Name:	san_CommonEquityCapitalConservationBufferPercentage
Namespace Prefix:	san_
Data Type:	dtr-types1:percentItemType
Balance Type:	na
Period Type:	instant

Percentage of Common Equity Pillar One Risk-based Capital to total risk-weighted assets, as defined by regulatory framework.

No definition available.

Name:	san_CommonEquityPillarOneCapitalRatio
Namespace Prefix:	san_
Data Type:	dtr-types1:percentItemType
Balance Type:	na
Period Type:	instant

Percentage of Common Equity Pillar 2 Risk-based Capital to total risk-weighted assets, as defined by regulatory framework.

No definition available.

Name:	san_CommonEquityPillarTwoCapitalRatio
Namespace Prefix:	san_
Data Type:	dtr-types1:percentItemType
Balance Type:	na
Period Type:	instant

Percentage of countercyclical buffer on common equity Tier1 capital.

No definition available.

Name:	san_CommonEquityTierOneCapitalCountercyclicalBufferPercentage
Namespace Prefix:	san_
Data Type:	dtr-types1:percentItemType
Balance Type:	na
Period Type:	duration

Percentage of Common Equity Tier One Risk-based Capital to total risk-weighted assets, as defined by regulatory framework.

No definition available.

Name:	san_CommonEquityTierOneCapitalRatio1
Namespace Prefix:	san_
Data Type:	dtr-types1:percentItemType
Balance Type:	na
Period Type:	instant

Additional percentage of Common Equity Tier One Risk-based Capital to total risk-weighted assets required for an entity defined as a systemically important financial institution (SIFI), as defined by regulatory framework.

No definition available.

Name:	san_CommonEquityTierOneCapitalRatioGlobalSystemicallyImportantEntity
Namespace Prefix:	san_
Data Type:	dtr-types1:percentItemType
Balance Type:	na
Period Type:	instant

Common Equity Tier One Capital, Systematic Risk Requirement

No definition available.

Name:	san_CommonEquityTierOneCapitalSystematicRiskRequirement
Namespace Prefix:	san_
Data Type:	dtr-types1:percentItemType
Balance Type:	na
Period Type:	duration

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

No definition available.

Name:	san_DisclosureOfIFRSComplianceWithRegulatoryCapitalRequirementsUnderBankingRegulationsLineItems
Namespace Prefix:	san_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

Domestic Systemically Important Entities, Capital Buffer Percentage

No definition available.

Name:	san_DomesticSystemicallyImportantEntitiesCapitalBufferPercentage
Namespace Prefix:	san_
Data Type:	dtr-types1:percentItemType
Balance Type:	na
Period Type:	duration

Number of criteria used to determine designation as global systemically important bank.

No definition available.

Name:	san_GlobalSystemicallyImportantBankDesignationNumberOfCriteria
Namespace Prefix:	san_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	duration

Percentage of capital buffer specified in total loss absorbing capacity (TLAC) requirements.

No definition available.

Name:	san_GlobalSystemicallyImportantBanksCapitalBufferPercentage
Namespace Prefix:	san_
Data Type:	dtr-types1:percentItemType
Balance Type:	na
Period Type:	duration

Total Capital divided by risk weighted assets as defined in the international regulations.

No definition available.

Name:	san_IFRSCapitalToRiskWeightedAssets
Namespace Prefix:	san_
Data Type:	dtr-types1:percentItemType
Balance Type:	na
Period Type:	instant

Tier 1 capital divided by risk weighted assets as defined by international regulations.

No definition available.

Name:	san_IFRSTierOneRiskBasedCapitalToRiskWeightedAssets
Namespace Prefix:	san_
Data Type:	dtr-types1:percentItemType
Balance Type:	na
Period Type:	instant

The number of banks designated as global systemically important banks (G-SIBs).

No definition available.

Name:	san_NumberOfBanksDesignatedAsGlobalSystemicallyImportantBanks
Namespace Prefix:	san_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	duration

Number Of Capital Buffer

No definition available.