Change in Fair Value of Financial Instruments for which the FVO has been Elected (Detail) (USD $)	3 Months Ended				9 Months Ended
	Sep. 30, 2012		Sep. 30, 2011		Sep. 30, 2012		Sep. 30, 2011
Trading Account Assets [Member]
Fair Value Gain/(Loss) for Items Measured at Fair Value Pursuant to Election of the Fair Value Option	$ 9,000,000	[1]	$ 3,000,000	[2]	$ 25,000,000	[1]	$ 15,000,000	[2]
Loans Held-for-Sale
Fair Value Gain/(Loss) for Items Measured at Fair Value Pursuant to Election of the Fair Value Option	341,000,000	[1]	170,000,000	[2]	749,000,000	[1]	316,000,000	[2]
Mortgage Servicing Rights
Fair Value Gain/(Loss) for Items Measured at Fair Value Pursuant to Election of the Fair Value Option	(115,000,000)	[1]	(436,000,000)	[2]	(299,000,000)	[1]	(577,000,000)	[2]
Brokered Deposits
Fair Value Gain/(Loss) for Items Measured at Fair Value Pursuant to Election of the Fair Value Option	(3,000,000)	[1]	27,000,000	[2]	4,000,000	[1]	24,000,000	[2]
Long-term Debt [Member]
Fair Value Gain/(Loss) for Items Measured at Fair Value Pursuant to Election of the Fair Value Option	(41,000,000)	[1]	7,000,000	[2]	(55,000,000)	[1]	(31,000,000)	[2]
Loans Held For Investment [Member]
Fair Value Gain/(Loss) for Items Measured at Fair Value Pursuant to Election of the Fair Value Option	5,000,000	[1]	16,000,000	[2]	8,000,000	[1]	16,000,000	[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	9,000,000		3,000,000		25,000,000		15,000,000
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	5,000,000		(11,000,000)		10,000,000		(14,000,000)
Trading Account Profits And Commissions [Member] | Mortgage Servicing Rights
Fair Value Gain/(Loss) for Items Measured at Fair Value Pursuant to Election of the Fair Value Option	0		0		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	(3,000,000)		27,000,000		4,000,000		24,000,000
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	(41,000,000)		7,000,000		(55,000,000)		(31,000,000)
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		(1,000,000)		1,000,000		3,000,000
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		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	336,000,000	[3]	181,000,000	[4]	739,000,000	[3]	330,000,000	[4]
Mortgage Production Income [Member] | Mortgage Servicing Rights
Fair Value Gain/(Loss) for Items Measured at Fair Value Pursuant to Election of the Fair Value Option	1,000,000	[3]	1,000,000	[4]	31,000,000	[3]	5,000,000	[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		0		0		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		0		0
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	5,000,000	[3]	17,000,000	[4]	7,000,000	[3]	13,000,000	[4]
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		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		0		0
Mortgage Servicing Income [Member] | Mortgage Servicing Rights
Fair Value Gain/(Loss) for Items Measured at Fair Value Pursuant to Election of the Fair Value Option	(116,000,000)		(437,000,000)		(330,000,000)		(582,000,000)
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		0		0		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		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		$ 0		$ 0

[1] Changes in fair value for the three and nine months ended September 30, 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 recorded in interest income or interest expense in the Consolidated Statements of Income.

[2] Changes in fair value for the three and nine months ended September 30, 2011, 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 recorded in interest income or interest expense in the Consolidated Statements of Income.

[3] For the three and nine months ended September 30, 2012, income related to LHFS includes $82 million and $213 million, respectively, related to MSRs recognized upon the sale of loans reported at fair value. For the three and nine months ended September 30, 2012, income related to MSRs includes $1 million and $31 million, respectively, of MSRs recognized upon the sale of loans reported at LOCOM.

[4] For the three and nine months ended September 30, 2011, income related to LHFS includes $46 million and $178 million, respectively, related to MSRs recognized upon the sale of loans reported at fair value. For the three and nine months ended September 30, 2011, income related to MSRs includes $1 million and $5 million, respectively, of MSRs recognized upon the sale of loans reported at LOCOM.