Derivatives (Net Gains (Losses) Recorded in the Consolidated Statements of Income Relating to Free-Standing Derivative Instruments Used For Customer Accommodation) (Detail) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
Interest Rate Contract | Customer Contracts | Corporate Banking Revenue
Derivative Instruments, Gain (Loss)
Net gains (losses) recorded in earnings	$ 5	$ 7
Interest Rate Contract | Fair Value Adjustments on Hedges and Derivative Contracts | Other noninterest expense
Derivative Instruments, Gain (Loss)
Net gains (losses) recorded in earnings	0	(1)
Interest Rate Contract | Interest Rate Lock Commitments | Mortgage Banking Revenue
Derivative Instruments, Gain (Loss)
Net gains (losses) recorded in earnings	22	42
Commodity Contract | Customer Contracts | Corporate Banking Revenue
Derivative Instruments, Gain (Loss)
Net gains (losses) recorded in earnings	1	1
Commodity Contract | Fair Value Adjustments on Hedges and Derivative Contracts | Other noninterest expense
Derivative Instruments, Gain (Loss)
Net gains (losses) recorded in earnings	1	(1)
Foreign Exchange Contract | Customer Contracts | Corporate Banking Revenue
Derivative Instruments, Gain (Loss)
Net gains (losses) recorded in earnings	13	16
Foreign Exchange Contract | Fair Value Adjustments on Hedges and Derivative Contracts | Other noninterest expense
Derivative Instruments, Gain (Loss)
Net gains (losses) recorded in earnings	$ 1	$ (2)