Derivatives and Hedging Activities - Pre-Tax Net Gains (Losses) on Derivatives not Designated as Hedging Instruments (Detail) (USD $) In Millions, unless otherwise specified	9 Months Ended
	Sep. 30, 2012	Sep. 30, 2011
Derivative [Line Items]
Derivative Instruments Not Designated as Hedging Instruments, Gain (Loss), Net, Total	$ 35	$ 31
Interest rate [Member]
Derivative [Line Items]
Derivative Instruments Not Designated as Hedging Instruments, Gain (Loss), Net, Total	16	11
Foreign Exchange [Member]
Derivative [Line Items]
Derivative Instruments Not Designated as Hedging Instruments, Gain (Loss), Net, Total	27	31
Energy and commodity [Member]
Derivative [Line Items]
Derivative Instruments Not Designated as Hedging Instruments, Gain (Loss), Net, Total	8	3
Credit [Member]
Derivative [Line Items]
Derivative Instruments Not Designated as Hedging Instruments, Gain (Loss), Net, Total	$ (16)	$ (14)