v3.25.4
Derivative financial instruments - Disclosure of derivatives held for trading and risk management (Details) - GBP (£)
£ in Millions
Dec. 31, 2025
Dec. 31, 2024
Disclosure of detailed information about financial instruments [line items]    
Notional contract amount £ 100,079,291 £ 83,792,768
Held for risk management    
Disclosure of detailed information about financial instruments [line items]    
Notional contract amount 239,559 221,158
At fair value    
Disclosure of detailed information about financial instruments [line items]    
Derivative assets held for trading 250,285 291,562
Derivative liabilities held for trading (240,158) (278,636)
Derivative financial assets held for hedging 1,907 794
Derivative liabilities held for risk management (599) (695)
At fair value | Held for risk management    
Disclosure of detailed information about financial instruments [line items]    
Derivative financial assets held for hedging 1,907 794
Derivative liabilities held for risk management (599) (695)
At fair value | Held for risk management | Cash flow hedges    
Disclosure of detailed information about financial instruments [line items]    
Derivative financial assets held for hedging 1,677 611
Derivative liabilities held for risk management (39) (307)
At fair value | Held for risk management | Fair value hedges    
Disclosure of detailed information about financial instruments [line items]    
Derivative financial assets held for hedging 75 147
Derivative liabilities held for risk management (517) (322)
At fair value | Held for risk management | Hedges of net investments    
Disclosure of detailed information about financial instruments [line items]    
Derivative financial assets held for hedging 155 36
Derivative liabilities held for risk management (43) (66)
Foreign exchange derivatives | At fair value | Held for risk management | Cash flow hedges    
Disclosure of detailed information about financial instruments [line items]    
Derivative financial assets held for hedging 1,677 611
Derivative liabilities held for risk management (39) (307)
Foreign exchange derivatives | At fair value | Held for risk management | Hedges of net investments    
Disclosure of detailed information about financial instruments [line items]    
Derivative financial assets held for hedging 155 36
Derivative liabilities held for risk management (43) (66)
Interest rate derivatives | At fair value | Held for risk management | Fair value hedges    
Disclosure of detailed information about financial instruments [line items]    
Derivative financial assets held for hedging 75 147
Derivative liabilities held for risk management (517) (322)
OTC derivatives | At fair value | Held for risk management    
Disclosure of detailed information about financial instruments [line items]    
Derivative financial assets held for hedging 1,907 794
Derivative liabilities held for risk management (599) (695)
Derivatives cleared by central counterparty | At fair value | Held for risk management    
Disclosure of detailed information about financial instruments [line items]    
Derivative financial assets held for hedging 0 0
Derivative liabilities held for risk management 0 0
Derivatives cleared by central counterparty | Interest rate derivatives | At fair value | Held for risk management | Cash flow hedges    
Disclosure of detailed information about financial instruments [line items]    
Derivative financial assets held for hedging 0 0
Derivative liabilities held for risk management 0 0
Derivatives cleared by central counterparty | Interest rate derivatives | At fair value | Held for risk management | Fair value hedges    
Disclosure of detailed information about financial instruments [line items]    
Derivative financial assets held for hedging 0 0
Derivative liabilities held for risk management 0 0
Held for trading    
Disclosure of detailed information about financial instruments [line items]    
Notional contract amount 99,839,732 83,571,610
Held for trading | At fair value    
Disclosure of detailed information about financial instruments [line items]    
Derivative assets held for trading 250,285 291,562
Derivative liabilities held for trading (240,158) (278,636)
Held for trading | Foreign exchange derivatives | At fair value    
Disclosure of detailed information about financial instruments [line items]    
Derivative assets held for trading 74,231 123,614
Derivative liabilities held for trading (71,747) (116,727)
Held for trading | Interest rate derivatives | At fair value    
Disclosure of detailed information about financial instruments [line items]    
Derivative assets held for trading 93,721 96,313
Derivative liabilities held for trading (79,780) (83,953)
Held for trading | Credit derivatives | At fair value    
Disclosure of detailed information about financial instruments [line items]    
Derivative assets held for trading 7,851 6,898
Derivative liabilities held for trading (8,379) (7,455)
Held for trading | Equity and stock index derivatives | At fair value    
Disclosure of detailed information about financial instruments [line items]    
Derivative assets held for trading 72,341 62,911
Derivative liabilities held for trading (78,155) (68,627)
Held for trading | Commodity derivatives | At fair value    
Disclosure of detailed information about financial instruments [line items]    
Derivative assets held for trading 2,141 1,826
Derivative liabilities held for trading (2,097) (1,874)
Held for trading | OTC derivatives | At fair value    
Disclosure of detailed information about financial instruments [line items]    
