Loans (Summary of Nonperforming Loans) (Details) - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2016	Dec. 31, 2015	Jun. 30, 2015
Financing Receivable, Recorded Investment [Line Items]
Modified Loans Not Reported as TDR Included in Nonaccrual Loans	$ 32,400	$ 35,900	$ 35,700
Summary of nonperforming loans
Total TDRs	98,232	103,111	99,428
Total loans	$ 7,647,269	7,271,147	7,034,743
Minimum number of days accruing loans past due move to nonaccrual status	90 days
Commercial Loan Portfolio [Member]
Summary of nonperforming loans
Total TDRs	$ 74,085	78,823	74,751
Total loans	4,396,882	4,250,117	4,110,698
Consumer Loan Portfolio [Member]
Summary of nonperforming loans
Total TDRs	24,147	24,288	24,677
Total loans	3,250,387	3,021,030	2,924,045
Nonperforming [Member]
Summary of nonperforming loans
Total nonaccrual loans	43,997	62,225	51,215
Total accruing loans contractually past due 90 days or more as to interest or principal payments	1,484	2,287	1,779
Total TDRs	16,473	19,368	17,912
Total loans	61,954	$ 83,880	70,906
Nonperforming [Member] | Commercial Loan Portfolio [Member]
Summary of nonperforming loans
Total TDRs	14,240		14,547
Nonperforming [Member] | Consumer Loan Portfolio [Member]
Summary of nonperforming loans
Total TDRs	2,233		3,365
Nonperforming [Member] | Commercial [Member]
Summary of nonperforming loans
Total nonaccrual loans	14,577		17,260
Total accruing loans contractually past due 90 days or more as to interest or principal payments	3		711
Nonperforming [Member] | Real estate commercial [Member]
Summary of nonperforming loans
Total nonaccrual loans	21,325		25,287
Total accruing loans contractually past due 90 days or more as to interest or principal payments	3		56
Nonperforming [Member] | Real Estate Construction Loans [Member]
Summary of nonperforming loans
Total nonaccrual loans	496		502
Nonperforming [Member] | Real estate residential [Member]
Summary of nonperforming loans
Total nonaccrual loans	5,343		6,004
Total accruing loans contractually past due 90 days or more as to interest or principal payments	407		424
Nonperforming [Member] | Consumer Installment Loans [Member]
Summary of nonperforming loans
Total nonaccrual loans	285		393
Nonperforming [Member] | Home Equity Loans [Member]
Summary of nonperforming loans
Total nonaccrual loans	1,971		1,769
Total accruing loans contractually past due 90 days or more as to interest or principal payments	$ 1,071		$ 588