Derivative Financial Instruments - Gains and Losses on Hedged Items in Fair Value Hedges (Detail) (USD $) In Millions, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012
Derivative Instruments, Gain (Loss) [Line Items]
Net Ineffective Gain (Loss) Recognined - Other Income	$ 0	$ 0	$ 0	$ 0
Interest Income Expense [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Gain (Loss) on Derivative - Interest Income (Expense)	(52)	(30)	(156)	(107)
Gain (Loss) on Hedged Items - Interest Income (Expense)	97	126	291	436
Interest Income Expense [Member] | Interest rate contracts/AFS securities [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Gain (Loss) on Derivative - Interest Income (Expense)	(56)	(33)	(168)	(117)
Gain (Loss) on Hedged Items - Interest Income (Expense)	112	141	337	482
Interest Income Expense [Member] | Interest rate contracts/subordinated debt [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Gain (Loss) on Derivative - Interest Income (Expense)	4	3	12	10
Gain (Loss) on Hedged Items - Interest Income (Expense)	(15)	(15)	(46)	(46)
Other Income [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Gain (Loss) on Derivative - Interest Income (Expense)	42	(38)	608	(317)
Gain (Loss) on Hedged Items - Interest Income (Expense)	(38)	55	(592)	314
Net Ineffective Gain (Loss) Recognined - Other Income	4	17	16	(3)
Other Income [Member] | Interest rate contracts/AFS securities [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Gain (Loss) on Derivative - Interest Income (Expense)	42	(41)	609	(326)
Gain (Loss) on Hedged Items - Interest Income (Expense)	(39)	58	(593)	323
Net Ineffective Gain (Loss) Recognined - Other Income	3	17	16	(3)
Other Income [Member] | Interest rate contracts/subordinated debt [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Gain (Loss) on Derivative - Interest Income (Expense)	0	3	(1)	9
Gain (Loss) on Hedged Items - Interest Income (Expense)	1	(3)	1	(9)
Net Ineffective Gain (Loss) Recognined - Other Income	$ 1	$ 0	$ 0	$ 0