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		6 Months Ended
	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014	Jun. 30, 2013
Derivative Instruments, Gain (Loss)
Amount of pretax net gain recognized in OCI	$ 19	$ (2)	$ 34	$ (1)
Interest Income (Expense) Net
Derivative Instruments, Gain (Loss)
Amount of pretax net gain reclassified from OCI into net interest income	$ 11	$ 10	$ 21	$ 31