Trading Assets and Liabilities - Gains and Losses from Market Making (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Trading activity, gains and losses, net [Line Items]
Market making	$ 10,157	$ 9,724	$ 7,853
Interest Rates [Member]
Trading activity, gains and losses, net [Line Items]
Market making	3,272	(1,917)	6,587
Credit [Member]
Trading activity, gains and losses, net [Line Items]
Market making	682	1,268	696
Currencies [Member]
Trading activity, gains and losses, net [Line Items]
Market making	2,902	4,646	(3,240)
Equities [Member]
Trading activity, gains and losses, net [Line Items]
Market making	2,946	5,264	3,170
Commodities [Member]
Trading activity, gains and losses, net [Line Items]
Market making	$ 355	$ 463	$ 640