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, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013
Interest Rate Contract | Forward Contracts | Loans Held For Sale [Member] | Mortgage Banking Revenue
Derivative Instruments, Gain (Loss) [Line Items]
Net gains (losses) recorded in earnings	$ 9	$ (191)	$ (14)	$ (20)
Interest Rate Contract | Servicing Rights | Mortgage Banking Revenue
Derivative Instruments, Gain (Loss) [Line Items]
Net gains (losses) recorded in earnings	(22)	24	40	(13)
Foreign Exchange Contract | Forward Contracts | Other Noninterest Income
Derivative Instruments, Gain (Loss) [Line Items]
Net gains (losses) recorded in earnings	9	(2)	8	3
Equity Contract | Warrant | Other Noninterest Income
Derivative Instruments, Gain (Loss) [Line Items]
Net gains (losses) recorded in earnings	(53)	6	(25)	116
Equity Contract | Swap | Other Noninterest Income
Derivative Instruments, Gain (Loss) [Line Items]
Net gains (losses) recorded in earnings	$ (3)	$ (2)	$ (18)	$ (13)