Trading Assets and Liabilities - Gains and Losses from Market Making (Detail) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Trading activity, gains and losses, net [Line Items]
Market making	$ 3,682	$ 2,723
Interest Rates [Member]
Trading activity, gains and losses, net [Line Items]
Market making	737	1,260
Credit [Member]
Trading activity, gains and losses, net [Line Items]
Market making	1,842	242
Currencies [Member]
Trading activity, gains and losses, net [Line Items]
Market making	(735)	718
Equities [Member]
Trading activity, gains and losses, net [Line Items]
Market making	1,700	390
Commodities [Member]
Trading activity, gains and losses, net [Line Items]
Market making	$ 138	$ 113