Loans - Credit Quality Indicators (Details) - USD ($) $ in Thousands	Mar. 31, 2020	Dec. 31, 2019
Credit quality categories
Total	$ 1,348,041	$ 1,354,357
Pass
Credit quality categories
Total	1,322,930	1,328,050
Special Mention
Credit quality categories
Total	10,588	10,690
Substandard
Credit quality categories
Total	14,523	15,617
Commercial, financial, and agricultural
Credit quality categories
Total	158,150	156,213
Commercial, financial, and agricultural | Pass
Credit quality categories
Total	151,756	149,349
Commercial, financial, and agricultural | Special Mention
Credit quality categories
Total	3,154	3,174
Commercial, financial, and agricultural | Substandard
Credit quality categories
Total	3,240	3,690
Consumer automobile
Credit quality categories
Total	151,715	150,517
Consumer automobile | Pass
Credit quality categories
Total	151,715	150,517
Consumer automobile | Special Mention
Credit quality categories
Total	0	0
Consumer automobile | Substandard
Credit quality categories
Total	0	0
Other consumer installment loans
Credit quality categories
Total	21,988	23,043
Other consumer installment loans | Pass
Credit quality categories
Total	21,985	23,039
Other consumer installment loans | Special Mention
Credit quality categories
Total	0	0
Other consumer installment loans | Substandard
Credit quality categories
Total	3	4
Residential | Real Estate Mortgages
Credit quality categories
Total	616,154	623,256
Residential | Real Estate Mortgages | Pass
Credit quality categories
Total	611,584	618,350
Residential | Real Estate Mortgages | Special Mention
Credit quality categories
Total	2,416	2,436
Residential | Real Estate Mortgages | Substandard
Credit quality categories
Total	2,154	2,470
Commercial | Real Estate Mortgages
Credit quality categories
Total	360,737	363,261
Commercial | Real Estate Mortgages | Pass
Credit quality categories
Total	346,727	348,864
Commercial | Real Estate Mortgages | Special Mention
Credit quality categories
Total	5,018	5,080
Commercial | Real Estate Mortgages | Substandard
Credit quality categories
Total	8,992	9,317
Construction | Real Estate Mortgages
Credit quality categories
Total	39,297	38,067
Construction | Real Estate Mortgages | Pass
Credit quality categories
Total	39,163	37,931
Construction | Real Estate Mortgages | Special Mention
Credit quality categories
Total	0	0
Construction | Real Estate Mortgages | Substandard
Credit quality categories
Total	$ 134	$ 136