Financial assets at amortised cost - Narrative (Details) - GBP (£) £ in Millions	Jun. 30, 2022	Dec. 31, 2021
Disclosure of financial assets [line items]
Allowance account for credit losses of financial assets	£ 4,120	£ 4,042
Residual value and voluntary terminations
Disclosure of financial assets [line items]
Allowance account for credit losses of financial assets	£ 94	£ 95

The amount of an allowance account used to record impairments to financial assets due to credit losses. [Refer: Financial assets]

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Note Expiry date 2023-01-01
-Name IFRS
-Number 7
-IssueDate 2021-01-01
-Paragraph 16
-URI http://eifrs.ifrs.org/eifrs/xifrs-link?type=IFRS&num=7&code=ifrs-tx-2017-en-b&anchor=para_16&doctype=Standard&book=b
-URIDate 2021-03-24

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