v3.25.2
Credit Risk - Disclosure of measurement uncertainty - ECL under 100% weighted scenarios for modelled portfolios (Details)
£ in Millions
Jun. 30, 2025
GBP (£)
Dec. 31, 2024
GBP (£)
Impairment allowance    
Disclosure of nature and extent of risks arising from financial instruments [line items]    
Financial assets £ (5,395) £ (5,532)
Impairment allowance | Total weighted model ECL    
Disclosure of nature and extent of risks arising from financial instruments [line items]    
Financial assets (4,499) (4,737)
Impairment allowance | ECL from individually assessed impairments    
Disclosure of nature and extent of risks arising from financial instruments [line items]    
Financial assets (485) (461)
Impairment allowance | ECL from non-modelled exposures and others    
Disclosure of nature and extent of risks arising from financial instruments [line items]    
Financial assets (459) (358)
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 (295) (209)
Impairment allowance | ECL from debt securities at amortised cost    
Disclosure of nature and extent of risks arising from financial instruments [line items]    
Financial assets (24) (23)
Impairment allowance | ECL from held for sale assets (co-branded card portfolio)    
Disclosure of nature and extent of risks arising from financial instruments [line items]    
Financial assets 239 282
Impairment allowance | ECL from post model management adjustments    
Disclosure of nature and extent of risks arising from financial instruments [line items]    
Financial assets (167) (235)
Impairment allowance | ECL from economic uncertainty adjustments    
Disclosure of nature and extent of risks arising from financial instruments [line items]    
Financial assets (153) (78)
Loans and advances | Financial assets at amortised cost    
Disclosure of nature and extent of risks arising from financial instruments [line items]    
Financial assets £ 347,828 £ 346,273
Coverage ratio 0.014 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 £ 309,960 £ 305,836
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 £ 33,080 £ 35,402
Coverage ratio 0.051 0.047
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 £ 352,774 £ 351,343
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 310,773 306,774
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 34,840 37,153
Loans and advances | Impairment allowance | Total weighted model ECL    
Disclosure of nature and extent of risks arising from financial instruments [line items]    
Financial assets (4,500) (4,700)
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 (500) (500)
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 (4,946) (5,070)
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 (813) (938)
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 (1,760) (1,751)
Retail mortgages | Financial assets at amortised cost    
Disclosure of nature and extent of risks arising from financial instruments [line items]    
Financial assets £ 171,790 £ 168,061
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 £ 152,824 £ 146,652
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 £ 17,166 £ 19,534
Coverage ratio 0.003 0.003
Retail mortgages | Gross exposure    
Disclosure of nature and extent of risks arising from financial instruments [line items]    
Financial assets £ 171,970 £ 168,248
Retail mortgages | Gross exposure | Stage 1    
Disclosure of nature and extent of risks arising from financial instruments [line items]    
Financial assets 152,861 146,690
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 17,225 19,596
Retail mortgages | Gross exposure | Financial assets at amortised cost    
Disclosure of nature and extent of risks arising from financial instruments [line items]    
Financial assets 171,970 168,248
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 152,861 146,690
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 17,225 19,596
Retail mortgages | Impairment allowance    
Disclosure of nature and extent of risks arising from financial instruments [line items]    
Financial assets (180) (187)
Retail mortgages | Impairment allowance | Stage 1    
Disclosure of nature and extent of risks arising from financial instruments [line items]    
Financial assets (37) (38)
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 (59) (62)
Retail mortgages | Impairment allowance | Financial assets at amortised cost    
Disclosure of nature and extent of risks arising from financial instruments [line items]    
Financial assets (180) (187)
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 (37) (38)
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 (59) (62)
Retail credit cards | Financial assets at amortised cost    
Disclosure of nature and extent of risks arising from financial instruments [line items]    
Financial assets £ 33,600 £ 34,779
Coverage ratio 0.085 0.087
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 £ 29,311 £ 30,573
Coverage ratio 0.015 0.018
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 £ 3,872 £ 3,770
Coverage ratio 0.235 0.249
Retail credit cards | Gross exposure    
Disclosure of nature and extent of risks arising from financial instruments [line items]    
Financial assets £ 36,708 £ 38,086
Retail credit cards | Gross exposure | Stage 1    
Disclosure of nature and extent of risks arising from financial instruments [line items]    
Financial assets 29,768 31,126
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 5,064 5,017
