v3.26.1
DERIVATIVE FINANCIAL INSTRUMENTS (Details) - GBP (£)
£ in Millions
Jun. 30, 2026
Dec. 31, 2025
Disclosure of detailed information about hedges    
Notional amount £ 341,548 £ 266,336
Assets 2,089 870
Liabilities 1,012 687
Derivatives held for trading:    
Disclosure of detailed information about hedges    
Notional amount 89,871 35,452
Derivatives held for hedging    
Disclosure of detailed information about hedges    
Notional amount 251,677 230,884
Designated as fair value hedges: | Derivatives held for hedging    
Disclosure of detailed information about hedges    
Notional amount 193,785 175,033
Designated as cash flow hedges: | Derivatives held for hedging    
Disclosure of detailed information about hedges    
Notional amount 57,892 55,851
Exchange rate contracts | Derivatives held for trading:    
Disclosure of detailed information about hedges    
Notional amount 11,651 9,341
Exchange rate contracts | Designated as fair value hedges: | Derivatives held for hedging    
Disclosure of detailed information about hedges    
Notional amount 6,093 4,099
Exchange rate contracts | Designated as cash flow hedges: | Derivatives held for hedging    
Disclosure of detailed information about hedges    
Notional amount 19,220 18,343
Interest rate contracts | Derivatives held for trading:    
Disclosure of detailed information about hedges    
Notional amount 77,601 25,372
Interest rate contracts | Designated as fair value hedges: | Derivatives held for hedging    
Disclosure of detailed information about hedges    
Notional amount 185,842 169,084
Interest rate contracts | Designated as cash flow hedges: | Derivatives held for hedging    
Disclosure of detailed information about hedges    
Notional amount 38,672 37,508
Inflation rate contracts | Derivatives held for trading:    
Disclosure of detailed information about hedges    
Notional amount 85 171
Inflation rate contracts | Designated as fair value hedges: | Derivatives held for hedging    
Disclosure of detailed information about hedges    
Notional amount 1,850 1,850
Equity and credit contracts | Derivatives held for trading:    
Disclosure of detailed information about hedges    
Notional amount 534 568
Derivative assets    
Disclosure of detailed information about hedges    
Cash collateral received subject to enforceable master netting arrangement or similar agreement not set off against financial assets 1,148 827
Derivative liabilities    
Disclosure of detailed information about hedges    
Collateral cash 36 23
Fair value    
Disclosure of detailed information about hedges    
Assets 2,089 870
Liabilities 1,012 687
Fair value | Derivatives held for trading:    
Disclosure of detailed information about hedges    
Assets 742 393
Liabilities 869 505
Fair value | Derivatives held for hedging    
Disclosure of detailed information about hedges    
Assets 2,204 1,535
Liabilities 1,000 1,240
Fair value | Designated as fair value hedges: | Derivatives held for hedging    
Disclosure of detailed information about hedges    
Assets 1,652 719
Liabilities 317 495
Fair value | Designated as cash flow hedges: | Derivatives held for hedging    
Disclosure of detailed information about hedges    
Assets 552 816
Liabilities 683 745
Fair value | Exchange rate contracts | Derivatives held for trading:    
Disclosure of detailed information about hedges    
Assets 78 85
Liabilities 69 118
Fair value | Exchange rate contracts | Designated as fair value hedges: | Derivatives held for hedging    
Disclosure of detailed information about hedges    
Assets 73 86
Liabilities 39 16
Fair value | Exchange rate contracts | Designated as cash flow hedges: | Derivatives held for hedging    
Disclosure of detailed information about hedges    
Assets 350 500
Liabilities 271 378
Fair value | Interest rate contracts | Derivatives held for trading:    
Disclosure of detailed information about hedges    
Assets 571 198
Liabilities 763 336
Fair value | Interest rate contracts | Designated as fair value hedges: | Derivatives held for hedging    
Disclosure of detailed information about hedges    
Assets 1,567 564
Liabilities 275 479
Fair value | Interest rate contracts | Designated as cash flow hedges: | Derivatives held for hedging    
Disclosure of detailed information about hedges    
Assets 202 316
Liabilities 412 367
Fair value | Inflation rate contracts | Derivatives held for trading:    
Disclosure of detailed information about hedges    
Assets 6 16
Liabilities 16 30
Fair value | Inflation rate contracts | Designated as fair value hedges: | Derivatives held for hedging    
Disclosure of detailed information about hedges    
Assets 12 69
Liabilities 3 0
Fair value | Equity and credit contracts | Derivatives held for trading:    
Disclosure of detailed information about hedges    
Assets 87 94
Liabilities 21 21
Fair value | Derivative netting    
Disclosure of detailed information about hedges    
Assets (857) (1,058)
Liabilities £ (857) £ (1,058)