Assets and Liabilities Measured at Fair Value on a Nonrecurring Basis (Detail) (USD $) In Millions, unless otherwise specified	3 Months Ended			9 Months Ended
	Sep. 30, 2013	Sep. 30, 2012		Sep. 30, 2013		Sep. 30, 2012
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Fair Value Measurements	$ 1,522	$ 952		$ 1,522		$ 952
Fair Value Measured On Nonrecurring Basis Gains Losses	(125)	(139)		(66)		(339)
Loans Held-for-Sale
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Fair Value Measurements		13	[1]			13	[1]
Fair Value Measured On Nonrecurring Basis Gains Losses		(4)	[1]	(5)	[1]	(10)	[1]
Commercial and Industrial Loans
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Fair Value Measurements	431	79		431		79
Fair Value Measured On Nonrecurring Basis Gains Losses	(103)	(31)		(134)		(86)
Commercial Mortgage Loans
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Fair Value Measurements	63	59		63		59
Fair Value Measured On Nonrecurring Basis Gains Losses	(9)	(11)		(34)		(40)
Commercial Construction
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Fair Value Measurements	3	8		3		8
Fair Value Measured On Nonrecurring Basis Gains Losses	(4)	(5)		(6)		(21)
Commercial Leases
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Fair Value Measurements	1			1
Servicing Rights
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Fair Value Measurements	915	679		915		679
Fair Value Measured On Nonrecurring Basis Gains Losses	(1)	(72)		150		(122)
Other Real Estate Owned
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Fair Value Measurements	109	114		109		114
Fair Value Measured On Nonrecurring Basis Gains Losses	(8)	(16)		(37)		(60)
Fair Value, Inputs, Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Fair Value Measurements	1,522	952		1,522		952
Fair Value, Inputs, Level 3 | Loans Held-for-Sale
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Fair Value Measurements		13	[1]			13	[1]
Fair Value, Inputs, Level 3 | Commercial and Industrial Loans
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Fair Value Measurements	431	79		431		79
Fair Value, Inputs, Level 3 | Commercial Mortgage Loans
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Fair Value Measurements	63	59		63		59
Fair Value, Inputs, Level 3 | Commercial Construction
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Fair Value Measurements	3	8		3		8
Fair Value, Inputs, Level 3 | Commercial Leases
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Fair Value Measurements	1			1
Fair Value, Inputs, Level 3 | Servicing Rights
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Fair Value Measurements	915	679		915		679
Fair Value, Inputs, Level 3 | Other Real Estate Owned
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Fair Value Measurements	$ 109	$ 114		$ 109		$ 114

[1]  Includes commercial nonaccrual loans held for sale