Loans, Allowance for Loan Losses (Details) - USD ($) $ in Thousands	Sep. 30, 2018	Jun. 30, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Dec. 31, 2016
Summary of allowance for loan losses into amount required for loans individually evaluated for impairment and the amount required for loans collectively evaluated for impairment [Abstract]
Individually evaluated for impairment	$ 654		$ 410
Collectively evaluated for impairment	11,729		10,780
Total	12,383	$ 11,941	11,190	$ 10,447	$ 9,979	$ 8,886
Real Estate Loans [Member] | Residential [Member]
Summary of allowance for loan losses into amount required for loans individually evaluated for impairment and the amount required for loans collectively evaluated for impairment [Abstract]
Individually evaluated for impairment	27		56
Collectively evaluated for impairment	1,025		993
Total	1,052	1,045	1,049	1,080	1,104	1,064
Real Estate Loans [Member] | Commercial [Member]
Summary of allowance for loan losses into amount required for loans individually evaluated for impairment and the amount required for loans collectively evaluated for impairment [Abstract]
Individually evaluated for impairment	224		94
Collectively evaluated for impairment	3,701		3,773
Total	3,925	3,794	3,867	3,582	3,541	3,589
Real Estate Loans [Member] | Agricultural [Member]
Summary of allowance for loan losses into amount required for loans individually evaluated for impairment and the amount required for loans collectively evaluated for impairment [Abstract]
Individually evaluated for impairment	86		3
Collectively evaluated for impairment	3,843		3,140
Total	3,929	3,673	3,143	2,694	2,452	1,494
Real Estate Loans [Member] | Construction [Member]
Summary of allowance for loan losses into amount required for loans individually evaluated for impairment and the amount required for loans collectively evaluated for impairment [Abstract]
Individually evaluated for impairment	0		0
Collectively evaluated for impairment	49		23
Total	49	44	23	31	45	47
Consumer [Member]
Summary of allowance for loan losses into amount required for loans individually evaluated for impairment and the amount required for loans collectively evaluated for impairment [Abstract]
Individually evaluated for impairment	0		0
Collectively evaluated for impairment	123		124
Total	123	115	124	137	125	122
Other Commercial Loans [Member]
Summary of allowance for loan losses into amount required for loans individually evaluated for impairment and the amount required for loans collectively evaluated for impairment [Abstract]
Individually evaluated for impairment	152		231
Collectively evaluated for impairment	1,067		1,041
Total	1,219	1,266	1,272	1,112	1,131	1,327
Other Agricultural Loans [Member]
Summary of allowance for loan losses into amount required for loans individually evaluated for impairment and the amount required for loans collectively evaluated for impairment [Abstract]
Individually evaluated for impairment	165		26
Collectively evaluated for impairment	534		466
Total	699	589	492	462	431	312
State and Political Subdivision Loans [Member]
Summary of allowance for loan losses into amount required for loans individually evaluated for impairment and the amount required for loans collectively evaluated for impairment [Abstract]
Individually evaluated for impairment	0		0
Collectively evaluated for impairment	751		816
Total	751	767	816	874	838	833
Unallocated [Member]
Summary of allowance for loan losses into amount required for loans individually evaluated for impairment and the amount required for loans collectively evaluated for impairment [Abstract]
Individually evaluated for impairment	0		0
Collectively evaluated for impairment	636		404
Total	$ 636	$ 648	$ 404	$ 475	$ 312	$ 98