Derivative Financial Instruments - Gains and Losses on Derivative Instruments Held For Other Purpose (Detail) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
Derivatives, Fair Value [Line Items]
Mark-to-market on the related derivatives	$ (308)	$ 379	$ 80	$ 593
Gain (Loss) on Instruments Designated at Fair Value and Related Derivatives [Member]
Derivatives, Fair Value [Line Items]
Mark-to-market on the related derivatives	(281)	369	68	570
Gain (Loss) on Instruments Designated at Fair Value and Related Derivatives [Member] | Interest rate contracts [Member]
Derivatives, Fair Value [Line Items]
Mark-to-market on the related derivatives	(142)	111	(33)	227
Gain (Loss) on Instruments Designated at Fair Value and Related Derivatives [Member] | Foreign exchange contracts [Member]
Derivatives, Fair Value [Line Items]
Mark-to-market on the related derivatives	6	9	5	13
Gain (Loss) on Instruments Designated at Fair Value and Related Derivatives [Member] | Equity contracts [Member]
Derivatives, Fair Value [Line Items]
Mark-to-market on the related derivatives	(125)	258	132	339
Gain (Loss) on Instruments Designated at Fair Value and Related Derivatives [Member] | Precious metals contracts [Member]
Derivatives, Fair Value [Line Items]
Mark-to-market on the related derivatives	0	8	1	24
Gain (Loss) on Instruments Designated at Fair Value and Related Derivatives [Member] | Credit contracts [Member]
Derivatives, Fair Value [Line Items]
Mark-to-market on the related derivatives	(3)	0	(3)	1
Residential mortgage banking revenue [Member] | Interest rate contracts [Member]
Derivatives, Fair Value [Line Items]
Mark-to-market on the related derivatives	1	0	1	0
Other Income [Member] | Credit contracts [Member]
Derivatives, Fair Value [Line Items]
Mark-to-market on the related derivatives	$ (45)	$ (7)	$ (23)	$ (11)