Block (HTML)) For Period ncna:DescriptionOfAccountingPolicyForJudgementsAndEstimatesExplanatory
211 Research and development expenses Concept (Text Block (HTML)) For Period ifrs-full:DescriptionOfAccountingPolicyForResearchAndDevelopmentExpenseExplanatory
212 Taxation Concept (Text Block (HTML)) For Period ifrs-full:DescriptionOfAccountingPolicyForDeferredIncomeTaxExplanatory
213 Recognition of Clinical Trial Expenses Concept (Text Block (HTML)) For Period ncna:DescriptionOfAccountingPolicyForRecognitionOfClinicalTrialExpensesExplanatory
214 Recognition of Manufacturing Contract Expenses Concept (Text Block (HTML)) For Period ifrs-full:DescriptionOfAccountingPolicyForExpensesExplanatory
215 Share-based payments Concept (Text Block (HTML)) For Period ifrs-full:DescriptionOfAccountingPolicyForSharebasedPaymentTransactionsExplanatory
216 Basis of consolidation Concept (Text Block (HTML)) For Period ifrs-full:DisclosureOfBasisOfConsolidationExplanatory
217 Segment reporting Concept (Text Block (HTML)) For Period ifrs-full:DisclosureOfEntitysReportableSegmentsExplanatory
218 Initial public offering (IPO) related expenses Concept (Text Block (HTML)) For Period ncna:DisclosureOfInitialPublicOfferingAndRelatedExpensesExplanatory
219 Property, plant and equipment Concept (Text Block (HTML)) For Period ifrs-full:DescriptionOfAccountingPolicyForPropertyPlantAndEquipmentExplanatory
220 Intangible assets Concept (Text Block (HTML)) For Period ifrs-full:DescriptionOfAccountingPolicyForIntangibleAssetsOtherThanGoodwillExplanatory
221 Cash, cash equivalents and short-term deposits Concept (Text Block (HTML)) For Period ncna:DescriptionOfAccountingPolicyForCashCashEquivalentsAndShortTermDepositsExplanatory
222 Research and development Concept (Text Block (HTML)) For Period ncna:DescriptionOfAccountingPolicyForResearchAndDevelopmentExplanatory
223 Income Taxes Concept (Text Block (HTML)) For Period ifrs-full:DescriptionOfAccountingPolicyForIncomeTaxExplanatory
224 Operating leases Concept (Text Block (HTML)) For Period ifrs-full:DescriptionOfAccountingPolicyForLeasesExplanatory
225 Impairment of non-financial assets Concept (Text Block (HTML)) For Period ifrs-full:DescriptionOfAccountingPolicyForImpairmentOfNonfinancialAssetsExplanatory
226 Calculation of recoverable amount Concept (Text Block (HTML)) For Period ncna:DescriptionOfAccountingPolicyForCalculationOfRecoverableAmountExplanatory
227 Reversal of impairment Concept (Text Block (HTML)) For Period ncna:DescriptionOfAccountingPolicyForReversalOfImpairmentExplanatory
228 Share-based payments Concept (Text Block (HTML)) For Period ifrs-full:DescriptionOfAccountingPolicyForEmployeeBenefitsExplanatory
229 Fair value measurement Concept (Text Block (HTML)) For Period ifrs-full:DescriptionOfAccountingPolicyForFairValueMeasurementExplanatory
230 Accounting Standards Concept (Text Block (HTML)) For Period ifrs-full:DescriptionOfInitialApplicationOfStandardsOrInterpretations
231 100240 - Disclosure - Significant Accounting Policies (Tables) Network

*

*

 http://www.nucana.com/20181231/taxonomy/role/DisclosureSignificantAccountingPoliciesTables
232 Implied Table Table

*

*

 implied:Table
233 Disclosure Of Summary Of Significant Accounting Policies [Abstract] Abstract ncna:DisclosureOfSummaryOfSignificantAccountingPoliciesAbstract
234 Summary of Depreciation on Property, Plant and Equipment Over Their Expected Useful Economic Life Concept (Text Block (HTML)) For Period ncna:SummaryOfDepreciationOnPropertyPlantAndEquipmentOverTheirExpectedUsefulEconomicLifeExplanatory
235 Summary of Amortization Method and Amortization Period for the Principal Categories of Intangible Assets Concept (Text Block (HTML)) For Period ncna:SummaryOfAmortizationMethodAndAmortizationPeriodForPrincipalCategoriesOfIntangibleAssetsExplanatory
236 100250 - Disclosure - Staff Costs (Tables) Network

*

*

 http://www.nucana.com/20181231/taxonomy/role/DisclosureStaffCostsTables
237 Staff Costs [Table] Table

*

*

 ncna:StaffCostsTable
238 Income Statement Location Axis us-gaap:IncomeStatementLocationAxis
239 Income Statement Location Member us-gaap:IncomeStatementLocationDomain
240 Research and Development Expenses Member ncna:ResearchAndDevelopmentExpensesMember
241 Administrative Expenses Member us-gaap:GeneralAndAdministrativeExpenseMember
242 Categories of related parties [axis] Axis ifrs-full:CategoriesOfRelatedPartiesAxis
243 Entity's total for related parties [member] Member ifrs-full:EntitysTotalForRelatedPartiesMember
244 Highest Paid Director Member ncna:HighestPaidDirectorMember
245 Staff Costs [Line Items] LineItems ncna:StaffCostsLineItems
246 Disclosure of Employee Benefit Expense Concept (Text Block (HTML)) For Period ncna:DisclosureOfDetailedInformationAboutStaffCostsExplanatory
247 Schedule of Average Number of Staff Employed Under Contracts of Service Explanatory Concept (Text Block (HTML)) For Period ncna:DisclosureOfAverageNumberOfStaffEmployedUnderContractsOfServiceExplanatory
248 Summary of Directors’ Remuneration and Other Benefits Concept (Text Block (HTML)) For Period ncna:DisclosureOfDirectorsRemunerationAndOtherBenefitsExplanatory
249 100260 - Disclosure - Basic and Diluted Loss Per Share (Tables) Network

*

*

 http://www.nucana.com/20181231/taxonomy/role/DisclosureBasicAndDilutedLossPerShareTables
250 Implied Table Table

*

*

 implied:Table
251 Earnings Per Share [Abstract] Abstract ifrs-full:EarningsPerShareAbstract
252 Schedule of Basic and Diluted Loss Per Share Concept (Text Block (HTML)) For Period ifrs-full:EarningsPerShareExplanatory
253 100270 - Disclosure - Loss Before Tax (Tables) Network

*

*

 http://www.nucana.com/20181231/taxonomy/role/DisclosureLossBeforeTaxTables
254 Implied Table Table

*

*

 implied:Table
255 Material Income And Expense [Abstract] Abstract ifrs-full:MaterialIncomeAndExpenseAbstract
256 Summary of Loss Before Tax Stated After Charging Concept (Text Block (HTML)) For Period ncna:DisclosureOfDetailedInformationAboutLossBeforeTaxExplanatory
257 100280 - Disclosure - Capital Commitments and Contingencies (Tables) Network

*

*

 http://www.nucana.com/20181231/taxonomy/role/DisclosureCapitalCommitmentsAndContingenciesTables
258 Implied Table Table

*

*

 implied:Table
259 Disclosure Of Capital Commitments And Contingencies [Abstract] Abstract ncna:DisclosureOfCapitalCommitmentsAndContingenciesAbstract
260 Summary of Capital Commitments Concept (Text Block (HTML)) For Period ncna:DisclosureOfCapitalCommitmentsExplanatory
261 Future Minimum Rentals Payable Under Non-cancellable Operating Leases Concept (Text Block (HTML)) For Period ifrs-full:DisclosureOfFinanceLeaseAndOperatingLeaseByLesseeExplanatory
262 100290 - Disclosure - Income Tax Credit (Tables) Network

*

*

 http://www.nucana.com/20181231/taxonomy/role/DisclosureIncomeTaxCreditTables
263 Implied Table Table

*

*

 implied:Table
264 Major Components Of Tax Expense Income [Abstract] Abstract ifrs-full:MajorComponentsOfTaxExpenseIncomeAbstract
265 Schedule of Major Components of Income Tax Concept (Text Block (HTML)) For Period ncna:DisclosureOfMajorComponentsOfIncomeTaxExplanatory
266 Schedule of Reconciliation of Accounting Loss per Statement of Operations Concept (Text Block (HTML)) For Period ncna:DisclosureOfReconciliationOfAccountingProfitMultipliedByApplicableTaxRatesExplanatory
267 100300 - Disclosure - Intangible Assets (Tables) Network

*

*

 http://www.nucana.com/20181231/taxonomy/role/DisclosureIntangibleAssetsTables
268 Implied Table Table

*

*

 implied:Table
269 Disclosure Of Intangible Assets [Abstract] Abstract ifrs-full:DisclosureOfIntangibleAssetsAbstract
270 Summary of Intangible Assets Concept (Text Block (HTML)) For Period ifrs-full:DisclosureOfDetailedInformationAboutIntangibleAssetsExplanatory
271 100310 - Disclosure - Property, Plant and Equipment (Tables) Network

*

*

 http://www.nucana.com/20181231/taxonomy/role/DisclosurePropertyPlantAndEquipmentTables
272 Implied Table Table

