v3.26.1
Credit Risk - Disclosure of measurement uncertainty - ECL under 100% weighted scenarios for modelled portfolios (Details)
£ in Millions
Jun. 30, 2026
GBP (£)
Dec. 31, 2025
GBP (£)
Impairment allowance    
Disclosure of nature and extent of risks arising from financial instruments [line items]    
Financial assets £ (5,969) £ (5,727)
Impairment allowance | Total weighted model ECL    
Disclosure of nature and extent of risks arising from financial instruments [line items]    
Financial assets (4,328) (4,358)
Impairment allowance | ECL from individually assessed impairments    
Disclosure of nature and extent of risks arising from financial instruments [line items]    
Financial assets (882) (672)
Impairment allowance | ECL from non-modelled exposures and others    
Disclosure of nature and extent of risks arising from financial instruments [line items]    
Financial assets (452) (542)
Impairment allowance | ECL from non-modelled exposures and others | Tesco Personal Finance PLC    
Disclosure of nature and extent of risks arising from financial instruments [line items]    
Financial assets (430) (400)
Impairment allowance | ECL from debt securities at amortised cost    
Disclosure of nature and extent of risks arising from financial instruments [line items]    
Financial assets (20) (22)
Impairment allowance | ECL from held for sale assets (AA portfolio)    
Disclosure of nature and extent of risks arising from financial instruments [line items]    
Financial assets   235
Impairment allowance | ECL from post model management adjustments    
Disclosure of nature and extent of risks arising from financial instruments [line items]    
Financial assets (287) (368)
Impairment allowance | ECL from economic uncertainty adjustments    
Disclosure of nature and extent of risks arising from financial instruments [line items]    
Financial assets (74) (114)
Loans and advances | Financial assets at amortised cost    
Disclosure of nature and extent of risks arising from financial instruments [line items]    
Financial assets £ 371,301 £ 361,523
Coverage ratio 0.015 0.014
Loans and advances | Financial assets at amortised cost | Stage 1    
Disclosure of nature and extent of risks arising from financial instruments [line items]    
Financial assets £ 336,829 £ 327,688
Coverage ratio 0.003 0.003
Loans and advances | Financial assets at amortised cost | Lifetime expected credit losses | Stage 2    
Disclosure of nature and extent of risks arising from financial instruments [line items]    
Financial assets £ 29,653 £ 28,956
Coverage ratio 0.055 0.056
Loans and advances | Gross exposure | Financial assets at amortised cost    
Disclosure of nature and extent of risks arising from financial instruments [line items]    
Financial assets £ 376,817 £ 366,812
Loans and advances | Gross exposure | Financial assets at amortised cost | Stage 1    
Disclosure of nature and extent of risks arising from financial instruments [line items]    
Financial assets 337,729 328,579
Loans and advances | Gross exposure | Financial assets at amortised cost | Lifetime expected credit losses | Stage 2    
Disclosure of nature and extent of risks arising from financial instruments [line items]    
Financial assets 31,394 30,664
Loans and advances | Impairment allowance | Total weighted model ECL    
Disclosure of nature and extent of risks arising from financial instruments [line items]    
Financial assets (4,300) (4,300)
Loans and advances | Impairment allowance | ECL from individually assessed impairments    
Disclosure of nature and extent of risks arising from financial instruments [line items]    
Financial assets (900) (700)
Loans and advances | Impairment allowance | Financial assets at amortised cost    
Disclosure of nature and extent of risks arising from financial instruments [line items]    
Financial assets (5,516) (5,289)
Loans and advances | Impairment allowance | Financial assets at amortised cost | Stage 1    
Disclosure of nature and extent of risks arising from financial instruments [line items]    
Financial assets (900) (891)
Loans and advances | Impairment allowance | Financial assets at amortised cost | Lifetime expected credit losses | Stage 2    
Disclosure of nature and extent of risks arising from financial instruments [line items]    
Financial assets (1,741) (1,708)
Retail mortgages | Financial assets at amortised cost    
Disclosure of nature and extent of risks arising from financial instruments [line items]    
Financial assets £ 181,542 £ 177,333
Coverage ratio 0.001 0.001
Retail mortgages | Financial assets at amortised cost | Stage 1    
Disclosure of nature and extent of risks arising from financial instruments [line items]    
Financial assets £ 165,613 £ 161,637
Coverage ratio 0 0
Retail mortgages | Financial assets at amortised cost | Lifetime expected credit losses | Stage 2    
Disclosure of nature and extent of risks arising from financial instruments [line items]    
Financial assets £ 14,079 £ 13,813
Coverage ratio 0.001 0.001
Retail mortgages | Gross exposure    
Disclosure of nature and extent of risks arising from financial instruments [line items]    
Financial assets £ 181,669 £ 177,450
Retail mortgages | Gross exposure | Stage 1    
Disclosure of nature and extent of risks arising from financial instruments [line items]    
Financial assets 165,632 161,654
Retail mortgages | Gross exposure | Lifetime expected credit losses | Stage 2    
Disclosure of nature and extent of risks arising from financial instruments [line items]    
Financial assets 14,100 13,829
Retail mortgages | Gross exposure | Financial assets at amortised cost    
Disclosure of nature and extent of risks arising from financial instruments [line items]    
Financial assets 181,669 177,450
Retail mortgages | Gross exposure | Financial assets at amortised cost | Stage 1    
Disclosure of nature and extent of risks arising from financial instruments [line items]    
Financial assets 165,632 161,654
Retail mortgages | Gross exposure | Financial assets at amortised cost | Lifetime expected credit losses | Stage 2    
Disclosure of nature and extent of risks arising from financial instruments [line items]    
Financial assets 14,100 13,829
Retail mortgages | Impairment allowance    
Disclosure of nature and extent of risks arising from financial instruments [line items]    
Financial assets (127) (117)
Retail mortgages | Impairment allowance | Stage 1    
Disclosure of nature and extent of risks arising from financial instruments [line items]    
Financial assets (19) (17)
Retail mortgages | Impairment allowance | Lifetime expected credit losses | Stage 2    
Disclosure of nature and extent of risks arising from financial instruments [line items]    
Financial assets (21) (16)
Retail mortgages | Impairment allowance | Financial assets at amortised cost    
Disclosure of nature and extent of risks arising from financial instruments [line items]    
Financial assets (127) (117)
Retail mortgages | Impairment allowance | Financial assets at amortised cost | Stage 1    
Disclosure of nature and extent of risks arising from financial instruments [line items]    
Financial assets (19) (17)
Retail mortgages | Impairment allowance | Financial assets at amortised cost | Lifetime expected credit losses | Stage 2    
Disclosure of nature and extent of risks arising from financial instruments [line items]    
Financial assets (21) (16)
Retail credit cards | Financial assets at amortised cost    
Disclosure of nature and extent of risks arising from financial instruments [line items]    
Financial assets £ 37,667 £ 36,952
Coverage ratio 0.084 0.083
Retail credit cards | Financial assets at amortised cost | Stage 1    
Disclosure of nature and extent of risks arising from financial instruments [line items]    
Financial assets £ 33,526 £ 33,157
Coverage ratio 0.017 0.017
Retail credit cards | Financial assets at amortised cost | Lifetime expected credit losses | Stage 2    
Disclosure of nature and extent of risks arising from financial instruments [line items]    
Financial assets £ 3,650 £ 3,285
Coverage ratio 0.250 0.267
Retail credit cards | Gross exposure    
Disclosure of nature and extent of risks arising from financial instruments [line items]    
Financial assets £ 41,103 £ 40,281
Retail credit cards | Gross exposure | Stage 1    
Disclosure of nature and extent of risks arising from financial instruments [line items]    
Financial assets 34,108 33,723
Retail credit cards | Gross exposure | Lifetime expected credit losses | Stage 2    
Disclosure of nature and extent of risks arising from financial instruments [line items]    
Financial assets 4,865 4,479
Retail credit cards | Gross exposure | Financial assets at amortised cost    
Disclosure of nature and extent of risks arising from financial instruments [line items]    
Financial assets 41,103 40,281
Retail credit cards | Gross exposure | Financial assets at amortised cost | Stage 1    
Disclosure of nature and extent of risks arising from financial instruments [line items]    
Financial assets 34,108 33,723
Retail credit cards | Gross exposure | Financial assets at amortised cost | Lifetime expected credit losses | Stage 2    
Disclosure of nature and extent of risks arising from financial instruments [line items]    
Financial assets 4,865 4,479
Retail credit cards | Impairment allowance    
Disclosure of nature and extent of risks arising from financial instruments [line items]    
Financial assets (3,436) (3,329)
Retail credit cards | Impairment allowance | Stage 1    
Disclosure of nature and extent of risks arising from financial instruments [line items]    
Financial assets (582) (566)
Retail credit cards | Impairment allowance | Lifetime expected credit losses | Stage 2    
Disclosure of nature and extent of risks arising from financial instruments [line items]    
Financial assets (1,215) (1,194)
Retail credit cards | Impairment allowance | Financial assets at amortised cost    
Disclosure of nature and extent of risks arising from financial instruments [line items]    
Financial assets (3,436) (3,329)
