Loans - Summary of Past Due Loans (Detail) - USD ($) $ in Millions	Jun. 30, 2026	Dec. 31, 2025
Financing Receivable, Past Due [Line Items]
Carrying Value	$ 263,076	$ 239,882
Total divided by gross loans at amortized cost	0.40%	0.40%
Corporate
Financing Receivable, Past Due [Line Items]
Carrying Value	$ 35,564	$ 30,676
Commercial real estate
Financing Receivable, Past Due [Line Items]
Carrying Value	40,309	37,409
Residential real estate
Financing Receivable, Past Due [Line Items]
Carrying Value	35,542	31,957
Securities-based
Financing Receivable, Past Due [Line Items]
Carrying Value	19,110	18,079
Other collateralized
Financing Receivable, Past Due [Line Items]
Carrying Value	108,991	98,999
Other
Financing Receivable, Past Due [Line Items]
Carrying Value	4,054	3,020
Past due
Financing Receivable, Past Due [Line Items]
Carrying Value	851	770
Past due \| Corporate
Financing Receivable, Past Due [Line Items]
Carrying Value	232	32
Past due \| Commercial real estate
Financing Receivable, Past Due [Line Items]
Carrying Value	571	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	4	2
Past due \| Other collateralized
Financing Receivable, Past Due [Line Items]
Carrying Value	6	63
Past due \| Other
Financing Receivable, Past Due [Line Items]
Carrying Value	23	34
30-89 days
Financing Receivable, Past Due [Line Items]
Carrying Value	205	398
30-89 days \| Corporate
Financing Receivable, Past Due [Line Items]
Carrying Value	75	0
30-89 days \| Commercial real estate
Financing Receivable, Past Due [Line Items]
Carrying Value	103	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	4	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	23	0
90 days or more
Financing Receivable, Past Due [Line Items]
Carrying Value	646	372
90 days or more \| Corporate
Financing Receivable, Past Due [Line Items]
Carrying Value	157	32
90 days or more \| Commercial real estate
Financing Receivable, Past Due [Line Items]
Carrying Value	468	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	0
90 days or more \| Other collateralized
Financing Receivable, Past Due [Line Items]
Carrying Value	6	6
90 days or more \| Other
Financing Receivable, Past Due [Line Items]
Carrying Value	$ 0	$ 34