Loans, Allowance for Loan Losses by Portfolio Segment (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Balance at beginning of period	$ 16,931	$ 14,827	$ 15,815	$ 13,845
Charge-offs	(7)	(237)	(149)	(256)
Recoveries	10	29	118	80
Provision	400	550	1,550	1,500
Balance at end of period	17,334	15,169	17,334	15,169
Real Estate Loans [Member] | Residential [Member]
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Balance at beginning of period	1,174	1,206	1,174	1,114
Charge-offs	0	0	0	0
Recoveries	0	0	0	0
Provision	16	13	16	105
Balance at end of period	1,190	1,219	1,190	1,219
Real Estate Loans [Member] | Commercial [Member]
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Balance at beginning of period	7,106	4,944	6,216	4,549
Charge-offs	0	(220)	0	(221)
Recoveries	0	3	89	37
Provision	572	579	1,373	941
Balance at end of period	7,678	5,306	7,678	5,306
Real Estate Loans [Member] | Agricultural [Member]
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Balance at beginning of period	4,706	5,061	4,953	5,022
Charge-offs	0	(4)	0	(4)
Recoveries	0	19	0	19
Provision	40	(270)	(207)	(231)
Balance at end of period	4,746	4,806	4,746	4,806
Real Estate Loans [Member] | Construction [Member]
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Balance at beginning of period	496	81	122	43
Charge-offs	0	0	0	0
Recoveries	0	0	0	0
Provision	42	4	416	42
Balance at end of period	538	85	538	85
Consumer [Member]
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Balance at beginning of period	85	362	321	112
Charge-offs	(7)	(12)	(16)	(30)
Recoveries	4	3	16	15
Provision	236	(1)	(3)	255
Balance at end of period	318	352	318	352
Other Commercial Loans [Member]
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Balance at beginning of period	1,328	1,201	1,226	1,255
Charge-offs	0	(1)	(133)	(1)
Recoveries	6	4	13	9
Provision	(203)	26	25	(33)
Balance at end of period	1,131	1,230	1,131	1,230
Other Agricultural Loans [Member]
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Balance at beginning of period	583	821	864	961
Charge-offs	0	0	0	0
Recoveries	0	0	0	0
Provision	(135)	(86)	(416)	(226)
Balance at end of period	448	735	448	735
State and Political Subdivision Loans [Member]
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Balance at beginning of period	404	547	479	536
Charge-offs	0	0	0	0
Recoveries	0	0	0	0
Provision	(108)	(33)	(183)	(22)
Balance at end of period	296	514	296	514
Unallocated [Member]
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Balance at beginning of period	1,049	604	460	253
Charge-offs	0	0	0	0
Recoveries	0	0	0	0
Provision	(60)	318	529	669
Balance at end of period	$ 989	$ 922	$ 989	$ 922