v3.26.1
Loans - Summary of Past Due Status of Loans (Detail) - USD ($)
$ in Millions
Jun. 30, 2026
Dec. 31, 2025
Financing Receivable, Past Due [Line Items]    
Loans, net $ 62,103 $ 59,894
Commercial loans    
Financing Receivable, Past Due [Line Items]    
Loans, net 41,671 39,344
Commercial loans | Commercial mortgages    
Financing Receivable, Past Due [Line Items]    
Loans, net 944 1,439
Commercial loans | Business and corporate banking    
Financing Receivable, Past Due [Line Items]    
Loans, net 30,926 28,305
Commercial loans | Other commercial    
Financing Receivable, Past Due [Line Items]    
Loans, net 9,801 9,600
Consumer loans    
Financing Receivable, Past Due [Line Items]    
Loans, net 20,432 20,550
Consumer loans | Residential mortgages    
Financing Receivable, Past Due [Line Items]    
Loans, net 19,584 19,789
Consumer loans | Other Consumer    
Financing Receivable, Past Due [Line Items]    
Loans, net 848 761
Total Past Due 30 Days or More    
Financing Receivable, Past Due [Line Items]    
Loans, net 541 693
Total Past Due 30 Days or More | Commercial loans    
Financing Receivable, Past Due [Line Items]    
Loans, net 228 401
Total Past Due 30 Days or More | Commercial loans | Commercial mortgages    
Financing Receivable, Past Due [Line Items]    
Loans, net 0 106
Total Past Due 30 Days or More | Commercial loans | Business and corporate banking    
Financing Receivable, Past Due [Line Items]    
Loans, net 114 254
Total Past Due 30 Days or More | Commercial loans | Other commercial    
Financing Receivable, Past Due [Line Items]    
Loans, net 114 41
Total Past Due 30 Days or More | Consumer loans    
Financing Receivable, Past Due [Line Items]    
Loans, net 313 292
Total Past Due 30 Days or More | Consumer loans | Residential mortgages    
Financing Receivable, Past Due [Line Items]    
Loans, net 292 278
Total Past Due 30 Days or More | Consumer loans | Other Consumer    
Financing Receivable, Past Due [Line Items]    
Loans, net 21 14
30 - 89 Days    
Financing Receivable, Past Due [Line Items]    
Loans, net 344 464
30 - 89 Days | Commercial loans    
Financing Receivable, Past Due [Line Items]    
Loans, net 159 280
30 - 89 Days | Commercial loans | Commercial mortgages    
Financing Receivable, Past Due [Line Items]    
Loans, net 0 0
30 - 89 Days | Commercial loans | Business and corporate banking    
Financing Receivable, Past Due [Line Items]    
Loans, net 45 239
30 - 89 Days | Commercial loans | Other commercial    
Financing Receivable, Past Due [Line Items]    
Loans, net 114 41
30 - 89 Days | Consumer loans    
Financing Receivable, Past Due [Line Items]    
Loans, net 185 184
30 - 89 Days | Consumer loans | Residential mortgages    
Financing Receivable, Past Due [Line Items]    
Loans, net 173 178
30 - 89 Days | Consumer loans | Other Consumer    
Financing Receivable, Past Due [Line Items]    
Loans, net 12 6
90+ Days    
Financing Receivable, Past Due [Line Items]    
Loans, net 197 229
90+ Days | Commercial loans    
Financing Receivable, Past Due [Line Items]    
Loans, net 69 121
90+ Days | Commercial loans | Commercial mortgages    
Financing Receivable, Past Due [Line Items]    
Loans, net 0 106
90+ Days | Commercial loans | Business and corporate banking    
Financing Receivable, Past Due [Line Items]    
Loans, net 69 15
90+ Days | Commercial loans | Other commercial    
Financing Receivable, Past Due [Line Items]    
Loans, net 0 0
90+ Days | Consumer loans    
Financing Receivable, Past Due [Line Items]    
Loans, net 128 108
90+ Days | Consumer loans | Residential mortgages    
Financing Receivable, Past Due [Line Items]    
Loans, net 119 100
90+ Days | Consumer loans | Other Consumer    
Financing Receivable, Past Due [Line Items]    
Loans, net 9 8
Current    
Financing Receivable, Past Due [Line Items]    
Loans, net 61,562 59,201
Current | Commercial loans    
Financing Receivable, Past Due [Line Items]    
Loans, net 41,443 38,943
Current | Commercial loans | Commercial mortgages    
Financing Receivable, Past Due [Line Items]    
Loans, net 944 1,333
Current | Commercial loans | Business and corporate banking    
Financing Receivable, Past Due [Line Items]    
Loans, net 30,812 28,051
Current | Commercial loans | Other commercial    
Financing Receivable, Past Due [Line Items]    
Loans, net 9,687 9,559
Current | Consumer loans    
Financing Receivable, Past Due [Line Items]    
Loans, net 20,119 20,258
Current | Consumer loans | Residential mortgages    
Financing Receivable, Past Due [Line Items]    
Loans, net 19,292 19,511
Current | Consumer loans | Other Consumer    
Financing Receivable, Past Due [Line Items]    
Loans, net $ 827 $ 747