Derivative Financial Instruments - Gains and Losses on Hedged Items in Fair Value Hedges (Detail) (USD $) In Millions, unless otherwise specified	3 Months Ended
	Mar. 31, 2014	Mar. 31, 2013
Derivative Instruments, Gain (Loss) [Line Items]
Net Ineffective Gain (Loss) Recognined - Other Income	$ 0	$ 0
Interest Income Expense [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Gain (Loss) on Derivative - Interest Income (Expense)	(60)	(52)
Gain (Loss) on Hedged Items - Interest Income (Expense)	87	98
Interest Income Expense [Member] | Interest rate contracts/AFS securities [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Gain (Loss) on Derivative - Interest Income (Expense)	(64)	(56)
Gain (Loss) on Hedged Items - Interest Income (Expense)	102	112
Interest Income Expense [Member] | Interest rate contracts/subordinated debt [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Gain (Loss) on Derivative - Interest Income (Expense)	4	4
Gain (Loss) on Hedged Items - Interest Income (Expense)	(15)	(14)
Other Income [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Gain (Loss) on Derivative - Interest Income (Expense)	(220)	169
Gain (Loss) on Hedged Items - Interest Income (Expense)	214	(173)
Net Ineffective Gain (Loss) Recognined - Other Income	(6)	(4)
Other Income [Member] | Interest rate contracts/AFS securities [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Gain (Loss) on Derivative - Interest Income (Expense)	(219)	170
Gain (Loss) on Hedged Items - Interest Income (Expense)	213	(174)
Net Ineffective Gain (Loss) Recognined - Other Income	(6)	(4)
Other Income [Member] | Interest rate contracts/subordinated debt [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Gain (Loss) on Derivative - Interest Income (Expense)	(1)	(1)
Gain (Loss) on Hedged Items - Interest Income (Expense)	1	1
Net Ineffective Gain (Loss) Recognined - Other Income	$ 0	$ 0