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		9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014
Interest Rate Contract | Customer Contracts | Corporate Banking Revenue
Derivative Instruments, Gain (Loss) [Line Items]
Net gains (losses) recorded in earnings	$ 7	$ 5	$ 18	$ 14
Interest Rate Contract | Customer Contracts | Other noninterest expense
Derivative Instruments, Gain (Loss) [Line Items]
Net gains (losses) recorded in earnings			(1)	(1)
Interest Rate Contract | Fair Value Adjustments on Hedges and Derivative Contracts | Other noninterest expense
Derivative Instruments, Gain (Loss) [Line Items]
Net gains (losses) recorded in earnings	(1)	1	(1)	2
Interest Rate Contract | Interest Rate Lock Commitments | Mortgage Banking Revenue
Derivative Instruments, Gain (Loss) [Line Items]
Net gains (losses) recorded in earnings	38	18	90	92
Commodity Contract | Customer Contracts | Corporate Banking Revenue
Derivative Instruments, Gain (Loss) [Line Items]
Net gains (losses) recorded in earnings	1	2	4	5
Commodity Contract | Customer Contracts | Other noninterest expense
Derivative Instruments, Gain (Loss) [Line Items]
Net gains (losses) recorded in earnings			(2)
Commodity Contract | Fair Value Adjustments on Hedges and Derivative Contracts | Other noninterest expense
Derivative Instruments, Gain (Loss) [Line Items]
Net gains (losses) recorded in earnings		1	6
Foreign Exchange Contract | Customer Contracts | Corporate Banking Revenue
Derivative Instruments, Gain (Loss) [Line Items]
Net gains (losses) recorded in earnings	$ 17	19	$ 55	51
Foreign Exchange Contract | Fair Value Adjustments on Hedges and Derivative Contracts | Other noninterest expense
Derivative Instruments, Gain (Loss) [Line Items]
Net gains (losses) recorded in earnings		$ (1)		$ 1