v3.26.1
Credit risk - Disclosure of assets held for sale (Details)
£ in Millions
Jun. 30, 2026
GBP (£)
Dec. 31, 2025
GBP (£)
Gross exposure | Retail credit cards    
Disclosure of reconciliation of changes in loss allowance and explanation of changes in gross carrying amount for financial instruments [line items]    
Financial assets £ 23,635 £ 23,113
Gross exposure | Retail credit cards | Stage 1    
Disclosure of reconciliation of changes in loss allowance and explanation of changes in gross carrying amount for financial instruments [line items]    
Financial assets 19,041 18,801
Gross exposure | Retail credit cards | Lifetime expected credit losses | Stage 2    
Disclosure of reconciliation of changes in loss allowance and explanation of changes in gross carrying amount for financial instruments [line items]    
Financial assets 2,780 2,536
Gross exposure | Retail credit cards | Lifetime expected credit losses | Stage 3    
Disclosure of reconciliation of changes in loss allowance and explanation of changes in gross carrying amount for financial instruments [line items]    
Financial assets 1,814 1,776
Gross exposure | Corporate loans    
Disclosure of reconciliation of changes in loss allowance and explanation of changes in gross carrying amount for financial instruments [line items]    
Financial assets 127,136 122,145
Gross exposure | Corporate loans | Stage 1    
Disclosure of reconciliation of changes in loss allowance and explanation of changes in gross carrying amount for financial instruments [line items]    
Financial assets 116,622 111,629
Gross exposure | Corporate loans | Lifetime expected credit losses | Stage 2    
Disclosure of reconciliation of changes in loss allowance and explanation of changes in gross carrying amount for financial instruments [line items]    
Financial assets 7,988 8,156
Gross exposure | Corporate loans | Lifetime expected credit losses | Stage 3    
Disclosure of reconciliation of changes in loss allowance and explanation of changes in gross carrying amount for financial instruments [line items]    
Financial assets 2,526 2,360
Impairment allowance | Retail credit cards    
Disclosure of reconciliation of changes in loss allowance and explanation of changes in gross carrying amount for financial instruments [line items]    
Financial assets (2,647) (2,586)
Impairment allowance | Retail credit cards | Stage 1    
Disclosure of reconciliation of changes in loss allowance and explanation of changes in gross carrying amount for financial instruments [line items]    
Financial assets (412) (395)
Impairment allowance | Retail credit cards | Lifetime expected credit losses | Stage 2    
Disclosure of reconciliation of changes in loss allowance and explanation of changes in gross carrying amount for financial instruments [line items]    
Financial assets (785) (796)
Impairment allowance | Retail credit cards | Lifetime expected credit losses | Stage 3    
Disclosure of reconciliation of changes in loss allowance and explanation of changes in gross carrying amount for financial instruments [line items]    
Financial assets (1,450) (1,395)
Impairment allowance | Corporate loans    
Disclosure of reconciliation of changes in loss allowance and explanation of changes in gross carrying amount for financial instruments [line items]    
Financial assets (1,088) (966)
Impairment allowance | Corporate loans | Stage 1    
Disclosure of reconciliation of changes in loss allowance and explanation of changes in gross carrying amount for financial instruments [line items]    
Financial assets (144) (141)
Impairment allowance | Corporate loans | Lifetime expected credit losses | Stage 2    
Disclosure of reconciliation of changes in loss allowance and explanation of changes in gross carrying amount for financial instruments [line items]    
Financial assets (239) (235)
Impairment allowance | Corporate loans | Lifetime expected credit losses | Stage 3    
Disclosure of reconciliation of changes in loss allowance and explanation of changes in gross carrying amount for financial instruments [line items]    
Financial assets £ (705) £ (590)
Assets classified as held for sale | Total loans and advances at amortised cost    
Disclosure of reconciliation of changes in loss allowance and explanation of changes in gross carrying amount for financial instruments [line items]    
Coverage ratio   0.039
Assets classified as held for sale | Total loans and advances at amortised cost | Stage 1    
Disclosure of reconciliation of changes in loss allowance and explanation of changes in gross carrying amount for financial instruments [line items]    
Coverage ratio   0.012
Assets classified as held for sale | Total loans and advances at amortised cost | Lifetime expected credit losses | Stage 2    
Disclosure of reconciliation of changes in loss allowance and explanation of changes in gross carrying amount for financial instruments [line items]    
Coverage ratio   0.267
