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		6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 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	$ 11	$ (11)	$ 12	$ (23)
Interest Rate Contract | Servicing Rights | Mortgage Banking Revenue
Derivative Instruments, Gain (Loss) [Line Items]
Net gains (losses) recorded in earnings	(30)	38	35	61
Foreign Exchange Contract | Forward Contracts | Other Noninterest Income
Derivative Instruments, Gain (Loss) [Line Items]
Net gains (losses) recorded in earnings	(1)	(5)	13	(1)
Equity Contract | Warrant | Other Noninterest Income
Derivative Instruments, Gain (Loss) [Line Items]
Net gains (losses) recorded in earnings	14	63	85	28
Equity Contract | Swap | Other Noninterest Income
Derivative Instruments, Gain (Loss) [Line Items]
Net gains (losses) recorded in earnings	$ (2)	$ (16)	$ (19)	$ (15)