Loans and Allowance for Loan Losses (Narrative) (Details)	3 Months Ended		6 Months Ended		12 Months Ended
	Jun. 30, 2017 USD ($) Contract	Jun. 30, 2016 USD ($) Contract	Jun. 30, 2017 USD ($) Contract	Jun. 30, 2016 USD ($) Contract	Dec. 31, 2016 USD ($)
Accounts, Notes, Loans and Financing Receivable [Line Items]
Average recorded investment in impaired loans	$ 232,532,000	$ 281,900,000	$ 233,791,000	$ 290,300,000	$ 274,515,000
Interest income recognized	1,834,000	0	3,523,000		8,196,000
Interest income recognized for accruing TDRs		2,000,000		4,000,000
Non-accrual status	$ 60,800,000		60,800,000		53,700,000
Number of contracts | Contract	3
Post-default balance for modifications classified as TDRs	$ 292,000
Provision for loan losses	10,260,000	$ 6,693,000	$ 18,934,000	$ 16,070,000
Troubled Debt Restructurings That Subsequently Defaulted
Accounts, Notes, Loans and Financing Receivable [Line Items]
Number of contracts | Contract		1	3	1
Post-default balance for modifications classified as TDRs		$ 92,000	$ 292,000	$ 92,000
Accruing TDRs With Modifications And Renewals Completed
Accounts, Notes, Loans and Financing Receivable [Line Items]
Accruing troubled debt restructuring	$ 167,400,000		$ 167,400,000		8,500,000
Provision for loan losses					9,800,000
Substandard
Accounts, Notes, Loans and Financing Receivable [Line Items]
Retail loan substandard period (in days)			90 days
Loss And Charged Off
Accounts, Notes, Loans and Financing Receivable [Line Items]
Retail loans downgraded to loss (in days)			120 days
Accruing TDRs With Modifications And Renewals Completed
Accounts, Notes, Loans and Financing Receivable [Line Items]
Accruing troubled debt restructuring					$ 195,800,000
Accruing TDRs With Modifications And Renewals Completed | Minimum
Accounts, Notes, Loans and Financing Receivable [Line Items]
Commercial-type impaired loans			$ 1,000,000