Retail credit cards | Impairment allowance | Financial assets at amortised cost | Stage 1    
Disclosure of nature and extent of risks arising from financial instruments [line items]    
Financial assets (582) (566)
Retail credit cards | Impairment allowance | Financial assets at amortised cost | Lifetime expected credit losses | Stage 2    
Disclosure of nature and extent of risks arising from financial instruments [line items]    
Financial assets (1,215) (1,194)
Retail other | Financial assets at amortised cost    
Disclosure of nature and extent of risks arising from financial instruments [line items]    
Financial assets £ 14,235 £ 13,914
Coverage ratio 0.036 0.036
Retail other | Financial assets at amortised cost | Stage 1    
Disclosure of nature and extent of risks arising from financial instruments [line items]    
Financial assets £ 12,187 £ 12,248
Coverage ratio 0.009 0.008
Retail other | Financial assets at amortised cost | Lifetime expected credit losses | Stage 2    
Disclosure of nature and extent of risks arising from financial instruments [line items]    
Financial assets £ 1,851 £ 1,535
Coverage ratio 0.093 0.107
Retail other | Gross exposure    
Disclosure of nature and extent of risks arising from financial instruments [line items]    
Financial assets £ 14,771 £ 14,431
Retail other | Gross exposure | Stage 1    
Disclosure of nature and extent of risks arising from financial instruments [line items]    
Financial assets 12,297 12,349
Retail other | Gross exposure | Lifetime expected credit losses | Stage 2    
Disclosure of nature and extent of risks arising from financial instruments [line items]    
Financial assets 2,041 1,718
Retail other | Gross exposure | Financial assets at amortised cost    
Disclosure of nature and extent of risks arising from financial instruments [line items]    
Financial assets 14,771 14,431
Retail other | Gross exposure | Financial assets at amortised cost | Stage 1    
Disclosure of nature and extent of risks arising from financial instruments [line items]    
Financial assets 12,297 12,349
Retail other | Gross exposure | Financial assets at amortised cost | Lifetime expected credit losses | Stage 2    
Disclosure of nature and extent of risks arising from financial instruments [line items]    
Financial assets 2,041 1,718
Retail other | Impairment allowance    
Disclosure of nature and extent of risks arising from financial instruments [line items]    
Financial assets (536) (517)
Retail other | Impairment allowance | Stage 1    
Disclosure of nature and extent of risks arising from financial instruments [line items]    
Financial assets (110) (101)
Retail other | Impairment allowance | Lifetime expected credit losses | Stage 2    
Disclosure of nature and extent of risks arising from financial instruments [line items]    
Financial assets (190) (183)
Retail other | Impairment allowance | Financial assets at amortised cost    
Disclosure of nature and extent of risks arising from financial instruments [line items]    
Financial assets (536) (517)
Retail other | Impairment allowance | Financial assets at amortised cost | Stage 1    
Disclosure of nature and extent of risks arising from financial instruments [line items]    
Financial assets (110) (101)
Retail other | Impairment allowance | Financial assets at amortised cost | Lifetime expected credit losses | Stage 2    
Disclosure of nature and extent of risks arising from financial instruments [line items]    
Financial assets (190) (183)
Corporate loans | Financial assets at amortised cost    
Disclosure of nature and extent of risks arising from financial instruments [line items]    
Financial assets £ 137,857 £ 133,324
Coverage ratio 0.010 0.010
Corporate loans | Financial assets at amortised cost | Stage 1    
Disclosure of nature and extent of risks arising from financial instruments [line items]    
Financial assets £ 125,503 £ 120,646
Coverage ratio 0.002 0.002
Corporate loans | Financial assets at amortised cost | Lifetime expected credit losses | Stage 2    
Disclosure of nature and extent of risks arising from financial instruments [line items]    
Financial assets £ 10,073 £ 10,323
Coverage ratio 0.030 0.030
Corporate loans | Gross exposure    
Disclosure of nature and extent of risks arising from financial instruments [line items]    
Financial assets £ 139,274 £ 134,650
Corporate loans | Gross exposure | Stage 1    
Disclosure of nature and extent of risks arising from financial instruments [line items]    
Financial assets 125,692 120,853
Corporate loans | Gross exposure | Lifetime expected credit losses | Stage 2    
Disclosure of nature and extent of risks arising from financial instruments [line items]    
Financial assets 10,388 10,638
Corporate loans | Gross exposure | Financial assets at amortised cost    
Disclosure of nature and extent of risks arising from financial instruments [line items]    
Financial assets 139,274 134,650
Corporate loans | Gross exposure | Financial assets at amortised cost | Stage 1    
Disclosure of nature and extent of risks arising from financial instruments [line items]    
Financial assets 125,692 120,853
Corporate loans | Gross exposure | Financial assets at amortised cost | Lifetime expected credit losses | Stage 2    
Disclosure of nature and extent of risks arising from financial instruments [line items]    
Financial assets 10,388 10,638
Corporate loans | Impairment allowance    
Disclosure of nature and extent of risks arising from financial instruments [line items]    
Financial assets (1,417) (1,326)
Corporate loans | Impairment allowance | Stage 1    
Disclosure of nature and extent of risks arising from financial instruments [line items]    
Financial assets (189) (207)
Corporate loans | Impairment allowance | Lifetime expected credit losses | Stage 2    
Disclosure of nature and extent of risks arising from financial instruments [line items]    
Financial assets (315) (315)
Corporate loans | Impairment allowance | Financial assets at amortised cost    
Disclosure of nature and extent of risks arising from financial instruments [line items]    
Financial assets (1,417) (1,326)
Corporate loans | Impairment allowance | Financial assets at amortised cost | Stage 1    
Disclosure of nature and extent of risks arising from financial instruments [line items]    
Financial assets (189) (207)
Corporate loans | Impairment allowance | Financial assets at amortised cost | Lifetime expected credit losses | Stage 2    
Disclosure of nature and extent of risks arising from financial instruments [line items]    
Financial assets (315) (315)
Weighted | Loans and advances | Impairment allowance | Financial assets at amortised cost | Total weighted model ECL    
Disclosure of nature and extent of risks arising from financial instruments [line items]    
Financial assets £ (4,328) £ (4,358)
Weighted | Retail mortgages | Financial assets at amortised cost | Stage 1 | Total weighted model ECL    
Disclosure of nature and extent of risks arising from financial instruments [line items]    
Coverage ratio 0 0
Weighted | Retail mortgages | Financial assets at amortised cost | Lifetime expected credit losses | Stage 2 | Total weighted model ECL    
Disclosure of nature and extent of risks arising from financial instruments [line items]    
Coverage ratio 0.002 0.001
Weighted | Retail mortgages | Financial assets at amortised cost | Lifetime expected credit losses | Stage 3 | Total weighted model ECL    
Disclosure of nature and extent of risks arising from financial instruments [line items]    
Coverage ratio 0.027 0.027
Weighted | Retail mortgages | Gross exposure | Financial assets at amortised cost | Stage 1 | Total weighted model ECL    
Disclosure of nature and extent of risks arising from financial instruments [line items]    
Financial assets £ 156,076 £ 149,004
Weighted | Retail mortgages | Gross exposure | Financial assets at amortised cost | Lifetime expected credit losses | Stage 2 | Total weighted model ECL    
Disclosure of nature and extent of risks arising from financial instruments [line items]    
Financial assets 13,985 13,586
Weighted | Retail mortgages | Gross exposure | Financial assets at amortised cost | Lifetime expected credit losses | Stage 3 | Total weighted model ECL    
Disclosure of nature and extent of risks arising from financial instruments [line items]    
Financial assets 1,617 1,621
Weighted | Retail mortgages | Impairment allowance | Financial assets at amortised cost | Total weighted model ECL    
Disclosure of nature and extent of risks arising from financial instruments [line items]    
Financial assets (81) (62)
Weighted | Retail mortgages | Impairment allowance | Financial assets at amortised cost | Stage 1 | Total weighted model ECL    
Disclosure of nature and extent of risks arising from financial instruments [line items]    
Financial assets (12) (3)
Weighted | Retail mortgages | Impairment allowance | Financial assets at amortised cost | Lifetime expected credit losses | Stage 2 | Total weighted model ECL    
Disclosure of nature and extent of risks arising from financial instruments [line items]    
Financial assets (25) (16)
Weighted | Retail mortgages | Impairment allowance | Financial assets at amortised cost | Lifetime expected credit losses | Stage 3 | Total weighted model ECL    
Disclosure of nature and extent of risks arising from financial instruments [line items]    
Financial assets £ (44) £ (43)
Weighted | Retail credit cards | Financial assets at amortised cost | Stage 1 | Total weighted model ECL    
Disclosure of nature and extent of risks arising from financial instruments [line items]    
Coverage ratio 0.009 0.009
Weighted | Retail credit cards | Financial assets at amortised cost | Lifetime expected credit losses | Stage 2 | Total weighted model ECL    
Disclosure of nature and extent of risks arising from financial instruments [line items]    
Coverage ratio 0.217 0.223
Weighted | Retail credit cards | Financial assets at amortised cost | Lifetime expected credit losses | Stage 3 | Total weighted model ECL    