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 36,708 38,086
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 29,768 31,126
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 5,064 5,017
Retail credit cards | Impairment allowance    
Disclosure of nature and extent of risks arising from financial instruments [line items]    
Financial assets (3,108) (3,307)
Retail credit cards | Impairment allowance | Stage 1    
Disclosure of nature and extent of risks arising from financial instruments [line items]    
Financial assets (457) (553)
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 (1,192) (1,247)
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 (3,108) (3,307)
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 (457) (553)
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 (1,192) (1,247)
Retail other | Financial assets at amortised cost    
Disclosure of nature and extent of risks arising from financial instruments [line items]    
Financial assets £ 13,806 £ 13,808
Coverage ratio 0.032 0.029
Retail other | Financial assets at amortised cost | Stage 1    
Disclosure of nature and extent of risks arising from financial instruments [line items]    
Financial assets £ 12,142 £ 12,312
Coverage ratio 0.008 0.011
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 £ 1,447 £ 1,262
Coverage ratio 0.096 0.081
Retail other | Gross exposure    
Disclosure of nature and extent of risks arising from financial instruments [line items]    
Financial assets £ 14,261 £ 14,218
Retail other | Gross exposure | Stage 1    
Disclosure of nature and extent of risks arising from financial instruments [line items]    
Financial assets 12,245 12,450
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 1,600 1,373
Retail other | Gross exposure | Financial assets at amortised cost    
Disclosure of nature and extent of risks arising from financial instruments [line items]    
Financial assets 14,261 14,218
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 12,245 12,450
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 1,600 1,373
Retail other | Impairment allowance    
Disclosure of nature and extent of risks arising from financial instruments [line items]    
Financial assets (455) (410)
Retail other | Impairment allowance | Stage 1    
Disclosure of nature and extent of risks arising from financial instruments [line items]    
Financial assets (103) (138)
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 (153) (111)
Retail other | Impairment allowance | Financial assets at amortised cost    
Disclosure of nature and extent of risks arising from financial instruments [line items]    
Financial assets (455) (410)
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 (103) (138)
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 (153) (111)
Corporate loans | Financial assets at amortised cost    
Disclosure of nature and extent of risks arising from financial instruments [line items]    
Financial assets £ 128,632 £ 129,625
Coverage ratio 0.009 0.009
Corporate loans | Financial assets at amortised cost | Stage 1    
Disclosure of nature and extent of risks arising from financial instruments [line items]    
Financial assets £ 115,683 £ 116,299
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 £ 10,595 £ 10,836
Coverage ratio 0.033 0.030
Corporate loans | Gross exposure    
Disclosure of nature and extent of risks arising from financial instruments [line items]    
Financial assets £ 129,835 £ 130,791
Corporate loans | Gross exposure | Stage 1    
Disclosure of nature and extent of risks arising from financial instruments [line items]    
Financial assets 115,899 116,508
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 10,951 11,167
Corporate loans | Gross exposure | Financial assets at amortised cost    
Disclosure of nature and extent of risks arising from financial instruments [line items]    
Financial assets 129,835 130,791
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 115,899 116,508
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 10,951 11,167
Corporate loans | Impairment allowance    
Disclosure of nature and extent of risks arising from financial instruments [line items]    
Financial assets (1,203) (1,166)
Corporate loans | Impairment allowance | Stage 1    
Disclosure of nature and extent of risks arising from financial instruments [line items]    
Financial assets (216) (209)
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 (356) (331)
Corporate loans | Impairment allowance | Financial assets at amortised cost    
Disclosure of nature and extent of risks arising from financial instruments [line items]    
Financial assets (1,203) (1,166)
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 (216) (209)
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 (356) (331)
Credit risk | 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 £ (4,499) £ (4,737)
Credit risk | 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
Credit risk | 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 0
Credit risk | Retail mortgages | Financial assets at amortised cost | Lifetime expected credit losses | Financial instruments credit-impaired | Total weighted model ECL    
Disclosure of nature and extent of risks arising from financial instruments [line items]    
Coverage ratio 0.016 0.018
Credit risk | 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 £ 143,893 £ 139,086
