Loans and Asset Quality Information (Schedule of Analysis of Payment Status of Loans) (Details) - USD ($) $ in Thousands	Sep. 30, 2015	Dec. 31, 2014	Sep. 30, 2014
Analysis of the payment status of loans
Nonaccrual loans	$ 47,720	$ 60,574
Current	2,415,609	2,303,372
Total loans	2,375,094	2,268,580	$ 2,292,841
Total Covered Loans - Carrying Value	106,609	127,594	133,249
Loans	2,481,703	2,396,174	2,426,090
30-59 Days past due [Member]
Analysis of the payment status of loans
Financing receivable, past due	13,942	24,849
60-89 Days past due [Member]
Analysis of the payment status of loans
Financing receivable, past due	3,667	6,433
Commercial Unsecured [Member]
Analysis of the payment status of loans
Nonaccrual loans	492	188
Commercial Secured [Member]
Analysis of the payment status of loans
Nonaccrual loans	2,253	2,927
Secured by Inventory and Accounts Receivable [Member]
Analysis of the payment status of loans
Nonaccrual loans	107	557
Real Estate construction, land development and other land loans [Member]
Analysis of the payment status of loans
Nonaccrual loans	5,434	9,031
Real estate residential, farmland and mutli-family [Member]
Analysis of the payment status of loans
Nonaccrual loans	25,206	32,244
Real estate home equity lines of credit [Member]
Analysis of the payment status of loans
Nonaccrual loans	2,472	2,851
Real estate commercial [Member]
Analysis of the payment status of loans
Nonaccrual loans	11,398	12,271
Consumer [Member]
Analysis of the payment status of loans
Nonaccrual loans	358	505
Non-covered [Member]
Analysis of the payment status of loans
Nonaccrual loans	42,347	50,066
Current	2,315,464	2,191,635
Total loans	2,375,094	2,268,580	2,292,841
Non-covered [Member] | 30-59 Days past due [Member]
Analysis of the payment status of loans
Financing receivable, past due	13,602	20,464
Non-covered [Member] | 60-89 Days past due [Member]
Analysis of the payment status of loans
Financing receivable, past due	2,916	5,469
Non-covered [Member] | Commercial Unsecured [Member]
Analysis of the payment status of loans
Nonaccrual loans	470	187
Current	49,325	36,871
Total loans	50,529	37,284
Non-covered [Member] | Commercial Unsecured [Member] | 30-59 Days past due [Member]
Analysis of the payment status of loans
Financing receivable, past due	$ 734	191
Non-covered [Member] | Commercial Unsecured [Member] | 60-89 Days past due [Member]
Analysis of the payment status of loans
Financing receivable, past due		35
Non-covered [Member] | Commercial Secured [Member]
Analysis of the payment status of loans
Nonaccrual loans	$ 2,253	2,927
Current	114,989	102,671
Total loans	118,087	106,974
Non-covered [Member] | Commercial Secured [Member] | 30-59 Days past due [Member]
Analysis of the payment status of loans
Financing receivable, past due	772	1,003
Non-covered [Member] | Commercial Secured [Member] | 60-89 Days past due [Member]
Analysis of the payment status of loans
Financing receivable, past due	73	373
Non-covered [Member] | Secured by Inventory and Accounts Receivable [Member]
Analysis of the payment status of loans
Nonaccrual loans	84	454
Current	33,177	21,761
Total loans	33,627	22,470
Non-covered [Member] | Secured by Inventory and Accounts Receivable [Member] | 30-59 Days past due [Member]
Analysis of the payment status of loans
Financing receivable, past due	$ 366	30
Non-covered [Member] | Secured by Inventory and Accounts Receivable [Member] | 60-89 Days past due [Member]
Analysis of the payment status of loans
Financing receivable, past due		225
Non-covered [Member] | Real Estate construction, land development and other land loans [Member]
Analysis of the payment status of loans
Nonaccrual loans	$ 5,374	7,891
Current	269,002	247,535
Total loans	275,404	257,515
Non-covered [Member] | Real Estate construction, land development and other land loans [Member] | 30-59 Days past due [Member]
