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, 2012	Mar. 31, 2011
Interest Rate Contract | Customer Contracts | Corporate Banking Revenue [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Net gains (losses) recorded in earnings	$ 6	$ 7
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)
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	3	7
Interest Rate Contract | Interest Rate Lock Commitments | Mortgage Banking Revenue [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Net gains (losses) recorded in earnings	50	24
Commodity Contract | Customer Contracts | Corporate Banking Revenue [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Net gains (losses) recorded in earnings	2	1
Foreign Exchange Contract | Customer Contracts | Corporate Banking Revenue [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Net gains (losses) recorded in earnings	15	16
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	$ (5)