Fair Value (Fair Value Measurements- Nonrecurring Quantitative Information) (Details) - Fair Value, Measurements, Nonrecurring [Member] - USD ($)	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Nonrecurring Assets - Fair Value	$ 195,000,000	$ 269,000,000
Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Nonrecurring Assets - Fair Value	195,000,000	261,000,000
Level 3 [Member] | Other Assets [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Nonrecurring Assets - Fair Value	170,000,000	215,000,000
Level 3 [Member] | Nonaccrual Loans [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Nonrecurring Assets - Fair Value	30,000,000	54,000,000
Level 3 [Member] | Nonaccrual Loans [Member] | Other Assets [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Nonrecurring Assets - Fair Value	10,000,000	25,000,000
Level 3 [Member] | Nonaccrual Loans [Member] | LGD percentage [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Nonrecurring Assets - Fair Value	$ 20,000,000	$ 29,000,000
Level 3 [Member] | Nonaccrual Loans [Member] | LGD percentage [Member] | Minimum [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Loss Severity	8.10%	2.90%
Level 3 [Member] | Nonaccrual Loans [Member] | LGD percentage [Member] | Maximum [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Loss Severity	73.30%	68.50%
Level 3 [Member] | Nonaccrual Loans [Member] | LGD percentage [Member] | Weighted Average [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Loss Severity	58.60%	42.10%
Level 3 [Member] | Equity Investments [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Nonrecurring Assets - Fair Value	$ 5,000,000	$ 17,000,000
Level 3 [Member] | Equity Investments [Member] | Discounted Cash Flow [Member] | Minimum [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Market rate of return	5.00%	6.00%
Level 3 [Member] | Equity Investments [Member] | Discounted Cash Flow [Member] | Maximum [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Market rate of return	5.00%	6.00%
Level 3 [Member] | Equity Investments [Member] | Discounted Cash Flow [Member] | Weighted Average [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Market rate of return	5.00%	6.00%
Level 3 [Member] | OREO and Foreclosed Assets [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Nonrecurring Assets - Fair Value	$ 137,000,000	$ 168,000,000
Level 3 [Member] | OREO and Foreclosed Assets [Member] | Other Assets [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Nonrecurring Assets - Fair Value	137,000,000	168,000,000
Level 3 [Member] | Long-lived assets held for sale [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Nonrecurring Assets - Fair Value	23,000,000	22,000,000
Level 3 [Member] | Long-lived assets held for sale [Member] | Other Assets [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Nonrecurring Assets - Fair Value	$ 23,000,000	$ 22,000,000