Fair Values of Assets and Liabilities (Significant Unobservable Level 3 Inputs Nonrecurring Basis) (Detail) (USD $) In Millions, unless otherwise specified	9 Months Ended
	Sep. 30, 2014	Sep. 30, 2013
Commercial Loans Held For Sale
Fair Value Inputs [Line Items]
Fair value measurements nonrecurring assets	$ 25
Commercial and Industrial Loans
Fair Value Inputs [Line Items]
Fair value measurements nonrecurring assets	387	431
Commercial Mortgage Loans
Fair Value Inputs [Line Items]
Fair value measurements nonrecurring assets	49	63
Commercial Construction Loans
Fair Value Inputs [Line Items]
Fair value measurements nonrecurring assets	4	3
Commercial Leases
Fair Value Inputs [Line Items]
Fair value measurements nonrecurring assets		1
Servicing Rights
Fair Value Inputs [Line Items]
Fair value measurements nonrecurring assets	933	915
OREO Property
Fair Value Inputs [Line Items]
Fair value measurements nonrecurring assets	77	109
Bank premises and equipment
Fair Value Inputs [Line Items]
Fair value measurements nonrecurring assets	$ 4
Minimum | Servicing Rights
Fair Value Inputs [Line Items]
Prepayment speed	0.00%	0.00%
Discount rate	9.60%	9.40%
Maximum | Servicing Rights
Fair Value Inputs [Line Items]
Prepayment speed	100.00%	100.00%
Discount rate	13.20%	18.00%
Weighted average | Commercial Loans Held For Sale
Fair Value Inputs [Line Items]
Cost to sell	10.00%	10.00%
Fixed | Servicing Rights
Fair Value Inputs [Line Items]
Prepayment speed	10.80%	11.40%
Discount rate	9.90%	10.40%
Adjustable | Servicing Rights
Fair Value Inputs [Line Items]
Prepayment speed	26.00%	25.70%
Discount rate	11.80%	11.60%