Derivative Financial Instruments - Gains and Losses on Derivative Instruments Held For Trading Purpose (Detail) (USD $) In Millions, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2012	Sep. 30, 2011	Sep. 30, 2012	Sep. 30, 2011
Derivative Instruments, Gain (Loss) [Line Items]
Amount of Gain (Loss) Recognized in income on Derivatives	$ 5	$ (113)	$ (869)	$ 159
Trading revenue [Member] | Interest rate contracts [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Amount of Gain (Loss) Recognized in income on Derivatives	(24)	(87)	(8)	(206)
Trading revenue [Member] | Foreign exchange contracts [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Amount of Gain (Loss) Recognized in income on Derivatives	3	(246)	648	131
Trading revenue [Member] | Equity contracts [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Amount of Gain (Loss) Recognized in income on Derivatives	2	101	62	105
Trading revenue [Member] | Precious metals contracts [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Amount of Gain (Loss) Recognized in income on Derivatives	44	175	96	97
Trading revenue [Member] | Credit contracts [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Amount of Gain (Loss) Recognized in income on Derivatives	(27)	(176)	(1,695)	(86)
Residential mortgage banking revenue [Member] | Interest rate contracts [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Amount of Gain (Loss) Recognized in income on Derivatives	$ 7	$ 120	$ 28	$ 118