Loans - Company's Recorded Investments in Impaired Loans and the Related Valuation Allowances (Details) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Recorded Investment
Total Impaired Loans	$ 30,291	$ 32,718
Unpaid Principal Balance
Total Impaired Loans	35,519	39,157
Related Valuation Allowance
Total Impaired Loans	2,402	2,454
Construction and Land Development [Member]
Recorded Investment
Impaired Loans with No Related Allowance Recorded	223	226
Impaired Loans with an Allowance Recorded	251	51
Total Impaired Loans	474	277
Unpaid Principal Balance
Impaired Loans with No Related Allowance Recorded	510	321
Impaired Loans with an Allowance Recorded	264	51
Total Impaired Loans	774	372
Related Valuation Allowance
Impaired Loans with No Related Allowance Recorded	0	0
Impaired Loans with an Allowance Recorded	23	0
Total Impaired Loans	23	0
Commercial Real Estate [Member]
Recorded Investment
Impaired Loans with No Related Allowance Recorded	3,475	3,267
Impaired Loans with an Allowance Recorded	4,780	6,937
Total Impaired Loans	8,255	10,204
Unpaid Principal Balance
Impaired Loans with No Related Allowance Recorded	4,873	4,813
Impaired Loans with an Allowance Recorded	4,780	6,949
Total Impaired Loans	9,653	11,762
Related Valuation Allowance
Impaired Loans with No Related Allowance Recorded	0	0
Impaired Loans with an Allowance Recorded	195	395
Total Impaired Loans	195	395
Residential Real Estate [Member]
Recorded Investment
Impaired Loans with No Related Allowance Recorded	10,272	9,706
Impaired Loans with an Allowance Recorded	8,448	12,332
Total Impaired Loans	18,720	22,038
Unpaid Principal Balance
Impaired Loans with No Related Allowance Recorded	15,063	14,136
Impaired Loans with an Allowance Recorded	8,651	12,681
Total Impaired Loans	23,714	26,817
Related Valuation Allowance
Impaired Loans with No Related Allowance Recorded	0	0
Impaired Loans with an Allowance Recorded	1,091	2,059
Total Impaired Loans	1,091	2,059
Commercial And Financial [Member]
Recorded Investment
Impaired Loans with No Related Allowance Recorded	19	199
Impaired Loans with an Allowance Recorded	2,436	0
Total Impaired Loans	2,455	199
Unpaid Principal Balance
Impaired Loans with No Related Allowance Recorded	29	206
Impaired Loans with an Allowance Recorded	883	0
Total Impaired Loans	912	206
Related Valuation Allowance
Impaired Loans with No Related Allowance Recorded	0	0
Impaired Loans with an Allowance Recorded	1,050	0
Total Impaired Loans	1,050	0
Consumer [Member]
Recorded Investment
Impaired Loans with No Related Allowance Recorded	105	0
Impaired Loans with an Allowance Recorded	282	0
Total Impaired Loans	387	0
Unpaid Principal Balance
Impaired Loans with No Related Allowance Recorded	180	0
Impaired Loans with an Allowance Recorded	286	0
Total Impaired Loans	466	0
Related Valuation Allowance
Impaired Loans with No Related Allowance Recorded	0	0
Impaired Loans with an Allowance Recorded	43	0
Total Impaired Loans	$ 43	$ 0