Assets classified as held for sale | Total loans and advances at amortised cost | Lifetime expected credit losses | Stage 3    
Disclosure of reconciliation of changes in loss allowance and explanation of changes in gross carrying amount for financial instruments [line items]    
Coverage ratio   0.815
Assets classified as held for sale | Retail credit cards | American Airlines Portfolio    
Disclosure of reconciliation of changes in loss allowance and explanation of changes in gross carrying amount for financial instruments [line items]    
Coverage ratio   0.039
Assets classified as held for sale | Retail credit cards | Stage 1 | American Airlines Portfolio    
Disclosure of reconciliation of changes in loss allowance and explanation of changes in gross carrying amount for financial instruments [line items]    
Coverage ratio   0.012
Assets classified as held for sale | Retail credit cards | Lifetime expected credit losses | Stage 2 | American Airlines Portfolio    
Disclosure of reconciliation of changes in loss allowance and explanation of changes in gross carrying amount for financial instruments [line items]    
Coverage ratio   0.266
Assets classified as held for sale | Retail credit cards | Lifetime expected credit losses | Stage 3 | American Airlines Portfolio    
Disclosure of reconciliation of changes in loss allowance and explanation of changes in gross carrying amount for financial instruments [line items]    
Coverage ratio   0.815
Assets classified as held for sale | Corporate loans | American Airlines Portfolio    
Disclosure of reconciliation of changes in loss allowance and explanation of changes in gross carrying amount for financial instruments [line items]    
Coverage ratio   0.061
Assets classified as held for sale | Corporate loans | Stage 1 | American Airlines Portfolio    
Disclosure of reconciliation of changes in loss allowance and explanation of changes in gross carrying amount for financial instruments [line items]    
Coverage ratio   0.023
Assets classified as held for sale | Corporate loans | Lifetime expected credit losses | Stage 2 | American Airlines Portfolio    
Disclosure of reconciliation of changes in loss allowance and explanation of changes in gross carrying amount for financial instruments [line items]    
Coverage ratio   0.333
Assets classified as held for sale | Corporate loans | Lifetime expected credit losses | Stage 3 | American Airlines Portfolio    
Disclosure of reconciliation of changes in loss allowance and explanation of changes in gross carrying amount for financial instruments [line items]    
Coverage ratio   0
Assets classified as held for sale | Gross exposure | Total loans and advances at amortised cost    
Disclosure of reconciliation of changes in loss allowance and explanation of changes in gross carrying amount for financial instruments [line items]    
Financial assets   £ 6,037
Assets classified as held for sale | Gross exposure | Total loans and advances at amortised cost | Stage 1    
Disclosure of reconciliation of changes in loss allowance and explanation of changes in gross carrying amount for financial instruments [line items]    
Financial assets   5,511
Assets classified as held for sale | Gross exposure | Total loans and advances at amortised cost | Lifetime expected credit losses | Stage 2    
Disclosure of reconciliation of changes in loss allowance and explanation of changes in gross carrying amount for financial instruments [line items]    
Financial assets   472
Assets classified as held for sale | Gross exposure | Total loans and advances at amortised cost | Lifetime expected credit losses | Stage 3    
Disclosure of reconciliation of changes in loss allowance and explanation of changes in gross carrying amount for financial instruments [line items]    
Financial assets   54
Assets classified as held for sale | Gross exposure | Retail credit cards | American Airlines Portfolio    
Disclosure of reconciliation of changes in loss allowance and explanation of changes in gross carrying amount for financial instruments [line items]    
Financial assets   5,988
Assets classified as held for sale | Gross exposure | Retail credit cards | Stage 1 | American Airlines Portfolio    
Disclosure of reconciliation of changes in loss allowance and explanation of changes in gross carrying amount for financial instruments [line items]    
Financial assets   5,468
Assets classified as held for sale | Gross exposure | Retail credit cards | Lifetime expected credit losses | Stage 2 | American Airlines Portfolio    
Disclosure of reconciliation of changes in loss allowance and explanation of changes in gross carrying amount for financial instruments [line items]    
Financial assets   466
Assets classified as held for sale | Gross exposure | Retail credit cards | Lifetime expected credit losses | Stage 3 | American Airlines Portfolio    
Disclosure of reconciliation of changes in loss allowance and explanation of changes in gross carrying amount for financial instruments [line items]    
