Loans - Summary of Past Due Loans (Detail) - USD ($) $ in Millions	Sep. 30, 2022	Dec. 31, 2021
Financing Receivable, Past Due [Line Items]
Loans	$ 181,515	$ 162,135
Total divided by gross loans at amortized cost	0.80%	0.30%
Corporate
Financing Receivable, Past Due [Line Items]
Loans	$ 63,181	$ 55,927
Wealth management
Financing Receivable, Past Due [Line Items]
Loans	50,101	43,998
Commercial real estate
Financing Receivable, Past Due [Line Items]
Loans	26,082	25,883
Residential real estate
Financing Receivable, Past Due [Line Items]
Loans	14,342	15,913
Installment
Financing Receivable, Past Due [Line Items]
Loans	5,157	3,672
Credit cards
Financing Receivable, Past Due [Line Items]
Loans	13,691	8,212
Other
Financing Receivable, Past Due [Line Items]
Loans	8,961	8,530
Past due
Financing Receivable, Past Due [Line Items]
Loans	1,276	474
Past due | Corporate
Financing Receivable, Past Due [Line Items]
Loans	141	95
Past due | Wealth management
Financing Receivable, Past Due [Line Items]
Loans	290	20
Past due | Commercial real estate
Financing Receivable, Past Due [Line Items]
Loans	340	150
Past due | Residential real estate
Financing Receivable, Past Due [Line Items]
Loans	9	7
Past due | Installment
Financing Receivable, Past Due [Line Items]
Loans	46	27
Past due | Credit cards
Financing Receivable, Past Due [Line Items]
Loans	422	157
Past due | Other
Financing Receivable, Past Due [Line Items]
Loans	28	18
30-89 days
Financing Receivable, Past Due [Line Items]
Loans	571	136
30-89 days | Corporate
Financing Receivable, Past Due [Line Items]
Loans	12	5
30-89 days | Wealth management
Financing Receivable, Past Due [Line Items]
Loans	253	0
30-89 days | Commercial real estate
Financing Receivable, Past Due [Line Items]
Loans	24	7
30-89 days | Residential real estate
Financing Receivable, Past Due [Line Items]
Loans	2	3
30-89 days | Installment
Financing Receivable, Past Due [Line Items]
Loans	34	20
30-89 days | Credit cards
Financing Receivable, Past Due [Line Items]
Loans	226	86
30-89 days | Other
Financing Receivable, Past Due [Line Items]
Loans	20	15
90 days or more
Financing Receivable, Past Due [Line Items]
Loans	705	338
90 days or more | Corporate
Financing Receivable, Past Due [Line Items]
Loans	129	90
90 days or more | Wealth management
Financing Receivable, Past Due [Line Items]
Loans	37	20
90 days or more | Commercial real estate
Financing Receivable, Past Due [Line Items]
Loans	316	143
90 days or more | Residential real estate
Financing Receivable, Past Due [Line Items]
Loans	7	4
90 days or more | Installment
Financing Receivable, Past Due [Line Items]
Loans	12	7
90 days or more | Credit cards
Financing Receivable, Past Due [Line Items]
Loans	196	71
90 days or more | Other
Financing Receivable, Past Due [Line Items]
Loans	$ 8	$ 3