Principal subsidiaries - Excluded from consolidation because the Group does not have exposure to its variable returns (Details) - Unconsolidated structured entities £ in Millions	12 Months Ended
Dec. 31, 2022 GBP (£)
Disclosure of unconsolidated structured entities [line items]
Percentage of voting rights held	100.00%
Equity shareholders' funds (£m)	£ 0
Retained profit for the year (£m)	£ 0

The proportion of the voting rights in a subsidiary held by the entity. [Refer: Subsidiaries [member]]

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Name IAS
-Number 27
-IssueDate 2022-03-24
-Paragraph 17
-Subparagraph b
-Clause iii
-URI https://taxonomy.ifrs.org/xifrs-link?type=IAS&num=27&code=ifrs-tx-2022-en-r&anchor=para_17_b_iii&doctype=Standard
-URIDate 2022-03-24

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Name IAS
-Number 27
-IssueDate 2022-03-24
-Paragraph 16
-Subparagraph b
-Clause iii
-URI https://taxonomy.ifrs.org/xifrs-link?type=IAS&num=27&code=ifrs-tx-2022-en-r&anchor=para_16_b_iii&doctype=Standard
-URIDate 2022-03-24

Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Name IFRS
-Number 12
-IssueDate 2022-03-24
-Paragraph 19B
-Subparagraph c
-URI https://taxonomy.ifrs.org/xifrs-link?type=IFRS&num=12&code=ifrs-tx-2022-en-r&anchor=para_19B_c&doctype=Standard
-URIDate 2022-03-24

Name:	ifrs-full_ProportionOfVotingPowerHeldInSubsidiary
Namespace Prefix:	ifrs-full_
Data Type:	dtr-types:percentItemType
Balance Type:	na
Period Type:	duration