*

*

 implied:Table
273 Disclosure Of Property Plant And Equipment [Abstract] Abstract ifrs-full:DisclosureOfPropertyPlantAndEquipmentAbstract
274 Summary of Property, Plant and Equipment Concept (Text Block (HTML)) For Period ifrs-full:DisclosureOfDetailedInformationAboutPropertyPlantAndEquipmentExplanatory
275 100320 - Disclosure - Prepayments, Accrued Income and Other Receivables (Tables) Network

*

*

 http://www.nucana.com/20181231/taxonomy/role/DisclosurePrepaymentsAccruedIncomeAndOtherReceivablesTables
276 Implied Table Table

*

*

 implied:Table
277 Prepayments Accrued Income And Other Receivables [Abstract] Abstract ncna:PrepaymentsAccruedIncomeAndOtherReceivablesAbstract
278 Summary of Prepayments, Accrued Income and Other Receivables Concept (Text Block (HTML)) For Period ncna:DisclosureOfPrepaymentsAccruedIncomeAndOtherReceivablesExplanatory
279 100330 - Disclosure - Share Capital and Share Premium (Tables) Network

*

*

 http://www.nucana.com/20181231/taxonomy/role/DisclosureShareCapitalAndSharePremiumTables
280 Implied Table Table

*

*

 implied:Table
281 Disclosure Of Classes Of Share Capital [Abstract] Abstract ifrs-full:DisclosureOfClassesOfShareCapitalAbstract
282 Summary of Share Capital and Share Premium Concept (Text Block (HTML)) For Period ifrs-full:DisclosureOfClassesOfShareCapitalExplanatory
283 Summary of Movement in the Share Capital Concept (Text Block (HTML)) For Period ncna:DisclosureOfMovementInTheShareCapitalExplanatory
284 100340 - Disclosure - Other Reserves (Tables) Network

*

*

 http://www.nucana.com/20181231/taxonomy/role/DisclosureOtherReservesTables
285 Disclosure Of Other Reserves [Table] Table

*

*

 ncna:DisclosureOfOtherReservesTable
286 Components of equity [axis] Axis ifrs-full:ComponentsOfEquityAxis
287 Equity [member] Member ifrs-full:EquityMember
288 Other Reserves Member ifrs-full:OtherReservesMember
289 Disclosure Of Other Reserves [Line Items] LineItems ncna:DisclosureOfOtherReservesLineItems
290 Schedule of Other Reserves Concept (Text Block (HTML)) For Period ifrs-full:DisclosureOfReservesAndOtherEquityInterestExplanatory
291 100350 - Disclosure - Share-based Payments (Tables) Network

*

*

 http://www.nucana.com/20181231/taxonomy/role/DisclosureShareBasedPaymentsTables
292 Implied Table Table

*

*

 implied:Table
293 Disclosure Of Terms And Conditions Of Sharebased Payment Arrangement [Abstract] Abstract ifrs-full:DisclosureOfTermsAndConditionsOfSharebasedPaymentArrangementAbstract
294 Summary of Share Options and Weighted Average Exercise Prices Concept (Text Block (HTML)) For Period ifrs-full:DisclosureOfNumberAndWeightedAverageExercisePricesOfShareOptionsExplanatory
295 Summary of Principal Assumptions used for Valuation of Share Options Concept (Text Block (HTML)) For Period ifrs-full:DisclosureOfIndirectMeasurementOfFairValueOfGoodsOrServicesReceivedShareOptionsGrantedDuringPeriodExplanatory
296 100360 - Disclosure - Related Party Disclosures (Tables) Network

*

*

 http://www.nucana.com/20181231/taxonomy/role/DisclosureRelatedPartyDisclosuresTables
297 Implied Table Table

*

*

 implied:Table
298 Related Party Transactions [Abstract] Abstract ifrs-full:RelatedPartyTransactionsAbstract
299 Summary of Compensation of Key Management Personnel Concept (Text Block (HTML)) For Period ifrs-full:DisclosureOfInformationAboutKeyManagementPersonnelExplanatory
300 100370 - Disclosure - Cash And Cash Equivalents (Tables) Network

*

*

 http://www.nucana.com/20181231/taxonomy/role/DisclosureCashAndCashEquivalentsTables
301 Implied Table Table

*

*

 implied:Table
302 Cash And Cash Equivalents [Abstract] Abstract ifrs-full:CashAndCashEquivalentsAbstract
303 Schedule of Cash and Cash Equivalents Concept (Text Block (HTML)) For Period ncna:DisclosureOfCashCashEquivalentsAndShortTermDepositsExplanatory
304 100380 - Disclosure - Financial Instruments Risk Management (Tables) Network

*

*

 http://www.nucana.com/20181231/taxonomy/role/DisclosureFinancialInstrumentsRiskManagementTables
305 Implied Table Table

*

*

 implied:Table
306 Disclosure Of Financial Instruments [Abstract] Abstract ifrs-full:DisclosureOfFinancialInstrumentsAbstract
307 Schedule of Financial Assets Subject to Fixed or Variable Interest Rates Concept (Text Block (HTML)) For Period ifrs-full:DisclosureOfFinancialInstrumentsByTypeOfInterestRateExplanatory
308 Summary of Financial Assets and Liabilities in Foreign Currencies, Primarily Held in U.S Dollars Concept (Text Block (HTML)) For Period ifrs-full:DisclosureOfDetailedInformationAboutFinancialInstrumentsExplanatory
309 100390 - Disclosure - General Information- Additional Information (Details) Network

*

*

 http://www.nucana.com/20181231/taxonomy/role/DisclosureGeneralInformationAdditionalInformationDetails
310 Implied Table Table

*

*

 implied:Table
311 Disclosure Of General Information About Financial Statements [Abstract] Abstract ncna:DisclosureOfGeneralInformationAboutFinancialStatementsAbstract
312 Name of reporting entity Concept (Text/String) For Period ifrs-full:NameOfReportingEntityOrOtherMeansOfIdentification
313 Description of nature of entity's operations Concept (Text/String) For Period ifrs-full:DescriptionOfNatureOfEntitysOperationsAndPrincipalActivities
314 Domicile of entity Concept (Text/String) For Period ifrs-full:DomicileOfEntity
315 Country of incorporation Concept (Text/String) For Period ifrs-full:CountryOfIncorporation
316 Name of subsidiary Concept (Text/String) For Period ifrs-full:NameOfSubsidiary
317 Number of subsidiaries Concept (Integer) For Period ncna:NumberOfSubsidiaries
318 100400 - Disclosure - Significant Accounting Policies - Additional Information (Details) Network

*

*

 http://www.nucana.com/20181231/taxonomy/role/DisclosureSignificantAccountingPoliciesAdditionalInformationDetails
319 Disclosure Of Summary Of Significant Accounting Policies [Table] Table

*

*

 ncna:DisclosureOfSummaryOfSignificantAccountingPoliciesTable
320 Classes of intangible assets other than goodwill [axis] Axis ifrs-full:ClassesOfIntangibleAssetsOtherThanGoodwillAxis
321 Intangible assets other than goodwill [member] Member ifrs-full:IntangibleAssetsOtherThanGoodwillMember
322 Patents Member ifrs-full:BrandNamesMember
323 Range [axis] Axis ifrs-full:RangeAxis
324 Ranges [member] Member ifrs-full:RangesMember
325 Maximum Member ifrs-full:TopOfRangeMember
326 Bottom Of Range [Member] Member ifrs-full:BottomOfRangeMember
327 Non-adjusting events after reporting period [axis] Axis ifrs-full:NonadjustingEventsAfterReportingPeriodAxis
328 Non-adjusting events after reporting period [member] Member ifrs-full:NonadjustingEventsMember
329 Adoption of IFRS 16 Member ncna:AdoptionOfIFRSMember
330 Retrospective application and retrospective restatement [axis] Axis ifrs-full:RetrospectiveApplicationAndRetrospectiveRestatementAxis
331 Currently stated [member] Member ifrs-full:RestatedMember
332 Increase (decrease) due to application of IFRS Member ifrs-full:IncreaseDecreaseDueToVoluntaryChangesInAccountingPolicyMember
333 Disclosure Of Summary Of Significant Accounting Policies [Line Items] LineItems ncna:DisclosureOfSummaryOfSignificantAccountingPoliciesLineItems
334 Cash and cash equivalents Concept (Monetary) As Of Debit ifrs-full:CashAndCashEquivalents
335 Number of operating segment Concept (Integer) For Period ncna:NumberOfOperatingSegment
336 Patent life Concept (Text/String) For Period ifrs-full:UsefulLivesOrAmortisationRatesIntangibleAssetsOtherThanGoodwill
337 Cash at banks maturity period Concept (Text/String) For Period ncna:CashAtBanksMaturityPeriod
338 Certificates of deposits maturity period Concept (Text/String) For Period ncna:CertificatesOfDepositsMaturityPeriod
339 Income tax credit, cash rebate percentage Concept (Percent) For Period ncna:IncomeTaxCreditCashRebatePercentage
340 Increase (decrease) in total assets due to adoption of accounting new standard Concept (Monetary) For Period Debit ncna:IncreaseDecreaseInTotalAssetsDueToAdoptionOfAccountingNewStandard
341 Increase (decrease) in total liabilities due to adoption of accounting new standard Concept (Monetary) For Period Credit ncna:IncreaseDecreaseInTotalLiabilitiesDueToAdoptionOfAccountingNewStandard
342 100410 - Disclosure - Significant Accounting Policies - Summary of Depreciation on Property, Plant and Equipment Over Their Expected Useful Economic Life (Details) Network

