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	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Interest Rate Contract | Customer Contracts | Corporate Banking Revenue [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Net gains (losses) recorded in earnings	$ 30	$ 28	$ 26
Interest Rate Contract | Allowance for Loan and Lease Losses (Member) | Other Noninterest Expense [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Net gains (losses) recorded in earnings	(2)	(13)	(22)
Interest Rate Contract | Fair Value Adjustments on Hedges and Derivative Contracts | Other Noninterest Expense [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Net gains (losses) recorded in earnings	6	13	(1)
Interest Rate Contract | Interest Rate Lock Commitments [Member] | Mortgage Banking Revenue [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Net gains (losses) recorded in earnings	417	206	187
Commodity Contract | Customer Contracts | Corporate Banking Revenue [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Net gains (losses) recorded in earnings	7	8	8
Commodity Contract | Fair Value Adjustments on Hedges and Derivative Contracts | Other Noninterest Expense [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Net gains (losses) recorded in earnings	2
Foreign Exchange Contract | Customer Contracts | Corporate Banking Revenue [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Net gains (losses) recorded in earnings	65	47	63
Foreign Exchange Contract | Fair Value Adjustments on Hedges and Derivative Contracts | Other Noninterest Expense [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Net gains (losses) recorded in earnings	$ 2	$ 1	$ (1)