Loans - Aging Categories of Loans by Segment (Details) - USD ($) $ in Thousands	Mar. 31, 2017	Dec. 31, 2016	Mar. 31, 2016	Dec. 31, 2015
Aging categories of loans by segment
Current	$ 1,094,655	$ 1,071,656
Past Due 30 To 89 Days	6,898	11,656
Past Due 90 Days Or More & Still Accruing	141	870
Non-Accrual	10,730	10,756
Total	1,112,424	1,094,938
Net deferred loan fees and discounts	(1,324)	(1,257)
Allowance for loan losses	(12,905)	(12,896)	$ (12,382)	$ (12,044)
Current loans, net	1,080,426	1,057,503
Loans, net	1,098,195	1,080,785
Commercial, financial, and agricultural
Aging categories of loans by segment
Current	141,648	145,179
Past Due 30 To 89 Days	277	785
Past Due 90 Days Or More & Still Accruing	9	14
Non-Accrual	128	132
Total	142,062	146,110
Allowance for loan losses	(1,441)	(1,554)	(1,254)	(1,532)
Real estate mortgage | Residential
Aging categories of loans by segment
Current	558,068	553,053
Past Due 30 To 89 Days	5,244	9,112
Past Due 90 Days Or More & Still Accruing	0	587
Non-Accrual	1,899	1,988
Total	565,211	564,740
Allowance for loan losses	(5,571)	(5,383)	(5,123)	(5,116)
Real estate mortgage | Commercial
Aging categories of loans by segment
Current	302,700	296,537
Past Due 30 To 89 Days	671	786
Past Due 90 Days Or More & Still Accruing	132	268
Non-Accrual	8,682	8,591
Total	312,185	306,182
Allowance for loan losses	(4,466)	(4,975)	(4,472)	(4,217)
Real estate mortgage | Construction
Aging categories of loans by segment
Current	37,289	33,879
Past Due 30 To 89 Days	101	771
Past Due 90 Days Or More & Still Accruing	0	0
Non-Accrual	0	0
Total	37,390	34,650
Allowance for loan losses	(187)	(178)	(147)	(160)
Installment loans to individuals
Aging categories of loans by segment
Current	54,950	43,008
Past Due 30 To 89 Days	605	202
Past Due 90 Days Or More & Still Accruing	0	1
Non-Accrual	21	45
Total	55,576	43,256
Allowance for loan losses	$ (548)	$ (416)	$ (264)	$ (243)