Revenue from Foreign Exchange and Other Trading (Detail) (USD $) In Millions, unless otherwise specified	3 Months Ended						6 Months Ended
	Jun. 30, 2012		Mar. 31, 2012		Jun. 30, 2011		Jun. 30, 2012		Jun. 30, 2011
Trading Activity, Gains and Losses, Net [Line Items]
Foreign exchange and other trading revenue	$ 180		$ 191		$ 222		$ 371		$ 420
Foreign Exchange
Trading Activity, Gains and Losses, Net [Line Items]
Foreign exchange and other trading revenue	157		136		184		293		357
Fixed Income
Trading Activity, Gains and Losses, Net [Line Items]
Foreign exchange and other trading revenue	16		47		28		63		45
Credit Derivatives
Trading Activity, Gains and Losses, Net [Line Items]
Foreign exchange and other trading revenue	1	[1]	(2)	[1]	(1)	[1]	(1)	[1]	(2)	[1]
Other Trading
Trading Activity, Gains and Losses, Net [Line Items]
Foreign exchange and other trading revenue	$ 6		$ 10		$ 11		$ 16		$ 20

[1] Used as economic hedges of loans.