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		6 Months Ended
	Jun. 30, 2013	Jun. 30, 2012	Jun. 30, 2013	Jun. 30, 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	$ (5)	$ 3	$ (7)	$ 3
Asset and Liability Management Positions [Member] | Interest Rate Contracts [Member] | Mortgage Banking Revenue [Member] | Other Economic Hedges [Member] | Futures and Forwards [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Gains (losses) recognized in earnings	300	(58)	536	111
Asset and Liability Management Positions [Member] | Interest Rate Contracts [Member] | Mortgage Banking Revenue [Member] | Other Economic Hedges [Member] | Options [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Gains (losses) recognized in earnings	17	245	146	399
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	(219)	195	(259)	138
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] | Foreign Exchange Forward Contracts [Member] | Commercial Products Revenue [Member] | Other Economic Hedges [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Gains (losses) recognized in earnings	26	(30)	34	(37)
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		1	(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	(205)	146	(301)	6
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	212	(143)	308	(4)
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	$ 14	$ 12	$ 21	$ 23