Analysis of the payment status of loans
Financing receivable, past due	938	1,950
Non-covered [Member] | Real Estate construction, land development and other land loans [Member] | 60-89 Days past due [Member]
Analysis of the payment status of loans
Financing receivable, past due	90	139
Non-covered [Member] | Real estate residential, farmland and mutli-family [Member]
Analysis of the payment status of loans
Nonaccrual loans	21,936	24,459
Current	822,084	807,884
Total loans	851,372	846,833
Non-covered [Member] | Real estate residential, farmland and mutli-family [Member] | 30-59 Days past due [Member]
Analysis of the payment status of loans
Financing receivable, past due	5,404	11,272
Non-covered [Member] | Real estate residential, farmland and mutli-family [Member] | 60-89 Days past due [Member]
Analysis of the payment status of loans
Financing receivable, past due	1,948	3,218
Non-covered [Member] | Real estate home equity lines of credit [Member]
Analysis of the payment status of loans
Nonaccrual loans	2,110	2,573
Current	199,180	194,067
Total loans	202,618	198,577
Non-covered [Member] | Real estate home equity lines of credit [Member] | 30-59 Days past due [Member]
Analysis of the payment status of loans
Financing receivable, past due	996	1,585
Non-covered [Member] | Real estate home equity lines of credit [Member] | 60-89 Days past due [Member]
Analysis of the payment status of loans
Financing receivable, past due	332	352
Non-covered [Member] | Real estate commercial [Member]
Analysis of the payment status of loans
Nonaccrual loans	9,762	11,070
Current	785,182	738,981
Total loans	799,191	754,785
Non-covered [Member] | Real estate commercial [Member] | 30-59 Days past due [Member]
Analysis of the payment status of loans
Financing receivable, past due	4,013	3,738
Non-covered [Member] | Real estate commercial [Member] | 60-89 Days past due [Member]
Analysis of the payment status of loans
Financing receivable, past due	234	996
Non-covered [Member] | Consumer [Member]
Analysis of the payment status of loans
Nonaccrual loans	358	505
Current	42,525	41,865
Total loans	43,501	43,196
Non-covered [Member] | Consumer [Member] | 30-59 Days past due [Member]
Analysis of the payment status of loans
Financing receivable, past due	379	695
Non-covered [Member] | Consumer [Member] | 60-89 Days past due [Member]
Analysis of the payment status of loans
Financing receivable, past due	239	131
Covered [Member]
Analysis of the payment status of loans
Nonaccrual loans	5,373	10,508
Current	100,145	111,737
Total Covered Loans - Carrying Value	106,609	127,594	$ 133,249
Covered [Member] | 30-59 Days past due [Member]
Analysis of the payment status of loans
Financing receivable, past due	340	4,385
Covered [Member] | 60-89 Days past due [Member]
Analysis of the payment status of loans
Financing receivable, past due	751	964
Covered [Member] | Commercial Unsecured [Member]
Analysis of the payment status of loans
Nonaccrual loans	$ 22	$ 1
Covered [Member] | Commercial Secured [Member]
Analysis of the payment status of loans
Nonaccrual loans
Covered [Member] | Secured by Inventory and Accounts Receivable [Member]
Analysis of the payment status of loans
Nonaccrual loans	$ 23	$ 103
Covered [Member] | Real Estate construction, land development and other land loans [Member]
Analysis of the payment status of loans
Nonaccrual loans	60	1,140
Covered [Member] | Real estate residential, farmland and mutli-family [Member]
Analysis of the payment status of loans
Nonaccrual loans	3,270	7,785
Covered [Member] | Real estate home equity lines of credit [Member]
Analysis of the payment status of loans
Nonaccrual loans	362	278
Covered [Member] | Real estate commercial [Member]
Analysis of the payment status of loans
Nonaccrual loans	$ 1,636	$ 1,201
Covered [Member] | Consumer [Member]
Analysis of the payment status of loans
Nonaccrual loans