Loans, Credit Quality Indicator (Details) - USD ($)	9 Months Ended
	Sep. 30, 2021	Dec. 31, 2020
Financing Receivable by credit exposure [Abstract]
Total	$ 235,895,000	$ 232,188,000
Minimum [Member]
Financing Receivable [Abstract]
Amount over which all relationships to be reviewed, minimum	$ 500,000
Percentage of dollar volume of commercial loan portfolio to be reviewed	50.00%
Amount over which all new loans to be reviewed	$ 1,000,000.0
Amount over which all relationships to be reviewed	1,000,000.0
Amount which is 30 days past due to be reviewed for all aggregate loan relationships	750,000
Real Estate Loans [Member] | Commercial [Member]
Financing Receivable by credit exposure [Abstract]
Total	657,485,000	596,255,000
Real Estate Loans [Member] | Agricultural [Member]
Financing Receivable by credit exposure [Abstract]
Total	312,442,000	315,158,000
Real Estate Loans [Member] | Construction [Member]
Financing Receivable by credit exposure [Abstract]
Total	68,408,000	35,404,000
Real Estate Loans [Member] | Mortgages [Member]
Financing Receivable by credit exposure [Abstract]
Total	152,536,000	146,902,000
Real Estate Loans [Member] | Home Equity [Member]
Financing Receivable by credit exposure [Abstract]
Total	52,317,000	55,009,000
Consumer [Member]
Financing Receivable by credit exposure [Abstract]
Total	31,042,000	30,277,000
Other Commercial Loans [Member]
Financing Receivable by credit exposure [Abstract]
Total	92,188,000	114,169,000
Other Agricultural Loans [Member]
Financing Receivable by credit exposure [Abstract]
Total	28,562,000	48,779,000
State and Political Subdivision Loans [Member]
Financing Receivable by credit exposure [Abstract]
Total	47,928,000	63,328,000
Pass [Member]
Financing Receivable by credit exposure [Abstract]
Total	1,145,765,000	1,098,752,000
Pass [Member] | Real Estate Loans [Member] | Commercial [Member]
Financing Receivable by credit exposure [Abstract]
Total	621,044,000	563,121,000
Pass [Member] | Real Estate Loans [Member] | Agricultural [Member]
Financing Receivable by credit exposure [Abstract]
Total	293,926,000	289,216,000
Pass [Member] | Real Estate Loans [Member] | Construction [Member]
Financing Receivable by credit exposure [Abstract]
Total	68,408,000	35,404,000
Pass [Member] | Other Commercial Loans [Member]
Financing Receivable by credit exposure [Abstract]
Total	88,080,000	106,604,000
Pass [Member] | Other Agricultural Loans [Member]
Financing Receivable by credit exposure [Abstract]
Total	26,583,000	45,758,000
Pass [Member] | State and Political Subdivision Loans [Member]
Financing Receivable by credit exposure [Abstract]
Total	47,724,000	58,649,000
Special Mention [Member]
Financing Receivable by credit exposure [Abstract]
Total	44,637,000	48,247,000
Special Mention [Member] | Real Estate Loans [Member] | Commercial [Member]
Financing Receivable by credit exposure [Abstract]
Total	27,862,000	24,329,000
Special Mention [Member] | Real Estate Loans [Member] | Agricultural [Member]
Financing Receivable by credit exposure [Abstract]
Total	12,679,000	14,307,000
Special Mention [Member] | Real Estate Loans [Member] | Construction [Member]
Financing Receivable by credit exposure [Abstract]
Total	0	0
Special Mention [Member] | Other Commercial Loans [Member]
Financing Receivable by credit exposure [Abstract]
Total	2,908,000	3,808,000
Special Mention [Member] | Other Agricultural Loans [Member]
Financing Receivable by credit exposure [Abstract]
Total	984,000	1,431,000
Special Mention [Member] | State and Political Subdivision Loans [Member]
Financing Receivable by credit exposure [Abstract]
Total	204,000	4,372,000
Substandard [Member]
Financing Receivable by credit exposure [Abstract]
Total	16,561,000	26,009,000
Substandard [Member] | Real Estate Loans [Member] | Commercial [Member]
Financing Receivable by credit exposure [Abstract]
Total	8,579,000	8,805,000
