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
	Mar. 31, 2015	Mar. 31, 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		$ (12)
Interest Rate Contract | Servicing Rights | Mortgage Banking Revenue
Derivative Instruments, Gain (Loss) [Line Items]
Net gains (losses) recorded in earnings	65	24
Foreign Exchange Contract | Forward Contracts | Other Noninterest Income
Derivative Instruments, Gain (Loss) [Line Items]
Net gains (losses) recorded in earnings	15	4
Equity Contract | Warrant | Other Noninterest Income
Derivative Instruments, Gain (Loss) [Line Items]
Net gains (losses) recorded in earnings	70	(36)
Equity Contract | Swap | Other Noninterest Income
Derivative Instruments, Gain (Loss) [Line Items]
Net gains (losses) recorded in earnings	$ (17)	$ 1