Disclosure of nature and extent of risks arising from financial instruments [line items]    
Coverage ratio 0.737 0.738
Weighted | Retail credit cards | Gross exposure | Financial assets at amortised cost | Stage 1 | Total weighted model ECL    
Disclosure of nature and extent of risks arising from financial instruments [line items]    
Financial assets £ 61,160 £ 61,320
Weighted | Retail credit cards | Gross exposure | Financial assets at amortised cost | Lifetime expected credit losses | Stage 2 | Total weighted model ECL    
Disclosure of nature and extent of risks arising from financial instruments [line items]    
Financial assets 5,004 5,307
Weighted | Retail credit cards | Gross exposure | Financial assets at amortised cost | Lifetime expected credit losses | Stage 3 | Total weighted model ECL    
Disclosure of nature and extent of risks arising from financial instruments [line items]    
Financial assets 2,229 2,158
Weighted | Retail credit cards | Impairment allowance | Financial assets at amortised cost | Total weighted model ECL    
Disclosure of nature and extent of risks arising from financial instruments [line items]    
Financial assets (3,290) (3,336)
Weighted | Retail credit cards | Impairment allowance | Financial assets at amortised cost | Stage 1 | Total weighted model ECL    
Disclosure of nature and extent of risks arising from financial instruments [line items]    
Financial assets (563) (561)
Weighted | Retail credit cards | Impairment allowance | Financial assets at amortised cost | Lifetime expected credit losses | Stage 2 | Total weighted model ECL    
Disclosure of nature and extent of risks arising from financial instruments [line items]    
Financial assets (1,085) (1,183)
Weighted | Retail credit cards | Impairment allowance | Financial assets at amortised cost | Lifetime expected credit losses | Stage 3 | Total weighted model ECL    
Disclosure of nature and extent of risks arising from financial instruments [line items]    
Financial assets £ (1,642) £ (1,592)
Weighted | Retail other | Financial assets at amortised cost | Stage 1 | Total weighted model ECL    
Disclosure of nature and extent of risks arising from financial instruments [line items]    
Coverage ratio 0.003 0.005
Weighted | Retail other | Financial assets at amortised cost | Lifetime expected credit losses | Stage 2 | Total weighted model ECL    
Disclosure of nature and extent of risks arising from financial instruments [line items]    
Coverage ratio 0.050 0.070
Weighted | Retail other | Financial assets at amortised cost | Lifetime expected credit losses | Stage 3 | Total weighted model ECL    
Disclosure of nature and extent of risks arising from financial instruments [line items]    
Coverage ratio 0.362 0.617
Weighted | Retail other | Gross exposure | Financial assets at amortised cost | Stage 1 | Total weighted model ECL    
Disclosure of nature and extent of risks arising from financial instruments [line items]    
Financial assets £ 13,173 £ 6,260
Weighted | Retail other | Gross exposure | Financial assets at amortised cost | Lifetime expected credit losses | Stage 2 | Total weighted model ECL    
Disclosure of nature and extent of risks arising from financial instruments [line items]    
Financial assets 1,692 1,164
Weighted | Retail other | Gross exposure | Financial assets at amortised cost | Lifetime expected credit losses | Stage 3 | Total weighted model ECL    
Disclosure of nature and extent of risks arising from financial instruments [line items]    
Financial assets 185 128
Weighted | Retail other | Impairment allowance | Financial assets at amortised cost | Total weighted model ECL    
Disclosure of nature and extent of risks arising from financial instruments [line items]    
Financial assets (189) (192)
Weighted | Retail other | Impairment allowance | Financial assets at amortised cost | Stage 1 | Total weighted model ECL    
Disclosure of nature and extent of risks arising from financial instruments [line items]    
Financial assets (38) (32)
Weighted | Retail other | Impairment allowance | Financial assets at amortised cost | Lifetime expected credit losses | Stage 2 | Total weighted model ECL    
Disclosure of nature and extent of risks arising from financial instruments [line items]    
Financial assets (84) (81)
Weighted | Retail other | Impairment allowance | Financial assets at amortised cost | Lifetime expected credit losses | Stage 3 | Total weighted model ECL    
Disclosure of nature and extent of risks arising from financial instruments [line items]    
Financial assets £ (67) £ (79)
Weighted | Corporate loans | Financial assets at amortised cost | Stage 1 | Total weighted model ECL    
Disclosure of nature and extent of risks arising from financial instruments [line items]    
Coverage ratio 0.001 0.001
Weighted | Corporate loans | Financial assets at amortised cost | Lifetime expected credit losses | Stage 2 | Total weighted model ECL    
Disclosure of nature and extent of risks arising from financial instruments [line items]    
Coverage ratio 0.024 0.026
Weighted | Corporate loans | Financial assets at amortised cost | Lifetime expected credit losses | Stage 3 | Total weighted model ECL    
Disclosure of nature and extent of risks arising from financial instruments [line items]    
Coverage ratio 0.018 0.016
Weighted | Corporate loans | Gross exposure | Financial assets at amortised cost | Stage 1 | Total weighted model ECL    
Disclosure of nature and extent of risks arising from financial instruments [line items]    
Financial assets £ 235,090 £ 220,292
Weighted | Corporate loans | Gross exposure | Financial assets at amortised cost | Lifetime expected credit losses | Stage 2 | Total weighted model ECL    
Disclosure of nature and extent of risks arising from financial instruments [line items]    
Financial assets 19,210 18,172
Weighted | Corporate loans | Gross exposure | Financial assets at amortised cost | Lifetime expected credit losses | Stage 3 | Total weighted model ECL    
Disclosure of nature and extent of risks arising from financial instruments [line items]    
Financial assets 3,658 3,650
Weighted | Corporate loans | Impairment allowance | Financial assets at amortised cost | Total weighted model ECL    
Disclosure of nature and extent of risks arising from financial instruments [line items]    
Financial assets (768) (768)
Weighted | Corporate loans | Impairment allowance | Financial assets at amortised cost | Stage 1 | Total weighted model ECL    
Disclosure of nature and extent of risks arising from financial instruments [line items]    
Financial assets (249) (231)
Weighted | Corporate loans | Impairment allowance | Financial assets at amortised cost | Lifetime expected credit losses | Stage 2 | Total weighted model ECL    
Disclosure of nature and extent of risks arising from financial instruments [line items]    
Financial assets (453) (477)
Weighted | Corporate loans | Impairment allowance | Financial assets at amortised cost | Lifetime expected credit losses | Stage 3 | Total weighted model ECL    
Disclosure of nature and extent of risks arising from financial instruments [line items]    
Financial assets (66) (60)
Upside 2 | Loans and advances | Impairment allowance | Financial assets at amortised cost | Total weighted model ECL    
Disclosure of nature and extent of risks arising from financial instruments [line items]    
Financial assets £ (3,963) £ (4,023)
Upside 2 | Retail mortgages | Financial assets at amortised cost | Stage 1 | Total weighted model ECL    
Disclosure of nature and extent of risks arising from financial instruments [line items]    
Coverage ratio 0 0
Upside 2 | Retail mortgages | Financial assets at amortised cost | Lifetime expected credit losses | Stage 2 | Total weighted model ECL    
Disclosure of nature and extent of risks arising from financial instruments [line items]    
Coverage ratio 0.001 0.001
Upside 2 | Retail mortgages | Financial assets at amortised cost | Lifetime expected credit losses | Stage 3 | Total weighted model ECL    
Disclosure of nature and extent of risks arising from financial instruments [line items]    
Coverage ratio 0.019 0.020
Upside 2 | Retail mortgages | Gross exposure | Financial assets at amortised cost | Stage 1 | Total weighted model ECL    
Disclosure of nature and extent of risks arising from financial instruments [line items]    
Financial assets £ 158,653 £ 151,314
Upside 2 | Retail mortgages | Gross exposure | Financial assets at amortised cost | Lifetime expected credit losses | Stage 2 | Total weighted model ECL    
Disclosure of nature and extent of risks arising from financial instruments [line items]    
Financial assets 11,408 11,276
Upside 2 | Retail mortgages | Gross exposure | Financial assets at amortised cost | Lifetime expected credit losses | Stage 3 | Total weighted model ECL    
Disclosure of nature and extent of risks arising from financial instruments [line items]    
Financial assets 1,617 1,621
Upside 2 | Retail mortgages | Impairment allowance | Financial assets at amortised cost | Total weighted model ECL    
Disclosure of nature and extent of risks arising from financial instruments [line items]    
Financial assets (42) (39)
Upside 2 | Retail mortgages | Impairment allowance | Financial assets at amortised cost | Stage 1 | Total weighted model ECL    
Disclosure of nature and extent of risks arising from financial instruments [line items]    
Financial assets (4) (1)
Upside 2 | Retail mortgages | Impairment allowance | Financial assets at amortised cost | Lifetime expected credit losses | Stage 2 | Total weighted model ECL    
Disclosure of nature and extent of risks arising from financial instruments [line items]    
Financial assets (7) (6)
Upside 2 | Retail mortgages | Impairment allowance | Financial assets at amortised cost | Lifetime expected credit losses | Stage 3 | Total weighted model ECL    
Disclosure of nature and extent of risks arising from financial instruments [line items]    
Financial assets £ (31) £ (32)
Upside 2 | Retail credit cards | Financial assets at amortised cost | Stage 1 | Total weighted model ECL    
