Derivative Instruments - Summary of Gains (Losses) Recognized in Earnings for Fair Value Hedges, Other Economic Hedges and Customer-Related Positions (Detail) (USD $) In Millions, unless otherwise specified	3 Months Ended
	Mar. 31, 2013	Mar. 31, 2012
Asset and Liability Management Positions [Member] | Interest rate contracts [Member] | Other noninterest income [Member] | Fair value hedges [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Gains (losses) recognized in earnings	$ (2)
Asset and Liability Management Positions [Member] | Interest rate contracts [Member] | Mortgage banking revenue [Member] | Other economic hedges [Member] | Receive fixed/pay floating swaps [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Gains (losses) recognized in earnings	(40)	(57)
Asset and Liability Management Positions [Member] | Foreign exchange cross-currency swaps [Member] | Other noninterest income [Member] | Fair value hedges [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Gains (losses) recognized in earnings		42
Asset and Liability Management Positions [Member] | Futures and forwards interest rate contract [Member] | Mortgage banking revenue [Member] | Other economic hedges [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Gains (losses) recognized in earnings	236	169
Asset and Liability Management Positions [Member] | Purchased and written options interest rate contract [Member] | Mortgage banking revenue [Member] | Other economic hedges [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Gains (losses) recognized in earnings	129	154
Asset and Liability Management Positions [Member] | Foreign exchange forward contracts [Member] | Commercial products revenue [Member] | Other economic hedges [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Gains (losses) recognized in earnings	8	(17)
Asset and Liability Management Positions [Member] | Equity contracts [Member] | Compensation expense [Member] | Other economic hedges [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Gains (losses) recognized in earnings		(1)
Asset and Liability Management Positions [Member] | Credit contracts [Member] | Other noninterest income expense [Member] | Other economic hedges [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Gains (losses) recognized in earnings	(1)	(6)
Customer-Related Positions [Member] | Interest rate contracts [Member] | Other noninterest income [Member] | Receive fixed/pay floating swaps [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Gains (losses) recognized in earnings	(96)	(140)
Customer-Related Positions [Member] | Interest rate contracts [Member] | Other noninterest income [Member] | Pay fixed/receive floating swaps [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Gains (losses) recognized in earnings	96	139
Customer-Related Positions [Member] | Foreign exchange contract [Member] | Commercial products revenue [Member] | Forwards, spots and swaps [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Gains (losses) recognized in earnings	$ 7	$ 21