Name:	ifrs-full_DisclosureOfSignificantInvestmentsInSubsidiariesLineItems
Namespace Prefix:	ifrs-full_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

The amount of equity in a subsidiary not attributable, directly or indirectly, to a parent. [Refer: Total for all subsidiaries [member]]

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Name IFRS
-Number 10
-IssueDate 2025-01-01
-Paragraph 22
-URI https://taxonomy.ifrs.org/xifrs-link?type=IFRS&num=10&code=ifrs-tx-2025-en-r&anchor=para_22&doctype=Standard
-URIDate 2025-03-27

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Name IFRS
-Number 12
-IssueDate 2025-01-01
-Paragraph 12
-Subparagraph f
-URI https://taxonomy.ifrs.org/xifrs-link?type=IFRS&num=12&code=ifrs-tx-2025-en-r&anchor=para_12_f&doctype=Standard
-URIDate 2025-03-27

Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Note Expiry date 2027-01-01
-Name IAS
-Number 1
-IssueDate 2025-01-01
-Paragraph 54
-Subparagraph q
-URI https://taxonomy.ifrs.org/xifrs-link?type=IAS&num=1&code=ifrs-tx-2025-en-b&anchor=para_54_q&doctype=Standard
-URIDate 2025-03-27

Name:	ifrs-full_NoncontrollingInterests
Namespace Prefix:	ifrs-full_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

The amount of equity interest of an entity without share capital that the entity does not separately disclose in the same statement or note.

Reference 1: http://www.xbrl.org/2003/role/exampleRef
-Note Effective 2027-01-01
-Name IFRS
-Number 19
-IssueDate 2025-01-01
-Paragraph B9
-Subparagraph f
-URI https://taxonomy.ifrs.org/xifrs-link?type=IFRS&num=19&code=ifrs-tx-2025-en-r&anchor=para_B9_f&doctype=Appendix&subtype=B
-URIDate 2025-03-27

Reference 2: http://www.xbrl.org/2003/role/exampleRef
-Note Expiry date 2027-01-01
-Name IAS
-Number 1
-IssueDate 2025-01-01
-Paragraph 78
-Subparagraph e
-URI https://taxonomy.ifrs.org/xifrs-link?type=IAS&num=1&code=ifrs-tx-2025-en-b&anchor=para_78_e&doctype=Standard
-URIDate 2025-03-27

Name:	ifrs-full_OtherEquityInterest
Namespace Prefix:	ifrs-full_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

The profit (loss) from continuing and discontinued operations attributable to non-controlling interests. [Refer: Profit (loss); Non-controlling interests]

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Name IFRS
-Number 12
-IssueDate 2025-01-01
-Paragraph 12
-Subparagraph e
-URI https://taxonomy.ifrs.org/xifrs-link?type=IFRS&num=12&code=ifrs-tx-2025-en-r&anchor=para_12_e&doctype=Standard
-URIDate 2025-03-27

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Note Expiry date 2027-01-01
-Name IAS
-Number 1
-IssueDate 2025-01-01
-Paragraph 81B
-Subparagraph a
-Clause i
-URI https://taxonomy.ifrs.org/xifrs-link?type=IAS&num=1&code=ifrs-tx-2025-en-b&anchor=para_81B_a_i&doctype=Standard
-URIDate 2025-03-27

Name:	ifrs-full_ProfitLossAttributableToNoncontrollingInterests
Namespace Prefix:	ifrs-full_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

The amount of equity in a subsidiary not attributable, directly or indirectly, to a parent excluding the profit (loss) attributable to non-controlling interests for the current period.

No definition available.

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

Name:	ifrs-full_SignificantInvestmentsInSubsidiariesAxis=san_SantanderBankPolskaSAMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Name:	ifrs-full_SignificantInvestmentsInSubsidiariesAxis=san_GrupoPSAMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Name:	ifrs-full_SignificantInvestmentsInSubsidiariesAxis=san_BancoSantanderChileMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Name:	ifrs-full_SignificantInvestmentsInSubsidiariesAxis=san_BancoSantanderBrasilSAMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Name:	ifrs-full_SignificantInvestmentsInSubsidiariesAxis=san_OtherCompaniesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Name:	ifrs-full_SignificantInvestmentsInSubsidiariesAxis=san_SantanderUKPLCMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type: