INTERESTS IN OTHER ENTITIES (Details)	Apr. 30, 2026 structuredEntities subsidiary
Investments accounted for using equity method [abstract [Line Items]
Number of structured entities \| structuredEntities	4
TSB
Investments accounted for using equity method [abstract [Line Items]
Percentage of voting equity interests acquired	100.00%
TSB Covered Bonds (LM)
Investments accounted for using equity method [abstract [Line Items]
Percentage of voting equity interests acquired	20.00%
TSB Covered Bonds (Holdings) Ltd and TSB Banking Group plc Employee Share Trust
Investments accounted for using equity method [abstract [Line Items]
Number of subsidiaries \| subsidiary	2

The percentage of voting equity interests acquired in a business combination. [Refer: Total for all business combinations [member]]

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Name IFRS
-Number 3
-IssueDate 2025-01-01
-Paragraph B64
-Subparagraph c
-URI https://taxonomy.ifrs.org/xifrs-link?type=IFRS&num=3&code=ifrs-tx-2025-en-r&anchor=para_B64_c&doctype=Appendix&subtype=B
-URIDate 2025-03-27

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Note Effective 2027-01-01
-Name IFRS
-Number 19
-IssueDate 2025-01-01
-Paragraph 35
-Subparagraph c
-URI https://taxonomy.ifrs.org/xifrs-link?type=IFRS&num=19&code=ifrs-tx-2025-en-r&anchor=para_35_c&doctype=Standard
-URIDate 2025-03-27

Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Note Effective 2027-01-01
-Name IFRS
-Number 19
-IssueDate 2025-01-01
-Paragraph 35
-Subparagraph c
-URI https://taxonomy.ifrs.org/xifrs-link?type=IFRS&num=19&code=ifrs-tx-2025-en-r&anchor=para_35_c&doctype=Standard
-URIDate 2025-03-27

Name:	ifrs-full_PercentageOfVotingEquityInterestsAcquired
Namespace Prefix:	ifrs-full_
Data Type:	dtr-2022:percentItemType
Balance Type:	na
Period Type:	instant