Credit risk | 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 17,837 20,401
Credit risk | Retail mortgages | Gross exposure | Financial assets at amortised cost | Lifetime expected credit losses | Financial instruments credit-impaired | Total weighted model ECL    
Disclosure of nature and extent of risks arising from financial instruments [line items]    
Financial assets 1,128 1,062
Credit risk | 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 (23) (24)
Credit risk | 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 (2) (1)
Credit risk | 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 (3) (4)
Credit risk | Retail mortgages | Impairment allowance | Financial assets at amortised cost | Lifetime expected credit losses | Financial instruments credit-impaired | Total weighted model ECL    
Disclosure of nature and extent of risks arising from financial instruments [line items]    
Financial assets £ (18) £ (19)
Credit risk | 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 0.008
Credit risk | 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 0.212 0.213
Credit risk | Retail credit cards | Financial assets at amortised cost | Lifetime expected credit losses | Financial instruments credit-impaired | Total weighted model ECL    
Disclosure of nature and extent of risks arising from financial instruments [line items]    
Coverage ratio 0.744 0.740
Credit risk | 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 £ 61,346 £ 63,937
Credit risk | 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 6,381 6,904
Credit risk | Retail credit cards | Gross exposure | Financial assets at amortised cost | Lifetime expected credit losses | Financial instruments credit-impaired | Total weighted model ECL    
Disclosure of nature and extent of risks arising from financial instruments [line items]    
Financial assets 2,050 2,197
Credit risk | 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 (3,392) (3,633)
Credit risk | 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 (514) (535)
Credit risk | 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 (1,353) (1,473)
Credit risk | Retail credit cards | Impairment allowance | Financial assets at amortised cost | Lifetime expected credit losses | Financial instruments credit-impaired | Total weighted model ECL    
Disclosure of nature and extent of risks arising from financial instruments [line items]    
Financial assets £ (1,525) £ (1,625)
Credit risk | 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 0.005 0.004
Credit risk | 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 0.067 0.066
Credit risk | Retail other | Financial assets at amortised cost | Lifetime expected credit losses | Financial instruments credit-impaired | Total weighted model ECL    
Disclosure of nature and extent of risks arising from financial instruments [line items]    
Coverage ratio 0.564 0.582
Credit risk | 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 £ 6,361 £ 7,952
Credit risk | 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 1,181 1,232
Credit risk | Retail other | Gross exposure | Financial assets at amortised cost | Lifetime expected credit losses | Financial instruments credit-impaired | Total weighted model ECL    
Disclosure of nature and extent of risks arising from financial instruments [line items]    
Financial assets 133 158
Credit risk | 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 (185) (207)
Credit risk | 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 (31) (34)
Credit risk | 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 (79) (81)
Credit risk | Retail other | Impairment allowance | Financial assets at amortised cost | Lifetime expected credit losses | Financial instruments credit-impaired | Total weighted model ECL    
Disclosure of nature and extent of risks arising from financial instruments [line items]    
Financial assets £ (75) £ (92)
Credit risk | 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
Credit risk | 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 0.025
Credit risk | Corporate loans | Financial assets at amortised cost | Lifetime expected credit losses | Financial instruments credit-impaired | Total weighted model ECL    
Disclosure of nature and extent of risks arising from financial instruments [line items]    
Coverage ratio 0.016 0.018
Credit risk | 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 £ 206,132 £ 213,905
Credit risk | 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 20,327 21,197
Credit risk | Corporate loans | Gross exposure | Financial assets at amortised cost | Lifetime expected credit losses | Financial instruments credit-impaired | Total weighted model ECL    
Disclosure of nature and extent of risks arising from financial instruments [line items]    
Financial assets 3,858 4,051
Credit risk | 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 (899) (873)
Credit risk | 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 (288) (270)
Credit risk | 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 (550) (532)
Credit risk | Corporate loans | Impairment allowance | Financial assets at amortised cost | Lifetime expected credit losses | Financial instruments credit-impaired | Total weighted model ECL    
Disclosure of nature and extent of risks arising from financial instruments [line items]    
Financial assets (61) (71)
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 £ (4,154) £ (4,412)