Derivative assets held for trading 191,157 241,040
Derivative liabilities held for trading (180,498) (227,078)
Held for trading | OTC derivatives | Foreign exchange derivatives | At fair value    
Disclosure of detailed information about financial instruments [line items]    
Derivative assets held for trading 73,979 123,379
Derivative liabilities held for trading (71,525) (116,485)
Held for trading | OTC derivatives | Interest rate derivatives | At fair value    
Disclosure of detailed information about financial instruments [line items]    
Derivative assets held for trading 90,814 92,206
Derivative liabilities held for trading (77,199) (79,936)
Held for trading | OTC derivatives | Credit derivatives | At fair value    
Disclosure of detailed information about financial instruments [line items]    
Derivative assets held for trading 4,169 3,474
Derivative liabilities held for trading (4,666) (4,307)
Held for trading | OTC derivatives | Equity and stock index derivatives | At fair value    
Disclosure of detailed information about financial instruments [line items]    
Derivative assets held for trading 22,180 21,964
Derivative liabilities held for trading (27,092) (26,318)
Held for trading | OTC derivatives | Commodity derivatives | At fair value    
Disclosure of detailed information about financial instruments [line items]    
Derivative assets held for trading 15 17
Derivative liabilities held for trading (16) (32)
Held for trading | Derivatives cleared by central counterparty | At fair value    
Disclosure of detailed information about financial instruments [line items]    
Derivative assets held for trading 5,342 5,095
Derivative liabilities held for trading (5,058) (4,702)
Held for trading | Derivatives cleared by central counterparty | Foreign exchange derivatives | At fair value    
Disclosure of detailed information about financial instruments [line items]    
Derivative assets held for trading 251 228
Derivative liabilities held for trading (221) (235)
Held for trading | Derivatives cleared by central counterparty | Interest rate derivatives | At fair value    
Disclosure of detailed information about financial instruments [line items]    
Derivative assets held for trading 1,409 1,443
Derivative liabilities held for trading (1,124) (1,319)
Held for trading | Derivatives cleared by central counterparty | Credit derivatives | At fair value    
Disclosure of detailed information about financial instruments [line items]    
Derivative assets held for trading 3,682 3,424
Derivative liabilities held for trading (3,713) (3,148)
Held for trading | Exchange traded derivatives | At fair value    
Disclosure of detailed information about financial instruments [line items]    
Derivative assets held for trading 53,786 45,427
Derivative liabilities held for trading (54,602) (46,856)
Held for trading | Exchange traded derivatives | Foreign exchange derivatives | At fair value    
Disclosure of detailed information about financial instruments [line items]    
Derivative assets held for trading 1 7
Derivative liabilities held for trading (1) (7)
Held for trading | Exchange traded derivatives | Interest rate derivatives | At fair value    
Disclosure of detailed information about financial instruments [line items]    
Derivative assets held for trading 1,498 2,664
Derivative liabilities held for trading (1,457) (2,698)
Held for trading | Exchange traded derivatives | Equity and stock index derivatives | At fair value    
Disclosure of detailed information about financial instruments [line items]    
Derivative assets held for trading 50,161 40,947
Derivative liabilities held for trading (51,063) (42,309)
Held for trading | Exchange traded derivatives | Commodity derivatives | At fair value    
Disclosure of detailed information about financial instruments [line items]    
Derivative assets held for trading 2,126 1,809
Derivative liabilities held for trading (2,081) (1,842)
Derivative financial instruments | Held for risk management    
Disclosure of detailed information about financial instruments [line items]    
Notional contract amount 239,559 221,158
Derivative financial instruments | Held for risk management | Cash flow hedges    
Disclosure of detailed information about financial instruments [line items]    
Notional contract amount 127,147 113,323
Derivative financial instruments | Held for risk management | Fair value hedges    
Disclosure of detailed information about financial instruments [line items]    
Notional contract amount 108,093 103,822
Derivative financial instruments | Held for risk management | Hedges of net investments    
Disclosure of detailed information about financial instruments [line items]    
Notional contract amount 4,319 4,013
Derivative financial instruments | Foreign exchange derivatives | Held for risk management | Cash flow hedges    
Disclosure of detailed information about financial instruments [line items]    
Notional contract amount 26,048 26,564
Derivative financial instruments | Foreign exchange derivatives | Held for risk management | Hedges of net investments    
Disclosure of detailed information about financial instruments [line items]    
Notional contract amount 4,319 4,013
Derivative financial instruments | Interest rate derivatives | Held for risk management | Fair value hedges    
Disclosure of detailed information about financial instruments [line items]    
Notional contract amount 4,900 7,234
Derivative financial instruments | OTC derivatives | Held for risk management    