*

*

 http://www.nucana.com/20181231/taxonomy/role/DisclosureSignificantAccountingPoliciesSummaryOfDepreciationOnPropertyPlantAndEquipmentOverTheirExpectedUsefulEconomicLifeDetails
343 Disclosure Of Property Plant And Equipment [Table] Table

*

*

 ifrs-full:DisclosureOfPropertyPlantAndEquipmentTable
344 Classes of property, plant and equipment [axis] Axis ifrs-full:ClassesOfPropertyPlantAndEquipmentAxis
345 Property, plant and equipment [member] Member ifrs-full:PropertyPlantAndEquipmentMember
346 Office and Computer Equipment Member ncna:OfficeAndComputerEquipmentMember
347 Fixtures and Fittings Member ifrs-full:FixturesAndFittingsMember
348 Disclosure Of Property Plant And Equipment [Line Items] LineItems ifrs-full:DisclosureOfPropertyPlantAndEquipmentLineItems
349 Depreciation method Concept (Text/String) For Period ifrs-full:DepreciationMethodPropertyPlantAndEquipment
350 Depreciation rate Concept (Text/String) For Period ifrs-full:UsefulLivesOrDepreciationRatesPropertyPlantAndEquipment
351 100420 - Disclosure - Significant Accounting Policies - Summery of Amortization Method and Amortization Period for the Principal Categories of Intangible Assets (Details) Network

*

*

 http://www.nucana.com/20181231/taxonomy/role/DisclosureSignificantAccountingPoliciesSummeryOfAmortizationMethodAndAmortizationPeriodForPrincipalCategoriesOfIntangibleAssetsDetails
352 Disclosure Of Intangible Assets [Table] Table

*

*

 ifrs-full:DisclosureOfIntangibleAssetsTable
353 Classes of intangible assets other than goodwill [axis] Axis ifrs-full:ClassesOfIntangibleAssetsOtherThanGoodwillAxis
354 Intangible assets other than goodwill [member] Member ifrs-full:IntangibleAssetsOtherThanGoodwillMember
355 Patents Member ifrs-full:BrandNamesMember
356 Computer Software Member ifrs-full:ComputerSoftwareMember
357 Range [axis] Axis ifrs-full:RangeAxis
358 Ranges [member] Member ifrs-full:RangesMember
359 Bottom Of Range [Member] Member ifrs-full:BottomOfRangeMember
360 Maximum Member ifrs-full:TopOfRangeMember
361 Disclosure Of Intangible Assets [Line Items] LineItems ifrs-full:DisclosureOfIntangibleAssetsLineItems
362 Amortization method Concept (Text/String) For Period ifrs-full:AmortisationMethodIntangibleAssetsOtherThanGoodwill
363 Amortization rate Concept (Text/String) For Period ifrs-full:UsefulLivesOrAmortisationRatesIntangibleAssetsOtherThanGoodwill
364 100430 - Disclosure - Staff Costs - Disclosure of Employee Benefit Expense (Details) Network

*

*

 http://www.nucana.com/20181231/taxonomy/role/DisclosureStaffCostsDisclosureOfEmployeeBenefitExpenseDetails
365 Staff Costs [Table] Table

*

*

 ncna:StaffCostsTable
366 Income Statement Location Axis us-gaap:IncomeStatementLocationAxis
367 Income Statement Location Member us-gaap:IncomeStatementLocationDomain
368 Research and Development Expenses Member ncna:ResearchAndDevelopmentExpensesMember
369 Administrative Expenses Member us-gaap:GeneralAndAdministrativeExpenseMember
370 Staff Costs [Line Items] LineItems ncna:StaffCostsLineItems
371 Wages and salaries Concept (Monetary) For Period Debit ifrs-full:WagesAndSalaries
372 Social security costs Concept (Monetary) For Period Debit ifrs-full:SocialSecurityContributions
373 Pension costs and other benefits Concept (Monetary) For Period Debit ifrs-full:PostemploymentBenefitExpenseDefinedBenefitPlans
374 Share-based payments Concept (Monetary) For Period Debit ifrs-full:ExpenseFromSharebasedPaymentTransactionsWithEmployees
375 Total employee benefit expense Concept (Monetary) For Period Debit ifrs-full:EmployeeBenefitsExpense
376 100440 - Disclosure - Staff Costs - Schedule of Average Number of Staff Employed Under Contracts of Service Explanatory (Details) Network

*

*

 http://www.nucana.com/20181231/taxonomy/role/DisclosureStaffCostsScheduleOfAverageNumberOfStaffEmployedUnderContractsOfServiceExplanatoryDetails
377 Staff Costs [Table] Table

*

*

 ncna:StaffCostsTable
378 Income Statement Location Axis us-gaap:IncomeStatementLocationAxis
379 Income Statement Location Member us-gaap:IncomeStatementLocationDomain
380 Research and Development Expenses Member ncna:ResearchAndDevelopmentExpensesMember
381 Administrative Expenses Member us-gaap:GeneralAndAdministrativeExpenseMember
382 Staff Costs [Line Items] LineItems ncna:StaffCostsLineItems
383 Average number of staff employed under contracts of service Concept (Decimal) For Period ifrs-full:AverageNumberOfEmployees
384 100450 - Disclosure - Staff Costs - Summary of Directors' Remuneration and Other Benefits (Details) Network

*

*

 http://www.nucana.com/20181231/taxonomy/role/DisclosureStaffCostsSummaryOfDirectorsRemunerationAndOtherBenefitsDetails
385 Staff Costs [Table] Table

*

*

 ncna:StaffCostsTable
386 Categories of related parties [axis] Axis ifrs-full:CategoriesOfRelatedPartiesAxis
387 Entity's total for related parties [member] Member ifrs-full:EntitysTotalForRelatedPartiesMember
388 Highest Paid Director Member ncna:HighestPaidDirectorMember
389 Staff Costs [Line Items] LineItems ncna:StaffCostsLineItems
390 Directors’ remuneration Concept (Monetary) For Period Debit ifrs-full:DirectorsRemunerationExpense
391 Pension and other benefits Concept (Monetary) For Period Debit ncna:DirectorsRemunerationPensionAndOtherBenefitsExpense
392 Directors’ remuneration & other benefits Concept (Monetary) For Period Debit ncna:DirectorsRemunerationExpenseIncludingPensionAndOtherBenefitsExpense
393 100460 - Disclosure - Staff Costs - Additional Information (Details) Network

*

*

 http://www.nucana.com/20181231/taxonomy/role/DisclosureStaffCostsAdditionalInformationDetails
394 Implied Table Table

*

*

 implied:Table
395 Classes Of Employee Benefits Expense [Abstract] Abstract ifrs-full:ClassesOfEmployeeBenefitsExpenseAbstract
396 Number of directors, exercised share options Concept (Integer) For Period ncna:NumberOfDirectorsExercisedShareOptions
397 Gain on exercise of option Concept (Monetary) For Period Credit ncna:GainOnExerciseOfOption
398 Director cease holding office period from grant date Concept (xbrli:durationItemType) For Period ncna:DirectorCeaseHoldingOfficePeriodFromGrantDate
399 100470 - Disclosure - Basic and Diluted Loss Per Share - Schedule of Basic and Diluted Loss Per Share (Details) Network

*

*

 http://www.nucana.com/20181231/taxonomy/role/DisclosureBasicAndDilutedLossPerShareScheduleOfBasicAndDilutedLossPerShareDetails
400 Implied Table Table

*

*

 implied:Table
401 Earnings Per Share [Abstract] Abstract ifrs-full:EarningsPerShareAbstract
402 Loss for the year Concept (Monetary) For Period Credit ifrs-full:ProfitLoss
403 Basic and diluted weighted average number of shares Concept (Shares) For Period ifrs-full:WeightedAverageShares
404 Basic and diluted loss per share Concept (Share) For Period ifrs-full:BasicAndDilutedEarningsLossPerShare
405 100480 - Disclosure - Loss Before Tax - Summary of Loss Before Tax Stated After Charging (Details) Network

*

*

 http://www.nucana.com/20181231/taxonomy/role/DisclosureLossBeforeTaxSummaryOfLossBeforeTaxStatedAfterChargingDetails
406 Implied Table Table

*

*

 implied:Table
407 Material Income And Expense [Abstract] Abstract ifrs-full:MaterialIncomeAndExpenseAbstract
408 Amortization Concept (Monetary) For Period Debit ifrs-full:AmortisationExpense
409 Depreciation Concept (Monetary) For Period Debit ifrs-full:DepreciationExpense
410 IPO related expenses Concept (Monetary) For Period Debit ncna:InitialPublicOfferingRelatedExpenses
411 100490 - Disclosure - Capital Commitments and Contingencies - Summary of Capital Commitments (Details) Network

*

*

 http://www.nucana.com/20181231/taxonomy/role/DisclosureCapitalCommitmentsAndContingenciesSummaryOfCapitalCommitmentsDetails
412 Implied Table Table

*

*

 implied:Table
413 Capital Commitments [Abstract] Abstract ifrs-full:CapitalCommitmentsAbstract
414 Future capital expenditure contracted but not provided for Concept (Monetary) As Of Credit ifrs-full:ContractualCapitalCommitments
415 100500 - Disclosure - Capital Commitments and Contingencies - Additional Information (Details) Network

