Loans, Allowance for Loan Losses by Portfolio Segment (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Balance at beginning of period	$ 14,827	$ 13,304	$ 13,845	$ 12,884
Charge-offs	(237)	(34)	(256)	(387)
Recoveries	29	9	80	32
Provision (Credit)	550	400	1,500	1,150
Balance at end of period	15,169	13,679	15,169	13,679
Real Estate Loans [Member] | Residential [Member]
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Balance at beginning of period	1,206	1,066	1,114	1,105
Charge-offs		(24)	0	(24)
Recoveries	0	0	0	0
Provision (Credit)	13	49	105	10
Balance at end of period	1,219	1,091	1,219	1,091
Real Estate Loans [Member] | Commercial [Member]
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Balance at beginning of period	4,944	4,400	4,549	4,115
Charge-offs	(220)	0	(221)	(293)
Recoveries	3	0	37	0
Provision (Credit)	579	241	941	819
Balance at end of period	5,306	4,641	5,306	4,641
Real Estate Loans [Member] | Agricultural [Member]
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Balance at beginning of period	5,061	4,532	5,022	4,264
Charge-offs	(4)	0	(4)	0
Recoveries	19	0	19	0
Provision (Credit)	(270)	180	(231)	448
Balance at end of period	4,806	4,712	4,806	4,712
Real Estate Loans [Member] | Construction [Member]
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Balance at beginning of period	81	36	43	58
Charge-offs	0	0	0	0
Recoveries	0	0	0	0
Provision (Credit)	4	(17)	42	(39)
Balance at end of period	85	19	85	19
Consumer [Member]
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Balance at beginning of period	362	118	112	120
Charge-offs	(12)	(10)	(30)	(32)
Recoveries	3	6	15	24
Provision (Credit)	(1)	5	255	7
Balance at end of period	352	119	352	119
Other Commercial Loans [Member]
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Balance at beginning of period	1,201	1,328	1,255	1,354
Charge-offs	(1)	0	(1)	(38)
Recoveries	4	3	9	8
Provision (Credit)	26	18	(33)	25
Balance at end of period	1,230	1,349	1,230	1,349
Other Agricultural Loans [Member]
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Balance at beginning of period	821	741	961	752
Charge-offs	0	0	0	0
Recoveries	0	0	0	0
Provision (Credit)	(86)	128	(226)	117
Balance at end of period	735	869	735	869
State and Political Subdivision Loans [Member]
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Balance at beginning of period	547	539	536	762
Charge-offs	0	0	0	0
Recoveries	0	0	0	0
Provision (Credit)	(33)	(3)	(22)	(226)
Balance at end of period	514	536	514	536
Unallocated [Member]
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Balance at beginning of period	604	544	253	354
Charge-offs	0	0	0	0
Recoveries	0	0	0	0
Provision (Credit)	318	(201)	669	(11)
Balance at end of period	$ 922	$ 343	$ 922	$ 343