Disclosure of nature and extent of risks arising from financial instruments [line items]    
Coverage ratio 0.008 0.009
Upside 2 | Retail credit cards | Financial assets at amortised cost | Lifetime expected credit losses | Stage 2 | Total weighted model ECL    
Disclosure of nature and extent of risks arising from financial instruments [line items]    
Coverage ratio 0.213 0.214
Upside 2 | Retail credit cards | Financial assets at amortised cost | Lifetime expected credit losses | Stage 3 | Total weighted model ECL    
Disclosure of nature and extent of risks arising from financial instruments [line items]    
Coverage ratio 0.716 0.717
Upside 2 | Retail credit cards | Gross exposure | Financial assets at amortised cost | Stage 1 | Total weighted model ECL    
Disclosure of nature and extent of risks arising from financial instruments [line items]    
Financial assets £ 60,777 £ 61,096
Upside 2 | Retail credit cards | Gross exposure | Financial assets at amortised cost | Lifetime expected credit losses | Stage 2 | Total weighted model ECL    
Disclosure of nature and extent of risks arising from financial instruments [line items]    
Financial assets 4,748 5,133
Upside 2 | Retail credit cards | Gross exposure | Financial assets at amortised cost | Lifetime expected credit losses | Stage 3 | Total weighted model ECL    
Disclosure of nature and extent of risks arising from financial instruments [line items]    
Financial assets 2,229 2,158
Upside 2 | Retail credit cards | Impairment allowance | Financial assets at amortised cost | Total weighted model ECL    
Disclosure of nature and extent of risks arising from financial instruments [line items]    
Financial assets (3,114) (3,170)
Upside 2 | Retail credit cards | Impairment allowance | Financial assets at amortised cost | Stage 1 | Total weighted model ECL    
Disclosure of nature and extent of risks arising from financial instruments [line items]    
Financial assets (508) (523)
Upside 2 | Retail credit cards | Impairment allowance | Financial assets at amortised cost | Lifetime expected credit losses | Stage 2 | Total weighted model ECL    
Disclosure of nature and extent of risks arising from financial instruments [line items]    
Financial assets (1,010) (1,099)
Upside 2 | Retail credit cards | Impairment allowance | Financial assets at amortised cost | Lifetime expected credit losses | Stage 3 | Total weighted model ECL    
Disclosure of nature and extent of risks arising from financial instruments [line items]    
Financial assets £ (1,596) £ (1,548)
Upside 2 | Retail other | Financial assets at amortised cost | Stage 1 | Total weighted model ECL    
Disclosure of nature and extent of risks arising from financial instruments [line items]    
Coverage ratio 0.003 0.005
Upside 2 | Retail other | Financial assets at amortised cost | Lifetime expected credit losses | Stage 2 | Total weighted model ECL    
Disclosure of nature and extent of risks arising from financial instruments [line items]    
Coverage ratio 0.047 0.064
Upside 2 | Retail other | Financial assets at amortised cost | Lifetime expected credit losses | Stage 3 | Total weighted model ECL    
Disclosure of nature and extent of risks arising from financial instruments [line items]    
Coverage ratio 0.357 0.594
Upside 2 | Retail other | Gross exposure | Financial assets at amortised cost | Stage 1 | Total weighted model ECL    
Disclosure of nature and extent of risks arising from financial instruments [line items]    
Financial assets £ 13,298 £ 6,378
Upside 2 | Retail other | Gross exposure | Financial assets at amortised cost | Lifetime expected credit losses | Stage 2 | Total weighted model ECL    
Disclosure of nature and extent of risks arising from financial instruments [line items]    
Financial assets 1,567 1,046
Upside 2 | Retail other | Gross exposure | Financial assets at amortised cost | Lifetime expected credit losses | Stage 3 | Total weighted model ECL    
Disclosure of nature and extent of risks arising from financial instruments [line items]    
Financial assets 185 128
Upside 2 | Retail other | Impairment allowance | Financial assets at amortised cost | Total weighted model ECL    
Disclosure of nature and extent of risks arising from financial instruments [line items]    
Financial assets (174) (173)
Upside 2 | Retail other | Impairment allowance | Financial assets at amortised cost | Stage 1 | Total weighted model ECL    
Disclosure of nature and extent of risks arising from financial instruments [line items]    
Financial assets (35) (30)
Upside 2 | Retail other | Impairment allowance | Financial assets at amortised cost | Lifetime expected credit losses | Stage 2 | Total weighted model ECL    
Disclosure of nature and extent of risks arising from financial instruments [line items]    
Financial assets (73) (67)
Upside 2 | Retail other | Impairment allowance | Financial assets at amortised cost | Lifetime expected credit losses | Stage 3 | Total weighted model ECL    
Disclosure of nature and extent of risks arising from financial instruments [line items]    
Financial assets £ (66) £ (76)
Upside 2 | Corporate loans | Financial assets at amortised cost | Stage 1 | Total weighted model ECL    
Disclosure of nature and extent of risks arising from financial instruments [line items]    
Coverage ratio 0.001 0.001
Upside 2 | Corporate loans | Financial assets at amortised cost | Lifetime expected credit losses | Stage 2 | Total weighted model ECL    
Disclosure of nature and extent of risks arising from financial instruments [line items]    
Coverage ratio 0.021 0.024
Upside 2 | Corporate loans | Financial assets at amortised cost | Lifetime expected credit losses | Stage 3 | Total weighted model ECL    
Disclosure of nature and extent of risks arising from financial instruments [line items]    
Coverage ratio 0.017 0.016
Upside 2 | Corporate loans | Gross exposure | Financial assets at amortised cost | Stage 1 | Total weighted model ECL    
Disclosure of nature and extent of risks arising from financial instruments [line items]    
Financial assets £ 236,716 £ 222,057
Upside 2 | Corporate loans | Gross exposure | Financial assets at amortised cost | Lifetime expected credit losses | Stage 2 | Total weighted model ECL    
Disclosure of nature and extent of risks arising from financial instruments [line items]    
Financial assets 17,431 16,264
Upside 2 | Corporate loans | Gross exposure | Financial assets at amortised cost | Lifetime expected credit losses | Stage 3 | Total weighted model ECL    
Disclosure of nature and extent of risks arising from financial instruments [line items]    
Financial assets 3,658 3,650
Upside 2 | Corporate loans | Impairment allowance | Financial assets at amortised cost | Total weighted model ECL    
Disclosure of nature and extent of risks arising from financial instruments [line items]    
Financial assets (633) (641)
Upside 2 | Corporate loans | Impairment allowance | Financial assets at amortised cost | Stage 1 | Total weighted model ECL    
Disclosure of nature and extent of risks arising from financial instruments [line items]    
Financial assets (212) (201)
Upside 2 | Corporate loans | Impairment allowance | Financial assets at amortised cost | Lifetime expected credit losses | Stage 2 | Total weighted model ECL    
Disclosure of nature and extent of risks arising from financial instruments [line items]    
Financial assets (359) (383)
Upside 2 | Corporate loans | Impairment allowance | Financial assets at amortised cost | Lifetime expected credit losses | Stage 3 | Total weighted model ECL    
Disclosure of nature and extent of risks arising from financial instruments [line items]    
Financial assets (62) (57)
Upside 1 | Loans and advances | Impairment allowance | Financial assets at amortised cost | Total weighted model ECL    
Disclosure of nature and extent of risks arising from financial instruments [line items]    
Financial assets £ (4,094) £ (4,161)
Upside 1 | Retail mortgages | Financial assets at amortised cost | Stage 1 | Total weighted model ECL    
Disclosure of nature and extent of risks arising from financial instruments [line items]    
Coverage ratio 0 0
Upside 1 | Retail mortgages | Financial assets at amortised cost | Lifetime expected credit losses | Stage 2 | Total weighted model ECL    
Disclosure of nature and extent of risks arising from financial instruments [line items]    
Coverage ratio 0.001 0.001
Upside 1 | Retail mortgages | Financial assets at amortised cost | Lifetime expected credit losses | Stage 3 | Total weighted model ECL    
Disclosure of nature and extent of risks arising from financial instruments [line items]    
Coverage ratio 0.021 0.022
Upside 1 | Retail mortgages | Gross exposure | Financial assets at amortised cost | Stage 1 | Total weighted model ECL    
Disclosure of nature and extent of risks arising from financial instruments [line items]    
Financial assets £ 157,553 £ 150,144
Upside 1 | Retail mortgages | Gross exposure | Financial assets at amortised cost | Lifetime expected credit losses | Stage 2 | Total weighted model ECL    
Disclosure of nature and extent of risks arising from financial instruments [line items]    
Financial assets 12,509 12,446
Upside 1 | Retail mortgages | Gross exposure | Financial assets at amortised cost | Lifetime expected credit losses | Stage 3 | Total weighted model ECL    
Disclosure of nature and extent of risks arising from financial instruments [line items]    
Financial assets 1,617 1,621
Upside 1 | Retail mortgages | Impairment allowance | Financial assets at amortised cost | Total weighted model ECL    
Disclosure of nature and extent of risks arising from financial instruments [line items]    
Financial assets (50) (45)
Upside 1 | Retail mortgages | Impairment allowance | Financial assets at amortised cost | Stage 1 | Total weighted model ECL    
Disclosure of nature and extent of risks arising from financial instruments [line items]    
Financial assets (5) (2)
Upside 1 | Retail mortgages | Impairment allowance | Financial assets at amortised cost | Lifetime expected credit losses | Stage 2 | Total weighted model ECL    
