Loans (Summary of Nonperforming Loans) (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2014	Dec. 31, 2013	Mar. 31, 2013
Summary of nonperforming loans
Total nonperforming TDRs	$ 103,671	$ 94,943	$ 96,651
Total loans	4,753,289	4,647,621	4,185,261
Minimum number of days accruing loans past due move to nonaccrual status	90 days
Commercial Loan Portfolio [Member]
Summary of nonperforming loans
Total nonperforming TDRs	79,852	72,214	74,439
Total loans	2,586,653	2,518,826	2,298,505
Consumer Loan Portfolio [Member]
Summary of nonperforming loans
Total nonperforming TDRs	23,819	22,729	22,212
Total loans	2,166,636	2,128,795	1,886,756
Nonperforming [Member]
Summary of nonperforming loans
Total nonaccrual loans	57,687	61,897	66,251
Total accruing loans contractually past due 90 days or more as to interest or principal payments	1,395	1,997	1,251
Total nonperforming TDRs	17,462	18,090	18,915
Total loans	76,544	81,984	86,417
Nonperforming [Member] | Commercial Loan Portfolio [Member]
Summary of nonperforming loans
Total nonperforming TDRs	11,218	13,414	14,587
Nonperforming [Member] | Consumer Loan Portfolio [Member]
Summary of nonperforming loans
Total nonperforming TDRs	6,244	4,676	4,328
Nonperforming [Member] | Commercial [Member]
Summary of nonperforming loans
Total nonaccrual loans	18,251	18,374	12,186
Total accruing loans contractually past due 90 days or more as to interest or principal payments	43	536	4
Nonperforming [Member] | Real estate commercial [Member]
Summary of nonperforming loans
Total nonaccrual loans	27,568	28,598	35,849
Total accruing loans contractually past due 90 days or more as to interest or principal payments	730	190	177
Nonperforming [Member] | Real Estate Construction Loans [Member]
Summary of nonperforming loans
Total nonaccrual loans	160	371	168
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	2,267	2,309	4,105
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	6,589	8,921	10,407
Total accruing loans contractually past due 90 days or more as to interest or principal payments	0	537	196
Nonperforming [Member] | Consumer Installment Loans [Member]
Summary of nonperforming loans
Total nonaccrual loans	806	676	699
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	2,046	2,648	2,837
Total accruing loans contractually past due 90 days or more as to interest or principal payments	$ 622	$ 734	$ 874