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		6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
Interest Rate Contract | Customer Contracts | Corporate Banking Revenue
Derivative Instruments, Gain (Loss) [Line Items]
Net gains (losses) recorded in earnings	$ 4	$ 5	$ 11	$ 9
Interest Rate Contract | Customer Contracts | Other noninterest expense
Derivative Instruments, Gain (Loss) [Line Items]
Net gains (losses) recorded in earnings	(1)	(1)	(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
Interest Rate Contract | Interest Rate Lock Commitments | Mortgage Banking Revenue
Derivative Instruments, Gain (Loss) [Line Items]
Net gains (losses) recorded in earnings	17	38	52	74
Commodity Contract | Customer Contracts | Corporate Banking Revenue
Derivative Instruments, Gain (Loss) [Line Items]
Net gains (losses) recorded in earnings	2	2	3	3
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	18	$ 17	$ 39	32
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			$ 2