Fair Value Measurements (Fair Values of Assets and Liabilities (Significant Unobservable Level 3 Inputs Nonrecurring Basis)) (Detail) - USD ($) $ in Millions	6 Months Ended
	Jun. 30, 2016	Jun. 30, 2015
Commercial Loans Held For Sale | Commercial
Fair Value Inputs [Line Items]
Fair value measurements nonrecurring assets	$ 20	$ 15
Residential Mortgagel Loans Held For Sale
Fair Value Inputs [Line Items]
Fair value measurements nonrecurring assets		91
Automobile Loans Held For Sale
Fair Value Inputs [Line Items]
Fair value measurements nonrecurring assets		3
Commercial and Industrial Loans | Commercial
Fair Value Inputs [Line Items]
Fair value measurements nonrecurring assets	426	397
Commercial Mortgage Loans | Commercial
Fair Value Inputs [Line Items]
Fair value measurements nonrecurring assets	67	85
Commercial construction loans | Commercial
Fair Value Inputs [Line Items]
Fair value measurements nonrecurring assets		55
Commercial Leases | Commercial
Fair Value Inputs [Line Items]
Fair value measurements nonrecurring assets	3
Servicing Rights
Fair Value Inputs [Line Items]
Fair value measurements nonrecurring assets	621	854
OREO Property
Fair Value Inputs [Line Items]
Fair value measurements nonrecurring assets	38	46
Bank premises and equipment
Fair Value Inputs [Line Items]
Fair value measurements nonrecurring assets	20	130
Operating lease equipment
Fair Value Inputs [Line Items]
Fair value measurements nonrecurring assets	$ 38	$ 57
Minimum | Residential Mortgagel Loans Held For Sale
Fair Value Inputs [Line Items]
Interest rate risk factor		(7.50%)
Minimum | Residential mortgage loans
Fair Value Inputs [Line Items]
Interest rate risk factor	(5.20%)	(9.70%)
Minimum | Servicing Rights
Fair Value Inputs [Line Items]
Prepayment speed		1.00%
OAS spread (bps)	404	430
Maximum | Residential Mortgagel Loans Held For Sale
Fair Value Inputs [Line Items]
Interest rate risk factor		0.10%
Maximum | Residential mortgage loans
Fair Value Inputs [Line Items]
Interest rate risk factor	16.30%	20.00%
Credit risk factor	80.50%	85.50%
Maximum | Servicing Rights
Fair Value Inputs [Line Items]
Prepayment speed	100.00%	100.00%
OAS spread (bps)	1515	1750
Weighted average | Commercial Loans Held For Sale | Commercial
Fair Value Inputs [Line Items]
Cost to sell	10.00%
Discount spread		4.40%
Weighted average | Residential Mortgagel Loans Held For Sale
Fair Value Inputs [Line Items]
Interest rate risk factor		(1.60%)
Credit risk factor		0.10%
Weighted average | Automobile Loans Held For Sale
Fair Value Inputs [Line Items]
Discount spread		3.10%
Weighted average | Residential mortgage loans
Fair Value Inputs [Line Items]
Interest rate risk factor	5.00%	2.70%
Credit risk factor	1.10%	0.90%
Weighted average | Fixed | Servicing Rights
Fair Value Inputs [Line Items]
Prepayment speed	15.00%	7.60%
OAS spread (bps)	648	930
Weighted average | Adjustable | Servicing Rights
Fair Value Inputs [Line Items]
Prepayment speed	26.90%	32.70%
OAS spread (bps)	762	651