Loans (Details 2) (USD $) In Thousands, unless otherwise specified	9 Months Ended	12 Months Ended
	Sep. 30, 2013	Dec. 31, 2012
Balance in the recorded investment in loans and allowance for loan losses by portfolio segment and based on impairment method
Loans	$ 1,709,258	$ 1,584,594
Loans individually evaluated for impairment	28,869	29,329
Loans collectively evaluated for impairment	1,677,958	1,555,265
Loans acquired with deteriorated credit quality	2,431
Allowance for loan losses
Balance at the beginning of the period	31,881	29,745
Provision	4,975	11,500
Charge-offs	(9,033)	(10,498)
Recoveries	1,167	1,134
Balance at the end of the period	28,990	31,881
Allowance for loans individually evaluated for impairment	1,660	3,617
Allowance for loans collectively evaluated for impairment	27,330	28,264
Commercial and industrial
Balance in the recorded investment in loans and allowance for loan losses by portfolio segment and based on impairment method
Loans	500,478	426,930
Loans individually evaluated for impairment	8,461	8,667
Loans collectively evaluated for impairment	491,384	418,263
Loans acquired with deteriorated credit quality	633
Allowance for loan losses
Balance at the beginning of the period	5,949	7,364
Provision	2,598	3,024
Charge-offs	(257)	(4,523)
Recoveries	434	84
Balance at the end of the period	8,724	5,949
Allowance for loans individually evaluated for impairment	682	156
Allowance for loans collectively evaluated for impairment	8,042	5,793
Construction and development
Balance in the recorded investment in loans and allowance for loan losses by portfolio segment and based on impairment method
Loans	135,786	131,253
Loans individually evaluated for impairment	9,870	10,863
Loans collectively evaluated for impairment	124,647	120,390
Loans acquired with deteriorated credit quality	1,269
Allowance for loan losses
Balance at the beginning of the period	4,536	3,546
Provision	3,838	2,716
Charge-offs	(6,440)	(1,726)
Recoveries	164
Balance at the end of the period	2,098	4,536
Allowance for loans individually evaluated for impairment	148	2,898
Allowance for loans collectively evaluated for impairment	1,950	1,638
Real estate mortgage
Balance in the recorded investment in loans and allowance for loan losses by portfolio segment and based on impairment method
Loans	1,038,864	989,631
Loans individually evaluated for impairment	10,450	9,795
Loans collectively evaluated for impairment	1,027,906	979,836
Loans acquired with deteriorated credit quality	508
Allowance for loan losses
Balance at the beginning of the period	14,288	11,182
Provision	5,042	6,308
Charge-offs	(1,817)	(3,451)
Recoveries	153	249
Balance at the end of the period	17,666	14,288
Allowance for loans individually evaluated for impairment	744	563
Allowance for loans collectively evaluated for impairment	16,922	13,725
Consumer
Balance in the recorded investment in loans and allowance for loan losses by portfolio segment and based on impairment method
Loans	34,130	36,780
Loans individually evaluated for impairment	88	4
Loans collectively evaluated for impairment	34,021	36,776
Loans acquired with deteriorated credit quality	21
Allowance for loan losses
Balance at the beginning of the period	362	540
Provision	243	(181)
Charge-offs	(519)	(798)
Recoveries	416	801
Balance at the end of the period	502	362
Allowance for loans individually evaluated for impairment	86
Allowance for loans collectively evaluated for impairment	416	362
Unallocated
Allowance for loan losses
Balance at the beginning of the period	6,746	7,113
Provision	(6,746)	(367)
Balance at the end of the period		6,746
Allowance for loans collectively evaluated for impairment		$ 6,746