Change in Fair Value of Financial Instruments for which the FVO has been Elected (Detail) (USD $) In Millions, unless otherwise specified	3 Months Ended
	Mar. 31, 2013		Mar. 31, 2012
Gain (Loss) on Sales of Loans, Net	$ 4		$ 13
Trading Account Assets [Member]
Fair Value Gain/(Loss) for Items Measured at Fair Value Pursuant to Election of the Fair Value Option	4	[1]	8	[2]
Loans Held-for-Sale
Fair Value Gain/(Loss) for Items Measured at Fair Value Pursuant to Election of the Fair Value Option	(19)	[1]	(10)	[2]
Loans Held For Investment [Member]
Fair Value Gain/(Loss) for Items Measured at Fair Value Pursuant to Election of the Fair Value Option	(3)	[1]	(3)	[2]
Mortgage Servicing Rights [Member]
Fair Value Gain/(Loss) for Items Measured at Fair Value Pursuant to Election of the Fair Value Option	18	[1]	77	[2]
Brokered Deposits
Fair Value Gain/(Loss) for Items Measured at Fair Value Pursuant to Election of the Fair Value Option	2	[1]
Long-term Debt [Member]
Fair Value Gain/(Loss) for Items Measured at Fair Value Pursuant to Election of the Fair Value Option	(10)	[1]	(4)	[2]
Trading Account Profits And Commissions [Member] | Trading Account Assets [Member]
Fair Value Gain/(Loss) for Items Measured at Fair Value Pursuant to Election of the Fair Value Option	4		8
Trading Account Profits And Commissions [Member] | Loans Held-for-Sale
Fair Value Gain/(Loss) for Items Measured at Fair Value Pursuant to Election of the Fair Value Option	2		7
Trading Account Profits And Commissions [Member] | Loans Held For Investment [Member]
Fair Value Gain/(Loss) for Items Measured at Fair Value Pursuant to Election of the Fair Value Option	0		0
Trading Account Profits And Commissions [Member] | Mortgage Servicing Rights [Member]
Fair Value Gain/(Loss) for Items Measured at Fair Value Pursuant to Election of the Fair Value Option	0		0
Trading Account Profits And Commissions [Member] | Brokered Deposits
Fair Value Gain/(Loss) for Items Measured at Fair Value Pursuant to Election of the Fair Value Option	2
Trading Account Profits And Commissions [Member] | Long-term Debt [Member]
Fair Value Gain/(Loss) for Items Measured at Fair Value Pursuant to Election of the Fair Value Option	(10)		(4)
Mortgage Production Income [Member] | Trading Account Assets [Member]
Fair Value Gain/(Loss) for Items Measured at Fair Value Pursuant to Election of the Fair Value Option	0		0
Mortgage Production Income [Member] | Loans Held-for-Sale
Fair Value Gain/(Loss) for Items Measured at Fair Value Pursuant to Election of the Fair Value Option	(21)	[3]	(17)	[4]
Mortgage Production Income [Member] | Loans Held For Investment [Member]
Fair Value Gain/(Loss) for Items Measured at Fair Value Pursuant to Election of the Fair Value Option	(3)	[3]	(3)	[4]
Mortgage Production Income [Member] | Mortgage Servicing Rights [Member]
Fair Value Gain/(Loss) for Items Measured at Fair Value Pursuant to Election of the Fair Value Option	1	[3]	10	[4]
Mortgage Production Income [Member] | Brokered Deposits
Fair Value Gain/(Loss) for Items Measured at Fair Value Pursuant to Election of the Fair Value Option	0
Mortgage Production Income [Member] | Long-term Debt [Member]
Fair Value Gain/(Loss) for Items Measured at Fair Value Pursuant to Election of the Fair Value Option	0		0
Mortgage Servicing Income [Member] | Trading Account Assets [Member]
Fair Value Gain/(Loss) for Items Measured at Fair Value Pursuant to Election of the Fair Value Option	0		0
Mortgage Servicing Income [Member] | Loans Held-for-Sale
Fair Value Gain/(Loss) for Items Measured at Fair Value Pursuant to Election of the Fair Value Option	0		0
Mortgage Servicing Income [Member] | Loans Held For Investment [Member]
Fair Value Gain/(Loss) for Items Measured at Fair Value Pursuant to Election of the Fair Value Option	0		0
Mortgage Servicing Income [Member] | Mortgage Servicing Rights [Member]
Fair Value Gain/(Loss) for Items Measured at Fair Value Pursuant to Election of the Fair Value Option	17		67
Mortgage Servicing Income [Member] | Brokered Deposits
Fair Value Gain/(Loss) for Items Measured at Fair Value Pursuant to Election of the Fair Value Option	0
Mortgage Servicing Income [Member] | Long-term Debt [Member]
Fair Value Gain/(Loss) for Items Measured at Fair Value Pursuant to Election of the Fair Value Option	$ 0		$ 0

[1] Changes in fair value for the three months ended March 31, 2013, exclude accrued interest for the period then ended. Interest income or interest expense on trading loans, LHFS, LHFI, brokered time deposits, and long-term debt that have been elected to be carried at fair value are recognized in interest income or interest expense in the Consolidated Statements of Income.

[2] Changes in fair value for the three months ended March 31, 2012, exclude accrued interest for the period then ended. Interest income or interest expense on trading loans, LHFS, LHFI, brokered time deposits, and long-term debt that have been elected to be carried at fair value are recognized in interest income or interest expense in the Consolidated Statements of Income.

[3] Income related to LHFS does not include income from IRLCs. For the three months ended March 31, 2013, income related to MSRs includes $1 million of MSRs recognized upon the sale of loans reported at LOCOM.

[4] Income related to LHFS does not include income from IRLCs. For the three months ended March 31, 2012, income related to MSRs includes $10 million of MSRs recognized upon the sale of loans reported at LOCOM.