Loans, Credit Quality Indicator (Details) - USD ($)	6 Months Ended
	Jun. 30, 2021	Dec. 31, 2020
Financing Receivable by credit exposure [Abstract]
Total	$ 210,855,000	$ 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	641,633,000	596,255,000
Real Estate Loans [Member] | Agricultural [Member]
Financing Receivable by credit exposure [Abstract]
Total	310,274,000	315,158,000
Real Estate Loans [Member] | Construction [Member]
Financing Receivable by credit exposure [Abstract]
Total	63,065,000	35,404,000
Real Estate Loans [Member] | Mortgages [Member]
Financing Receivable by credit exposure [Abstract]
Total	149,747,000	146,902,000
Real Estate Loans [Member] | Home Equity [Member]
Financing Receivable by credit exposure [Abstract]
Total	52,424,000	55,009,000
Consumer [Member]
Financing Receivable by credit exposure [Abstract]
Total	8,684,000	30,277,000
Other Commercial Loans [Member]
Financing Receivable by credit exposure [Abstract]
Total	104,349,000	114,169,000
Other Agricultural Loans [Member]
Financing Receivable by credit exposure [Abstract]
Total	33,720,000	48,779,000
State and Political Subdivision Loans [Member]
Financing Receivable by credit exposure [Abstract]
Total	51,213,000	63,328,000
Pass [Member]
Financing Receivable by credit exposure [Abstract]
Total	1,139,917,000	1,098,752,000
Pass [Member] | Real Estate Loans [Member] | Commercial [Member]
Financing Receivable by credit exposure [Abstract]
Total	610,776,000	563,121,000
Pass [Member] | Real Estate Loans [Member] | Agricultural [Member]
Financing Receivable by credit exposure [Abstract]
Total	290,149,000	289,216,000
Pass [Member] | Real Estate Loans [Member] | Construction [Member]
Financing Receivable by credit exposure [Abstract]
Total	63,065,000	35,404,000
Pass [Member] | Other Commercial Loans [Member]
Financing Receivable by credit exposure [Abstract]
Total	97,731,000	106,604,000
Pass [Member] | Other Agricultural Loans [Member]
Financing Receivable by credit exposure [Abstract]
Total	31,594,000	45,758,000
Pass [Member] | State and Political Subdivision Loans [Member]
Financing Receivable by credit exposure [Abstract]
Total	46,602,000	58,649,000
Special Mention [Member]
Financing Receivable by credit exposure [Abstract]
Total	42,549,000	48,247,000
Special Mention [Member] | Real Estate Loans [Member] | Commercial [Member]
Financing Receivable by credit exposure [Abstract]
Total	24,148,000	24,329,000
Special Mention [Member] | Real Estate Loans [Member] | Agricultural [Member]
Financing Receivable by credit exposure [Abstract]
Total	10,068,000	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	3,038,000	3,808,000
Special Mention [Member] | Other Agricultural Loans [Member]
Financing Receivable by credit exposure [Abstract]
Total	923,000	1,431,000
Special Mention [Member] | State and Political Subdivision Loans [Member]
Financing Receivable by credit exposure [Abstract]
Total	4,372,000	4,372,000
Substandard [Member]
Financing Receivable by credit exposure [Abstract]
Total	21,736,000	26,009,000
Substandard [Member] | Real Estate Loans [Member] | Commercial [Member]
Financing Receivable by credit exposure [Abstract]
Total	6,709,000	8,805,000
Substandard [Member] | Real Estate Loans [Member] | Agricultural [Member]
Financing Receivable by credit exposure [Abstract]
Total	10,057,000	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	3,528,000	3,672,000
Substandard [Member] | Other Agricultural Loans [Member]
Financing Receivable by credit exposure [Abstract]
Total	1,203,000	1,590,000
Substandard [Member] | State and Political Subdivision Loans [Member]
Financing Receivable by credit exposure [Abstract]
Total	239,000	307,000
Doubtful [Member]
Financing Receivable by credit exposure [Abstract]
Total	52,000	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	52,000	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	1,204,254,000	1,173,093,000
Performing [Member]
Financing Receivable by credit exposure [Abstract]
Total	210,236,000	231,051,000
Performing [Member] | Real Estate Loans [Member] | Mortgages [Member]
Financing Receivable by credit exposure [Abstract]
Total	149,149,000	145,843,000
Performing [Member] | Real Estate Loans [Member] | Home Equity [Member]
Financing Receivable by credit exposure [Abstract]
Total	52,403,000	54,961,000
Performing [Member] | Consumer [Member]
Financing Receivable by credit exposure [Abstract]
Total	8,684,000	30,247,000
Nonperforming [Member]
Financing Receivable by credit exposure [Abstract]
Total	600,000	1,117,000
Nonperforming [Member] | Real Estate Loans [Member] | Mortgages [Member]
Financing Receivable by credit exposure [Abstract]
Total	579,000	1,039,000
Nonperforming [Member] | Real Estate Loans [Member] | Home Equity [Member]
Financing Receivable by credit exposure [Abstract]
Total	21,000	48,000
Nonperforming [Member] | Consumer [Member]
Financing Receivable by credit exposure [Abstract]
Total	0	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