Assets and Liabilities Measured at Fair Value on a Nonrecurring Basis (Detail) (USD $) In Millions	3 Months Ended				9 Months Ended
	Sep. 30, 2011		Sep. 30, 2010		Sep. 30, 2011		Sep. 30, 2010
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value Measurements	$ 1,262		$ 1,772		$ 1,262		$ 1,772
Fair Value Measured On Nonrecurring Basis Gains Losses	(398)		(809)		(849)		(1,525)
Fair Value, Inputs, Level 1 | Loans Held For Sale [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value Measurements			33				33
Fair Value, Inputs, Level 3 | Loans Held For Sale [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value Measurements	60	[1]	541	[1]	60	[1]	541	[1]
Loans Held For Sale [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value Measurements	60	[1]	574	[1]	60	[1]	574	[1]
Fair Value Measured On Nonrecurring Basis Gains Losses	(23)	[1]	(398)	[1]	(48)	[1]	(413)	[1]
Fair Value, Inputs, Level 3 | Commercial And Industrial Loans [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value Measurements	155		122		155		122
Commercial And Industrial Loans [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value Measurements	155		122		155		122
Fair Value Measured On Nonrecurring Basis Gains Losses	(84)		(112)		(283)		(373)
Fair Value, Inputs, Level 3 | Commercial Mortgage Loans [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value Measurements	145		94		145		94
Commercial Mortgage Loans [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value Measurements	145		94		145		94
Fair Value Measured On Nonrecurring Basis Gains Losses	(46)		(52)		(99)		(184)
Fair Value, Inputs, Level 3 | Commercial Construction
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value Measurements	59		45		59		45
Commercial Construction
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value Measurements	59		45		59		45
Fair Value Measured On Nonrecurring Basis Gains Losses	(14)		(44)		(52)		(152)
Fair Value, Inputs, Level 3 | Mortgage Servicing Rights
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value Measurements	662		599		662		599
Mortgage Servicing Rights
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value Measurements	662		599		662		599
Fair Value Measured On Nonrecurring Basis Gains Losses	(201)		(83)		(228)		(189)
Fair Value, Inputs, Level 3 | Other Real Estate Owned [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value Measurements	181		254		181		254
Other Real Estate Owned [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value Measurements	181		254		181		254
Fair Value Measured On Nonrecurring Basis Gains Losses	(30)		(102)		(139)		(196)
Fair Value, Inputs, Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value Measurements			33				33
Fair Value, Inputs, Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value Measurements	$ 1,262		$ 1,668		$ 1,262		$ 1,668

[1] Includes commercial nonaccrual loans held for sale