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 0
Upside 2 | Retail mortgages | Financial assets at amortised cost | Lifetime expected credit losses | Financial instruments credit-impaired | Total weighted model ECL    
Disclosure of nature and extent of risks arising from financial instruments [line items]    
Coverage ratio 0.010 0.011
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 £ 144,499 £ 140,828
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 16,768 18,178
Upside 2 | Retail mortgages | Gross exposure | Financial assets at amortised cost | Lifetime expected credit losses | Financial instruments credit-impaired | Total weighted model ECL    
Disclosure of nature and extent of risks arising from financial instruments [line items]    
Financial assets 1,128 1,062
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 (13) (13)
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 (1) 0
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 (1) (1)
Upside 2 | Retail mortgages | Impairment allowance | Financial assets at amortised cost | Lifetime expected credit losses | Financial instruments credit-impaired | Total weighted model ECL    
Disclosure of nature and extent of risks arising from financial instruments [line items]    
Financial assets £ (11) £ (12)
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 0.008
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 0.204 0.206
Upside 2 | Retail credit cards | Financial assets at amortised cost | Lifetime expected credit losses | Financial instruments credit-impaired | Total weighted model ECL    
Disclosure of nature and extent of risks arising from financial instruments [line items]    
Coverage ratio 0.725 0.721
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 £ 61,301 £ 63,821
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 6,216 6,747
Upside 2 | Retail credit cards | Gross exposure | Financial assets at amortised cost | Lifetime expected credit losses | Financial instruments credit-impaired | Total weighted model ECL    
Disclosure of nature and extent of risks arising from financial instruments [line items]    
Financial assets 2,050 2,197
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 (3,247) (3,484)
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 (493) (512)
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 (1,268) (1,387)
Upside 2 | Retail credit cards | Impairment allowance | Financial assets at amortised cost | Lifetime expected credit losses | Financial instruments credit-impaired | Total weighted model ECL    
Disclosure of nature and extent of risks arising from financial instruments [line items]    
Financial assets £ (1,486) £ (1,585)
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 0.004 0.004
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 0.063 0.061
Upside 2 | Retail other | Financial assets at amortised cost | Lifetime expected credit losses | Financial instruments credit-impaired | Total weighted model ECL    
Disclosure of nature and extent of risks arising from financial instruments [line items]    
Coverage ratio 0.549 0.570
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 £ 6,488 £ 8,074
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 1,054 1,110
Upside 2 | Retail other | Gross exposure | Financial assets at amortised cost | Lifetime expected credit losses | Financial instruments credit-impaired | Total weighted model ECL    
Disclosure of nature and extent of risks arising from financial instruments [line items]    
Financial assets 133 158
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 (167) (190)
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 (28) (32)
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 (66) (68)
Upside 2 | Retail other | Impairment allowance | Financial assets at amortised cost | Lifetime expected credit losses | Financial instruments credit-impaired | Total weighted model ECL    
Disclosure of nature and extent of risks arising from financial instruments [line items]    
Financial assets £ (73) £ (90)
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 0.024 0.022
Upside 2 | Corporate loans | Financial assets at amortised cost | Lifetime expected credit losses | Financial instruments credit-impaired | Total weighted model ECL    
Disclosure of nature and extent of risks arising from financial instruments [line items]    
Coverage ratio 0.015 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 £ 208,928 £ 216,064
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 17,378 18,889
Upside 2 | Corporate loans | Gross exposure | Financial assets at amortised cost | Lifetime expected credit losses | Financial instruments credit-impaired | Total weighted model ECL    
Disclosure of nature and extent of risks arising from financial instruments [line items]    
Financial assets 3,858 4,051
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 (727) (725)
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 (251) (235)
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 (418) (424)
Upside 2 | Corporate loans | Impairment allowance | Financial assets at amortised cost | Lifetime expected credit losses | Financial instruments credit-impaired | Total weighted model ECL    
Disclosure of nature and extent of risks arising from financial instruments [line items]    
Financial assets (58) (66)
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 £ (4,285) £ (4,538)
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 0