Substandard [Member] | Real Estate Loans [Member] | Agricultural [Member]
Financing Receivable by credit exposure [Abstract]
Total	5,837,000	11,635,000
Substandard [Member] | Real Estate Loans [Member] | Construction [Member]
Financing Receivable by credit exposure [Abstract]
Total	0	0
Substandard [Member] | Other Commercial Loans [Member]
Financing Receivable by credit exposure [Abstract]
Total	1,150,000	3,672,000
Substandard [Member] | Other Agricultural Loans [Member]
Financing Receivable by credit exposure [Abstract]
Total	995,000	1,590,000
Substandard [Member] | State and Political Subdivision Loans [Member]
Financing Receivable by credit exposure [Abstract]
Total	0	307,000
Doubtful [Member]
Financing Receivable by credit exposure [Abstract]
Total	50,000	85,000
Doubtful [Member] | Real Estate Loans [Member] | Commercial [Member]
Financing Receivable by credit exposure [Abstract]
Total	0	0
Doubtful [Member] | Real Estate Loans [Member] | Agricultural [Member]
Financing Receivable by credit exposure [Abstract]
Total	0	0
Doubtful [Member] | Real Estate Loans [Member] | Construction [Member]
Financing Receivable by credit exposure [Abstract]
Total	0	0
Doubtful [Member] | Other Commercial Loans [Member]
Financing Receivable by credit exposure [Abstract]
Total	50,000	85,000
Doubtful [Member] | Other Agricultural Loans [Member]
Financing Receivable by credit exposure [Abstract]
Total	0	0
Doubtful [Member] | State and Political Subdivision Loans [Member]
Financing Receivable by credit exposure [Abstract]
Total	0	0
Loss [Member]
Financing Receivable by credit exposure [Abstract]
Total	0	0
Loss [Member] | Real Estate Loans [Member] | Commercial [Member]
Financing Receivable by credit exposure [Abstract]
Total	0	0
Loss [Member] | Real Estate Loans [Member] | Agricultural [Member]
Financing Receivable by credit exposure [Abstract]
Total	0	0
Loss [Member] | Real Estate Loans [Member] | Construction [Member]
Financing Receivable by credit exposure [Abstract]
Total	0	0
Loss [Member] | Other Commercial Loans [Member]
Financing Receivable by credit exposure [Abstract]
Total	0	0
Loss [Member] | Other Agricultural Loans [Member]
Financing Receivable by credit exposure [Abstract]
Total	0	0
Loss [Member] | State and Political Subdivision Loans [Member]
Financing Receivable by credit exposure [Abstract]
Total	0	0
Internally Assigned Grade [Member]
Financing Receivable by credit exposure [Abstract]
Total	1,207,013,000	1,173,093,000
Performing [Member]
Financing Receivable by credit exposure [Abstract]
Total	235,203,000	231,051,000
Performing [Member] | Real Estate Loans [Member] | Mortgages [Member]
Financing Receivable by credit exposure [Abstract]
Total	151,907,000	145,843,000
Performing [Member] | Real Estate Loans [Member] | Home Equity [Member]
Financing Receivable by credit exposure [Abstract]
Total	52,256,000	54,961,000
Performing [Member] | Consumer [Member]
Financing Receivable by credit exposure [Abstract]
Total	31,040,000	30,247,000
Nonperforming [Member]
Financing Receivable by credit exposure [Abstract]
Total	673,000	1,117,000
Nonperforming [Member] | Real Estate Loans [Member] | Mortgages [Member]
Financing Receivable by credit exposure [Abstract]
Total	610,000	1,039,000
Nonperforming [Member] | Real Estate Loans [Member] | Home Equity [Member]
Financing Receivable by credit exposure [Abstract]
Total	61,000	48,000
Nonperforming [Member] | Consumer [Member]
Financing Receivable by credit exposure [Abstract]
Total	2,000	30,000
PCI [Member]
Financing Receivable by credit exposure [Abstract]
Total	19,000	20,000
PCI [Member] | Real Estate Loans [Member] | Mortgages [Member]
Financing Receivable by credit exposure [Abstract]
Total	19,000	20,000
PCI [Member] | Real Estate Loans [Member] | Home Equity [Member]
Financing Receivable by credit exposure [Abstract]
Total	0	0
PCI [Member] | Consumer [Member]
Financing Receivable by credit exposure [Abstract]
Total	$ 0	$ 0