Loans And Allowance For Loan Losses (Narrative) (Details)	3 Months Ended								12 Months Ended
	Dec. 31, 2016 USD ($)	Sep. 30, 2016 USD ($)	Jun. 30, 2016 USD ($)	Mar. 31, 2016 USD ($)	Dec. 31, 2015 USD ($)	Sep. 30, 2015 USD ($)	Jun. 30, 2015 USD ($)	Mar. 31, 2015 USD ($)	Dec. 31, 2016 USD ($) Contract	Dec. 31, 2015 USD ($) Contract	Dec. 31, 2014 USD ($) Contract
Accounts, Notes, Loans and Financing Receivable [Line Items]
Non-accrual loans	$ 153,378,000				$ 168,370,000				$ 153,378,000	$ 168,370,000
Loans and leases receivable, impaired, interest lost on nonaccrual loans									8,900,000	10,500,000
Interest income recognized									8,196,000	9,522,000
Average recorded investment in impaired loans									274,515,000	358,254,000	$ 622,000,000
Accrued interest income recognized											14,900,000
Investments income recognized in impairment loans, excluding TDRs									0	0	0
Impaired financing receivable, recorded investment, nonaccrual status	53,700,000				77,900,000				$ 53,700,000	$ 77,900,000	$ 93,700,000
Subsequent default, number of contracts | Contract									2	7	15
Accruing troubled debt restructuring	195,800,000				223,900,000				$ 195,800,000	$ 223,900,000
Provision for losses on loans	$ 6,259,000	$ 5,671,000	$ 6,693,000	$ 9,377,000	$ 5,021,000	$ 2,956,000	$ 6,636,000	$ 4,397,000	28,000,000	19,010,000	$ 33,831,000
Troubled Debt Restructurings That Subsequently Defaulted [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Modifications, post-modification recorded investment									181,000	12,500,000	$ 3,600,000
Minimum [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Commercial-type impaired loans									1,000,000
Interest Income Recorded [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Interest income recognized									$ 3,500,000	4,300,000
Loss And Charged Off [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Retail loan charge-off period (in days)									120 days
Substandard [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Retail loan substandard period (in days)									90 days
Accruing TDRs With Modifications And Renewals Completed [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Provision for losses on loans									$ 9,800,000	$ 12,600,000