Loans - Summary of Loans (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Loans Receivable [Line Items]
Total loans, gross	$ 184,829	$ 162,135
Allowance for loan losses	(5,543)	(3,573)	$ (3,874)
Total loans	179,286	158,562
Total loans, gross, Fair Value	7,655	10,769
Amortized Cost
Loans Receivable [Line Items]
Total loans, gross	172,580	143,507
Allowance for loan losses	(5,543)	(3,573)
Total loans	167,037	139,934
Fair Value
Loans Receivable [Line Items]
Allowance for loan losses	0	0
Total loans	7,655	10,769
Total loans, gross, Fair Value	7,655	10,769
Held For Sale
Loans Receivable [Line Items]
Allowance for loan losses	0	0
Total loans	4,594	7,859
Total loans, gross, Held For Sale	4,594	7,859
Corporate
Loans Receivable [Line Items]
Total loans, gross	40,135	37,643
Total loans, gross, Fair Value	996	1,609
Corporate | Amortized Cost
Loans Receivable [Line Items]
Total loans, gross	36,822	34,663
Corporate | Fair Value
Loans Receivable [Line Items]
Total loans, gross, Fair Value	996	1,609
Corporate | Held For Sale
Loans Receivable [Line Items]
Total loans, gross, Held For Sale	2,317	1,371
Commercial real estate
Loans Receivable [Line Items]
Total loans, gross	28,879	29,000
Total loans, gross, Fair Value	1,146	1,588
Commercial real estate | Amortized Cost
Loans Receivable [Line Items]
Total loans, gross	26,222	24,267
Commercial real estate | Fair Value
Loans Receivable [Line Items]
Total loans, gross, Fair Value	1,146	1,588
Commercial real estate | Held For Sale
Loans Receivable [Line Items]
Total loans, gross, Held For Sale	1,511	3,145
Residential real estate
Loans Receivable [Line Items]
Total loans, gross	23,035	24,674
Total loans, gross, Fair Value	4,511	6,185
Residential real estate | Amortized Cost
Loans Receivable [Line Items]
Total loans, gross	18,523	18,389
Residential real estate | Fair Value
Loans Receivable [Line Items]
Total loans, gross, Fair Value	4,511	6,185
Residential real estate | Held For Sale
Loans Receivable [Line Items]
Total loans, gross, Held For Sale	1	100
Securities-based
Loans Receivable [Line Items]
Total loans, gross	16,671	16,652
Securities-based | Amortized Cost
Loans Receivable [Line Items]
Total loans, gross	16,671	16,652
Securities-based | Fair Value
Loans Receivable [Line Items]
Total loans, gross, Fair Value	0	0
Securities-based | Held For Sale
Loans Receivable [Line Items]
Total loans, gross, Held For Sale	0	0
Other collateralized
Loans Receivable [Line Items]
Total loans, gross	51,702	38,263
Total loans, gross, Fair Value	716	955
Other collateralized | Amortized Cost
Loans Receivable [Line Items]
Total loans, gross	50,473	35,916
Other collateralized | Fair Value
Loans Receivable [Line Items]
Total loans, gross, Fair Value	716	955
Other collateralized | Held For Sale
Loans Receivable [Line Items]
Total loans, gross, Held For Sale	513	1,392
Installment
Loans Receivable [Line Items]
Total loans, gross	6,326	3,672
Installment | Amortized Cost
Loans Receivable [Line Items]
Total loans, gross	6,326	3,672
Installment | Fair Value
Loans Receivable [Line Items]
Total loans, gross, Fair Value	0	0
Installment | Held For Sale
Loans Receivable [Line Items]
Total loans, gross, Held For Sale	0	0
Credit cards
Loans Receivable [Line Items]
Total loans, gross	15,820	8,212
Increase in funded loans due to acquisition of GM credit card portfolio	2,000
Credit cards | Amortized Cost
Loans Receivable [Line Items]
Total loans, gross	15,820	8,212
Credit cards | Fair Value
Loans Receivable [Line Items]
Total loans, gross, Fair Value	0	0
Credit cards | Held For Sale
Loans Receivable [Line Items]
Total loans, gross, Held For Sale	0	0
Other
Loans Receivable [Line Items]
Total loans, gross	2,261	4,019
Total loans, gross, Fair Value	286	432
Other | Amortized Cost
Loans Receivable [Line Items]
Total loans, gross	1,723	1,736
Other | Fair Value
Loans Receivable [Line Items]
Total loans, gross, Fair Value	286	432
Other | Held For Sale
Loans Receivable [Line Items]
Total loans, gross, Held For Sale	$ 252	$ 1,851