Loans, Allowance for Loan Losses by Portfolio Segment (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Balance at beginning of period	$ 13,845	$ 12,884
Charge-offs	(9)	(214)
Recoveries	11	14
Provision (Credit)	400	400
Balance at end of period	14,247	13,084
Real Estate Loans [Member] | Residential [Member]
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Balance at beginning of period	1,114	1,105
Charge-offs	0	0
Recoveries	0	0
Provision (Credit)	40	(16)
Balance at end of period	1,154	1,089
Real Estate Loans [Member] | Commercial [Member]
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Balance at beginning of period	4,549	4,115
Charge-offs	(1)	(200)
Recoveries	1	0
Provision (Credit)	180	215
Balance at end of period	4,729	4,130
Real Estate Loans [Member] | Agricultural [Member]
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Balance at beginning of period	5,022	4,264
Charge-offs	0	0
Recoveries	0	0
Provision (Credit)	(144)	128
Balance at end of period	4,878	4,392
Real Estate Loans [Member] | Construction [Member]
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Balance at beginning of period	43	58
Charge-offs	0	0
Recoveries	0	0
Provision (Credit)	13	(26)
Balance at end of period	56	32
Consumer [Member]
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Balance at beginning of period	112	120
Charge-offs	(8)	(14)
Recoveries	8	11
Provision (Credit)	5	7
Balance at end of period	117	124
Other Commercial Loans [Member]
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Balance at beginning of period	1,255	1,354
Charge-offs	0	0
Recoveries	2	3
Provision (Credit)	40	(74)
Balance at end of period	1,297	1,283
Other Agricultural Loans [Member]
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Balance at beginning of period	961	752
Charge-offs	0	0
Recoveries	0	0
Provision (Credit)	(126)	4
Balance at end of period	835	756
State and Political Subdivision Loans [Member]
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Balance at beginning of period	536	762
Charge-offs	0	0
Recoveries	0	0
Provision (Credit)	22	(197)
Balance at end of period	558	565
Unallocated [Member]
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Balance at beginning of period	253	354
Charge-offs	0	0
Recoveries	0	0
Provision (Credit)	370	359
Balance at end of period	$ 623	$ 713