Loans and Allowance for Loan Losses - Credit Quality (Details) - USD ($) $ in Thousands	Sep. 30, 2019	Dec. 31, 2018
Credit quality of the loan portfolio using internal rating system reflecting management's risk assessment
Financing receivable	$ 1,151,518	$ 1,146,627
Watch
Credit quality of the loan portfolio using internal rating system reflecting management's risk assessment
Financing receivable	71,780	62,728
Substandard
Credit quality of the loan portfolio using internal rating system reflecting management's risk assessment
Financing receivable	3,281	2,169
Performing TDRs
Credit quality of the loan portfolio using internal rating system reflecting management's risk assessment
Financing receivable	2,632	3,064
Non-accrual and non-performing TDRs
Credit quality of the loan portfolio using internal rating system reflecting management's risk assessment
Financing receivable	4,623	5,414
Total
Credit quality of the loan portfolio using internal rating system reflecting management's risk assessment
Financing receivable	82,316	73,375
Commercial, financial, and agricultural
Credit quality of the loan portfolio using internal rating system reflecting management's risk assessment
Financing receivable	193,267	207,720
Commercial, financial, and agricultural | Watch
Credit quality of the loan portfolio using internal rating system reflecting management's risk assessment
Financing receivable	13,083	8,871
Commercial, financial, and agricultural | Substandard
Credit quality of the loan portfolio using internal rating system reflecting management's risk assessment
Financing receivable	1,257	53
Commercial, financial, and agricultural | Performing TDRs
Credit quality of the loan portfolio using internal rating system reflecting management's risk assessment
Financing receivable	551	570
Commercial, financial, and agricultural | Non-accrual and non-performing TDRs
Credit quality of the loan portfolio using internal rating system reflecting management's risk assessment
Financing receivable	1,027	1,857
Commercial, financial, and agricultural | Total
Credit quality of the loan portfolio using internal rating system reflecting management's risk assessment
Financing receivable	15,918	11,351
Residential real estate | Construction
Credit quality of the loan portfolio using internal rating system reflecting management's risk assessment
Financing receivable	23,782	28,610
Residential real estate | Construction | Watch
Credit quality of the loan portfolio using internal rating system reflecting management's risk assessment
Financing receivable	679	588
Residential real estate | Construction | Substandard
Credit quality of the loan portfolio using internal rating system reflecting management's risk assessment
Financing receivable	0	0
Residential real estate | Construction | Performing TDRs
Credit quality of the loan portfolio using internal rating system reflecting management's risk assessment
Financing receivable	0	0
Residential real estate | Construction | Non-accrual and non-performing TDRs
Credit quality of the loan portfolio using internal rating system reflecting management's risk assessment
Financing receivable	0	0
Residential real estate | Construction | Total
Credit quality of the loan portfolio using internal rating system reflecting management's risk assessment
Financing receivable	679	588
Residential real estate | Mortgages
Credit quality of the loan portfolio using internal rating system reflecting management's risk assessment
Financing receivable	248,435	241,517
Residential real estate | Mortgages | Watch
Credit quality of the loan portfolio using internal rating system reflecting management's risk assessment
Financing receivable	14,453	12,790
Residential real estate | Mortgages | Substandard
Credit quality of the loan portfolio using internal rating system reflecting management's risk assessment
Financing receivable	1,336	1,411
Residential real estate | Mortgages | Performing TDRs
Credit quality of the loan portfolio using internal rating system reflecting management's risk assessment
Financing receivable	1,685	2,073
Residential real estate | Mortgages | Non-accrual and non-performing TDRs
Credit quality of the loan portfolio using internal rating system reflecting management's risk assessment
Financing receivable	2,217	2,720
Residential real estate | Mortgages | Total
Credit quality of the loan portfolio using internal rating system reflecting management's risk assessment
Financing receivable	19,691	18,994
Commercial real estate | Construction
Credit quality of the loan portfolio using internal rating system reflecting management's risk assessment
Financing receivable	124,389	106,784
Commercial real estate | Construction | Watch
Credit quality of the loan portfolio using internal rating system reflecting management's risk assessment
Financing receivable	7,172	4,063
Commercial real estate | Construction | Substandard
Credit quality of the loan portfolio using internal rating system reflecting management's risk assessment
Financing receivable	0	0
Commercial real estate | Construction | Performing TDRs
Credit quality of the loan portfolio using internal rating system reflecting management's risk assessment
Financing receivable	0	0
Commercial real estate | Construction | Non-accrual and non-performing TDRs
Credit quality of the loan portfolio using internal rating system reflecting management's risk assessment
Financing receivable	145	153
Commercial real estate | Construction | Total
Credit quality of the loan portfolio using internal rating system reflecting management's risk assessment
Financing receivable	7,317	4,216
Commercial real estate | Mortgages
Credit quality of the loan portfolio using internal rating system reflecting management's risk assessment
Financing receivable	530,010	529,536
Commercial real estate | Mortgages | Watch
Credit quality of the loan portfolio using internal rating system reflecting management's risk assessment
Financing receivable	36,393	36,408
Commercial real estate | Mortgages | Substandard
Credit quality of the loan portfolio using internal rating system reflecting management's risk assessment
Financing receivable	685	702
Commercial real estate | Mortgages | Performing TDRs
Credit quality of the loan portfolio using internal rating system reflecting management's risk assessment
Financing receivable	358	377
Commercial real estate | Mortgages | Non-accrual and non-performing TDRs
Credit quality of the loan portfolio using internal rating system reflecting management's risk assessment
Financing receivable	1,111	474
Commercial real estate | Mortgages | Total
Credit quality of the loan portfolio using internal rating system reflecting management's risk assessment
Financing receivable	38,547	37,961
Installment and other consumer
Credit quality of the loan portfolio using internal rating system reflecting management's risk assessment
Financing receivable	31,635	32,460
Installment and other consumer | Watch
Credit quality of the loan portfolio using internal rating system reflecting management's risk assessment
Financing receivable	0	8
Installment and other consumer | Substandard
Credit quality of the loan portfolio using internal rating system reflecting management's risk assessment
Financing receivable	3	3
Installment and other consumer | Performing TDRs
Credit quality of the loan portfolio using internal rating system reflecting management's risk assessment
Financing receivable	38	44
Installment and other consumer | Non-accrual and non-performing TDRs
Credit quality of the loan portfolio using internal rating system reflecting management's risk assessment
Financing receivable	123	210
Installment and other consumer | Total
Credit quality of the loan portfolio using internal rating system reflecting management's risk assessment
Financing receivable	$ 164	$ 265