v3.21.2
Loans - Summary of Financing receivable, past due (Detail) - USD ($)
$ in Millions
Jun. 30, 2021
Dec. 31, 2020
Financing Receivable, Past Due [Line Items]    
Financing receivable, past due $ 474 $ 804
Past due loans divided by gross loans at amortized cost 0.40% 0.80%
Corporate [Member]    
Financing Receivable, Past Due [Line Items]    
Financing receivable, past due $ 80 $ 294
Wealth management [Member]    
Financing Receivable, Past Due [Line Items]    
Financing receivable, past due 39 92
Commercial real estate [Member]    
Financing Receivable, Past Due [Line Items]    
Financing receivable, past due 204 232
Residential real estate [Member]    
Financing Receivable, Past Due [Line Items]    
Financing receivable, past due 18 27
Installment [Member]    
Financing Receivable, Past Due [Line Items]    
Financing receivable, past due 28 58
Credit Card Receivable [Member]    
Financing Receivable, Past Due [Line Items]    
Financing receivable, past due 85 77
Other [Member]    
Financing Receivable, Past Due [Line Items]    
Financing receivable, past due 20 24
30-89 days [Member]    
Financing Receivable, Past Due [Line Items]    
Financing receivable, past due 100 219
30-89 days [Member] | Wealth management [Member]    
Financing Receivable, Past Due [Line Items]    
Financing receivable, past due 0 58
30-89 days [Member] | Commercial real estate [Member]    
Financing Receivable, Past Due [Line Items]    
Financing receivable, past due 14 49
30-89 days [Member] | Residential real estate [Member]    
Financing Receivable, Past Due [Line Items]    
Financing receivable, past due 1 4
30-89 days [Member] | Installment [Member]    
Financing Receivable, Past Due [Line Items]    
Financing receivable, past due 21 42
30-89 days [Member] | Credit Card Receivable [Member]    
Financing Receivable, Past Due [Line Items]    
Financing receivable, past due 49 46
30-89 days [Member] | Other [Member]    
Financing Receivable, Past Due [Line Items]    
Financing receivable, past due 15 20
90 days or more [Member]    
Financing Receivable, Past Due [Line Items]    
Financing receivable, past due 374 585
90 days or more [Member] | Corporate [Member]    
Financing Receivable, Past Due [Line Items]    
Financing receivable, past due 80 294
90 days or more [Member] | Wealth management [Member]    
Financing Receivable, Past Due [Line Items]    
Financing receivable, past due 39 34
90 days or more [Member] | Commercial real estate [Member]    
Financing Receivable, Past Due [Line Items]    
Financing receivable, past due 190 183
90 days or more [Member] | Residential real estate [Member]    
Financing Receivable, Past Due [Line Items]    
Financing receivable, past due 17 23
90 days or more [Member] | Installment [Member]    
Financing Receivable, Past Due [Line Items]    
Financing receivable, past due 7 16
90 days or more [Member] | Credit Card Receivable [Member]    
Financing Receivable, Past Due [Line Items]    
Financing receivable, past due 36 31
90 days or more [Member] | Other [Member]    
Financing Receivable, Past Due [Line Items]    
Financing receivable, past due $ 5 $ 4