Revenue from Foreign Exchange and Other Trading Activities (Detail) (USD $) In Millions, unless otherwise specified	3 Months Ended
	Mar. 31, 2012		Dec. 31, 2011		Mar. 31, 2011
Trading Activity, Gains and Losses, Net [Line Items]
Foreign exchange and other trading revenue	$ 191		$ 228		$ 198
Foreign Exchange
Trading Activity, Gains and Losses, Net [Line Items]
Foreign exchange and other trading revenue	136		183		173
Fixed income
Trading Activity, Gains and Losses, Net [Line Items]
Foreign exchange and other trading revenue	47		41		17
Credit derivatives
Trading Activity, Gains and Losses, Net [Line Items]
Foreign exchange and other trading revenue	(2)	[1]	(2)	[1]	(1)	[1]
Other
Trading Activity, Gains and Losses, Net [Line Items]
Foreign exchange and other trading revenue	$ 10		$ 6		$ 9

[1] Used as economic hedges of loans.