Loans - Allowance for Loan Losses (Details) - USD ($) $ in Thousands	Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018
Ending allowance balance attributable to loans:
Individually evaluated for impairment	$ 1,290		$ 1,393
Collectively evaluated for impairment	11,687		10,501
Total ending allowance balance	12,977	$ 12,500	11,894	$ 14,001	$ 13,792	$ 13,837
Loans:
Individually evaluated for impairment	14,904		17,247
Collectively evaluated for impairment	1,333,503		1,337,110
Total	1,348,407		1,354,357
Commercial, financial, and agricultural
Ending allowance balance attributable to loans:
Individually evaluated for impairment	0		0
Collectively evaluated for impairment	1,953		1,779
Total ending allowance balance	1,953	1,897	1,779	1,584	1,732	1,680
Loans:
Individually evaluated for impairment	1,836		2,285
Collectively evaluated for impairment	167,068		153,928
Total	168,904		156,213
Real Estate Mortgages | Residential
Ending allowance balance attributable to loans:
Individually evaluated for impairment	180		211
Collectively evaluated for impairment	4,298		4,095
Total ending allowance balance	4,478	4,537	4,306	5,749	5,730	5,616
Loans:
Individually evaluated for impairment	5,473		6,176
Collectively evaluated for impairment	600,741		617,080
Total	606,214		623,256
Real Estate Mortgages | Commercial
Ending allowance balance attributable to loans:
Individually evaluated for impairment	959		1,104
Collectively evaluated for impairment	2,376		2,106
Total ending allowance balance	3,335	3,414	3,210	3,523	3,802	4,047
Loans:
Individually evaluated for impairment	7,424		8,575
Collectively evaluated for impairment	345,106		354,686
Total	352,530		363,261
Real Estate Mortgages | Construction
Ending allowance balance attributable to loans:
Individually evaluated for impairment	0		0
Collectively evaluated for impairment	150		118
Total ending allowance balance	150	160	118	132	130	143
Loans:
Individually evaluated for impairment	60		65
Collectively evaluated for impairment	43,960		38,002
Total	44,020		38,067
Consumer automobile loans
Ending allowance balance attributable to loans:
Individually evaluated for impairment	151		62
Collectively evaluated for impairment	2,063		1,718
Total ending allowance balance	2,214	1,855	1,780	1,435	1,402	1,328
Loans:
Individually evaluated for impairment	111		130
Collectively evaluated for impairment	155,610		150,387
Total	155,721		150,517
Other consumer installment loans
Ending allowance balance attributable to loans:
Individually evaluated for impairment	0		16
Collectively evaluated for impairment	127		262
Total ending allowance balance	127	267	278	240	278	259
Loans:
Individually evaluated for impairment	0		16
Collectively evaluated for impairment	21,018		23,027
Total	21,018		23,043
Unallocated
Ending allowance balance attributable to loans:
Individually evaluated for impairment	0		0
Collectively evaluated for impairment	720		423
Total ending allowance balance	$ 720	$ 370	$ 423	$ 1,338	$ 718	$ 764