Loans and Allowance for Loan Losses (Narrative) (Details) (USD $)	3 Months Ended		12 Months Ended
	Mar. 31, 2014	Mar. 31, 2013	Dec. 31, 2013
Accounts, Notes, Loans and Financing Receivable [Line Items]
Increase in allocated allowance	$ 23,000,000
Average recorded investment in impaired loans	754,303,000	984,516,000
Interest income recognized	3,993,000	0	21,114,000
Interest income recognized for accruing TDRs		5,500,000
Accruing troubled debt restructuring	495,400,000	623,900,000
Provision for losses on loans	9,511,000	35,696,000
Substandard [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Retail loan substandard period (in days)	90 days
Loss And Charged Off [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Retail loan charge-off period (in days)	120 days
Accruing TDRs With Modifications And Renewals Completed [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Provision for losses on loans	24,900,000	38,900,000
Minimum [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Commercial-type impaired loans	$ 1,000,000