Financial assets at fair value through the income statement - Credit risk of loans and advances designated at fair value and related credit derivatives (Details) - GBP (£) £ in Millions	12 Months Ended
Dec. 31, 2022	Dec. 31, 2021
Credit derivatives \| Derivatives
Disclosure of financial assets [line items]
Value mitigated by related credit derivatives	£ 855	£ 1,617
Changes in fair value during the year ended	(1)	(3)
Cumulative changes in fair value from inception	(1)	(3)
Loans and advances at amortised cost
Disclosure of financial assets [line items]
Loans and advances designated at fair value, attributable to credit risk	1,679	2,813
Changes in fair value during the year ended	0	1
Cumulative changes in fair value from inception	£ (3)	£ (3)

The accumulated increase (decrease) in the fair value of loans or receivables that is attributable to changes in the credit risk of the assets determined either: (a) as the amount of change in their fair value that is not attributable to changes in the market conditions that gave rise to the market risk; or (b) using an alternative method the entity believes more faithfully represents the amount of change in its fair value that is attributable to changes in the credit risk of the asset. [Refer: Market risk [member]]

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Note Expiry date 2023-01-01
-Name IFRS
-Number 7
-IssueDate 2022-03-24
-Paragraph 9
-Subparagraph c
-URI https://taxonomy.ifrs.org/xifrs-link?type=IFRS&num=7&code=ifrs-tx-2017-en-b&anchor=para_9_c&doctype=Standard&book=b
-URIDate 2022-03-24

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- Definition

The amount by which credit derivatives or similar instruments related to loans or receivables mitigate maximum exposure to credit risk. [Refer: Loans and receivables; Credit risk [member]; Maximum exposure to credit risk; Derivatives [member]]

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Note Expiry date 2023-01-01
-Name IFRS
-Number 7
-IssueDate 2022-03-24
-Paragraph 9
-Subparagraph b
-URI https://taxonomy.ifrs.org/xifrs-link?type=IFRS&num=7&code=ifrs-tx-2017-en-b&anchor=para_9_b&doctype=Standard&book=b
-URIDate 2022-03-24

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- Definition

The increase (decrease) in the fair value of loans or receivables that is attributable to changes in the credit risk of the loans and receivables determined either: (a) as the amount of change in their fair value that is not attributable to changes in market conditions that gave rise to market risk; or (b) using an alternative method that the entity believes more faithfully represents the amount of change in its fair value that is attributable to changes in the credit risk of the asset. [Refer: Credit risk [member]; Market risk [member]]

+ References

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Line items represent concepts included in a table. These concepts are used to disclose reportable information associated with members defined in one or many axes of the table.

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The maximum exposure to the credit risk of loans or receivables. [Refer: Loans and receivables; Credit risk [member]; Maximum exposure to credit risk]

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Note Expiry date 2023-01-01
-Name IFRS
-Number 7
-IssueDate 2022-03-24
-Paragraph 9
-Subparagraph a
-URI https://taxonomy.ifrs.org/xifrs-link?type=IFRS&num=7&code=ifrs-tx-2017-en-b&anchor=para_9_a&doctype=Standard&book=b
-URIDate 2022-03-24

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