Disclosure of nature and extent of risks arising from financial instruments [line items]    
Financial assets (11) (8)
Upside 1 | Retail mortgages | Impairment allowance | Financial assets at amortised cost | Lifetime expected credit losses | Stage 3 | Total weighted model ECL    
Disclosure of nature and extent of risks arising from financial instruments [line items]    
Financial assets £ (34) £ (35)
Upside 1 | Retail credit cards | Financial assets at amortised cost | Stage 1 | Total weighted model ECL    
Disclosure of nature and extent of risks arising from financial instruments [line items]    
Coverage ratio 0.009 0.009
Upside 1 | Retail credit cards | Financial assets at amortised cost | Lifetime expected credit losses | Stage 2 | Total weighted model ECL    
Disclosure of nature and extent of risks arising from financial instruments [line items]    
Coverage ratio 0.211 0.218
Upside 1 | Retail credit cards | Financial assets at amortised cost | Lifetime expected credit losses | Stage 3 | Total weighted model ECL    
Disclosure of nature and extent of risks arising from financial instruments [line items]    
Coverage ratio 0.727 0.729
Upside 1 | Retail credit cards | Gross exposure | Financial assets at amortised cost | Stage 1 | Total weighted model ECL    
Disclosure of nature and extent of risks arising from financial instruments [line items]    
Financial assets £ 60,899 £ 61,204
Upside 1 | Retail credit cards | Gross exposure | Financial assets at amortised cost | Lifetime expected credit losses | Stage 2 | Total weighted model ECL    
Disclosure of nature and extent of risks arising from financial instruments [line items]    
Financial assets 4,925 5,224
Upside 1 | Retail credit cards | Gross exposure | Financial assets at amortised cost | Lifetime expected credit losses | Stage 3 | Total weighted model ECL    
Disclosure of nature and extent of risks arising from financial instruments [line items]    
Financial assets 2,229 2,158
Upside 1 | Retail credit cards | Impairment allowance | Financial assets at amortised cost | Total weighted model ECL    
Disclosure of nature and extent of risks arising from financial instruments [line items]    
Financial assets (3,187) (3,252)
Upside 1 | Retail credit cards | Impairment allowance | Financial assets at amortised cost | Stage 1 | Total weighted model ECL    
Disclosure of nature and extent of risks arising from financial instruments [line items]    
Financial assets (526) (541)
Upside 1 | Retail credit cards | Impairment allowance | Financial assets at amortised cost | Lifetime expected credit losses | Stage 2 | Total weighted model ECL    
Disclosure of nature and extent of risks arising from financial instruments [line items]    
Financial assets (1,040) (1,138)
Upside 1 | Retail credit cards | Impairment allowance | Financial assets at amortised cost | Lifetime expected credit losses | Stage 3 | Total weighted model ECL    
Disclosure of nature and extent of risks arising from financial instruments [line items]    
Financial assets £ (1,621) £ (1,573)
Upside 1 | Retail other | Financial assets at amortised cost | Stage 1 | Total weighted model ECL    
Disclosure of nature and extent of risks arising from financial instruments [line items]    
Coverage ratio 0.003 0.005
Upside 1 | Retail other | Financial assets at amortised cost | Lifetime expected credit losses | Stage 2 | Total weighted model ECL    
Disclosure of nature and extent of risks arising from financial instruments [line items]    
Coverage ratio 0.048 0.066
Upside 1 | Retail other | Financial assets at amortised cost | Lifetime expected credit losses | Stage 3 | Total weighted model ECL    
Disclosure of nature and extent of risks arising from financial instruments [line items]    
Coverage ratio 0.357 0.602
Upside 1 | Retail other | Gross exposure | Financial assets at amortised cost | Stage 1 | Total weighted model ECL    
Disclosure of nature and extent of risks arising from financial instruments [line items]    
Financial assets £ 13,243 £ 6,326
Upside 1 | Retail other | Gross exposure | Financial assets at amortised cost | Lifetime expected credit losses | Stage 2 | Total weighted model ECL    
Disclosure of nature and extent of risks arising from financial instruments [line items]    
Financial assets 1,622 1,098
Upside 1 | Retail other | Gross exposure | Financial assets at amortised cost | Lifetime expected credit losses | Stage 3 | Total weighted model ECL    
Disclosure of nature and extent of risks arising from financial instruments [line items]    
Financial assets 185 128
Upside 1 | Retail other | Impairment allowance | Financial assets at amortised cost | Total weighted model ECL    
Disclosure of nature and extent of risks arising from financial instruments [line items]    
Financial assets (180) (180)
Upside 1 | Retail other | Impairment allowance | Financial assets at amortised cost | Stage 1 | Total weighted model ECL    
Disclosure of nature and extent of risks arising from financial instruments [line items]    
Financial assets (36) (31)
Upside 1 | Retail other | Impairment allowance | Financial assets at amortised cost | Lifetime expected credit losses | Stage 2 | Total weighted model ECL    
Disclosure of nature and extent of risks arising from financial instruments [line items]    
Financial assets (78) (72)
Upside 1 | Retail other | Impairment allowance | Financial assets at amortised cost | Lifetime expected credit losses | Stage 3 | Total weighted model ECL    
Disclosure of nature and extent of risks arising from financial instruments [line items]    
Financial assets £ (66) £ (77)
Upside 1 | Corporate loans | Financial assets at amortised cost | Stage 1 | Total weighted model ECL    
Disclosure of nature and extent of risks arising from financial instruments [line items]    
Coverage ratio 0.001 0.001
Upside 1 | Corporate loans | Financial assets at amortised cost | Lifetime expected credit losses | Stage 2 | Total weighted model ECL    
Disclosure of nature and extent of risks arising from financial instruments [line items]    
Coverage ratio 0.022 0.024
Upside 1 | Corporate loans | Financial assets at amortised cost | Lifetime expected credit losses | Stage 3 | Total weighted model ECL    
Disclosure of nature and extent of risks arising from financial instruments [line items]    
Coverage ratio 0.017 0.016
Upside 1 | Corporate loans | Gross exposure | Financial assets at amortised cost | Stage 1 | Total weighted model ECL    
Disclosure of nature and extent of risks arising from financial instruments [line items]    
Financial assets £ 236,161 £ 221,337
Upside 1 | Corporate loans | Gross exposure | Financial assets at amortised cost | Lifetime expected credit losses | Stage 2 | Total weighted model ECL    
Disclosure of nature and extent of risks arising from financial instruments [line items]    
Financial assets 18,046 17,037
Upside 1 | Corporate loans | Gross exposure | Financial assets at amortised cost | Lifetime expected credit losses | Stage 3 | Total weighted model ECL    
Disclosure of nature and extent of risks arising from financial instruments [line items]    
Financial assets 3,658 3,650
Upside 1 | Corporate loans | Impairment allowance | Financial assets at amortised cost | Total weighted model ECL    
Disclosure of nature and extent of risks arising from financial instruments [line items]    
Financial assets (677) (684)
Upside 1 | Corporate loans | Impairment allowance | Financial assets at amortised cost | Stage 1 | Total weighted model ECL    
Disclosure of nature and extent of risks arising from financial instruments [line items]    
Financial assets (224) (212)
Upside 1 | Corporate loans | Impairment allowance | Financial assets at amortised cost | Lifetime expected credit losses | Stage 2 | Total weighted model ECL    
Disclosure of nature and extent of risks arising from financial instruments [line items]    
Financial assets (390) (415)
Upside 1 | Corporate loans | Impairment allowance | Financial assets at amortised cost | Lifetime expected credit losses | Stage 3 | Total weighted model ECL    
Disclosure of nature and extent of risks arising from financial instruments [line items]    
Financial assets (63) (57)
Baseline | Loans and advances | Impairment allowance | Financial assets at amortised cost | Total weighted model ECL    
Disclosure of nature and extent of risks arising from financial instruments [line items]    
Financial assets £ (4,240) £ (4,302)
Baseline | Retail mortgages | Financial assets at amortised cost | Stage 1 | Total weighted model ECL    
Disclosure of nature and extent of risks arising from financial instruments [line items]    
Coverage ratio 0 0
Baseline | Retail mortgages | Financial assets at amortised cost | Lifetime expected credit losses | Stage 2 | Total weighted model ECL    
Disclosure of nature and extent of risks arising from financial instruments [line items]    
Coverage ratio 0.001 0.001
Baseline | Retail mortgages | Financial assets at amortised cost | Lifetime expected credit losses | Stage 3 | Total weighted model ECL    
Disclosure of nature and extent of risks arising from financial instruments [line items]    
Coverage ratio 0.024 0.023
Baseline | Retail mortgages | Gross exposure | Financial assets at amortised cost | Stage 1 | Total weighted model ECL    
Disclosure of nature and extent of risks arising from financial instruments [line items]    
Financial assets £ 156,010 £ 148,760
Baseline | Retail mortgages | Gross exposure | Financial assets at amortised cost | Lifetime expected credit losses | Stage 2 | Total weighted model ECL    
Disclosure of nature and extent of risks arising from financial instruments [line items]    
Financial assets 14,051 13,830
Baseline | Retail mortgages | Gross exposure | Financial assets at amortised cost | Lifetime expected credit losses | Stage 3 | Total weighted model ECL    
Disclosure of nature and extent of risks arising from financial instruments [line items]    
Financial assets 1,617 1,621
