Assets and Liabilities Measured at Fair Value on a Nonrecurring Basis (Detail) (USD $) In Millions, unless otherwise specified	3 Months Ended
	Mar. 31, 2014	Mar. 31, 2013
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Fair Value Measurements	$ 1,122	$ 951
Fair Value Measured On Nonrecurring Basis Gains Losses	(61)
Loans Held-for-Sale
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Fair Value Measurements		4	[1]
Fair Value Measured On Nonrecurring Basis Gains Losses		(4)	[1]
Commercial and Industrial Loans
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Fair Value Measurements	22	20
Fair Value Measured On Nonrecurring Basis Gains Losses	(41)	(6)
Commercial Mortgage Loans
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Fair Value Measurements	31	34
Fair Value Measured On Nonrecurring Basis Gains Losses	(11)	(17)
Commercial Construction
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Fair Value Measurements	2	7
Servicing Rights
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Fair Value Measurements	972	766
Fair Value Measured On Nonrecurring Basis Gains Losses	4	49
Other Real Estate Owned
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Fair Value Measurements	95	120
Fair Value Measured On Nonrecurring Basis Gains Losses	(13)	(22)
Fair Value, Inputs, Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Fair Value Measurements	1,122	951
Fair Value, Inputs, Level 3 | Loans Held-for-Sale
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Fair Value Measurements		4	[1]
Fair Value, Inputs, Level 3 | Commercial and Industrial Loans
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Fair Value Measurements	22	20
Fair Value, Inputs, Level 3 | Commercial Mortgage Loans
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Fair Value Measurements	31	34
Fair Value, Inputs, Level 3 | Commercial Construction
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Fair Value Measurements	2	7
Fair Value, Inputs, Level 3 | Servicing Rights
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Fair Value Measurements	972	766
Fair Value, Inputs, Level 3 | Other Real Estate Owned
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Fair Value Measurements	$ 95	$ 120

[1]  Includes commercial nonaccrual loans held for sale