*

*

 http://www.nucana.com/20181231/taxonomy/role/DisclosureCapitalCommitmentsAndContingenciesAdditionalInformationDetails
416 Capital Commitments [Table] Table

*

*

 ncna:CapitalCommitmentsTable
417 Counterparties [axis] Axis ifrs-full:CounterpartiesAxis
418 Counterparties [member] Member ifrs-full:CounterpartiesMember
419 Cardiff University Member ncna:CardiffUniversityMember
420 Cardiff Consultants Member ncna:CardiffConsultantsMember
421 Cardiff ProTides Member ncna:CardiffProTidesMember
422 Non-adjusting events after reporting period [axis] Axis ifrs-full:NonadjustingEventsAfterReportingPeriodAxis
423 Non-adjusting events after reporting period [member] Member ifrs-full:NonadjustingEventsMember
424 Renewing Significant Commitments Member ncna:RenewingSignificantCommitmentsMember
425 Statement Scenario Axis us-gaap:StatementScenarioAxis
426 Scenario Unspecified Member us-gaap:ScenarioUnspecifiedDomain
427 Scenario Forecast Member us-gaap:ScenarioForecastMember
428 Capital Commitments [Line Items] LineItems ncna:CapitalCommitmentsLineItems
429 Research, collaboration and license agreement additional term Concept (xbrli:durationItemType) For Period ncna:ResearchCollaborationAndLicenseAgreementAdditionalTerm
430 Payments for work performed by sub-licensee Concept (Monetary) For Period Credit ifrs-full:PaymentsForDevelopmentProjectExpenditure
431 Milestone payments for sub-licensee Concept (Monetary) For Period Debit ncna:MilestonePayments
432 Employer national insurance contingent liability Concept (Monetary) As Of ifrs-full:EstimatedFinancialEffectOfContingentLiabilities
433 Prevailing rate of employer national insurance Concept (Percent) For Period ncna:CurrentlyPrevailingPercentageOfEmployerNationalInsurance
434 Disclosure - Capital Commitments and Contingencies - Additional Information (Details) [Line Items] LineItems ncna:DisclosureCapitalCommitmentsAndContingenciesAdditionalInformationDetailsLineItems
435 Operating lease expense Concept (Monetary) For Period Debit ifrs-full:MinimumOperatingLeasePayments
436 100510 - Disclosure - Capital Commitments and Contingencies - Future Minimum Rentals Payable Under Non-cancellable Operating Leases (Details) Network

*

*

 http://www.nucana.com/20181231/taxonomy/role/DisclosureCapitalCommitmentsAndContingenciesFutureMinimumRentalsPayableUnderNonCancellableOperatingLeasesDetails
437 Disclosure Of Finance Lease And Operating Lease By Lessee [Table] Table

*

*

 ifrs-full:DisclosureOfFinanceLeaseAndOperatingLeaseByLesseeTable
438 Maturity [axis] Axis ifrs-full:MaturityAxis
439 Aggregated time bands [member] Member ifrs-full:AggregatedTimeBandsMember
440 Not Later than 1 Year Member ifrs-full:NotLaterThanOneYearMember
441 Later than 1 Year and Not Later than 5 Years Member ifrs-full:LaterThanOneYearAndNotLaterThanFiveYearsMember
442 Disclosure Of Finance Lease And Operating Lease By Lessee [Line Items] LineItems ifrs-full:DisclosureOfFinanceLeaseAndOperatingLeaseByLesseeLineItems
443 Future minimum rentals payable under non-cancellable operating leases Concept (Monetary) As Of Credit ifrs-full:MinimumLeasePaymentsPayableUnderNoncancellableOperatingLease
444 100520 - Disclosure - Income Tax Credit - Schedule of Major Components of Income Tax (Details) Network

*

*

 http://www.nucana.com/20181231/taxonomy/role/DisclosureIncomeTaxCreditScheduleOfMajorComponentsOfIncomeTaxDetails
445 Major Components Of Tax Expense Income [Table] Table

*

*

 ncna:MajorComponentsOfTaxExpenseIncomeTable
446 Geographical areas [axis] Axis ifrs-full:GeographicalAreasAxis
447 Geographical areas [member] Member ifrs-full:GeographicalAreasMember
448 U.K. Member ifrs-full:CountryOfDomicileMember
449 U.S. Member ifrs-full:ForeignCountriesMember
450 Major Components Of Tax Expense Income [Line Items] LineItems ncna:MajorComponentsOfTaxExpenseIncomeLineItems
451 Current tax: Abstract ifrs-full:CurrentTaxExpenseIncomeAndAdjustmentsForCurrentTaxOfPriorPeriodsAbstract
452 In respect of current year Concept (Monetary) For Period Debit ifrs-full:CurrentTaxExpenseIncome
453 In respect of prior years Concept (Monetary) For Period Debit ifrs-full:AdjustmentsForCurrentTaxOfPriorPeriod
454 Total current tax Concept (Monetary) For Period Debit ifrs-full:CurrentTaxExpenseIncomeAndAdjustmentsForCurrentTaxOfPriorPeriods
455 Deferred tax: Abstract ifrs-full:DeferredTaxExpenseIncomeAbstract
456 In respect of current year, deferred tax Concept (Monetary) For Period Debit ifrs-full:DeferredTaxExpenseIncome
457 In respect of prior years, deferred tax Concept (Monetary) For Period Debit ifrs-full:AdjustmentsForDeferredTaxOfPriorPeriods
458 Total deferred tax Concept (Monetary) For Period ifrs-full:DeferredTaxExpenseIncomeRecognisedInProfitOrLoss
459 Income tax credit Concept (Monetary) For Period Debit ifrs-full:IncomeTaxExpenseContinuingOperations
460 Current income tax receivable Concept (Monetary) As Of Debit ifrs-full:CurrentTaxAssetsCurrent
461 Deferred tax Concept (Monetary) As Of Debit ifrs-full:DeferredTaxAssets
462 Current income tax payable Concept (Monetary) As Of Credit ifrs-full:CurrentTaxLiabilitiesCurrent
463 100530 - Disclosure - Income Tax Credit - Schedule of Reconciliation of Accounting Loss per Statement of Operations (Details) Network

*

*

 http://www.nucana.com/20181231/taxonomy/role/DisclosureIncomeTaxCreditScheduleOfReconciliationOfAccountingLossPerStatementOfOperationsDetails
464 Implied Table Table

*

*

 implied:Table
465 Reconciliation Of Accounting Profit Multiplied By Applicable Tax Rates [Abstract] Abstract ifrs-full:ReconciliationOfAccountingProfitMultipliedByApplicableTaxRatesAbstract
466 Loss before tax Concept (Monetary) For Period Credit ifrs-full:AccountingProfit
467 Tax on loss at standard U.K. tax rate Concept (Monetary) For Period Debit ifrs-full:TaxExpenseIncomeAtApplicableTaxRate
468 Expenses not deductible Concept (Monetary) For Period Debit ifrs-full:TaxEffectOfExpenseNotDeductibleInDeterminingTaxableProfitTaxLoss
469 Deduction for R&D Concept (Monetary) For Period Debit ncna:TaxEffectOfDeductionForResearchAndDevelopment
470 Losses surrendered for R&D tax credit Concept (Monetary) For Period Debit ifrs-full:TaxEffectOfTaxLosses
471 Deferred tax - PY adjustment Concept (Monetary) For Period Debit ncna:TaxEffectOfDeferredTaxPriorYearAdjustment
472 Overseas tax payable - current year Concept (Monetary) For Period Debit ncna:TaxEffectOfForeignTaxRatesCurrentYear
473 Overseas tax payable - prior years Concept (Monetary) For Period Debit ncna:TaxEffectOfForeignTaxRatesPriorYears
474 R&D tax credit— U.S. Concept (Monetary) For Period Debit ncna:TaxEffectOfResearchAndDevelopmentTaxCreditForeign
475 R&D tax credit—current year Concept (Monetary) For Period Debit ncna:TaxEffectOfResearchAndDevelopmentTaxCreditCurrentYear
476 R&D tax credit—prior years Concept (Monetary) For Period Debit ncna:TaxEffectOfResearchAndDevelopmentTaxCreditPriorYears
477 Deferred tax asset not recognized Concept (Monetary) For Period Debit ifrs-full:AdjustmentsForDeferredTaxOfPriorPeriods
478 Income tax credit Concept (Monetary) For Period Debit ifrs-full:IncomeTaxExpenseContinuingOperations
479 100540 - Disclosure - Income Tax Credit - Schedule of Reconciliation of Accounting Loss per Statement of Operations (Parenthetical) (Details) Network

*

*

 http://www.nucana.com/20181231/taxonomy/role/DisclosureIncomeTaxCreditScheduleOfReconciliationOfAccountingLossPerStatementOfOperationsParentheticalDetails
480 Reconciliation Of Accounting Profit Multiplied By Applicable Tax Rates [Table] Table