Baseline | Retail mortgages | Impairment allowance | Financial assets at amortised cost | Total weighted model ECL    
Disclosure of nature and extent of risks arising from financial instruments [line items]    
Financial assets (63) (51)
Baseline | Retail mortgages | Impairment allowance | Financial assets at amortised cost | Stage 1 | Total weighted model ECL    
Disclosure of nature and extent of risks arising from financial instruments [line items]    
Financial assets (8) (2)
Baseline | Retail mortgages | Impairment allowance | Financial assets at amortised cost | Lifetime expected credit losses | Stage 2 | Total weighted model ECL    
Disclosure of nature and extent of risks arising from financial instruments [line items]    
Financial assets (17) (11)
Baseline | Retail mortgages | Impairment allowance | Financial assets at amortised cost | Lifetime expected credit losses | Stage 3 | Total weighted model ECL    
Disclosure of nature and extent of risks arising from financial instruments [line items]    
Financial assets £ (38) £ (38)
Baseline | Retail credit cards | Financial assets at amortised cost | Stage 1 | Total weighted model ECL    
Disclosure of nature and extent of risks arising from financial instruments [line items]    
Coverage ratio 0.009 0.009
Baseline | Retail credit cards | Financial assets at amortised cost | Lifetime expected credit losses | Stage 2 | Total weighted model ECL    
Disclosure of nature and extent of risks arising from financial instruments [line items]    
Coverage ratio 0.215 0.222
Baseline | Retail credit cards | Financial assets at amortised cost | Lifetime expected credit losses | Stage 3 | Total weighted model ECL    
Disclosure of nature and extent of risks arising from financial instruments [line items]    
Coverage ratio 0.738 0.740
Baseline | Retail credit cards | Gross exposure | Financial assets at amortised cost | Stage 1 | Total weighted model ECL    
Disclosure of nature and extent of risks arising from financial instruments [line items]    
Financial assets £ 61,019 £ 61,325
Baseline | Retail credit cards | Gross exposure | Financial assets at amortised cost | Lifetime expected credit losses | Stage 2 | Total weighted model ECL    
Disclosure of nature and extent of risks arising from financial instruments [line items]    
Financial assets 4,985 5,301
Baseline | Retail credit cards | Gross exposure | Financial assets at amortised cost | Lifetime expected credit losses | Stage 3 | Total weighted model ECL    
Disclosure of nature and extent of risks arising from financial instruments [line items]    
Financial assets 2,229 2,158
Baseline | Retail credit cards | Impairment allowance | Financial assets at amortised cost | Total weighted model ECL    
Disclosure of nature and extent of risks arising from financial instruments [line items]    
Financial assets (3,261) (3,332)
Baseline | Retail credit cards | Impairment allowance | Financial assets at amortised cost | Stage 1 | Total weighted model ECL    
Disclosure of nature and extent of risks arising from financial instruments [line items]    
Financial assets (545) (561)
Baseline | Retail credit cards | Impairment allowance | Financial assets at amortised cost | Lifetime expected credit losses | Stage 2 | Total weighted model ECL    
Disclosure of nature and extent of risks arising from financial instruments [line items]    
Financial assets (1,071) (1,175)
Baseline | Retail credit cards | Impairment allowance | Financial assets at amortised cost | Lifetime expected credit losses | Stage 3 | Total weighted model ECL    
Disclosure of nature and extent of risks arising from financial instruments [line items]    
Financial assets £ (1,645) £ (1,596)
Baseline | Retail other | Financial assets at amortised cost | Stage 1 | Total weighted model ECL    
Disclosure of nature and extent of risks arising from financial instruments [line items]    
Coverage ratio 0.003 0.005
Baseline | Retail other | Financial assets at amortised cost | Lifetime expected credit losses | Stage 2 | Total weighted model ECL    
Disclosure of nature and extent of risks arising from financial instruments [line items]    
Coverage ratio 0.049 0.067
Baseline | Retail other | Financial assets at amortised cost | Lifetime expected credit losses | Stage 3 | Total weighted model ECL    
Disclosure of nature and extent of risks arising from financial instruments [line items]    
Coverage ratio 0.362 0.602
Baseline | Retail other | Gross exposure | Financial assets at amortised cost | Stage 1 | Total weighted model ECL    
Disclosure of nature and extent of risks arising from financial instruments [line items]    
Financial assets £ 13,176 £ 6,268
Baseline | Retail other | Gross exposure | Financial assets at amortised cost | Lifetime expected credit losses | Stage 2 | Total weighted model ECL    
Disclosure of nature and extent of risks arising from financial instruments [line items]    
Financial assets 1,689 1,156
Baseline | Retail other | Gross exposure | Financial assets at amortised cost | Lifetime expected credit losses | Stage 3 | Total weighted model ECL    
Disclosure of nature and extent of risks arising from financial instruments [line items]    
Financial assets 185 128
Baseline | Retail other | Impairment allowance | Financial assets at amortised cost | Total weighted model ECL    
Disclosure of nature and extent of risks arising from financial instruments [line items]    
Financial assets (188) (185)
Baseline | Retail other | Impairment allowance | Financial assets at amortised cost | Stage 1 | Total weighted model ECL    
Disclosure of nature and extent of risks arising from financial instruments [line items]    
Financial assets (38) (31)
Baseline | Retail other | Impairment allowance | Financial assets at amortised cost | Lifetime expected credit losses | Stage 2 | Total weighted model ECL    
Disclosure of nature and extent of risks arising from financial instruments [line items]    
Financial assets (83) (77)
Baseline | Retail other | Impairment allowance | Financial assets at amortised cost | Lifetime expected credit losses | Stage 3 | Total weighted model ECL    
Disclosure of nature and extent of risks arising from financial instruments [line items]    
Financial assets £ (67) £ (77)
Baseline | Corporate loans | Financial assets at amortised cost | Stage 1 | Total weighted model ECL    
Disclosure of nature and extent of risks arising from financial instruments [line items]    
Coverage ratio 0.001 0.001
Baseline | Corporate loans | Financial assets at amortised cost | Lifetime expected credit losses | Stage 2 | Total weighted model ECL    
Disclosure of nature and extent of risks arising from financial instruments [line items]    
Coverage ratio 0.023 0.025
Baseline | Corporate loans | Financial assets at amortised cost | Lifetime expected credit losses | Stage 3 | Total weighted model ECL    
Disclosure of nature and extent of risks arising from financial instruments [line items]    
Coverage ratio 0.017 0.016
Baseline | Corporate loans | Gross exposure | Financial assets at amortised cost | Stage 1 | Total weighted model ECL    
Disclosure of nature and extent of risks arising from financial instruments [line items]    
Financial assets £ 235,455 £ 220,646
Baseline | Corporate loans | Gross exposure | Financial assets at amortised cost | Lifetime expected credit losses | Stage 2 | Total weighted model ECL    
Disclosure of nature and extent of risks arising from financial instruments [line items]    
Financial assets 18,866 17,836
Baseline | Corporate loans | Gross exposure | Financial assets at amortised cost | Lifetime expected credit losses | Stage 3 | Total weighted model ECL    
Disclosure of nature and extent of risks arising from financial instruments [line items]    
Financial assets 3,658 3,650
Baseline | Corporate loans | Impairment allowance | Financial assets at amortised cost | Total weighted model ECL    
Disclosure of nature and extent of risks arising from financial instruments [line items]    
Financial assets (728) (734)
Baseline | Corporate loans | Impairment allowance | Financial assets at amortised cost | Stage 1 | Total weighted model ECL    
Disclosure of nature and extent of risks arising from financial instruments [line items]    
Financial assets (236) (221)
Baseline | Corporate loans | Impairment allowance | Financial assets at amortised cost | Lifetime expected credit losses | Stage 2 | Total weighted model ECL    
Disclosure of nature and extent of risks arising from financial instruments [line items]    
Financial assets (428) (454)
Baseline | Corporate loans | Impairment allowance | Financial assets at amortised cost | Lifetime expected credit losses | Stage 3 | Total weighted model ECL    
Disclosure of nature and extent of risks arising from financial instruments [line items]    
Financial assets (64) (59)
Downside 1 | Loans and advances | Impairment allowance | Financial assets at amortised cost | Total weighted model ECL    
Disclosure of nature and extent of risks arising from financial instruments [line items]    
Financial assets £ (4,800) £ (4,765)
Downside 1 | Retail mortgages | Financial assets at amortised cost | Stage 1 | Total weighted model ECL    
Disclosure of nature and extent of risks arising from financial instruments [line items]    
Coverage ratio 0 0
Downside 1 | Retail mortgages | Financial assets at amortised cost | Lifetime expected credit losses | Stage 2 | Total weighted model ECL    
Disclosure of nature and extent of risks arising from financial instruments [line items]    
Coverage ratio 0.003 0.002
Downside 1 | Retail mortgages | Financial assets at amortised cost | Lifetime expected credit losses | Stage 3 | Total weighted model ECL    
Disclosure of nature and extent of risks arising from financial instruments [line items]    
Coverage ratio 0.038 0.036
Downside 1 | Retail mortgages | Gross exposure | Financial assets at amortised cost | Stage 1 | Total weighted model ECL    
Disclosure of nature and extent of risks arising from financial instruments [line items]    
Financial assets £ 152,793 £ 146,786