Financial assets   54
Assets classified as held for sale | Gross exposure | Corporate loans | American Airlines Portfolio    
Disclosure of reconciliation of changes in loss allowance and explanation of changes in gross carrying amount for financial instruments [line items]    
Financial assets   49
Assets classified as held for sale | Gross exposure | Corporate loans | Stage 1 | American Airlines Portfolio    
Disclosure of reconciliation of changes in loss allowance and explanation of changes in gross carrying amount for financial instruments [line items]    
Financial assets   43
Assets classified as held for sale | Gross exposure | Corporate loans | Lifetime expected credit losses | Stage 2 | American Airlines Portfolio    
Disclosure of reconciliation of changes in loss allowance and explanation of changes in gross carrying amount for financial instruments [line items]    
Financial assets   6
Assets classified as held for sale | Gross exposure | Corporate loans | Lifetime expected credit losses | Stage 3 | American Airlines Portfolio    
Disclosure of reconciliation of changes in loss allowance and explanation of changes in gross carrying amount for financial instruments [line items]    
Financial assets   0
Assets classified as held for sale | Impairment allowance | Total loans and advances at amortised cost    
Disclosure of reconciliation of changes in loss allowance and explanation of changes in gross carrying amount for financial instruments [line items]    
Financial assets   (236)
Assets classified as held for sale | Impairment allowance | Total loans and advances at amortised cost | Stage 1    
Disclosure of reconciliation of changes in loss allowance and explanation of changes in gross carrying amount for financial instruments [line items]    
Financial assets   (66)
Assets classified as held for sale | Impairment allowance | Total loans and advances at amortised cost | Lifetime expected credit losses | Stage 2    
Disclosure of reconciliation of changes in loss allowance and explanation of changes in gross carrying amount for financial instruments [line items]    
Financial assets   (126)
Assets classified as held for sale | Impairment allowance | Total loans and advances at amortised cost | Lifetime expected credit losses | Stage 3    
Disclosure of reconciliation of changes in loss allowance and explanation of changes in gross carrying amount for financial instruments [line items]    
Financial assets   (44)
Assets classified as held for sale | Impairment allowance | Retail credit cards | American Airlines Portfolio    
Disclosure of reconciliation of changes in loss allowance and explanation of changes in gross carrying amount for financial instruments [line items]    
Financial assets   (233)
Assets classified as held for sale | Impairment allowance | Retail credit cards | Stage 1 | American Airlines Portfolio    
Disclosure of reconciliation of changes in loss allowance and explanation of changes in gross carrying amount for financial instruments [line items]    
Financial assets   (65)
Assets classified as held for sale | Impairment allowance | Retail credit cards | Lifetime expected credit losses | Stage 2 | American Airlines Portfolio    
Disclosure of reconciliation of changes in loss allowance and explanation of changes in gross carrying amount for financial instruments [line items]    
Financial assets   (124)
Assets classified as held for sale | Impairment allowance | Retail credit cards | Lifetime expected credit losses | Stage 3 | American Airlines Portfolio    
Disclosure of reconciliation of changes in loss allowance and explanation of changes in gross carrying amount for financial instruments [line items]    
Financial assets   (44)
Assets classified as held for sale | Impairment allowance | Corporate loans | American Airlines Portfolio    
Disclosure of reconciliation of changes in loss allowance and explanation of changes in gross carrying amount for financial instruments [line items]    
Financial assets   (3)
Assets classified as held for sale | Impairment allowance | Corporate loans | Stage 1 | American Airlines Portfolio    
Disclosure of reconciliation of changes in loss allowance and explanation of changes in gross carrying amount for financial instruments [line items]    
Financial assets   (1)
Assets classified as held for sale | Impairment allowance | Corporate loans | Lifetime expected credit losses | Stage 2 | American Airlines Portfolio    
Disclosure of reconciliation of changes in loss allowance and explanation of changes in gross carrying amount for financial instruments [line items]    
Financial assets   (2)
Assets classified as held for sale | Impairment allowance | Corporate loans | Lifetime expected credit losses | Stage 3 | American Airlines Portfolio    
Disclosure of reconciliation of changes in loss allowance and explanation of changes in gross carrying amount for financial instruments [line items]    
Financial assets   £ 0