Net Gains (Losses) Recorded in the Consolidated Statements of Income Relating to Free-Standing Derivative Instruments Used For Risk Management (Detail) (USD $) In Millions, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2012	Sep. 30, 2011	Sep. 30, 2012	Sep. 30, 2011
Interest Rate Contract | Forward Contracts | Mortgage Banking Revenue
Derivative Instruments, Gain (Loss) [Line Items]
Net gains (losses) recorded in earnings	$ (59)	$ (57)	$ (42)	$ (136)
Interest Rate Contract | Mortgage Servicing Rights | Mortgage Banking Revenue
Derivative Instruments, Gain (Loss) [Line Items]
Net gains (losses) recorded in earnings	32	235	75	337
Interest Rate Contract | Interest Rate Swap | Other Noninterest Income [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Net gains (losses) recorded in earnings	1	2	2	6
Foreign Exchange Contract | Forward Contracts | Other Noninterest Income [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Net gains (losses) recorded in earnings	(1)		(1)
Equity Contract | Warrants | Other Noninterest Income [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Net gains (losses) recorded in earnings	(16)	(3)	85	22
Equity Contract | Put Option | Other Noninterest Income [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Net gains (losses) recorded in earnings		6	1	8
Equity Contract | Swap | Other Noninterest Income [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Net gains (losses) recorded in earnings	$ (1)	$ (17)	$ (30)	$ (30)