Derivative Financial Instruments - Gains and Losses on Derivative Instruments Held For Other Purpose (Detail) (USD $) In Millions, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2013	Jun. 30, 2012	Jun. 30, 2013	Jun. 30, 2012
Derivatives, Fair Value [Line Items]
Derivative instruments, gain (loss) recognized in income net	$ (308)	$ 110	$ (87)	$ 403
Other Income [Member] | Interest rate contracts [Member]
Derivatives, Fair Value [Line Items]
Derivative instruments, gain (loss) recognized in income net	(176)	195	(238)	105
Other Income [Member] | Credit contracts [Member]
Derivatives, Fair Value [Line Items]
Derivative instruments, gain (loss) recognized in income net	3	(2)	3	(5)
Residential mortgage banking revenue [Member] | Interest rate contracts [Member]
Derivatives, Fair Value [Line Items]
Derivative instruments, gain (loss) recognized in income net	5	(2)	4	5
Gain (loss) on Instruments Designated at Fair Value and Related Derivatives [Member] | Foreign exchange contracts [Member]
Derivatives, Fair Value [Line Items]
Derivative instruments, gain (loss) recognized in income net	(24)	36	(55)	50
Gain (loss) on Instruments Designated at Fair Value and Related Derivatives [Member] | Equity contracts [Member]
Derivatives, Fair Value [Line Items]
Derivative instruments, gain (loss) recognized in income net	(75)	(118)	240	246
Gain (loss) on Instruments Designated at Fair Value and Related Derivatives [Member] | Precious metals contracts [Member]
Derivatives, Fair Value [Line Items]
Derivative instruments, gain (loss) recognized in income net	(42)	0	(42)	0
Gain (loss) on Instruments Designated at Fair Value and Related Derivatives [Member] | Credit contracts [Member]
Derivatives, Fair Value [Line Items]
Derivative instruments, gain (loss) recognized in income net	$ 1	$ 1	$ 1	$ 2