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		9 Months Ended
	Sep. 30, 2012	Sep. 30, 2011	Sep. 30, 2012	Sep. 30, 2011
Interest Rate Contract | Customer Contracts | Corporate Banking Revenue [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Net gains (losses) recorded in earnings	$ 7	$ 7	$ 20	$ 22
Interest Rate Contract | Customer Contracts | Other Noninterest Expense [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Net gains (losses) recorded in earnings	(1)		(2)	(12)
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	2		5	10
Interest Rate Contract | Interest Rate Lock Commitments | Mortgage Banking Revenue [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Net gains (losses) recorded in earnings	166	100	341	156
Commodity Contract | Customer Contracts | Corporate Banking Revenue [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Net gains (losses) recorded in earnings	1	3	6	6
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	1	(1)	1
Foreign Exchange Contract | Customer Contracts | Corporate Banking Revenue [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Net gains (losses) recorded in earnings	16	17	49	48
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	$ 1	$ (3)	$ 2	$ (2)