Loans, Allowance for Loan Losses by Portfolio Segment (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Balance at beginning of period	$ 16,560	$ 14,247	$ 15,815	$ 13,845
Charge-offs	(138)	(10)	(142)	(19)
Recoveries	9	40	108	51
Provision	500	550	1,150	950
Balance at end of period	16,931	14,827	16,931	14,827
Real Estate Loans [Member] | Residential [Member]
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Balance at beginning of period	1,167	1,154	1,174	1,114
Charge-offs		0	0	0
Recoveries	0	0	0	0
Provision	7	52	0	92
Balance at end of period	1,174	1,206	1,174	1,206
Real Estate Loans [Member] | Commercial [Member]
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Balance at beginning of period	6,683	4,729	6,216	4,549
Charge-offs	0	0	0	(1)
Recoveries	0	33	89	34
Provision	423	182	801	362
Balance at end of period	7,106	4,944	7,106	4,944
Real Estate Loans [Member] | Agricultural [Member]
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Balance at beginning of period	4,917	4,878	4,953	5,022
Charge-offs	0	0	0	0
Recoveries	0	0	0	0
Provision	(211)	183	(247)	39
Balance at end of period	4,706	5,061	4,706	5,061
Real Estate Loans [Member] | Construction [Member]
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Balance at beginning of period	151	56	122	43
Charge-offs	0	0	0	0
Recoveries	0	0	0	0
Provision	345	25	374	38
Balance at end of period	496	81	496	81
Consumer [Member]
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Balance at beginning of period	237	117	321	112
Charge-offs	(5)	(10)	(9)	(18)
Recoveries	6	4	12	12
Provision	(153)	251	(239)	256
Balance at end of period	85	362	85	362
Other Commercial Loans [Member]
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Balance at beginning of period	1,504	1,297	1,226	1,255
Charge-offs	(133)	0	(133)	0
Recoveries	3	3	7	5
Provision	(46)	(99)	228	(59)
Balance at end of period	1,328	1,201	1,328	1,201
Other Agricultural Loans [Member]
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Balance at beginning of period	789	835	864	961
Charge-offs	0	0	0	0
Recoveries	0	0	0	0
Provision	(206)	(14)	(281)	(140)
Balance at end of period	583	821	583	821
State and Political Subdivision Loans [Member]
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Balance at beginning of period	470	558	479	536
Charge-offs	0	0	0	0
Recoveries	0	0	0	0
Provision	(66)	(11)	(75)	11
Balance at end of period	404	547	404	547
Unallocated [Member]
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Balance at beginning of period	642	623	460	253
Charge-offs	0	0	0	0
Recoveries	0	0	0	0
Provision	407	(19)	589	351
Balance at end of period	$ 1,049	$ 604	$ 1,049	$ 604