Dividends - Summary of Dividends Declared (Parenthetical) (Detail) - £ / shares	12 Months Ended
Dec. 31, 2025	Dec. 31, 2024	Dec. 31, 2023
Final dividend [member]
Disclosure of dividends [line items]
Dividends paid per share	£ 0.166	£ 0.157	£ 0.149
Interim dividend [member]
Disclosure of dividends [line items]
Dividends paid per share	£ 0.078	£ 0.074	£ 0.07

The amount of dividends paid per ordinary share.

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
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Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Note Effective 2027-01-01
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Reference 3: http://www.xbrl.org/2003/role/disclosureRef
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Namespace Prefix:	ifrs-full_
Data Type:	dtr-2022:perShareItemType
Balance Type:	na
Period Type:	duration