Net Gains (Losses) Recorded in the Consolidated Statements of Income Relating to Free-Standing Derivative Instruments Used For Customer Accommodation (Detail) (USD $) In Millions, unless otherwise specified	3 Months Ended
	Mar. 31, 2015	Mar. 31, 2014
Interest Rate Contract | Customer Contracts | Corporate Banking Revenue
Derivative Instruments, Gain (Loss) [Line Items]
Net gains (losses) recorded in earnings	$ 6	$ 4
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	35	36
Commodity Contract | Customer Contracts | Corporate Banking Revenue
Derivative Instruments, Gain (Loss) [Line Items]
Net gains (losses) recorded in earnings	1	1
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	5
Foreign Exchange Contract | Customer Contracts | Corporate Banking Revenue
Derivative Instruments, Gain (Loss) [Line Items]
Net gains (losses) recorded in earnings	21	15
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