Loans - Summary of Past Due Loans (Detail) - USD ($) $ in Millions	Sep. 30, 2023	Dec. 31, 2022
Financing Receivable, Past Due [Line Items]
Carrying Value	$ 183,152	$ 184,829
Total divided by gross loans at amortized cost	1.10%	0.70%
Corporate
Financing Receivable, Past Due [Line Items]
Carrying Value	$ 36,815	$ 40,135
Commercial real estate
Financing Receivable, Past Due [Line Items]
Carrying Value	25,672	28,879
Residential real estate
Financing Receivable, Past Due [Line Items]
Carrying Value	23,953	23,035
Securities-based
Financing Receivable, Past Due [Line Items]
Carrying Value	15,053	16,671
Other collateralized
Financing Receivable, Past Due [Line Items]
Carrying Value	55,646	51,702
Installment
Financing Receivable, Past Due [Line Items]
Carrying Value	6,375	6,326
Credit cards
Financing Receivable, Past Due [Line Items]
Carrying Value	17,885	15,820
Other
Financing Receivable, Past Due [Line Items]
Carrying Value	1,753	2,261
Past due
Financing Receivable, Past Due [Line Items]
Carrying Value	1,900	1,168
Past due | Corporate
Financing Receivable, Past Due [Line Items]
Carrying Value	80	92
Past due | Commercial real estate
Financing Receivable, Past Due [Line Items]
Carrying Value	838	409
Past due | Residential real estate
Financing Receivable, Past Due [Line Items]
Carrying Value	6	10
Past due | Securities-based
Financing Receivable, Past Due [Line Items]
Carrying Value	1	1
Past due | Other collateralized
Financing Receivable, Past Due [Line Items]
Carrying Value	96	15
Past due | Installment
Financing Receivable, Past Due [Line Items]
Carrying Value	14	63
Past due | Credit cards
Financing Receivable, Past Due [Line Items]
Carrying Value	847	556
Past due | Other
Financing Receivable, Past Due [Line Items]
Carrying Value	18	22
30-89 days
Financing Receivable, Past Due [Line Items]
Carrying Value	768	416
30-89 days | Corporate
Financing Receivable, Past Due [Line Items]
Carrying Value	0	0
30-89 days | Commercial real estate
Financing Receivable, Past Due [Line Items]
Carrying Value	295	47
30-89 days | Residential real estate
Financing Receivable, Past Due [Line Items]
Carrying Value	1	4
30-89 days | Securities-based
Financing Receivable, Past Due [Line Items]
Carrying Value	1	1
30-89 days | Other collateralized
Financing Receivable, Past Due [Line Items]
Carrying Value	33	10
30-89 days | Installment
Financing Receivable, Past Due [Line Items]
Carrying Value	8	46
30-89 days | Credit cards
Financing Receivable, Past Due [Line Items]
Carrying Value	423	291
30-89 days | Other
Financing Receivable, Past Due [Line Items]
Carrying Value	7	17
90 days or more
Financing Receivable, Past Due [Line Items]
Carrying Value	1,132	752
90 days or more | Corporate
Financing Receivable, Past Due [Line Items]
Carrying Value	80	92
90 days or more | Commercial real estate
Financing Receivable, Past Due [Line Items]
Carrying Value	543	362
90 days or more | Residential real estate
Financing Receivable, Past Due [Line Items]
Carrying Value	5	6
90 days or more | Securities-based
Financing Receivable, Past Due [Line Items]
Carrying Value	0	0
90 days or more | Other collateralized
Financing Receivable, Past Due [Line Items]
Carrying Value	63	5
90 days or more | Installment
Financing Receivable, Past Due [Line Items]
Carrying Value	6	17
90 days or more | Credit cards
Financing Receivable, Past Due [Line Items]
Carrying Value	424	265
90 days or more | Other
Financing Receivable, Past Due [Line Items]
Carrying Value	$ 11	$ 5