Upside 1 | Retail mortgages | Financial assets at amortised cost | Lifetime expected credit losses | Financial instruments credit-impaired | Total weighted model ECL    
Disclosure of nature and extent of risks arising from financial instruments [line items]    
Coverage ratio 0.012 0.013
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 £ 144,220 £ 140,079
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 17,185 19,072
Upside 1 | Retail mortgages | Gross exposure | Financial assets at amortised cost | Lifetime expected credit losses | Financial instruments credit-impaired | Total weighted model ECL    
Disclosure of nature and extent of risks arising from financial instruments [line items]    
Financial assets 1,128 1,062
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 (17) (17)
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 (1) (1)
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 (2) (2)
Upside 1 | Retail mortgages | Impairment allowance | Financial assets at amortised cost | Lifetime expected credit losses | Financial instruments credit-impaired | Total weighted model ECL    
Disclosure of nature and extent of risks arising from financial instruments [line items]    
Financial assets £ (14) £ (14)
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 0.008 0.008
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 0.207 0.209
Upside 1 | Retail credit cards | Financial assets at amortised cost | Lifetime expected credit losses | Financial instruments credit-impaired | Total weighted model ECL    
Disclosure of nature and extent of risks arising from financial instruments [line items]    
Coverage ratio 0.735 0.731
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 £ 61,334 £ 63,859
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 6,288 6,817
Upside 1 | Retail credit cards | Gross exposure | Financial assets at amortised cost | Lifetime expected credit losses | Financial instruments credit-impaired | Total weighted model ECL    
Disclosure of nature and extent of risks arising from financial instruments [line items]    
Financial assets 2,050 2,197
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 (3,312) (3,551)
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 (503) (523)
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 (1,302) (1,422)
Upside 1 | Retail credit cards | Impairment allowance | Financial assets at amortised cost | Lifetime expected credit losses | Financial instruments credit-impaired | Total weighted model ECL    
Disclosure of nature and extent of risks arising from financial instruments [line items]    
Financial assets £ (1,507) £ (1,606)
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 0.005 0.004
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 0.063 0.062
Upside 1 | Retail other | Financial assets at amortised cost | Lifetime expected credit losses | Financial instruments credit-impaired | Total weighted model ECL    
Disclosure of nature and extent of risks arising from financial instruments [line items]    
Coverage ratio 0.549 0.576
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 £ 6,436 £ 8,025
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 1,106 1,159
Upside 1 | Retail other | Gross exposure | Financial assets at amortised cost | Lifetime expected credit losses | Financial instruments credit-impaired | Total weighted model ECL    
Disclosure of nature and extent of risks arising from financial instruments [line items]    
Financial assets 133 158
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 (172) (195)
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 (29) (32)
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 (70) (72)
Upside 1 | Retail other | Impairment allowance | Financial assets at amortised cost | Lifetime expected credit losses | Financial instruments credit-impaired | Total weighted model ECL    
Disclosure of nature and extent of risks arising from financial instruments [line items]    
Financial assets £ (73) £ (91)
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 0.025 0.023
Upside 1 | Corporate loans | Financial assets at amortised cost | Lifetime expected credit losses | Financial instruments credit-impaired | Total weighted model ECL    
Disclosure of nature and extent of risks arising from financial instruments [line items]    
Coverage ratio 0.015 0.017
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 £ 208,025 £ 215,215
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 18,338 19,793
Upside 1 | Corporate loans | Gross exposure | Financial assets at amortised cost | Lifetime expected credit losses | Financial instruments credit-impaired | Total weighted model ECL    
Disclosure of nature and extent of risks arising from financial instruments [line items]    
Financial assets 3,858 4,051
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 (784) (775)
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 (264) (247)
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 (462) (461)
Upside 1 | Corporate loans | Impairment allowance | Financial assets at amortised cost | Lifetime expected credit losses | Financial instruments credit-impaired | Total weighted model ECL    
Disclosure of nature and extent of risks arising from financial instruments [line items]    
Financial assets (58) (67)
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 £ (4,426) £ (4,675)
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 0
