Net Gains (Losses) Relating to Derivative Instruments Designated as Cash Flow Hedges (Detail) (Cash Flow Hedging, USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Derivative Instruments, Gain (Loss) [Line Items]
Amount of loss recognized in OCI	$ 89	$ 2	$ 75
Interest Income Expense Net [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Amount of gain reclassified from OCI into net interest income	69	60	49
Other Noninterest Income
Derivative Instruments, Gain (Loss) [Line Items]
Amount of ineffectiveness recognized in other noninterest income	$ 1	$ 6	$ (1)