Downside 1 | Retail mortgages | Gross exposure | Financial assets at amortised cost | Lifetime expected credit losses | Stage 2 | Total weighted model ECL    
Disclosure of nature and extent of risks arising from financial instruments [line items]    
Financial assets 17,268 15,804
Downside 1 | Retail mortgages | Gross exposure | Financial assets at amortised cost | Lifetime expected credit losses | Stage 3 | Total weighted model ECL    
Disclosure of nature and extent of risks arising from financial instruments [line items]    
Financial assets 1,617 1,621
Downside 1 | Retail mortgages | Impairment allowance | Financial assets at amortised cost | Total weighted model ECL    
Disclosure of nature and extent of risks arising from financial instruments [line items]    
Financial assets (136) (98)
Downside 1 | Retail mortgages | Impairment allowance | Financial assets at amortised cost | Stage 1 | Total weighted model ECL    
Disclosure of nature and extent of risks arising from financial instruments [line items]    
Financial assets (23) (6)
Downside 1 | Retail mortgages | Impairment allowance | Financial assets at amortised cost | Lifetime expected credit losses | Stage 2 | Total weighted model ECL    
Disclosure of nature and extent of risks arising from financial instruments [line items]    
Financial assets (51) (33)
Downside 1 | Retail mortgages | Impairment allowance | Financial assets at amortised cost | Lifetime expected credit losses | Stage 3 | Total weighted model ECL    
Disclosure of nature and extent of risks arising from financial instruments [line items]    
Financial assets £ (62) £ (59)
Downside 1 | Retail credit cards | Financial assets at amortised cost | Stage 1 | Total weighted model ECL    
Disclosure of nature and extent of risks arising from financial instruments [line items]    
Coverage ratio 0.010 0.010
Downside 1 | Retail credit cards | Financial assets at amortised cost | Lifetime expected credit losses | Stage 2 | Total weighted model ECL    
Disclosure of nature and extent of risks arising from financial instruments [line items]    
Coverage ratio 0.229 0.233
Downside 1 | Retail credit cards | Financial assets at amortised cost | Lifetime expected credit losses | Stage 3 | Total weighted model ECL    
Disclosure of nature and extent of risks arising from financial instruments [line items]    
Coverage ratio 0.756 0.756
Downside 1 | Retail credit cards | Gross exposure | Financial assets at amortised cost | Stage 1 | Total weighted model ECL    
Disclosure of nature and extent of risks arising from financial instruments [line items]    
Financial assets £ 61,810 £ 61,569
Downside 1 | Retail credit cards | Gross exposure | Financial assets at amortised cost | Lifetime expected credit losses | Stage 2 | Total weighted model ECL    
Disclosure of nature and extent of risks arising from financial instruments [line items]    
Financial assets 5,165 5,478
Downside 1 | Retail credit cards | Gross exposure | Financial assets at amortised cost | Lifetime expected credit losses | Stage 3 | Total weighted model ECL    
Disclosure of nature and extent of risks arising from financial instruments [line items]    
Financial assets 2,229 2,158
Downside 1 | Retail credit cards | Impairment allowance | Financial assets at amortised cost | Total weighted model ECL    
Disclosure of nature and extent of risks arising from financial instruments [line items]    
Financial assets (3,513) (3,508)
Downside 1 | Retail credit cards | Impairment allowance | Financial assets at amortised cost | Stage 1 | Total weighted model ECL    
Disclosure of nature and extent of risks arising from financial instruments [line items]    
Financial assets (643) (599)
Downside 1 | Retail credit cards | Impairment allowance | Financial assets at amortised cost | Lifetime expected credit losses | Stage 2 | Total weighted model ECL    
Disclosure of nature and extent of risks arising from financial instruments [line items]    
Financial assets (1,184) (1,277)
Downside 1 | Retail credit cards | Impairment allowance | Financial assets at amortised cost | Lifetime expected credit losses | Stage 3 | Total weighted model ECL    
Disclosure of nature and extent of risks arising from financial instruments [line items]    
Financial assets £ (1,686) £ (1,632)
Downside 1 | Retail other | Financial assets at amortised cost | Stage 1 | Total weighted model ECL    
Disclosure of nature and extent of risks arising from financial instruments [line items]    
Coverage ratio 0.003 0.006
Downside 1 | Retail other | Financial assets at amortised cost | Lifetime expected credit losses | Stage 2 | Total weighted model ECL    
Disclosure of nature and extent of risks arising from financial instruments [line items]    
Coverage ratio 0.053 0.077
Downside 1 | Retail other | Financial assets at amortised cost | Lifetime expected credit losses | Stage 3 | Total weighted model ECL    
Disclosure of nature and extent of risks arising from financial instruments [line items]    
Coverage ratio 0.368 0.625
Downside 1 | Retail other | Gross exposure | Financial assets at amortised cost | Stage 1 | Total weighted model ECL    
Disclosure of nature and extent of risks arising from financial instruments [line items]    
Financial assets £ 13,019 £ 6,106
Downside 1 | Retail other | Gross exposure | Financial assets at amortised cost | Lifetime expected credit losses | Stage 2 | Total weighted model ECL    
Disclosure of nature and extent of risks arising from financial instruments [line items]    
Financial assets 1,846 1,318
Downside 1 | Retail other | Gross exposure | Financial assets at amortised cost | Lifetime expected credit losses | Stage 3 | Total weighted model ECL    
Disclosure of nature and extent of risks arising from financial instruments [line items]    
Financial assets 185 128
Downside 1 | Retail other | Impairment allowance | Financial assets at amortised cost | Total weighted model ECL    
Disclosure of nature and extent of risks arising from financial instruments [line items]    
Financial assets (204) (217)
Downside 1 | Retail other | Impairment allowance | Financial assets at amortised cost | Stage 1 | Total weighted model ECL    
Disclosure of nature and extent of risks arising from financial instruments [line items]    
Financial assets (39) (35)
Downside 1 | Retail other | Impairment allowance | Financial assets at amortised cost | Lifetime expected credit losses | Stage 2 | Total weighted model ECL    
Disclosure of nature and extent of risks arising from financial instruments [line items]    
Financial assets (97) (102)
Downside 1 | Retail other | Impairment allowance | Financial assets at amortised cost | Lifetime expected credit losses | Stage 3 | Total weighted model ECL    
Disclosure of nature and extent of risks arising from financial instruments [line items]    
Financial assets £ (68) £ (80)
Downside 1 | Corporate loans | Financial assets at amortised cost | Stage 1 | Total weighted model ECL    
Disclosure of nature and extent of risks arising from financial instruments [line items]    
Coverage ratio 0.001 0.001
Downside 1 | Corporate loans | Financial assets at amortised cost | Lifetime expected credit losses | Stage 2 | Total weighted model ECL    
Disclosure of nature and extent of risks arising from financial instruments [line items]    
Coverage ratio 0.027 0.030
Downside 1 | Corporate loans | Financial assets at amortised cost | Lifetime expected credit losses | Stage 3 | Total weighted model ECL    
Disclosure of nature and extent of risks arising from financial instruments [line items]    
Coverage ratio 0.020 0.018
Downside 1 | Corporate loans | Gross exposure | Financial assets at amortised cost | Stage 1 | Total weighted model ECL    
Disclosure of nature and extent of risks arising from financial instruments [line items]    
Financial assets £ 233,473 £ 218,634
Downside 1 | Corporate loans | Gross exposure | Financial assets at amortised cost | Lifetime expected credit losses | Stage 2 | Total weighted model ECL    
Disclosure of nature and extent of risks arising from financial instruments [line items]    
Financial assets 20,974 19,979
Downside 1 | Corporate loans | Gross exposure | Financial assets at amortised cost | Lifetime expected credit losses | Stage 3 | Total weighted model ECL    
Disclosure of nature and extent of risks arising from financial instruments [line items]    
Financial assets 3,658 3,650
Downside 1 | Corporate loans | Impairment allowance | Financial assets at amortised cost | Total weighted model ECL    
Disclosure of nature and extent of risks arising from financial instruments [line items]    
Financial assets (947) (942)
Downside 1 | Corporate loans | Impairment allowance | Financial assets at amortised cost | Stage 1 | Total weighted model ECL    
Disclosure of nature and extent of risks arising from financial instruments [line items]    
Financial assets (299) (274)
Downside 1 | Corporate loans | Impairment allowance | Financial assets at amortised cost | Lifetime expected credit losses | Stage 2 | Total weighted model ECL    
Disclosure of nature and extent of risks arising from financial instruments [line items]    
Financial assets (576) (604)
Downside 1 | Corporate loans | Impairment allowance | Financial assets at amortised cost | Lifetime expected credit losses | Stage 3 | Total weighted model ECL    
Disclosure of nature and extent of risks arising from financial instruments [line items]    
Financial assets (72) (64)
Downside 2 | Loans and advances | Impairment allowance | Financial assets at amortised cost | Total weighted model ECL    
Disclosure of nature and extent of risks arising from financial instruments [line items]    
Financial assets £ (5,666) £ (5,443)
Downside 2 | Retail mortgages | Financial assets at amortised cost | Stage 1 | Total weighted model ECL    
Disclosure of nature and extent of risks arising from financial instruments [line items]    
Coverage ratio 0 0
Downside 2 | Retail mortgages | Financial assets at amortised cost | Lifetime expected credit losses | Stage 2 | Total weighted model ECL    
