Loans - Activity in allowance for loan losses by portfolio segment (Details 1) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015
Allowance for loan losses:
Beginning balance	$ 21,401	$ 23,372	$ 21,367	$ 25,506
Charge-offs	(238)	(1,394)	(999)	(3,424)
Recoveries	112	70	439	2,109
Provision	93	132	561	(2,011)
Ending balance	21,368	22,180	21,368	22,180
Commercial, Financial, and Agricultural
Allowance for loan losses:
Beginning balance	5,589	4,427	4,908	5,407
Charge-offs	(29)	(32)	(56)	(1,166)
Recoveries	7	6	25	223
Provision	(918)	27	(228)	(36)
Ending balance	4,649	4,428	4,649	4,428
CRE | Owner Occupied
Allowance for loan losses:
Beginning balance	4,431	5,441	4,667	4,805
Charge-offs				(74)
Recoveries	5	2	8	4
Provision	1,034	(434)	795	274
Ending balance	5,470	5,009	5,470	5,009
CRE | Non Owner occupied
Allowance for loan losses:
Beginning balance	2,617	3,841	2,709	3,817
Charge-offs		(1,119)		(1,119)
Recoveries			100
Provision	37	(93)	(155)	(69)
Ending balance	2,654	2,629	2,654	2,629
Residential Real Estate
Allowance for loan losses:
Beginning balance	5,107	6,336	5,027	6,591
Charge-offs		(77)	(139)	(363)
Recoveries	3	5	13	17
Provision	255	597	464	616
Ending balance	5,365	6,861	5,365	6,861
ADC | CSRA
Allowance for loan losses:
Beginning balance	2,050	1,805	2,469	1,943
Charge-offs			(60)	(255)
Recoveries			3
Provision	(310)	162	(672)	279
Ending balance	1,740	1,967	1,740	1,967
ADC | Other
Allowance for loan losses:
Beginning balance	940	921	914	2,320
Charge-offs			(200)	(20)
Recoveries	51	4	51	1,699
Provision	(184)	(266)	42	(3,340)
Ending balance	807	659	807	659
Consumer
Allowance for loan losses:
Beginning balance	667	601	673	623
Charge-offs	(209)	(166)	(544)	(427)
Recoveries	46	53	239	166
Provision	179	139	315	265
Ending balance	$ 683	$ 627	$ 683	$ 627