Derivative Financial Instruments - Gains and Losses on Hedged Items in Fair Value Hedges (Detail) (USD $) In Millions, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2013	Jun. 30, 2012	Jun. 30, 2013	Jun. 30, 2012
Interest Income Expense [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Gain (Loss) on Derivative - Interest Income (Expense)	$ (51)	$ (52)	$ (103)	$ (111)
Gain (Loss) on Hedged Items - Interest Income (Expense)	96	147	195	311
Interest Income Expense [Member] | Interest rate contracts/AFS securities [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Gain (Loss) on Derivative - Interest Income (Expense)	(55)	(39)	(111)	(84)
Gain (Loss) on Hedged Items - Interest Income (Expense)	111	162	225	341
Interest Income Expense [Member] | Interest rate contracts/subordinated debt [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Gain (Loss) on Derivative - Interest Income (Expense)	4	(13)	8	(27)
Gain (Loss) on Hedged Items - Interest Income (Expense)	(15)	(15)	(30)	(30)
Other Income [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Gain (Loss) on Derivative - Interest Income (Expense)	397	(581)	566	(279)
Gain (Loss) on Hedged Items - Interest Income (Expense)	(380)	551	(553)	259
Other Income [Member] | Interest rate contracts/AFS securities [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Gain (Loss) on Derivative - Interest Income (Expense)	397	(582)	567	(285)
Gain (Loss) on Hedged Items - Interest Income (Expense)	(380)	552	(554)	265
Other Income [Member] | Interest rate contracts/subordinated debt [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Gain (Loss) on Derivative - Interest Income (Expense)	0	1	(1)	6
Gain (Loss) on Hedged Items - Interest Income (Expense)	$ 0	$ (1)	$ 1	$ (6)