Loans - Allowance for Credit Losses by Loan Category (Details) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2020 USD ($)	Jun. 30, 2019 USD ($)	Jun. 30, 2020 USD ($) loan segment	Jun. 30, 2019 USD ($)	Jun. 30, 2020 USD ($)	Dec. 31, 2019 USD ($)	Jun. 30, 2019 USD ($)
Financing Receivable, Allowance for Credit Loss [Line Items]
Number of loan portfolio segment | segment			10
Number of loans entity experienced losses over past twelve quarters | loan			3
Summarizes activity in allowance for credit losses by loan category [Roll Forward]
Beginning balance	$ 9,120	$ 8,417	$ 7,908	$ 8,395
Provision (recovery of provision) for credit losses	428	4	2,134	10
Charge-offs	(700)	(5)	(1,208)	(119)
Recoveries	14	36	28	166
Net recoveries (charge-offs)	(686)	31	(1,180)	47
Ending balance	8,862	8,452	8,862	8,452
Period-end amount allocated to:
Loans individually evaluated for impairment					$ 449		$ 1,439
Loans collectively evaluated for impairment					8,413		7,013
Ending balance	8,862	8,452	7,908	8,395	8,862	$ 7,908	8,452
Loans Individually Evaluated for Impairment					15,453		18,054
Loans Collectively Evaluated for Impairment					634,201		555,367
Total Loans					649,654	597,374	573,421
Commercial and Industrial
Summarizes activity in allowance for credit losses by loan category [Roll Forward]
Beginning balance	914	1,614	1,322	1,673
Provision (recovery of provision) for credit losses	(166)	(167)	(579)	(274)
Charge-offs	0	0	0	0
Recoveries	8	9	13	57
Net recoveries (charge-offs)	8	9	13	57
Ending balance	756	1,456	756	1,456
Period-end amount allocated to:
Loans individually evaluated for impairment					0		609
Loans collectively evaluated for impairment					756		847
Ending balance	756	1,456	$ 756	1,673	756	1,322	1,456
Loans Individually Evaluated for Impairment					559		2,153
Loans Collectively Evaluated for Impairment					67,671		52,992
Total Loans					68,230	45,278	55,145
Commercial and Industrial | Commercial and business loans
Period-end amount allocated to:
Loans Individually Evaluated for Impairment					318		1,878
Loans Collectively Evaluated for Impairment					41,207		52,456
Total Loans					41,525	44,534	54,334
Commercial and Industrial | Government program loans
Period-end amount allocated to:
Loans Individually Evaluated for Impairment					241		275
Loans Collectively Evaluated for Impairment					26,464		536
Total Loans					26,705	744	811
Real Estate Mortgage
Financing Receivable, Allowance for Credit Loss [Line Items]
Number of segments | segment			3
Summarizes activity in allowance for credit losses by loan category [Roll Forward]
Beginning balance	910	995	$ 712	1,015
Provision (recovery of provision) for credit losses	(103)	(135)	91	(154)
Charge-offs	0	0	0	(5)
Recoveries	5	4	9	8
Net recoveries (charge-offs)	5	4	9	3
Ending balance	812	864	812	864
Period-end amount allocated to:
Loans individually evaluated for impairment					206		379
Loans collectively evaluated for impairment					606		485
Ending balance	812	864	812	1,015	812	712	864
Loans Individually Evaluated for Impairment					3,089		3,672
Loans Collectively Evaluated for Impairment					311,349		278,216
Total Loans					314,438	291,237	281,888
Real Estate Mortgage | Commercial real estate
Period-end amount allocated to:
Loans Individually Evaluated for Impairment					2,048		1,824
Loans Collectively Evaluated for Impairment					262,444		225,701
Total Loans					264,492	245,183	227,525
Real Estate Mortgage | Residential mortgages
Period-end amount allocated to:
Loans Individually Evaluated for Impairment					1,041		1,848
Loans Collectively Evaluated for Impairment					48,785		52,294
Total Loans					49,826	45,881	54,142
Real Estate Mortgage | Home improvement and home equity loans
Period-end amount allocated to:
Loans Individually Evaluated for Impairment					0		0
Loans Collectively Evaluated for Impairment					120		221
Total Loans					120	173	221
Real estate construction and development
Summarizes activity in allowance for credit losses by loan category [Roll Forward]
Beginning balance	3,461	2,188	2,808	2,424
Provision (recovery of provision) for credit losses	363	142	1,016	(94)
Charge-offs	(252)	0	(252)	0
Recoveries	0	0	0	0
Net recoveries (charge-offs)	(252)	0	(252)	0
Ending balance	3,572	2,330	3,572	2,330
Period-end amount allocated to:
Loans individually evaluated for impairment					0		0
Loans collectively evaluated for impairment					3,572		2,330
Ending balance	3,572	2,330	3,572	2,424	3,572	2,808	2,330
Loans Individually Evaluated for Impairment					11,109		11,562
Loans Collectively Evaluated for Impairment					142,546		103,049
Total Loans					153,655	138,784	114,611
Agricultural
Summarizes activity in allowance for credit losses by loan category [Roll Forward]
Beginning balance	868	969	761	1,131
Provision (recovery of provision) for credit losses	(32)	163	75	1
Charge-offs	0	0	0	0
Recoveries	0	0	0	0
Net recoveries (charge-offs)	0	0	0	0
Ending balance	836	1,132	836	1,132
Period-end amount allocated to:
Loans individually evaluated for impairment					243		451
Loans collectively evaluated for impairment					593		681
Ending balance	836	1,132	836	1,131	836	761	1,132
Loans Individually Evaluated for Impairment					696		667
Loans Collectively Evaluated for Impairment					48,283		51,360
Total Loans					48,979	52,197	52,027
Installment and Student Loans
Summarizes activity in allowance for credit losses by loan category [Roll Forward]
Beginning balance	2,616	1,838	2,132	1,559
Provision (recovery of provision) for credit losses	577	136	1,564	446
Charge-offs	(448)	(5)	(956)	(114)
Recoveries	1	23	6	101
Net recoveries (charge-offs)	(447)	18	(950)	(13)
Ending balance	2,746	1,992	2,746	1,992
Period-end amount allocated to:
Loans individually evaluated for impairment					0		0
Loans collectively evaluated for impairment					2,746		1,992
Ending balance	2,746	1,992	2,132	1,559	2,746	2,132	1,992
Loans Individually Evaluated for Impairment					0		0
Loans Collectively Evaluated for Impairment					64,352		69,750
Total Loans					64,352	69,878	69,750
Unallocated
Summarizes activity in allowance for credit losses by loan category [Roll Forward]
Beginning balance	351	813	173	593
Provision (recovery of provision) for credit losses	(211)	(135)	(33)	85
Charge-offs	0	0	0	0
Recoveries	0	0	0	0
Net recoveries (charge-offs)	0	0	0	0
Ending balance	140	678	140	678
Period-end amount allocated to:
Loans individually evaluated for impairment					0		0
Loans collectively evaluated for impairment					140		678
Ending balance	$ 140	$ 678	$ 173	$ 593	$ 140	$ 173	$ 678