Loans (Summary of Nonperforming Loans) (Details) (USD $) In Thousands, unless otherwise specified	6 Months Ended
	Jun. 30, 2014	Dec. 31, 2013	Jun. 30, 2013
Summary of nonperforming loans
Total TDRs	$ 104,383	$ 94,943	$ 95,099
Total loans	4,898,804	4,647,621	4,335,871
Minimum number of days accruing loans past due move to nonaccrual status	90 days
Commercial Loan Portfolio [Member]
Summary of nonperforming loans
Total TDRs	80,696	72,214	72,315
Total loans	2,622,872	2,518,826	2,364,870
Consumer Loan Portfolio [Member]
Summary of nonperforming loans
Total TDRs	23,687	22,729	22,784
Total loans	2,275,932	2,128,795	1,971,001
Nonperforming [Member]
Summary of nonperforming loans
Total nonaccrual loans	55,635	61,897	56,024
Total accruing loans contractually past due 90 days or more as to interest or principal payments	1,535	1,997	932
Total TDRs	16,565	18,090	22,386
Total loans	73,735	81,984	79,342
Nonperforming [Member] | Commercial Loan Portfolio [Member]
Summary of nonperforming loans
Total TDRs	11,049	13,414	19,140
Nonperforming [Member] | Consumer Loan Portfolio [Member]
Summary of nonperforming loans
Total TDRs	5,516	4,676	3,246
Nonperforming [Member] | Commercial [Member]
Summary of nonperforming loans
Total nonaccrual loans	18,773	18,374	11,052
Total accruing loans contractually past due 90 days or more as to interest or principal payments	15	536	1
Nonperforming [Member] | Real estate commercial [Member]
Summary of nonperforming loans
Total nonaccrual loans	25,361	28,598	28,498
Total accruing loans contractually past due 90 days or more as to interest or principal payments	69	190	78
Nonperforming [Member] | Real Estate Construction Loans [Member]
Summary of nonperforming loans
Total nonaccrual loans	160	371	183
Total accruing loans contractually past due 90 days or more as to interest or principal payments	0	0	0
Nonperforming [Member] | Land Development Loans [Member]
Summary of nonperforming loans
Total nonaccrual loans	2,184	2,309	3,434
Total accruing loans contractually past due 90 days or more as to interest or principal payments	0	0	0
Nonperforming [Member] | Real estate residential [Member]
Summary of nonperforming loans
Total nonaccrual loans	6,325	8,921	9,241
Total accruing loans contractually past due 90 days or more as to interest or principal payments	376	537	164
Nonperforming [Member] | Consumer Installment Loans [Member]
Summary of nonperforming loans
Total nonaccrual loans	536	676	552
Total accruing loans contractually past due 90 days or more as to interest or principal payments	0	0	0
Nonperforming [Member] | Home Equity Loans [Member]
Summary of nonperforming loans
Total nonaccrual loans	2,296	2,648	3,064
Total accruing loans contractually past due 90 days or more as to interest or principal payments	$ 1,075	$ 734	$ 689