Risk Management - Disclosure of net interest income sensitivity (AEaR) by currency (Details) - Net interest income - GBP (£) £ in Millions	12 Months Ended
Dec. 31, 2025	Dec. 31, 2024
Interest rate risk
Disclosure of operating segments [line items]
Increase (decrease) in profit for the year due to reasonable possibly increase	£ (33)	£ (11)
Increase (decrease) in profit for the year due to reasonably possible decrease	31	10
GBP
Disclosure of operating segments [line items]
Increase (decrease) in profit for the year due to reasonable possibly increase	4	27
Increase (decrease) in profit for the year due to reasonably possible decrease	(6)	(28)
USD
Disclosure of operating segments [line items]
Increase (decrease) in profit for the year due to reasonable possibly increase	(41)	(29)
Increase (decrease) in profit for the year due to reasonably possible decrease	41	29
EUR
Disclosure of operating segments [line items]
Increase (decrease) in profit for the year due to reasonable possibly increase	(5)	(6)
Increase (decrease) in profit for the year due to reasonably possible decrease	4	6
Other currencies
Disclosure of operating segments [line items]
Increase (decrease) in profit for the year due to reasonable possibly increase	9	(3)
Increase (decrease) in profit for the year due to reasonably possible decrease	£ (8)	£ 3

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- Definition

The increase (decrease) in profit (loss) that would have been caused by a reasonably possible decrease in the risk variable that arises from contracts within the scope of IFRS 17.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Name IFRS
-Number 17
-IssueDate 2025-01-01
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Reference 2: http://www.xbrl.org/2003/role/disclosureRef
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The increase (decrease) in profit (loss) that would have been caused by a reasonably possible increase in the risk variable that arises from contracts within the scope of IFRS 17.

+ References

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