Fair Values of Assets and Liabilities (Significant Unobservable Level 3 Inputs) (Detail) (Fair Value, Inputs, Level 3, USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2012
Residential mortgage loans | Fair value, recurring
Fair Value Inputs [Line Items]
Residential mortgage loans	$ 76
IRLCs, net | Fair value, recurring
Fair Value Inputs [Line Items]
Derivative instruments	60
Stock warrants associated with the sale of the processing business | Fair value, recurring
Fair Value Inputs [Line Items]
Derivative instruments	177
Swap associated with the sale of Visa, Inc. Class B shares | Fair value, recurring
Fair Value Inputs [Line Items]
Derivative instruments	(33)
Commercial Loans Held For Sale | Fair value, nonrecurring
Fair Value Inputs [Line Items]
Fair value measurements nonrecurring assets	9
OREO Property | Fair value, nonrecurring
Fair Value Inputs [Line Items]
Fair value measurements nonrecurring assets	165
Commercial and Industrial Loans | Fair value, nonrecurring
Fair Value Inputs [Line Items]
Default rates	100.00%
Fair value measurements nonrecurring assets	83
Commercial Mortgage Loans | Fair value, nonrecurring
Fair Value Inputs [Line Items]
Default rates	100.00%
Fair value measurements nonrecurring assets	46
Commercial Construction Loans | Fair value, nonrecurring
Fair Value Inputs [Line Items]
Default rates	100.00%
Fair value measurements nonrecurring assets	4
Mortgage Servicing Rights | Fair value, nonrecurring
Fair Value Inputs [Line Items]
Fair value measurements nonrecurring assets	$ 697
Minimum | Residential mortgage loans | Fair value, recurring
Fair Value Inputs [Line Items]
Interest rate risk factor	(91.20%)
Credit risk factor	0.00%
Minimum | IRLCs, net | Fair value, recurring
Fair Value Inputs [Line Items]
Loan closing rates	9.90%
Minimum | Stock warrants associated with the sale of the processing business | Fair value, recurring
Fair Value Inputs [Line Items]
Expected term (years)	2 years
Expected volatility	27.20%
Minimum | Swap associated with the sale of Visa, Inc. Class B shares | Fair value, recurring
Fair Value Inputs [Line Items]
Timing of the resolution of the covered litigation	12/31/2013
Minimum | Commercial and Industrial Loans | Fair value, nonrecurring
Fair Value Inputs [Line Items]
Loss severities	0.00%
Minimum | Commercial Mortgage Loans | Fair value, nonrecurring
Fair Value Inputs [Line Items]
Loss severities	0.00%
Minimum | Commercial Construction Loans | Fair value, nonrecurring
Fair Value Inputs [Line Items]
Loss severities	0.00%
Minimum | Mortgage Servicing Rights | Fair value, nonrecurring
Fair Value Inputs [Line Items]
Prepayment speed	0.00%
Discount rate	9.40%
Maximum | Residential mortgage loans | Fair value, recurring
Fair Value Inputs [Line Items]
Interest rate risk factor	17.00%
Credit risk factor	68.40%
Maximum | IRLCs, net | Fair value, recurring
Fair Value Inputs [Line Items]
Loan closing rates	95.00%
Maximum | Stock warrants associated with the sale of the processing business | Fair value, recurring
Fair Value Inputs [Line Items]
Expected term (years)	16 years 6 months
Expected volatility	40.00%
Maximum | Swap associated with the sale of Visa, Inc. Class B shares | Fair value, recurring
Fair Value Inputs [Line Items]
Timing of the resolution of the covered litigation	12/31/2016
Maximum | Commercial and Industrial Loans | Fair value, nonrecurring
Fair Value Inputs [Line Items]
Loss severities	100.00%
Maximum | Commercial Mortgage Loans | Fair value, nonrecurring
Fair Value Inputs [Line Items]
Loss severities	100.00%
Maximum | Commercial Construction Loans | Fair value, nonrecurring
Fair Value Inputs [Line Items]
Loss severities	21.50%
Maximum | Mortgage Servicing Rights | Fair value, nonrecurring
Fair Value Inputs [Line Items]
Prepayment speed	100.00%
Discount rate	18.00%
Weighted average | Residential mortgage loans | Fair value, recurring
Fair Value Inputs [Line Items]
Interest rate risk factor	5.80%
Credit risk factor	4.30%
Weighted average | IRLCs, net | Fair value, recurring
Fair Value Inputs [Line Items]
Loan closing rates	58.30%
Weighted average | Stock warrants associated with the sale of the processing business | Fair value, recurring
Fair Value Inputs [Line Items]
Expected term (years)	6 years 2 months 12 days
Expected volatility	33.80%
Weighted average | Commercial Loans Held For Sale | Fair value, nonrecurring
Fair Value Inputs [Line Items]
Cost to sell	10.00%
Weighted average | Commercial and Industrial Loans | Fair value, nonrecurring
Fair Value Inputs [Line Items]
Loss severities	8.90%
Weighted average | Commercial Mortgage Loans | Fair value, nonrecurring
Fair Value Inputs [Line Items]
Loss severities	19.90%
Weighted average | Commercial Construction Loans | Fair value, nonrecurring
Fair Value Inputs [Line Items]
Loss severities	8.90%
Fixed | Mortgage Servicing Rights | Fair value, nonrecurring
Fair Value Inputs [Line Items]
Prepayment speed	16.10%
Discount rate	10.50%
Adjustable | Mortgage Servicing Rights | Fair value, nonrecurring
Fair Value Inputs [Line Items]
Prepayment speed	26.90%
Discount rate	11.70%