Securitisations - Narrative (Details) - GBP (£) £ in Millions	Dec. 31, 2023	Dec. 31, 2022
Financial assets at amortised cost \| Retail credit cards
Disclosure of transferred financial assets that are not derecognised in their entirety [line items]
Assets that entity continues to recognise to extent of continuing involvement	£ 3,353	£ 828

The amount of transferred financial assets that the entity continues to recognise to the extent of its continuing involvement. [Refer: Financial assets]

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Name IFRS
-Number 7
-IssueDate 2023-01-01
-Paragraph 42D
-Subparagraph f
-URI https://taxonomy.ifrs.org/xifrs-link?type=IFRS&num=7&code=ifrs-tx-2023-en-r&anchor=para_42D_f&doctype=Standard
-URIDate 2023-03-23

Name:	ifrs-full_AssetsThatEntityContinuesToRecogniseToExtentOfContinuingInvolvement
Namespace Prefix:	ifrs-full_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant