Loans - Summary of Past Due Loans (Detail) - USD ($) $ in Millions	Mar. 31, 2026	Dec. 31, 2025
Financing Receivable, Past Due [Line Items]
Carrying Value	$ 255,194	$ 239,882
Total divided by gross loans at amortized cost	0.30%	0.40%
Corporate
Financing Receivable, Past Due [Line Items]
Carrying Value	$ 38,156	$ 30,676
Commercial real estate
Financing Receivable, Past Due [Line Items]
Carrying Value	38,779	37,409
Residential real estate
Financing Receivable, Past Due [Line Items]
Carrying Value	32,885	31,957
Securities-based
Financing Receivable, Past Due [Line Items]
Carrying Value	18,592	18,079
Other collateralized
Financing Receivable, Past Due [Line Items]
Carrying Value	104,592	98,999
Other
Financing Receivable, Past Due [Line Items]
Carrying Value	3,135	3,020
Past due
Financing Receivable, Past Due [Line Items]
Carrying Value	776	770
Past due \| Corporate
Financing Receivable, Past Due [Line Items]
Carrying Value	103	32
Past due \| Commercial real estate
Financing Receivable, Past Due [Line Items]
Carrying Value	641	617
Past due \| Residential real estate
Financing Receivable, Past Due [Line Items]
Carrying Value	15	22
Past due \| Securities-based
Financing Receivable, Past Due [Line Items]
Carrying Value		2
Past due \| Other collateralized
Financing Receivable, Past Due [Line Items]
Carrying Value	7	63
Past due \| Other
Financing Receivable, Past Due [Line Items]
Carrying Value	10	34
30-89 days
Financing Receivable, Past Due [Line Items]
Carrying Value	119	398
30-89 days \| Corporate
Financing Receivable, Past Due [Line Items]
Carrying Value	92	0
30-89 days \| Commercial real estate
Financing Receivable, Past Due [Line Items]
Carrying Value	27	336
30-89 days \| Residential real estate
Financing Receivable, Past Due [Line Items]
Carrying Value	0	3
30-89 days \| Securities-based
Financing Receivable, Past Due [Line Items]
Carrying Value		2
30-89 days \| Other collateralized
Financing Receivable, Past Due [Line Items]
Carrying Value	0	57
30-89 days \| Other
Financing Receivable, Past Due [Line Items]
Carrying Value	0	0
90 days or more
Financing Receivable, Past Due [Line Items]
Carrying Value	657	372
90 days or more \| Corporate
Financing Receivable, Past Due [Line Items]
Carrying Value	11	32
90 days or more \| Commercial real estate
Financing Receivable, Past Due [Line Items]
Carrying Value	614	281
90 days or more \| Residential real estate
Financing Receivable, Past Due [Line Items]
Carrying Value	15	19
90 days or more \| Securities-based
Financing Receivable, Past Due [Line Items]
Carrying Value		0
90 days or more \| Other collateralized
Financing Receivable, Past Due [Line Items]
Carrying Value	7	6
90 days or more \| Other
Financing Receivable, Past Due [Line Items]
Carrying Value	$ 10	$ 34