Net Gains (Losses) Recorded in the Consolidated Statements of Income Relating to Free-Standing Derivative Instruments Used For Risk Management (Detail) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014
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	$ (15)	$ 9	$ (4)	$ (14)
Interest Rate Contract | Servicing Rights | Mortgage Banking Revenue
Derivative Instruments, Gain (Loss) [Line Items]
Net gains (losses) recorded in earnings	85	(22)	119	40
Foreign Exchange Contract | Forward Contracts | Other Noninterest Income
Derivative Instruments, Gain (Loss) [Line Items]
Net gains (losses) recorded in earnings	6	9	19	8
Equity Contract | Warrant | Other Noninterest Income
Derivative Instruments, Gain (Loss) [Line Items]
Net gains (losses) recorded in earnings	130	(53)	215	(25)
Equity Contract | Swap | Other Noninterest Income
Derivative Instruments, Gain (Loss) [Line Items]
Net gains (losses) recorded in earnings	$ (8)	$ (3)	$ (27)	$ (18)