*

*

 ncna:ReconciliationOfAccountingProfitMultipliedByApplicableTaxRatesTable
481 Geographical areas [axis] Axis ifrs-full:GeographicalAreasAxis
482 Geographical areas [member] Member ifrs-full:GeographicalAreasMember
483 U.K. Member ifrs-full:CountryOfDomicileMember
484 Reconciliation Of Accounting Profit Multiplied By Applicable Tax Rates [Line Items] LineItems ncna:ReconciliationOfAccountingProfitMultipliedByApplicableTaxRatesLineItems
485 Applicable tax rate Concept (Percent) For Period ifrs-full:ApplicableTaxRate
486 100550 - Disclosure - Income Tax Credit - Additional Information (Details) Network

*

*

 http://www.nucana.com/20181231/taxonomy/role/DisclosureIncomeTaxCreditAdditionalInformationDetails
487 Disclosure Of Temporary Difference Unused Tax Losses And Unused Tax Credits [Table] Table

*

*

 ifrs-full:DisclosureOfTemporaryDifferenceUnusedTaxLossesAndUnusedTaxCreditsTable
488 Statement Scenario Axis us-gaap:StatementScenarioAxis
489 Scenario Unspecified Member us-gaap:ScenarioUnspecifiedDomain
490 Scenario Forecast Member us-gaap:ScenarioForecastMember
491 Geographical areas [axis] Axis ifrs-full:GeographicalAreasAxis
492 Geographical areas [member] Member ifrs-full:GeographicalAreasMember
493 U.K. Member ifrs-full:CountryOfDomicileMember
494 Disclosure Of Temporary Difference Unused Tax Losses And Unused Tax Credits [Line Items] LineItems ifrs-full:DisclosureOfTemporaryDifferenceUnusedTaxLossesAndUnusedTaxCreditsLineItems
495 Temporary differences and cumulative carry forward tax losses for which deferred tax has not been recognized Concept (Monetary) As Of ifrs-full:DeductibleTemporaryDifferencesForWhichNoDeferredTaxAssetIsRecognised
496 Temporary differences on share based compensation arrangements Concept (Monetary) As Of Debit ncna:TemporaryDifferencesForShareBasedCompensationArrangements
497 Cumulative carry forward tax losses Concept (Monetary) As Of Debit ncna:CumulativeCarryForwardTaxLosses
498 Applicable tax rate Concept (Percent) For Period ifrs-full:ApplicableTaxRate
499 Applicable tax rate initially declared Concept (Percent) For Period ncna:ApplicableTaxRateInitiallyDeclared
500 Future tax rate Concept (Percent) For Period ncna:FutureEnactedTaxRate
501 Percentage of change in tax rate Concept (Percent) For Period ifrs-full:TaxRateEffectFromChangeInTaxRate
502 100560 - Disclosure - Intangible Assets - Summary of Intangible Assets (Details) Network

*

*

 http://www.nucana.com/20181231/taxonomy/role/DisclosureIntangibleAssetsSummaryOfIntangibleAssetsDetails
503 Disclosure Of Intangible Assets [Table] Table

*

*

 ifrs-full:DisclosureOfIntangibleAssetsTable
504 Classes of intangible assets other than goodwill [axis] Axis ifrs-full:ClassesOfIntangibleAssetsOtherThanGoodwillAxis
505 Intangible assets other than goodwill [member] Member ifrs-full:IntangibleAssetsOtherThanGoodwillMember
506 Patents Member ncna:PatentMember
507 Computer Software Member ifrs-full:ComputerSoftwareMember
508 Carrying amount, accumulated depreciation, amortisation and impairment and gross carrying amount [axis] Axis ifrs-full:CarryingAmountAccumulatedDepreciationAmortisationAndImpairmentAndGrossCarryingAmountAxis
509 Carrying amount [member] Member ifrs-full:CarryingAmountMember
510 Cost Member ifrs-full:GrossCarryingAmountMember
511 Accumulated Amortization Member ifrs-full:AccumulatedDepreciationAndAmortisationMember
512 Disclosure Of Intangible Assets [Line Items] LineItems ifrs-full:DisclosureOfIntangibleAssetsLineItems
513 Beginning Balance Concept (Monetary) As Of Debit ifrs-full:IntangibleAssetsOtherThanGoodwill
514 Additions Concept (Monetary) For Period Debit ifrs-full:AdditionsOtherThanThroughBusinessCombinationsIntangibleAssetsOtherThanGoodwill
515 Charge for the year Concept (Monetary) For Period ifrs-full:AmortisationIntangibleAssetsOtherThanGoodwill
516 Ending Balance Concept (Monetary) As Of Debit ifrs-full:IntangibleAssetsOtherThanGoodwill
517 100570 - Disclosure - Property, Plant and Equipment - Summary of Property, Plant and Equipment (Details) Network

*

*

 http://www.nucana.com/20181231/taxonomy/role/DisclosurePropertyPlantAndEquipmentSummaryOfPropertyPlantAndEquipmentDetails
518 Disclosure Of Property Plant And Equipment [Table] Table

*

*

 ifrs-full:DisclosureOfPropertyPlantAndEquipmentTable
519 Classes of property, plant and equipment [axis] Axis ifrs-full:ClassesOfPropertyPlantAndEquipmentAxis
520 Property, plant and equipment [member] Member ifrs-full:PropertyPlantAndEquipmentMember
521 Office and Computer Equipment Member ncna:OfficeAndComputerEquipmentMember
522 Fixtures and Fittings Member ifrs-full:FixturesAndFittingsMember
523 Carrying amount, accumulated depreciation, amortisation and impairment and gross carrying amount [axis] Axis ifrs-full:CarryingAmountAccumulatedDepreciationAmortisationAndImpairmentAndGrossCarryingAmountAxis
524 Carrying amount [member] Member ifrs-full:CarryingAmountMember
525 Cost Member ifrs-full:GrossCarryingAmountMember
526 Depreciation Member ifrs-full:AccumulatedDepreciationAmortisationAndImpairmentMember
527 Disclosure Of Property Plant And Equipment [Line Items] LineItems ifrs-full:DisclosureOfPropertyPlantAndEquipmentLineItems
528 Beginning Balance Concept (Monetary) As Of Debit ifrs-full:PropertyPlantAndEquipment
529 Additions Concept (Monetary) For Period Debit ifrs-full:AdditionsOtherThanThroughBusinessCombinationsPropertyPlantAndEquipment
530 Charge for the year Concept (Monetary) For Period ifrs-full:DepreciationPropertyPlantAndEquipment
531 Disposals Concept (Monetary) For Period Credit ifrs-full:DisposalsPropertyPlantAndEquipment
532 Effect of foreign currency exchange differences Concept (Monetary) For Period Debit ifrs-full:IncreaseDecreaseThroughNetExchangeDifferencesPropertyPlantAndEquipment
533 Ending Balance Concept (Monetary) As Of Debit ifrs-full:PropertyPlantAndEquipment
534 100580 - Disclosure - Prepayments, Accrued Income and Other Receivables - Summary of Prepayments, Accrued Income and Other Receivables Explanatory (Details) Network

*

*

 http://www.nucana.com/20181231/taxonomy/role/DisclosurePrepaymentsAccruedIncomeAndOtherReceivablesSummaryOfPrepaymentsAccruedIncomeAndOtherReceivablesExplanatoryDetails
535 Implied Table Table

*

*

 implied:Table
536 Prepayments Accrued Income And Other Receivables [Abstract] Abstract ncna:PrepaymentsAccruedIncomeAndOtherReceivablesAbstract
537 Prepayments—manufacturing and clinical Concept (Monetary) As Of Debit ncna:PrepaymentsManufacturingAndClinical
538 Prepayments—other Concept (Monetary) As Of Debit ncna:PrepaymentsOther
539 Accrued income Concept (Monetary) As Of Debit ifrs-full:AccruedIncome
540 VAT Concept (Monetary) As Of Debit ifrs-full:ValueAddedTaxReceivables
541 Other receivables Concept (Monetary) As Of Debit ifrs-full:OtherReceivables
542 Prepayments, accrued income and other receivables Concept (Monetary) As Of Debit ifrs-full:TradeAndOtherReceivables
543 100590 - Disclosure - Share Capital and Share Premium - Summary of Share Capital and Share Premium (Details) Network

*

*

 http://www.nucana.com/20181231/taxonomy/role/DisclosureShareCapitalAndSharePremiumSummaryOfShareCapitalAndSharePremiumDetails
544 Disclosure Of Classes Of Share Capital [Table] Table

*

*

 ifrs-full:DisclosureOfClassesOfShareCapitalTable
545 Classes of share capital [axis] Axis ifrs-full:ClassesOfShareCapitalAxis
546 Share capital [member] Member ifrs-full:ClassesOfShareCapitalMember
547 Ordinary shares [member] Member ifrs-full:OrdinarySharesMember
548 Founder Ordinary 1 Shares Member ncna:FounderOrdinaryOneSharesMember
549 Founder Ordinary 2 Shares Member ncna:FounderOrdinaryTwoSharesMember
550 Series A Shares Member ncna:SeriesASharesMember
551 Series B Shares Member ncna:SeriesBSharesMember
552 Disclosure Of Classes Of Share Capital [Line Items] LineItems ifrs-full:DisclosureOfClassesOfShareCapitalLineItems
553 Share capital Concept (Monetary) As Of Credit ifrs-full:IssuedCapital
554 Share premium Concept (Monetary) As Of Credit ifrs-full:SharePremium
555 Share capital and share premium Concept (Monetary) As Of Credit ncna:ShareCapitalAndSharePremium
556 Number of shares issued Concept (Shares) As Of ifrs-full:NumberOfSharesIssued
557 100600 - Disclosure - Share Capital and Share Premium - Summary of Share Capital and Share Premium (Parenthetical) (Details) Network