Baseline | Retail mortgages | Financial assets at amortised cost | Lifetime expected credit losses | Financial instruments credit-impaired | Total weighted model ECL    
Disclosure of nature and extent of risks arising from financial instruments [line items]    
Coverage ratio 0.014 0.016
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 £ 143,894 £ 139,188
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 17,673 20,134
Baseline | Retail mortgages | Gross exposure | Financial assets at amortised cost | Lifetime expected credit losses | Financial instruments credit-impaired | Total weighted model ECL    
Disclosure of nature and extent of risks arising from financial instruments [line items]    
Financial assets 1,128 1,062
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 (19) (21)
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 (1) (1)
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 (2) (3)
Baseline | Retail mortgages | Impairment allowance | Financial assets at amortised cost | Lifetime expected credit losses | Financial instruments credit-impaired | Total weighted model ECL    
Disclosure of nature and extent of risks arising from financial instruments [line items]    
Financial assets £ (16) £ (17)
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 0.008 0.008
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 0.210 0.212
Baseline | Retail credit cards | Financial assets at amortised cost | Lifetime expected credit losses | Financial instruments credit-impaired | Total weighted model ECL    
Disclosure of nature and extent of risks arising from financial instruments [line items]    
Coverage ratio 0.745 0.741
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 £ 61,364 £ 63,894
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 6,363 6,889
Baseline | Retail credit cards | Gross exposure | Financial assets at amortised cost | Lifetime expected credit losses | Financial instruments credit-impaired | Total weighted model ECL    
Disclosure of nature and extent of risks arising from financial instruments [line items]    
Financial assets 2,050 2,197
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 (3,377) (3,620)
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 (513) (534)
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 (1,337) (1,459)
Baseline | Retail credit cards | Impairment allowance | Financial assets at amortised cost | Lifetime expected credit losses | Financial instruments credit-impaired | Total weighted model ECL    
Disclosure of nature and extent of risks arising from financial instruments [line items]    
Financial assets £ (1,527) £ (1,627)
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 0.005 0.004
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 0.064 0.063
Baseline | Retail other | Financial assets at amortised cost | Lifetime expected credit losses | Financial instruments credit-impaired | Total weighted model ECL    
Disclosure of nature and extent of risks arising from financial instruments [line items]    
Coverage ratio 0.556 0.582
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 £ 6,375 £ 7,968
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 1,167 1,215
Baseline | Retail other | Gross exposure | Financial assets at amortised cost | Lifetime expected credit losses | Financial instruments credit-impaired | Total weighted model ECL    
Disclosure of nature and extent of risks arising from financial instruments [line items]    
Financial assets 133 158
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 (179) (202)
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 (30) (33)
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 (75) (77)
Baseline | Retail other | Impairment allowance | Financial assets at amortised cost | Lifetime expected credit losses | Financial instruments credit-impaired | Total weighted model ECL    
Disclosure of nature and extent of risks arising from financial instruments [line items]    
Financial assets £ (74) £ (92)
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 0.026 0.024
Baseline | Corporate loans | Financial assets at amortised cost | Lifetime expected credit losses | Financial instruments credit-impaired | Total weighted model ECL    
Disclosure of nature and extent of risks arising from financial instruments [line items]    
Coverage ratio 0.016 0.017
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 £ 206,540 £ 214,293
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 19,936 20,827
Baseline | Corporate loans | Gross exposure | Financial assets at amortised cost | Lifetime expected credit losses | Financial instruments credit-impaired | Total weighted model ECL    
Disclosure of nature and extent of risks arising from financial instruments [line items]    
Financial assets 3,858 4,051
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 (851) (832)
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 (274) (258)
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 (517) (505)
Baseline | Corporate loans | Impairment allowance | Financial assets at amortised cost | Lifetime expected credit losses | Financial instruments credit-impaired | Total weighted model ECL    
Disclosure of nature and extent of risks arising from financial instruments [line items]    
Financial assets (60) (69)
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 £ (4,866) £ (5,107)
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 0
