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		9 Months Ended
	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 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		$ 2	$ (7)	$ 5
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	33	(44)	569	67
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	54	290	200	689
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	(5)	48	(264)	186
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	(16)	(25)	18	(62)
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	2
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	2	(2)	1	(8)
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	13	(16)	(288)	(10)
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	(10)	19	298	15
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	$ 15	$ 13	$ 36	$ 36