*

*

 http://www.nucana.com/20181231/taxonomy/role/DisclosureShareCapitalAndSharePremiumSummaryOfShareCapitalAndSharePremiumParentheticalDetails
558 Disclosure Of Classes Of Share Capital [Table] Table

*

*

 ifrs-full:DisclosureOfClassesOfShareCapitalTable
559 Classes of share capital [axis] Axis ifrs-full:ClassesOfShareCapitalAxis
560 Share capital [member] Member ifrs-full:ClassesOfShareCapitalMember
561 Ordinary shares [member] Member ifrs-full:OrdinarySharesMember
562 Founder Ordinary 1 Shares Member ncna:FounderOrdinaryOneSharesMember
563 Founder Ordinary 2 Shares Member ncna:FounderOrdinaryTwoSharesMember
564 Series A Shares Member ncna:SeriesASharesMember
565 Series B Shares Member ncna:SeriesBSharesMember
566 Disclosure Of Classes Of Share Capital [Line Items] LineItems ifrs-full:DisclosureOfClassesOfShareCapitalLineItems
567 Par value per share Concept (Share) As Of ifrs-full:ParValuePerShare
568 100610 - Disclosure - Share Capital and Share Premium - Additional Information (Details) Network

*

*

 http://www.nucana.com/20181231/taxonomy/role/DisclosureShareCapitalAndSharePremiumAdditionalInformationDetails
569 Disclosure Of Classes Of Share Capital [Table] Table

*

*

 ifrs-full:DisclosureOfClassesOfShareCapitalTable
570 Components of equity [axis] Axis ifrs-full:ComponentsOfEquityAxis
571 Equity [member] Member ifrs-full:EquityMember
572 Share Premium Member ifrs-full:SharePremiumMember
573 Classes of share capital [axis] Axis ifrs-full:ClassesOfShareCapitalAxis
574 Share capital [member] Member ifrs-full:ClassesOfShareCapitalMember
575 Ordinary shares [member] Member ifrs-full:OrdinarySharesMember
576 Founder Ordinary 1 Shares Member ncna:FounderOrdinaryOneSharesMember
577 Founder Ordinary 2 Shares Member ncna:FounderOrdinaryTwoSharesMember
578 Series A Shares Member ncna:SeriesASharesMember
579 Series B Shares Member ncna:SeriesBSharesMember
580 IPO Member ncna:InitialPublicOfferingMember
581 Disclosure Of Classes Of Share Capital [Line Items] LineItems ifrs-full:DisclosureOfClassesOfShareCapitalLineItems
582 Reduction of capital by reducing share premium Concept (Monetary) For Period Debit ifrs-full:ReductionOfIssuedCapital
583 Par value per share Concept (Share) As Of ifrs-full:ParValuePerShare
584 Par value per share after reverse share split Concept (Share) As Of ncna:ParValuePerShareAfterReverseStockSplit
585 Number of shares outstanding Concept (Shares) As Of ifrs-full:NumberOfSharesOutstanding
586 Number of shares issued Concept (Shares) As Of ifrs-full:NumberOfSharesIssued
587 Description of conversion of series b shares into ordinary shares Concept (Text/String) For Period ncna:DescriptionOfConversionOfSeriesBSharesIntoOrdinaryShares
588 Par value per share after stock conversion Concept (Share) As Of ncna:ParValuePerShareAfterStockConversion
589 Reserve to fund allotment of additional shares from reverse share split Concept (Monetary) For Period Credit ncna:ReserveToFundAllotmentOfAdditionalSharesFromReverseShareSplit
590 Number of share issued price per share Concept (Share) As Of ncna:NumberOfShareIssuedPricePerShare
591 Reverse share split conversion ratio Concept (Percent) For Period ncna:StockholdersEquityReverseShareSplitConversionRatio
592 Proportion of voting rate Concept (Percent) For Period ncna:ProportionOfVotingRate
593 100620 - Disclosure - Share Capital and Share Premium - Summary of Movement in the Share Capital (Details) Network

*

*

 http://www.nucana.com/20181231/taxonomy/role/DisclosureShareCapitalAndSharePremiumSummaryOfMovementInShareCapitalDetails
594 Disclosure Of Classes Of Share Capital [Table] Table

*

*

 ifrs-full:DisclosureOfClassesOfShareCapitalTable
595 Components of equity [axis] Axis ifrs-full:ComponentsOfEquityAxis
596 Equity [member] Member ifrs-full:EquityMember
597 Share Capital Member ifrs-full:IssuedCapitalMember
598 Share Premium Member ifrs-full:SharePremiumMember
599 Disclosure Of Classes Of Share Capital [Line Items] LineItems ifrs-full:DisclosureOfClassesOfShareCapitalLineItems
600 Beginning balance Concept (Monetary) As Of Credit ifrs-full:Equity
601 Beginning balance, Shares Concept (Shares) As Of ifrs-full:NumberOfSharesIssuedAndFullyPaid
602 Reduction in share premium Concept (Monetary) For Period Debit ncna:AdjustmentOnReductionOfSharePremium
603 Exercise of share options Concept (Monetary) For Period Credit ifrs-full:IncreaseDecreaseThroughExerciseOfOptions
604 Exercise of share options, Shares Concept (Decimal) For Period ifrs-full:NumberOfShareOptionsExercisedInSharebasedPaymentArrangement
605 Bonus issue to series B shareholders Concept (Monetary) For Period Credit ncna:BonusSharesIssued
606 Issue of share capital Concept (Monetary) For Period Credit ifrs-full:IssueOfEquity
607 Issue of share capital, Shares Concept (Shares) For Period ncna:NumberOfShareOfIssuedCapital
608 IPO costs Concept (Monetary) For Period Debit ifrs-full:ShareIssueRelatedCost
609 Ending balance Concept (Monetary) As Of Credit ifrs-full:Equity
610 Ending balance, Shares Concept (Shares) As Of ifrs-full:NumberOfSharesIssuedAndFullyPaid
611 100630 - Disclosure - Other Reserves - Schedule of Other Reserves (Details) Network

*

*

 http://www.nucana.com/20181231/taxonomy/role/DisclosureOtherReservesScheduleOfOtherReservesDetails
612 Disclosure Of Other Reserves [Table] Table

*

*

 ncna:DisclosureOfOtherReservesTable
613 Components of equity [axis] Axis ifrs-full:ComponentsOfEquityAxis
614 Equity [member] Member ifrs-full:EquityMember
615 Other Reserves Member ifrs-full:OtherReservesMember
616 Disclosure Of Other Reserves [Line Items] LineItems ncna:DisclosureOfOtherReservesLineItems
617 Own share reserve Concept (Monetary) As Of Credit ifrs-full:ReserveOfDiscretionaryParticipationFeatures
618 Foreign currency translation reserve Concept (Monetary) As Of Credit ifrs-full:ReserveOfExchangeDifferencesOnTranslation
619 Capital reserve Concept (Monetary) As Of Credit ifrs-full:CapitalReserve
620 Share option reserve Abstract ncna:ShareOptionReserveAbstract
621 Balance at beginning of year Concept (Monetary) As Of Credit ncna:ShareOptionReserve
622 Share-based payments Concept (Monetary) For Period Credit ncna:ReserveOfShareBasedPayment
623 Exercise of share options Concept (Monetary) For Period Credit ncna:ReserveOfShareOptionsExercised
624 Forfeiture of share options Concept (Monetary) For Period Credit ncna:ReserveOfShareOptionsForfeiture
625 Lapse of share options Concept (Monetary) For Period Credit ncna:LapseOfShareOptionsReserve
626 Balance at end of year Concept (Monetary) As Of Credit ncna:ShareOptionReserve
627 Total other reserves Concept (Monetary) As Of Credit ifrs-full:OtherReserves
628 100640 - Disclosure - Other Reserves - Additional Information (Details) Network

*

*

 http://www.nucana.com/20181231/taxonomy/role/DisclosureOtherReservesAdditionalInformationDetails
629 Implied Table Table

*

*

 implied:Table
630 Disclosure Of Other Reserves [Abstract] Abstract ncna:DisclosureOfOtherReservesAbstract
631 Number of shares purchased by employee benefit trust under share options plan Concept (Shares) As Of ifrs-full:SharesReservedForIssueUnderOptionsAndContractsForSaleOfShares
632 100650 - Disclosure - Share-based Payments - Additional Information (Details) Network

*

*

 http://www.nucana.com/20181231/taxonomy/role/DisclosureShareBasedPaymentsAdditionalInformationDetails
633 Disclosure Of Terms And Conditions Of Sharebased Payment Arrangement [Table] Table