Downside 1 | Retail mortgages | Financial assets at amortised cost | Lifetime expected credit losses | Financial instruments credit-impaired | Total weighted model ECL    
Disclosure of nature and extent of risks arising from financial instruments [line items]    
Coverage ratio 0.024 0.027
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 £ 142,404 £ 136,671
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 19,831 23,359
Downside 1 | Retail mortgages | Gross exposure | Financial assets at amortised cost | Lifetime expected credit losses | Financial instruments credit-impaired | Total weighted model ECL    
Disclosure of nature and extent of risks arising from financial instruments [line items]    
Financial assets 1,128 1,062
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 (35) (40)
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 (3) (3)
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 (5) (8)
Downside 1 | Retail mortgages | Impairment allowance | Financial assets at amortised cost | Lifetime expected credit losses | Financial instruments credit-impaired | Total weighted model ECL    
Disclosure of nature and extent of risks arising from financial instruments [line items]    
Financial assets £ (27) £ (29)
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 0.009 0.009
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 0.221 0.222
Downside 1 | Retail credit cards | Financial assets at amortised cost | Lifetime expected credit losses | Financial instruments credit-impaired | Total weighted model ECL    
Disclosure of nature and extent of risks arising from financial instruments [line items]    
Coverage ratio 0.760 0.757
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 £ 61,389 £ 63,980
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 6,525 7,052
Downside 1 | Retail credit cards | Gross exposure | Financial assets at amortised cost | Lifetime expected credit losses | Financial instruments credit-impaired | Total weighted model ECL    
Disclosure of nature and extent of risks arising from financial instruments [line items]    
Financial assets 2,050 2,197
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 (3,531) (3,790)
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 (533) (560)
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 (1,440) (1,567)
Downside 1 | Retail credit cards | Impairment allowance | Financial assets at amortised cost | Lifetime expected credit losses | Financial instruments credit-impaired | Total weighted model ECL    
Disclosure of nature and extent of risks arising from financial instruments [line items]    
Financial assets £ (1,558) £ (1,663)
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 0.005 0.005
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 0.074 0.073
Downside 1 | Retail other | Financial assets at amortised cost | Lifetime expected credit losses | Financial instruments credit-impaired | Total weighted model ECL    
Disclosure of nature and extent of risks arising from financial instruments [line items]    
Coverage ratio 0.586 0.601
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 £ 6,217 £ 7,804
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 1,325 1,380
Downside 1 | Retail other | Gross exposure | Financial assets at amortised cost | Lifetime expected credit losses | Financial instruments credit-impaired | Total weighted model ECL    
Disclosure of nature and extent of risks arising from financial instruments [line items]    
Financial assets 133 158
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 (209) (232)
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 (33) (36)
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 (98) (101)
Downside 1 | Retail other | Impairment allowance | Financial assets at amortised cost | Lifetime expected credit losses | Financial instruments credit-impaired | Total weighted model ECL    
Disclosure of nature and extent of risks arising from financial instruments [line items]    
Financial assets £ (78) £ (95)
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 0.002 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 0.031 0.028
Downside 1 | Corporate loans | Financial assets at amortised cost | Lifetime expected credit losses | Financial instruments credit-impaired | Total weighted model ECL    
Disclosure of nature and extent of risks arising from financial instruments [line items]    
Coverage ratio 0.017 0.020
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 £ 204,086 £ 212,007
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 22,509 23,238
Downside 1 | Corporate loans | Gross exposure | Financial assets at amortised cost | Lifetime expected credit losses | Financial instruments credit-impaired | Total weighted model ECL    
Disclosure of nature and extent of risks arising from financial instruments [line items]    
Financial assets 3,858 4,051
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 (1,091) (1,045)
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 (332) (311)
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 (693) (655)
Downside 1 | Corporate loans | Impairment allowance | Financial assets at amortised cost | Lifetime expected credit losses | Financial instruments credit-impaired | Total weighted model ECL    
Disclosure of nature and extent of risks arising from financial instruments [line items]    
Financial assets (66) (79)
