Provisions - Narrative (Details) - GBP (£) £ in Millions	Jun. 30, 2025	Dec. 31, 2024
Disclosure of other provisions [line items]
Provisions	£ 1,364	£ 1,383
Clydesdale Financial Services \| Customer Redress
Disclosure of other provisions [line items]
Provisions	£ 0	£ 90

The amount of liabilities of uncertain timing or amount, including provisions for employee benefits.

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Name IAS
-Number 1
-IssueDate 2024-01-01
-Paragraph 54
-Subparagraph l
-URI https://taxonomy.ifrs.org/xifrs-link?type=IAS&num=1&code=ifrs-tx-2024-en-r&anchor=para_54_l&doctype=Standard
-URIDate 2024-03-27

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