Net Gains (Losses) Relating to Derivative Instruments Designated as Cash Flow Hedges (Detail) (Cash Flow Hedging, 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 loss recognized in OCI	$ 10	$ 27	$ 35	$ 59
Interest Income Expense Net [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Amount of gain reclassified from OCI into net interest income	22	(10)	63	21
Other Noninterest Income
Derivative Instruments, Gain (Loss) [Line Items]
Amount of ineffectiveness recognized in other noninterest income				$ 2