*

*

 ifrs-full:DisclosureOfTermsAndConditionsOfSharebasedPaymentArrangementTable
634 Range [axis] Axis ifrs-full:RangeAxis
635 Ranges [member] Member ifrs-full:RangesMember
636 Maximum Member ifrs-full:TopOfRangeMember
637 Bottom Of Range [Member] Member ifrs-full:BottomOfRangeMember
638 Categories of related parties [axis] Axis ifrs-full:CategoriesOfRelatedPartiesAxis
639 Entity's total for related parties [member] Member ifrs-full:EntitysTotalForRelatedPartiesMember
640 Employees Member ncna:EmployeeMember
641 Directors Member ncna:DirectorsMember
642 Consultants Member ncna:ConsultantsMember
643 Types of share-based payment arrangements [axis] Axis ifrs-full:TypesOfSharebasedPaymentArrangementsAxis
644 Share-based payment arrangements [member] Member ifrs-full:SharebasedPaymentArrangementsMember
645 U.K. Share-based Payment Plans Member ncna:UKShareBasedPaymentPlansMember
646 Stock Option Plan (U.S. Sub-Plan) Member ncna:StockOptionPlanMember
647 2016 Share Options Member ncna:TwoThousandSixteenShareOptionsMember
648 2017 Share Options Member ncna:TwoThousandSeventeenShareOptionsMember
649 2018 Share Options Member ncna:TwoThousandEighteenShareOptionsMember
650 Disclosure Of Terms And Conditions Of Sharebased Payment Arrangement [Line Items] LineItems ifrs-full:DisclosureOfTermsAndConditionsOfSharebasedPaymentArrangementLineItems
651 Number of equity settled share-based payment plans Concept (Integer) For Period ncna:NumberOfEquitySettledShareBasedPaymentPlans
652 Expected option life (years) Concept (Decimal) For Period ifrs-full:DescriptionOfOptionLifeShareOptionsGranted
653 Share options granted, vesting period Concept (xbrli:durationItemType) For Period ncna:ShareOptionsGrantedVestingPeriod
654 Description of vesting requirements for share-based payment Concept (Text/String) For Period ifrs-full:DescriptionOfVestingRequirementsForSharebasedPaymentArrangement
655 Number of share options granted in share-based payment arrangement Concept (Decimal) For Period ifrs-full:NumberOfShareOptionsGrantedInSharebasedPaymentArrangement
656 Share options exercise price per share Concept (Monetary) For Period ifrs-full:ExercisePriceShareOptionsGranted
657 Share option exercised date Concept (Date) For Period ncna:DateOfShareOptionExercised
658 Term of share options exercised Concept (xbrli:durationItemType) For Period ncna:TermOfShareOptionsExercised
659 Reverse share split conversion ratio Concept (Percent) For Period ncna:StockholdersEquityReverseShareSplitConversionRatio
660 Weighted average remaining contractual life of outstanding share options Concept (Decimal) As Of ifrs-full:WeightedAverageRemainingContractualLifeOfOutstandingShareOptions
661 Discount rate used to compute present value Concept (Percent) As Of ifrs-full:ActuarialAssumptionOfDiscountRates
662 Employee remuneration expense, related to equity-settled share-based payments Concept (Monetary) For Period Debit ifrs-full:ExpenseFromSharebasedPaymentTransactionsWithEmployees
663 100660 - Disclosure - Share-based Payments - Summary of Share Options and Weighted Average Exercise Prices (Details) Network

*

*

 http://www.nucana.com/20181231/taxonomy/role/DisclosureShareBasedPaymentsSummaryOfShareOptionsAndWeightedAverageExercisePricesDetails
664 Implied Table Table

*

*

 implied:Table
665 Disclosure Of Terms And Conditions Of Sharebased Payment Arrangement [Abstract] Abstract ifrs-full:DisclosureOfTermsAndConditionsOfSharebasedPaymentArrangementAbstract
666 Number of shares, Outstanding, Beginning balance Concept (Decimal) As Of ifrs-full:NumberOfOutstandingShareOptions
667 Number of share options granted in share-based payment arrangement Concept (Decimal) For Period ifrs-full:NumberOfShareOptionsGrantedInSharebasedPaymentArrangement
668 Number of shares, Forfeited Concept (Decimal) For Period ifrs-full:NumberOfShareOptionsForfeitedInSharebasedPaymentArrangement
669 Number of shares, Cancelled Concept (Decimal) For Period ifrs-full:NumberOfShareOptionsExpiredInSharebasedPaymentArrangement
670 Number of shares, Exercised Concept (Decimal) For Period ifrs-full:NumberOfShareOptionsExercisedInSharebasedPaymentArrangement
671 Number of shares, Outstanding, Ending balance Concept (Decimal) As Of ifrs-full:NumberOfOutstandingShareOptions
672 Number of shares, Vested and exercisable, Ending balance Concept (Decimal) As Of ncna:NumberOfShareOptionsVestedAndExercisableInSharebasedPaymentArrangement
673 Weighted average exercise price per share, Outstanding, Beginning balance Concept (Monetary) As Of ifrs-full:WeightedAverageExercisePriceOfShareOptionsOutstandingInSharebasedPaymentArrangement
674 Weighted average exercise price per share, Granted Concept (Monetary) For Period ifrs-full:WeightedAverageExercisePriceOfShareOptionsGrantedInSharebasedPaymentArrangement
675 Weighted average exercise price per share, Forfeited Concept (Monetary) For Period ifrs-full:WeightedAverageExercisePriceOfShareOptionsForfeitedInSharebasedPaymentArrangement
676 Weighted average exercise price per share, Cancelled Concept (Monetary) For Period ifrs-full:WeightedAverageExercisePriceOfShareOptionsExpiredInSharebasedPaymentArrangement
677 Weighted average exercise price per share, Exercised Concept (Monetary) For Period ifrs-full:WeightedAverageExercisePriceOfShareOptionsExercisedInSharebasedPaymentArrangement
678 Weighted average exercise price per share, Outstanding, Ending balance Concept (Monetary) As Of ifrs-full:WeightedAverageExercisePriceOfShareOptionsOutstandingInSharebasedPaymentArrangement
679 Weighted average exercise price per share, Vested and exercisable, Ending balance Concept (Monetary) As Of ncna:WeightedAverageExercisePriceOfShareOptionsVestedAndExercisableInSharebasedPaymentArrangement
680 100670 - Disclosure - Share-based Payments - Summary of Share Options and Weighted Average Exercise Prices (Parenthetical) (Details) Network

*

*

 http://www.nucana.com/20181231/taxonomy/role/DisclosureShareBasedPaymentsSummaryOfShareOptionsAndWeightedAverageExercisePricesParentheticalDetails
681 Implied Table Table

*

*

 implied:Table
682 Disclosure Of Terms And Conditions Of Sharebased Payment Arrangement [Abstract] Abstract ifrs-full:DisclosureOfTermsAndConditionsOfSharebasedPaymentArrangementAbstract
683 Weighted average share price for share options at date of exercise Concept (Monetary) For Period ifrs-full:WeightedAverageExercisePriceOfShareOptionsInSharebasedPaymentArrangementExercisedDuringPeriodAtDateOfExercise
684 Vesting period of share options exercised Concept (xbrli:durationItemType) For Period ncna:VestingPeriodOfShareOptionsExercised
685 100680 - Disclosure - Share-based Payments - Summary of Principal Assumptions used for Valuation of Share Options (Details) Network

*

*

 http://www.nucana.com/20181231/taxonomy/role/DisclosureShareBasedPaymentsSummaryOfPrincipalAssumptionsUsedForValuationOfShareOptionsDetails
686 Disclosure Of Terms And Conditions Of Sharebased Payment Arrangement [Table] Table

