Derivatives (Net Gains (Losses) Recorded in the Consolidated Statements of Income Relating to Free-Standing Derivative Instruments Used for Risk Management and Other Business Purposes) (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Derivative Instruments, Gain (Loss)
Net gains (losses) recorded in earnings	$ 221	$ (21)	$ 2
Interest Rate Contract | Forward Contracts | Residential mortgages held for sale | Mortgage Banking Revenue
Derivative Instruments, Gain (Loss)
Net gains (losses) recorded in earnings	4	(8)	(17)
Interest Rate Contract | Mortgage Servicing Rights | Mortgage Banking Revenue
Derivative Instruments, Gain (Loss)
Net gains (losses) recorded in earnings	221	(21)	2
Foreign Exchange Contract | Forward Contracts | Other Noninterest Income
Derivative Instruments, Gain (Loss)
Net gains (losses) recorded in earnings	(7)	10	(7)
Equity Contract | Swap | Other Noninterest Income
Derivative Instruments, Gain (Loss)
Net gains (losses) recorded in earnings	(107)	(59)	(80)
Equity Contract | Stock warrant | Other Noninterest Income
Derivative Instruments, Gain (Loss)
Net gains (losses) recorded in earnings	$ 0	$ 0	$ (1)