Fair Value (Fair Value Measurements- Nonrecurring Quantitative Information) (Details) (Fair Value, Measurements, Nonrecurring [Member], Level 3 [Member], USD $) In Millions, unless otherwise specified	Jun. 30, 2013	Dec. 31, 2012
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Nonrecurring Assets - Fair Value	$ 1,068	$ 907
Other Assets
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Nonrecurring Assets - Fair Value	270	299
Nonaccrual Loans [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Nonrecurring Assets - Fair Value	83	158
Nonaccrual Loans [Member] | Other Assets
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Nonrecurring Assets - Fair Value	19	68
Nonaccrual Loans [Member] | Fair Value Of Collateral [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Nonrecurring Assets - Fair Value	64	90
Nonaccrual Loans [Member] | Fair Value Of Collateral [Member] | Loss Severity [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Range (Minimum % or bps amount)	6.30%	4.60%
Range (Maximum % or bps amount)	85.20%	97.20%
Weighted Average (% or bps amount)	35.10%	58.10%
Loans Held For Sale [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Nonrecurring Assets - Fair Value	209	315
Loans Held For Sale [Member] | Discounted Cash Flow [Member] | Spread Over Benchmark Curve [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Range (Minimum % or bps amount)	0.80%	0.40%
Range (Maximum % or bps amount)	2.47%	2.33%
Weighted Average (% or bps amount)	1.09%	0.86%
Loans Held For Sale [Member] | Discounted Cash Flow [Member] | Embedded Servicing Value [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Range (Minimum % or bps amount)	0.80%	0.80%
Range (Maximum % or bps amount)	3.00%	2.60%
Weighted Average (% or bps amount)	2.80%	2.00%
Equity Investments [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Nonrecurring Assets - Fair Value	6	12
Equity Investments [Member] | Discounted Cash Flow [Member] | Market Rate Of Return [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Range (Minimum % or bps amount)	6.50%	4.60%
Range (Maximum % or bps amount)	6.50%	6.50%
Weighted Average (% or bps amount)	6.50%	5.40%
Mortgage Servicing Rights [Member] | Commercial Mortgage [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Nonrecurring Assets - Fair Value	519	191
Mortgage Servicing Rights [Member] | Discounted Cash Flow [Member] | Constant Prepayment Rate [Member] | Commercial Mortgage [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Range (Minimum % or bps amount)	6.20%	7.10%
Range (Maximum % or bps amount)	11.70%	20.10%
Weighted Average (% or bps amount)	6.90%	7.80%
Mortgage Servicing Rights [Member] | Discounted Cash Flow [Member] | Discount Rate [Member] | Commercial Mortgage [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Range (Minimum % or bps amount)	6.20%	5.60%
Range (Maximum % or bps amount)	7.50%	7.80%
Weighted Average (% or bps amount)	7.10%	7.70%
OREO and Foreclosed Assets [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Nonrecurring Assets - Fair Value	199	207
OREO and Foreclosed Assets [Member] | Other Assets
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Nonrecurring Assets - Fair Value	199	207
Long-lived assets held for sale [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Nonrecurring Assets - Fair Value	52	24
Long-lived assets held for sale [Member] | Other Assets
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Nonrecurring Assets - Fair Value	$ 52	$ 24