Assets and Liabilities Measured at Fair Value on a Nonrecurring Basis (Detail) (USD $) In Millions, unless otherwise specified	3 Months Ended				6 Months Ended
	Jun. 30, 2014		Jun. 30, 2013		Jun. 30, 2014		Jun. 30, 2013
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Fair Value Measurements	$ 1,252		$ 1,134		$ 1,252		$ 1,134
Fair Value Measured On Nonrecurring Basis Gains Losses	(146)		59		(208)		59
Loans Held-for-Sale
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Fair Value Measurements	45	[1]	2	[1]	45	[1]	2	[1]
Fair Value Measured On Nonrecurring Basis Gains Losses	(1)	[1]	(1)	[1]	(2)	[1]	(5)	[1]
Commercial and Industrial Loans
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Fair Value Measurements	62		83		62		83
Fair Value Measured On Nonrecurring Basis Gains Losses	(83)		(25)		(124)		(31)
Commercial Mortgage Loans
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Fair Value Measurements	76		35		76		35
Fair Value Measured On Nonrecurring Basis Gains Losses	(6)		(8)		(17)		(25)
Commercial Construction
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Fair Value Measurements	2		8		2		8
Fair Value Measured On Nonrecurring Basis Gains Losses			(2)				(2)
Bank premises and equipment
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Fair Value Measurements	15				15
Fair Value Measured On Nonrecurring Basis Gains Losses	(18)				(18)
Servicing Rights
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Fair Value Measurements	928		894		928		894
Fair Value Measured On Nonrecurring Basis Gains Losses	(32)		102		(28)		151
Other Real Estate Owned
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Fair Value Measurements	124		112		124		112
Fair Value Measured On Nonrecurring Basis Gains Losses	(6)		(7)		(19)		(29)
Fair Value, Inputs, Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Fair Value Measurements	1,252		1,134		1,252		1,134
Fair Value, Inputs, Level 3 | Loans Held-for-Sale
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Fair Value Measurements	45	[1]	2	[1]	45	[1]	2	[1]
Fair Value, Inputs, Level 3 | Commercial and Industrial Loans
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Fair Value Measurements	62		83		62		83
Fair Value, Inputs, Level 3 | Commercial Mortgage Loans
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Fair Value Measurements	76		35		76		35
Fair Value, Inputs, Level 3 | Commercial Construction
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Fair Value Measurements	2		8		2		8
Fair Value, Inputs, Level 3 | Bank premises and equipment
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Fair Value Measurements	15				15
Fair Value, Inputs, Level 3 | Servicing Rights
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Fair Value Measurements	928		894		928		894
Fair Value, Inputs, Level 3 | Other Real Estate Owned
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Fair Value Measurements	$ 124		$ 112		$ 124		$ 112

[1]  Includes commercial nonaccrual loans held for sale