Loans - Summary of Loans (Detail) - USD ($) $ in Millions	9 Months Ended
	Sep. 30, 2022	Jun. 30, 2022	Dec. 31, 2021	Sep. 30, 2021	Jun. 30, 2021	Dec. 31, 2020
Loans Receivable [Line Items]
Total loans, gross	$ 181,515		$ 162,135
Allowance for loan losses	(4,846)	$ (4,562)	(3,573)	$ (3,332)	$ (3,271)	$ (3,874)
Total loans	176,669		158,562
Total loans, gross, Fair Value	8,250		10,769
Amortized Cost
Loans Receivable [Line Items]
Total loans, gross	166,465		143,507
Allowance for loan losses	(4,846)		(3,573)
Total loans	161,619		139,934
Fair Value
Loans Receivable [Line Items]
Allowance for loan losses	0		0
Total loans	8,250		10,769
Total loans, gross, Fair Value	8,250		10,769
Held For Sale
Loans Receivable [Line Items]
Allowance for loan losses	0		0
Total loans	6,800		7,859
Total loans, gross, Held For Sale	6,800		7,859
Corporate
Loans Receivable [Line Items]
Total loans, gross	63,181		55,927
Total loans, gross, Fair Value	1,844		2,492
Corporate | Amortized Cost
Loans Receivable [Line Items]
Total loans, gross	57,431		50,960
Corporate | Fair Value
Loans Receivable [Line Items]
Total loans, gross, Fair Value	1,844		2,492
Corporate | Held For Sale
Loans Receivable [Line Items]
Total loans, gross, Held For Sale	3,906		2,475
Wealth management
Loans Receivable [Line Items]
Total loans, gross	50,101		43,998
Total loans, gross, Fair Value	4,537		5,936
Wealth management | Amortized Cost
Loans Receivable [Line Items]
Total loans, gross	45,564		38,062
Wealth management | Fair Value
Loans Receivable [Line Items]
Total loans, gross, Fair Value	4,537		5,936
Wealth management | Held For Sale
Loans Receivable [Line Items]
Total loans, gross, Held For Sale	0		0
Commercial real estate
Loans Receivable [Line Items]
Total loans, gross	26,082		25,883
Total loans, gross, Fair Value	1,277		1,588
Commercial real estate | Amortized Cost
Loans Receivable [Line Items]
Total loans, gross	22,214		21,150
Commercial real estate | Fair Value
Loans Receivable [Line Items]
Total loans, gross, Fair Value	1,277		1,588
Commercial real estate | Held For Sale
Loans Receivable [Line Items]
Total loans, gross, Held For Sale	2,591		3,145
Residential real estate
Loans Receivable [Line Items]
Total loans, gross	14,342		15,913
Total loans, gross, Fair Value	257		320
Residential real estate | Amortized Cost
Loans Receivable [Line Items]
Total loans, gross	14,084		15,493
Residential real estate | Fair Value
Loans Receivable [Line Items]
Total loans, gross, Fair Value	257		320
Residential real estate | Held For Sale
Loans Receivable [Line Items]
Total loans, gross, Held For Sale	1		100
Installment
Loans Receivable [Line Items]
Total loans, gross	5,157		3,672
Installment | Amortized Cost
Loans Receivable [Line Items]
Total loans, gross	5,157		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	13,691		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	13,691		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	8,961		8,530
Total loans, gross, Fair Value	335		433
Other | Amortized Cost
Loans Receivable [Line Items]
Total loans, gross	8,324		5,958
Other | Fair Value
Loans Receivable [Line Items]
Total loans, gross, Fair Value	335		433
Other | Held For Sale
Loans Receivable [Line Items]
Total loans, gross, Held For Sale	$ 302		$ 2,139