Disclosure of detailed information about financial instruments [line items]    
Notional contract amount 35,267 37,811
Derivative financial instruments | Derivatives cleared by central counterparty | Held for risk management    
Disclosure of detailed information about financial instruments [line items]    
Notional contract amount 204,292 183,347
Derivative financial instruments | Derivatives cleared by central counterparty | Interest rate derivatives | Held for risk management | Cash flow hedges    
Disclosure of detailed information about financial instruments [line items]    
Notional contract amount 101,099 86,759
Derivative financial instruments | Derivatives cleared by central counterparty | Interest rate derivatives | Held for risk management | Fair value hedges    
Disclosure of detailed information about financial instruments [line items]    
Notional contract amount 103,193 96,588
Derivative financial instruments | Held for trading    
Disclosure of detailed information about financial instruments [line items]    
Notional contract amount 99,839,732 83,571,610
Derivative financial instruments | Held for trading | Foreign exchange derivatives    
Disclosure of detailed information about financial instruments [line items]    
Notional contract amount 8,526,457 8,510,940
Derivative financial instruments | Held for trading | Interest rate derivatives    
Disclosure of detailed information about financial instruments [line items]    
Notional contract amount 85,846,809 70,358,974
Derivative financial instruments | Held for trading | Credit derivatives    
Disclosure of detailed information about financial instruments [line items]    
Notional contract amount 1,736,768 1,537,115
Derivative financial instruments | Held for trading | Equity and stock index derivatives    
Disclosure of detailed information about financial instruments [line items]    
Notional contract amount 3,508,383 2,945,271
Derivative financial instruments | Held for trading | Commodity derivatives    
Disclosure of detailed information about financial instruments [line items]    
Notional contract amount 221,315 219,310
Derivative financial instruments | Held for trading | OTC derivatives    
Disclosure of detailed information about financial instruments [line items]    
Notional contract amount 41,917,033 35,878,783
Derivative financial instruments | Held for trading | OTC derivatives | Foreign exchange derivatives    
Disclosure of detailed information about financial instruments [line items]    
Notional contract amount 8,229,535 8,242,887
Derivative financial instruments | Held for trading | OTC derivatives | Interest rate derivatives    
Disclosure of detailed information about financial instruments [line items]    
Notional contract amount 32,272,598 26,437,086
Derivative financial instruments | Held for trading | OTC derivatives | Credit derivatives    
Disclosure of detailed information about financial instruments [line items]    
Notional contract amount 671,066 593,702
Derivative financial instruments | Held for trading | OTC derivatives | Equity and stock index derivatives    
Disclosure of detailed information about financial instruments [line items]    
Notional contract amount 739,153 598,024
Derivative financial instruments | Held for trading | OTC derivatives | Commodity derivatives    
Disclosure of detailed information about financial instruments [line items]    
Notional contract amount 4,681 7,084
Derivative financial instruments | Held for trading | Derivatives cleared by central counterparty    
Disclosure of detailed information about financial instruments [line items]    
Notional contract amount 43,442,632 37,433,417
Derivative financial instruments | Held for trading | Derivatives cleared by central counterparty | Foreign exchange derivatives    
Disclosure of detailed information about financial instruments [line items]    
Notional contract amount 276,189 240,612
Derivative financial instruments | Held for trading | Derivatives cleared by central counterparty | Interest rate derivatives    
Disclosure of detailed information about financial instruments [line items]    
Notional contract amount 42,100,741 36,249,392
Derivative financial instruments | Held for trading | Derivatives cleared by central counterparty | Credit derivatives    
Disclosure of detailed information about financial instruments [line items]    
Notional contract amount 1,065,702 943,413
Derivative financial instruments | Held for trading | Exchange traded derivatives    
Disclosure of detailed information about financial instruments [line items]    
Notional contract amount 14,480,067 10,259,410
Derivative financial instruments | Held for trading | Exchange traded derivatives | Foreign exchange derivatives    
Disclosure of detailed information about financial instruments [line items]    
Notional contract amount 20,733 27,441
Derivative financial instruments | Held for trading | Exchange traded derivatives | Interest rate derivatives    
Disclosure of detailed information about financial instruments [line items]    
Notional contract amount 11,473,470 7,672,496
Derivative financial instruments | Held for trading | Exchange traded derivatives | Equity and stock index derivatives    
Disclosure of detailed information about financial instruments [line items]    
Notional contract amount 2,769,230 2,347,247
Derivative financial instruments | Held for trading | Exchange traded derivatives | Commodity derivatives    
Disclosure of detailed information about financial instruments [line items]    
Notional contract amount £ 216,634 £ 212,226