Loans (Details 5) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Aging of the recorded investment in past due loans
30-59 days past due	$ 4,062	$ 9,931
60-89 days past due	6,278	1,119
Greater than 90 days past due (includes non-accrual)	19,078	19,897
Total past due	29,418	30,947
Current	1,555,176	1,513,898
Total loans	1,584,594	1,544,845	1,508,425
Recorded investment greater than 90 days and accruing	719	1,160
Commercial and industrial
Aging of the recorded investment in past due loans
30-59 days past due	212	989
60-89 days past due	42	162
Greater than 90 days past due (includes non-accrual)	1,554	2,665
Total past due	1,808	3,816
Current	425,122	389,913
Total loans	426,930	393,729	343,956
Construction and development
Aging of the recorded investment in past due loans
30-59 days past due		86
60-89 days past due	4,284
Greater than 90 days past due (includes non-accrual)	10,862	2,416
Total past due	15,146	2,502
Current	116,107	145,135
Total loans	131,253	147,637	159,482
Real estate mortgage
Aging of the recorded investment in past due loans
30-59 days past due	3,771	8,520
60-89 days past due	1,952	957
Greater than 90 days past due (includes non-accrual)	6,424	14,722
Total past due	12,147	24,199
Current	977,484	942,466
Total loans	989,631	966,665	968,440
Recorded investment greater than 90 days and accruing	485	1,160
Consumer
Aging of the recorded investment in past due loans
30-59 days past due	79	336
Greater than 90 days past due (includes non-accrual)	238	94
Total past due	317	430
Current	36,463	36,384
Total loans	36,780	36,814	36,547
Recorded investment greater than 90 days and accruing	$ 234