Name:	ifrs-full_DisclosureOfAnalysisOfOtherComprehensiveIncomeByItemLineItems
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A component of equity representing the accumulated portion of gain (loss) on a hedging instrument that is determined to be an effective hedge for cash flow hedges. [Refer: Cash flow hedges [member]]

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Name IAS
-Number 1
-IssueDate 2018-01-01
-Paragraph 78
-Subparagraph e
-URI http://eifrs.ifrs.org/eifrs/XBRL?type=IAS&num=1&date=2018-03-01&anchor=para_78_e&doctype=Standard
-URIDate 2018-03-16

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Name IFRS
-Number 9
-IssueDate 2018-01-01
-Paragraph 6.5.11
-URI http://eifrs.ifrs.org/eifrs/XBRL?type=IFRS&num=9&date=2018-03-01&anchor=para_6.5.11&doctype=Standard
-URIDate 2018-03-16

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Period Type:	instant

A component of equity representing the accumulated change in fair value of financial liabilities attributable to change in the credit risk of the liabilities. [Refer: Credit risk [member]; Financial liabilities]

Name:	ifrs-full_ReserveOfChangeInFairValueOfFinancialLiabilityAttributableToChangeInCreditRiskOfLiability
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Data Type:	xbrli:monetaryItemType
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Period Type:	instant

A component of equity representing exchange differences on translation of financial statements of foreign operations recognised in other comprehensive income and accumulated in equity. [Refer: Other comprehensive income]

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Name IAS
-Number 21
-IssueDate 2018-01-01
-Paragraph 52
-Subparagraph b
-URI http://eifrs.ifrs.org/eifrs/XBRL?type=IAS&num=21&date=2018-03-01&anchor=para_52_b&doctype=Standard
-URIDate 2018-03-16

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Period Type:	instant

A component of equity representing accumulated gains and losses from investments in equity instruments that the entity has designated at fair value through other comprehensive income.

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Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

A component of equity representing the reserve of gains and losses on financial assets measured at fair value through other comprehensive income. [Refer: Financial assets measured at fair value through other comprehensive income; Other comprehensive income]

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Period Type:	instant

A component of equity representing the accumulated gains and losses on hedging instruments that hedge investments in equity instruments that the entity has designated at fair value through other comprehensive income.

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Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

A component of equity representing the accumulated remeasurements of defined benefit plans. [Refer: Defined benefit plans [member]]

Name:	ifrs-full_ReserveOfRemeasurementsOfDefinedBenefitPlans
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Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

The amount attributable to parent of accumulated items of income and expense (including reclassification adjustments) that are not recognized in profit or loss as required or permitted by other IFRSs.

No definition available.

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Data Type:	xbrli:monetaryItemType
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Period Type:	instant

The portion of other recognized income and expense of investments in subsidiaries, joint ventures and associated entities that is recognised in other comprehensive income and accumulated in equity.

No definition available.

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The portion of The portion of other recognized income and expense of investments in subsidiaries, joint ventures and associated entities that is recognised in other comprehensive income and may be reclassified to profit or loss.

No definition available.

Name:	san_AmountRecognisedInOtherComprehensiveIncomeAndSubjectToReclassificationToProfitOrLossRelatingToInvestmentsInAssociatedEntities
Namespace Prefix:	san_
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Amount of other reserves not reclassified to profit or loss that is attributable to parent.

No definition available.

Name:	san_OtherReservesNotReclassifiedToProfitOrLossAttributableToParent
Namespace Prefix:	san_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

Amount of other reserves that may be reclassified to profit or loss that is attributable to parent.

No definition available.