Loans - Activity in allowance for loan losses by portfolio segment (Details 1) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015
Allowance for loan losses:
Beginning balance	$ 21,548	$ 25,391	$ 21,367	$ 25,506
Charge-offs	(302)	(1,238)	(762)	(2,030)
Recoveries	115	1,909	328	2,039
Provision	40	(2,690)	468	(2,143)
Ending balance	21,401	23,372	21,401	23,372
Commercial, Financial, and Agricultural
Allowance for loan losses:
Beginning balance	4,998	5,295	4,908	5,407
Charge-offs	(10)	(517)	(27)	(1,134)
Recoveries	9	187	18	217
Provision	592	(538)	690	(63)
Ending balance	5,589	4,427	5,589	4,427
CRE | Owner Occupied
Allowance for loan losses:
Beginning balance	4,605	5,373	4,667	4,805
Charge-offs		(74)		(74)
Recoveries	2	1	3	2
Provision	(176)	141	(239)	708
Ending balance	4,431	5,441	4,431	5,441
CRE | Non Owner occupied
Allowance for loan losses:
Beginning balance	2,836	3,838	2,709	3,817
Charge-offs
Recoveries			100
Provision	(219)	3	(192)	24
Ending balance	2,617	3,841	2,617	3,841
Residential Real Estate
Allowance for loan losses:
Beginning balance	5,024	6,355	5,027	6,591
Charge-offs	(43)	(245)	(139)	(286)
Recoveries	9	1	10	12
Provision	117	225	209	19
Ending balance	5,107	6,336	5,107	6,336
ADC | CSRA
Allowance for loan losses:
Beginning balance	2,553	1,631	2,469	1,943
Charge-offs	(1)	(250)	(61)	(255)
Recoveries	2		4
Provision	(504)	424	(362)	117
Ending balance	2,050	1,805	2,050	1,805
ADC | Other
Allowance for loan losses:
Beginning balance	828	2,197	914	2,320
Charge-offs	(100)	(20)	(200)	(20)
Recoveries		1,666		1,695
Provision	212	(2,922)	226	(3,074)
Ending balance	940	921	940	921
Consumer
Allowance for loan losses:
Beginning balance	704	702	673	623
Charge-offs	(148)	(132)	(335)	(261)
Recoveries	93	54	193	113
Provision	18	(23)	136	126
Ending balance	$ 667	$ 601	$ 667	$ 601