Loans, Credit Quality Indicator (Details) - USD ($)	9 Months Ended
	Sep. 30, 2020	Dec. 31, 2019
Financing Receivable by credit exposure [Abstract]
Total	$ 238,709,000	$ 227,035,000
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	535,456,000	342,023,000
Real Estate Loans [Member] | Agricultural [Member]
Financing Receivable by credit exposure [Abstract]
Total	310,702,000	311,464,000
Real Estate Loans [Member] | Construction [Member]
Financing Receivable by credit exposure [Abstract]
Total	28,656,000	15,519,000
Real Estate Loans [Member] | Mortgages [Member]
Financing Receivable by credit exposure [Abstract]
Total	150,657,000	157,078,000
Real Estate Loans [Member] | Home Equity [Member]
Financing Receivable by credit exposure [Abstract]
Total	57,427,000	60,010,000
Consumer [Member]
Financing Receivable by credit exposure [Abstract]
Total	30,625,000	9,947,000
Other Commercial Loans [Member]
Financing Receivable by credit exposure [Abstract]
Total	129,731,000	69,970,000
Other Agricultural Loans [Member]
Financing Receivable by credit exposure [Abstract]
Total	40,790,000	55,112,000
State and Political Subdivision Loans [Member]
Financing Receivable by credit exposure [Abstract]
Total	81,835,000	94,446,000
Pass [Member]
Financing Receivable by credit exposure [Abstract]
Total	1,074,530,000	844,978,000
Pass [Member] | Real Estate Loans [Member] | Commercial [Member]
Financing Receivable by credit exposure [Abstract]
Total	514,291,000	329,831,000
Pass [Member] | Real Estate Loans [Member] | Agricultural [Member]
Financing Receivable by credit exposure [Abstract]
Total	287,998,000	287,044,000
Pass [Member] | Real Estate Loans [Member] | Construction [Member]
Financing Receivable by credit exposure [Abstract]
Total	28,656,000	15,519,000
Pass [Member] | Other Commercial Loans [Member]
Financing Receivable by credit exposure [Abstract]
Total	124,563,000	66,880,000
Pass [Member] | Other Agricultural Loans [Member]
Financing Receivable by credit exposure [Abstract]
Total	37,529,000	51,711,000
Pass [Member] | State and Political Subdivision Loans [Member]
Financing Receivable by credit exposure [Abstract]
Total	81,493,000	93,993,000
Special Mention [Member]
Financing Receivable by credit exposure [Abstract]
Total	25,441,000	20,627,000
Special Mention [Member] | Real Estate Loans [Member] | Commercial [Member]
Financing Receivable by credit exposure [Abstract]
Total	10,727,000	4,305,000
Special Mention [Member] | Real Estate Loans [Member] | Agricultural [Member]
Financing Receivable by credit exposure [Abstract]
Total	11,882,000	14,261,000
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	1,239,000	984,000
Special Mention [Member] | Other Agricultural Loans [Member]
Financing Receivable by credit exposure [Abstract]
Total	1,593,000	1,077,000
Special Mention [Member] | State and Political Subdivision Loans [Member]
Financing Receivable by credit exposure [Abstract]
Total	0	0
Substandard [Member]
Financing Receivable by credit exposure [Abstract]
Total	27,075,000	22,826,000
Substandard [Member] | Real Estate Loans [Member] | Commercial [Member]
Financing Receivable by credit exposure [Abstract]
Total	10,400,000	7,848,000
Substandard [Member] | Real Estate Loans [Member] | Agricultural [Member]
Financing Receivable by credit exposure [Abstract]
Total	10,822,000	10,159,000
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	3,843,000	2,042,000
Substandard [Member] | Other Agricultural Loans [Member]
Financing Receivable by credit exposure [Abstract]
Total	1,668,000	2,324,000
Substandard [Member] | State and Political Subdivision Loans [Member]
Financing Receivable by credit exposure [Abstract]
Total	342,000	453,000
Doubtful [Member]
Financing Receivable by credit exposure [Abstract]
Total	124,000	103,000
Doubtful [Member] | Real Estate Loans [Member] | Commercial [Member]
Financing Receivable by credit exposure [Abstract]
Total	38,000	39,000
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	86,000	64,000
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	1,127,170,000	888,534,000
Performing [Member]
Financing Receivable by credit exposure [Abstract]
Total	237,191,000	226,040,000
Performing [Member] | Real Estate Loans [Member] | Mortgages [Member]
Financing Receivable by credit exposure [Abstract]
Total	149,171,000	156,151,000
Performing [Member] | Real Estate Loans [Member] | Home Equity [Member]
Financing Receivable by credit exposure [Abstract]
Total	57,407,000	59,950,000
Performing [Member] | Consumer [Member]
Financing Receivable by credit exposure [Abstract]
Total	30,613,000	9,939,000
Nonperforming [Member]
Financing Receivable by credit exposure [Abstract]
Total	1,498,000	972,000
Nonperforming [Member] | Real Estate Loans [Member] | Mortgages [Member]
Financing Receivable by credit exposure [Abstract]
Total	1,466,000	904,000
Nonperforming [Member] | Real Estate Loans [Member] | Home Equity [Member]
Financing Receivable by credit exposure [Abstract]
Total	20,000	60,000
Nonperforming [Member] | Consumer [Member]
Financing Receivable by credit exposure [Abstract]
Total	12,000	8,000
PCI [Member]
Financing Receivable by credit exposure [Abstract]
Total	20,000	23,000
PCI [Member] | Real Estate Loans [Member] | Mortgages [Member]
Financing Receivable by credit exposure [Abstract]
Total	20,000	23,000
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