*

*

 ifrs-full:DisclosureOfTermsAndConditionsOfSharebasedPaymentArrangementTable
687 Types of share-based payment arrangements [axis] Axis ifrs-full:TypesOfSharebasedPaymentArrangementsAxis
688 Share-based payment arrangements [member] Member ifrs-full:SharebasedPaymentArrangementsMember
689 2016 Share Options Member ncna:TwoThousandSixteenShareOptionsMember
690 2017 Share Options Member ncna:TwoThousandSeventeenShareOptionsMember
691 2018 Share Options Member ncna:TwoThousandEighteenShareOptionsMember
692 Vesting Date Axis ncna:VestingDateAxis
693 Vesting Date Member ncna:VestingDateDomain
694 Vesting Dates One Member ncna:ShareBasedCompensationAwardVestingDateOneMember
695 Vesting Dates Two Member ncna:ShareBasedCompensationAwardVestingDateTwoMember
696 Vesting Dates Three Member ncna:ShareBasedCompensationAwardVestingDateThreeMember
697 Vesting Dates Four Member ncna:ShareBasedCompensationAwardVestingDateFourMember
698 Grant Date Aug 22, 2016 One Axis ncna:GrantDateAxis
699 Grant Date Member ncna:GrantDateDomain
700 Grant Date June 30,2016 Member ncna:GrantDateJune302016Member
701 Grant Date Aug 22, 2016 One Member ncna:GrantDateAugust222016OneMember
702 Grant Date Aug 22, 2016 Two Member ncna:GrantDateAugust222016TwoMember
703 Grant Date Aug 22, 2016 Three Member ncna:GrantDateAugust222016ThreeMember
704 Grant Date Aug 22, 2016 Four Member ncna:GrantDateAugust222016FourMember
705 Grant Date Aug 22,2016 Six Member ncna:GrantDateAugust222016SixMember
706 Grant Date Aug 22, 2016 Five Member ncna:GrantDateAugust222016FiveMember
707 Grant Date Oct 28, 2016 One Member ncna:GrantDateOctober282016OneMember
708 Grant Date Oct 28, 2016 Two Member ncna:GrantDateOctober282016TwoMember
709 Grant Date Dec 12, 2016 Member ncna:GrantDateDecember122016Member
710 Grant Date May 16, 2017 Member ncna:GrantDateMay162017Member
711 Grant Date Sep 13, 2017 Member ncna:GrantDateSeptember132017Member
712 Grant Date Sep 14, 2017 One Member ncna:GrantDateSeptember142017OneMember
713 Grant Date Sep 14, 2017 Two Member ncna:GrantDateSeptember142017TwoMember
714 Grant Date Sep 14, 2017 Three Member ncna:GrantDateSeptember142017ThreeMember
715 Grant Date Sep 14, 2017 Four Member ncna:GrantDateSeptember142017FourMember
716 Grant Date Sep 15, 2017 One Member ncna:GrantDateSeptember152017OneMember
717 Grant Date Sep 15, 2017 Two Member ncna:GrantDateSeptember152017TwoMember
718 Grant Date Sep 27, 2017 One Member ncna:GrantDateSeptember272017OneMember
719 Grant Date Sep 27, 2017 Two Member ncna:GrantDateSeptember272017TwoMember
720 Grant Date April 11, 2018 One Member ncna:GrantDateApril112018OneMember
721 Grant Date April 11, 2018 Member ncna:GrantDateApril112018Member
722 Grant Date May 8, 2018 Member ncna:GrantDateMay82018Member
723 Grant Date Aug 14, 2018 Member ncna:GrantDateAugust142018Member
724 Disclosure Of Terms And Conditions Of Sharebased Payment Arrangement [Line Items] LineItems ifrs-full:DisclosureOfTermsAndConditionsOfSharebasedPaymentArrangementLineItems
725 Vesting dates Concept (Date) For Period ncna:DescriptionOfVestingDateOfShareOptionsGranted
726 Volatility Concept (Percent) For Period ifrs-full:DescriptionOfExpectedVolatilityShareOptionsGranted
727 Dividend yield Concept (Percent) For Period ifrs-full:ExpectedDividendAsPercentageShareOptionsGranted
728 Risk-free investment rate Concept (Percent) For Period ifrs-full:DescriptionOfRiskFreeInterestRateShareOptionsGranted
729 Fair value of option at grant date Concept (Monetary) As Of Credit ifrs-full:WeightedAverageFairValueAtMeasurementDateShareOptionsGranted
730 Fair value of share at grant date Concept (Monetary) For Period ifrs-full:WeightedAverageSharePriceShareOptionsGranted
731 Exercise price at date of grant Concept (Monetary) For Period ifrs-full:ExercisePriceShareOptionsGranted
732 Lapse date Concept (Date) For Period ncna:DescriptionOfLapseDateOfShareOptionsGranted
733 Expected option life (years) Concept (Decimal) For Period ifrs-full:DescriptionOfOptionLifeShareOptionsGranted
734 Number of options granted Concept (Decimal) For Period ifrs-full:NumberOfShareOptionsGrantedInSharebasedPaymentArrangement
735 100690 - Disclosure - Related Party Disclosures - Summary of Compensation of Key Management Personnel (Details) Network

*

*

 http://www.nucana.com/20181231/taxonomy/role/DisclosureRelatedPartyDisclosuresSummaryOfCompensationOfKeyManagementPersonnelDetails
736 Implied Table Table

*

*

 implied:Table
737 Disclosure Of Key Management Personnel Compensation [Abstract] Abstract ncna:DisclosureOfKeyManagementPersonnelCompensationAbstract
738 Short-term employee benefits Concept (Monetary) For Period Debit ifrs-full:KeyManagementPersonnelCompensationShorttermEmployeeBenefits
739 Severance payments Concept (Monetary) For Period Debit ncna:KeyManagementPersonnelCompensationSeverancePayment
740 Pension and other benefits Concept (Monetary) For Period Debit ifrs-full:KeyManagementPersonnelCompensationPostemploymentBenefits
741 Share-based payments Concept (Monetary) For Period Debit ifrs-full:KeyManagementPersonnelCompensationSharebasedPayment
742 Key management personnel compensation Concept (Monetary) For Period Debit ifrs-full:KeyManagementPersonnelCompensation
743 100700 - Disclosure - Cash and Cash Equivalents - Schedule of Cash and Cash Equivalents (Detail) Network

*

*

 http://www.nucana.com/20181231/taxonomy/role/DisclosureCashAndCashEquivalentsScheduleOfCashAndCashEquivalentsDetail
744 Implied Table Table

*

*

 implied:Table
745 Cash And Cash Equivalents [Abstract] Abstract ifrs-full:CashAndCashEquivalentsAbstract
746 Cash and cash equivalents Concept (Monetary) As Of Debit ifrs-full:CashAndCashEquivalents
747 100710 - Disclosure - Financial Instruments Risk Management - Additional Information (Details) Network

*

*

 http://www.nucana.com/20181231/taxonomy/role/DisclosureFinancialInstrumentsRiskManagementAdditionalInformationDetails
748 Disclosure Of Financial Instruments [Table] Table

*

*

 ifrs-full:DisclosureOfFinancialInstrumentsTable
749 Types of risks [axis] Axis ifrs-full:TypesOfRisksAxis
750 Risks [member] Member ifrs-full:TypesOfRisksMember
751 Interest Rate Risk Member ifrs-full:InterestRateRiskMember
752 Currency Risk Member ifrs-full:CurrencyRiskMember
753 Disclosure Of Financial Instruments [Line Items] LineItems ifrs-full:DisclosureOfFinancialInstrumentsLineItems
754 Cash and cash equivalents Concept (Monetary) As Of Debit ifrs-full:CashAndCashEquivalents
755 Increase in interest rates Concept (Percent) For Period ncna:IncreaseInInterestRates
756 Increase in interest income on cash and cash equivalents Concept (Monetary) For Period Credit ncna:IncreaseInInterestIncomeOnCashAndCashEquivalents
757 Percentage of increase in foreign exchange rate Concept (Percent) For Period ncna:PercentageOfIncreaseInForeignExchangeRate
758 Reduction in financial assets and liabilities in foreign currencies Concept (Monetary) For Period ncna:IncreaseDecreaseThroughForeignExchangeFinancialAssetsLiabilities
759 100720 - Disclosure - Financial Instruments Risk Management - Schedule of Financial Assets Subject to Fixed or Variable Interest Rates (Details) Network

*

*

 http://www.nucana.com/20181231/taxonomy/role/DisclosureFinancialInstrumentsRiskManagementScheduleOfFinancialAssetsSubjectToFixedOrVariableInterestRatesDetails
760 Disclosure Of Financial Instruments By Type Of Interest Rate [Table] Table

*

*

 ifrs-full:DisclosureOfFinancialInstrumentsByTypeOfInterestRateTable
761 Types of interest rates [axis] Axis ifrs-full:TypesOfInterestRatesAxis
762 Interest rate types [member] Member ifrs-full:InterestRateTypesMember
763 Financial Assets at Fixed Rates Member ifrs-full:FixedInterestRateMember
764 Financial Assets at Variable Rates Member ifrs-full:FloatingInterestRateMember
765 Non-Interest Bearing Cash Balances Member ncna:NonInterestBearingMember
766 Disclosure Of Financial Instruments By Type Of Interest Rate [Line Items] LineItems ifrs-full:DisclosureOfFinancialInstrumentsByTypeOfInterestRateLineItems
767 Cash and cash equivalents Concept (Monetary) As Of Debit ifrs-full:CashAndCashEquivalents
768 100730 - Disclosure - Financial Instruments Risk Management - Summary of Financial Assets and Liabilities in Foreign Currencies, Primarily Held in U.S Dollars (Details) Network

*

*

 http://www.nucana.com/20181231/taxonomy/role/DisclosureFinancialInstrumentsRiskManagementSummaryOfFinancialAssetsAndLiabilitiesInForeignCurrenciesPrimarilyHeldInUSDollarsDetails
769 Disclosure Of Financial Instruments [Table] Table

*

*

 ifrs-full:DisclosureOfFinancialInstrumentsTable
770 Types of risks [axis] Axis ifrs-full:TypesOfRisksAxis
771 Risks [member] Member ifrs-full:TypesOfRisksMember
772 Currency Risk Member ifrs-full:CurrencyRiskMember
773 Disclosure Of Financial Instruments [Line Items] LineItems ifrs-full:DisclosureOfFinancialInstrumentsLineItems
774 Financial assets Abstract ifrs-full:CategoriesOfFinancialAssetsAbstract
775 Prepayments, accrued income and other receivables Concept (Monetary) As Of Debit ncna:PrepaymentsAndAccruedIncomeAndOtherReceivables
776 Current income tax receivable Concept (Monetary) As Of Debit ifrs-full:CurrentTaxAssetsCurrent
777 Cash and cash equivalents Concept (Monetary) As Of Debit ifrs-full:CashAndCashEquivalents
778 Financial liabilities Abstract ifrs-full:CategoriesOfFinancialLiabilitiesAbstract
779 Trade payables Concept (Monetary) As Of Credit ifrs-full:TradeAndOtherPayablesToTradeSuppliers
780 Payroll taxes and social security Concept (Monetary) As Of Credit ifrs-full:CurrentProvisionsForEmployeeBenefits
781 Accrued expenditure Concept (Monetary) As Of Credit ifrs-full:AccrualsClassifiedAsCurrent

*

*