Cash and Cash Equivalents (Excluding Overdrafts) - Additional Information (Detail) - GBP (£) £ in Millions	Dec. 31, 2023	Dec. 31, 2022
Cash and cash equivalents [line items]
Financial liabilities	£ 23	£ 5
US Dollars [member]
Cash and cash equivalents [line items]
Cash and cash equivalents currency split	16.00%	31.00%
Sterling [member]
Cash and cash equivalents [line items]
Cash and cash equivalents currency split	11.00%	6.00%
Other currency [member]
Cash and cash equivalents [line items]
Cash and cash equivalents currency split	73.00%	63.00%

The amount remaining after deducting the amounts subject to an enforceable master netting arrangement or similar agreement that were not set off against financial liabilities, from the net amount of financial liabilities subject to offsetting or subject to an enforceable master netting arrangement or similar agreement presented in the statement of financial position.

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Name IFRS
-Number 7
-IssueDate 2023-01-01
-Paragraph 13C
-Subparagraph e
-URI https://taxonomy.ifrs.org/xifrs-link?type=IFRS&num=7&code=ifrs-tx-2023-en-r&anchor=para_13C_e&doctype=Standard
-URIDate 2023-03-23

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