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 £ (5,516) £ (5,713)
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 0.001
Downside 2 | Retail mortgages | Financial assets at amortised cost | Lifetime expected credit losses | Financial instruments credit-impaired | Total weighted model ECL    
Disclosure of nature and extent of risks arising from financial instruments [line items]    
Coverage ratio 0.031 0.039
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 £ 140,285 £ 134,861
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 23,057 26,339
Downside 2 | Retail mortgages | Gross exposure | Financial assets at amortised cost | Lifetime expected credit losses | Financial instruments credit-impaired | Total weighted model ECL    
Disclosure of nature and extent of risks arising from financial instruments [line items]    
Financial assets 1,128 1,062
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 (49) (63)
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 (5) (6)
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 (9) (16)
Downside 2 | Retail mortgages | Impairment allowance | Financial assets at amortised cost | Lifetime expected credit losses | Financial instruments credit-impaired | Total weighted model ECL    
Disclosure of nature and extent of risks arising from financial instruments [line items]    
Financial assets £ (35) £ (41)
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 0.009 0.009
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 0.233 0.234
Downside 2 | Retail credit cards | Financial assets at amortised cost | Lifetime expected credit losses | Financial instruments credit-impaired | Total weighted model ECL    
Disclosure of nature and extent of risks arising from financial instruments [line items]    
Coverage ratio 0.774 0.772
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 £ 61,315 £ 63,975
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 6,794 7,310
Downside 2 | Retail credit cards | Gross exposure | Financial assets at amortised cost | Lifetime expected credit losses | Financial instruments credit-impaired | Total weighted model ECL    
Disclosure of nature and extent of risks arising from financial instruments [line items]    
Financial assets 2,050 2,197
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 (3,721) (3,995)
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 (551) (586)
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 (1,584) (1,714)
Downside 2 | Retail credit cards | Impairment allowance | Financial assets at amortised cost | Lifetime expected credit losses | Financial instruments credit-impaired | Total weighted model ECL    
Disclosure of nature and extent of risks arising from financial instruments [line items]    
Financial assets £ (1,586) £ (1,695)
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 0.006 0.005
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 0.085 0.085
Downside 2 | Retail other | Financial assets at amortised cost | Lifetime expected credit losses | Financial instruments credit-impaired | Total weighted model ECL    
Disclosure of nature and extent of risks arising from financial instruments [line items]    
Coverage ratio 0.617 0.614
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 £ 6,047 £ 7,614
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 1,495 1,570
Downside 2 | Retail other | Gross exposure | Financial assets at amortised cost | Lifetime expected credit losses | Financial instruments credit-impaired | Total weighted model ECL    
Disclosure of nature and extent of risks arising from financial instruments [line items]    
Financial assets 133 158
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 (244) (271)
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 (35) (40)
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 (127) (134)
Downside 2 | Retail other | Impairment allowance | Financial assets at amortised cost | Lifetime expected credit losses | Financial instruments credit-impaired | Total weighted model ECL    
Disclosure of nature and extent of risks arising from financial instruments [line items]    
Financial assets £ (82) £ (97)
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 0.036 0.033
Downside 2 | Corporate loans | Financial assets at amortised cost | Lifetime expected credit losses | Financial instruments credit-impaired | Total weighted model ECL    
Disclosure of nature and extent of risks arising from financial instruments [line items]    
Coverage ratio 0.019 0.022
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 £ 197,488 £ 207,062
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 29,237 28,340
Downside 2 | Corporate loans | Gross exposure | Financial assets at amortised cost | Lifetime expected credit losses | Financial instruments credit-impaired | Total weighted model ECL    
Disclosure of nature and extent of risks arising from financial instruments [line items]    
Financial assets 3,858 4,051
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 (1,502) (1,384)
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 (385) (363)
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 (1,045) (932)
Downside 2 | Corporate loans | Impairment allowance | Financial assets at amortised cost | Lifetime expected credit losses | Financial instruments credit-impaired | Total weighted model ECL    
Disclosure of nature and extent of risks arising from financial instruments [line items]    
Financial assets £ (72) £ (89)