Derivatives (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
	Mar. 31, 2018	Mar. 31, 2017
Interest Rate Contract | Forward Contracts | Loans Held For Sale | Mortgage Banking Revenue
Derivative Instruments, Gain (Loss)
Net gains (losses) recorded in earnings	$ 0	$ (21)
Interest Rate Contract | Servicing Rights | Mortgage Banking Revenue
Derivative Instruments, Gain (Loss)
Net gains (losses) recorded in earnings	(49)	(1)
Foreign Exchange Contract | Forward Contracts | Other Noninterest Income
Derivative Instruments, Gain (Loss)
Net gains (losses) recorded in earnings	2	(1)
Equity Contract | Swap | Other Noninterest Income
Derivative Instruments, Gain (Loss)
Net gains (losses) recorded in earnings	$ (39)	$ (13)