Disclosure of nature and extent of risks arising from financial instruments [line items]    
Coverage ratio 0.006 0.004
Downside 2 | Retail mortgages | Financial assets at amortised cost | Lifetime expected credit losses | Stage 3 | Total weighted model ECL    
Disclosure of nature and extent of risks arising from financial instruments [line items]    
Coverage ratio 0.065 0.060
Downside 2 | Retail mortgages | Gross exposure | Financial assets at amortised cost | Stage 1 | Total weighted model ECL    
Disclosure of nature and extent of risks arising from financial instruments [line items]    
Financial assets £ 148,752 £ 144,360
Downside 2 | Retail mortgages | Gross exposure | Financial assets at amortised cost | Lifetime expected credit losses | Stage 2 | Total weighted model ECL    
Disclosure of nature and extent of risks arising from financial instruments [line items]    
Financial assets 21,309 18,230
Downside 2 | Retail mortgages | Gross exposure | Financial assets at amortised cost | Lifetime expected credit losses | Stage 3 | Total weighted model ECL    
Disclosure of nature and extent of risks arising from financial instruments [line items]    
Financial assets 1,617 1,621
Downside 2 | Retail mortgages | Impairment allowance | Financial assets at amortised cost | Total weighted model ECL    
Disclosure of nature and extent of risks arising from financial instruments [line items]    
Financial assets (294) (190)
Downside 2 | Retail mortgages | Impairment allowance | Financial assets at amortised cost | Stage 1 | Total weighted model ECL    
Disclosure of nature and extent of risks arising from financial instruments [line items]    
Financial assets (58) (13)
Downside 2 | Retail mortgages | Impairment allowance | Financial assets at amortised cost | Lifetime expected credit losses | Stage 2 | Total weighted model ECL    
Disclosure of nature and extent of risks arising from financial instruments [line items]    
Financial assets (131) (79)
Downside 2 | Retail mortgages | Impairment allowance | Financial assets at amortised cost | Lifetime expected credit losses | Stage 3 | Total weighted model ECL    
Disclosure of nature and extent of risks arising from financial instruments [line items]    
Financial assets £ (105) £ (98)
Downside 2 | Retail credit cards | Financial assets at amortised cost | Stage 1 | Total weighted model ECL    
Disclosure of nature and extent of risks arising from financial instruments [line items]    
Coverage ratio 0.012 0.010
Downside 2 | Retail credit cards | Financial assets at amortised cost | Lifetime expected credit losses | Stage 2 | Total weighted model ECL    
Disclosure of nature and extent of risks arising from financial instruments [line items]    
Coverage ratio 0.246 0.246
Downside 2 | Retail credit cards | Financial assets at amortised cost | Lifetime expected credit losses | Stage 3 | Total weighted model ECL    
Disclosure of nature and extent of risks arising from financial instruments [line items]    
Coverage ratio 0.772 0.771
Downside 2 | Retail credit cards | Gross exposure | Financial assets at amortised cost | Stage 1 | Total weighted model ECL    
Disclosure of nature and extent of risks arising from financial instruments [line items]    
Financial assets £ 62,521 £ 61,724
Downside 2 | Retail credit cards | Gross exposure | Financial assets at amortised cost | Lifetime expected credit losses | Stage 2 | Total weighted model ECL    
Disclosure of nature and extent of risks arising from financial instruments [line items]    
Financial assets 5,448 5,759
Downside 2 | Retail credit cards | Gross exposure | Financial assets at amortised cost | Lifetime expected credit losses | Stage 3 | Total weighted model ECL    
Disclosure of nature and extent of risks arising from financial instruments [line items]    
Financial assets 2,229 2,158
Downside 2 | Retail credit cards | Impairment allowance | Financial assets at amortised cost | Total weighted model ECL    
Disclosure of nature and extent of risks arising from financial instruments [line items]    
Financial assets (3,821) (3,715)
Downside 2 | Retail credit cards | Impairment allowance | Financial assets at amortised cost | Stage 1 | Total weighted model ECL    
Disclosure of nature and extent of risks arising from financial instruments [line items]    
Financial assets (761) (637)
Downside 2 | Retail credit cards | Impairment allowance | Financial assets at amortised cost | Lifetime expected credit losses | Stage 2 | Total weighted model ECL    
Disclosure of nature and extent of risks arising from financial instruments [line items]    
Financial assets (1,339) (1,415)
Downside 2 | Retail credit cards | Impairment allowance | Financial assets at amortised cost | Lifetime expected credit losses | Stage 3 | Total weighted model ECL    
Disclosure of nature and extent of risks arising from financial instruments [line items]    
Financial assets £ (1,721) £ (1,663)
Downside 2 | Retail other | Financial assets at amortised cost | Stage 1 | Total weighted model ECL    
Disclosure of nature and extent of risks arising from financial instruments [line items]    
Coverage ratio 0.003 0.006
Downside 2 | Retail other | Financial assets at amortised cost | Lifetime expected credit losses | Stage 2 | Total weighted model ECL    
Disclosure of nature and extent of risks arising from financial instruments [line items]    
Coverage ratio 0.056 0.090
Downside 2 | Retail other | Financial assets at amortised cost | Lifetime expected credit losses | Stage 3 | Total weighted model ECL    
Disclosure of nature and extent of risks arising from financial instruments [line items]    
Coverage ratio 0.373 0.680
Downside 2 | Retail other | Gross exposure | Financial assets at amortised cost | Stage 1 | Total weighted model ECL    
Disclosure of nature and extent of risks arising from financial instruments [line items]    
Financial assets £ 12,846 £ 5,927
Downside 2 | Retail other | Gross exposure | Financial assets at amortised cost | Lifetime expected credit losses | Stage 2 | Total weighted model ECL    
Disclosure of nature and extent of risks arising from financial instruments [line items]    
Financial assets 2,019 1,497
Downside 2 | Retail other | Gross exposure | Financial assets at amortised cost | Lifetime expected credit losses | Stage 3 | Total weighted model ECL    
Disclosure of nature and extent of risks arising from financial instruments [line items]    
Financial assets 185 128
Downside 2 | Retail other | Impairment allowance | Financial assets at amortised cost | Total weighted model ECL    
Disclosure of nature and extent of risks arising from financial instruments [line items]    
Financial assets (225) (259)
Downside 2 | Retail other | Impairment allowance | Financial assets at amortised cost | Stage 1 | Total weighted model ECL    
Disclosure of nature and extent of risks arising from financial instruments [line items]    
Financial assets (43) (38)
Downside 2 | Retail other | Impairment allowance | Financial assets at amortised cost | Lifetime expected credit losses | Stage 2 | Total weighted model ECL    
Disclosure of nature and extent of risks arising from financial instruments [line items]    
Financial assets (113) (134)
Downside 2 | Retail other | Impairment allowance | Financial assets at amortised cost | Lifetime expected credit losses | Stage 3 | Total weighted model ECL    
Disclosure of nature and extent of risks arising from financial instruments [line items]    
Financial assets £ (69) £ (87)
Downside 2 | Corporate loans | Financial assets at amortised cost | Stage 1 | Total weighted model ECL    
Disclosure of nature and extent of risks arising from financial instruments [line items]    
Coverage ratio 0.002 0.002
Downside 2 | Corporate loans | Financial assets at amortised cost | Lifetime expected credit losses | Stage 2 | Total weighted model ECL    
Disclosure of nature and extent of risks arising from financial instruments [line items]    
Coverage ratio 0.033 0.035
Downside 2 | Corporate loans | Financial assets at amortised cost | Lifetime expected credit losses | Stage 3 | Total weighted model ECL    
Disclosure of nature and extent of risks arising from financial instruments [line items]    
Coverage ratio 0.022 0.019
Downside 2 | Corporate loans | Gross exposure | Financial assets at amortised cost | Stage 1 | Total weighted model ECL    
Disclosure of nature and extent of risks arising from financial instruments [line items]    
Financial assets £ 228,609 £ 213,827
Downside 2 | Corporate loans | Gross exposure | Financial assets at amortised cost | Lifetime expected credit losses | Stage 2 | Total weighted model ECL    
Disclosure of nature and extent of risks arising from financial instruments [line items]    
Financial assets 25,984 24,927
Downside 2 | Corporate loans | Gross exposure | Financial assets at amortised cost | Lifetime expected credit losses | Stage 3 | Total weighted model ECL    
Disclosure of nature and extent of risks arising from financial instruments [line items]    
Financial assets 3,658 3,650
Downside 2 | Corporate loans | Impairment allowance | Financial assets at amortised cost | Total weighted model ECL    
Disclosure of nature and extent of risks arising from financial instruments [line items]    
Financial assets (1,326) (1,279)
Downside 2 | Corporate loans | Impairment allowance | Financial assets at amortised cost | Stage 1 | Total weighted model ECL    
Disclosure of nature and extent of risks arising from financial instruments [line items]    
Financial assets (379) (329)
Downside 2 | Corporate loans | Impairment allowance | Financial assets at amortised cost | Lifetime expected credit losses | Stage 2 | Total weighted model ECL    
Disclosure of nature and extent of risks arising from financial instruments [line items]    
Financial assets (867) (879)
Downside 2 | Corporate loans | Impairment allowance | Financial assets at amortised cost | Lifetime expected credit losses | Stage 3 | Total weighted model ECL    
Disclosure of nature and extent of risks arising from financial instruments [line items]    
Financial assets £ (80) £ (71)