Loans, Allowance for Loan Losses (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Allowance for loan losses [Roll Forward]
Balance, beginning of period	$ 3,603	$ 3,382	$ 3,403	$ 3,575
Provision charged to expenses	659	(12)	962	225
Losses charged off	(285)	(185)	(623)	(779)
Recoveries	39	222	274	386
Balance, end of period	4,016	3,407	4,016	3,407
Commercial and industrial [Member]
Allowance for loan losses [Roll Forward]
Balance, beginning of period	407	273	378	350
Provision charged to expenses	(3)	8	26	(84)
Losses charged off	0	0	0	0
Recoveries	0	19	0	34
Balance, end of period	404	300	404	300
Commercial Secured By Real Estate [Member]
Allowance for loan losses [Roll Forward]
Balance, beginning of period	2,383	2,136	2,178	2,179
Provision charged to expenses	488	(9)	546	287
Losses charged off	(116)	(118)	(145)	(462)
Recoveries	3	106	179	111
Balance, end of period	2,758	2,115	2,758	2,115
Residential Real Estate [Member]
Allowance for loan losses [Roll Forward]
Balance, beginning of period	690	822	717	885
Provision charged to expenses	25	(139)	211	(137)
Losses charged off	0	0	(227)	(135)
Recoveries	0	38	14	108
Balance, end of period	715	721	715	721
Consumer [Member]
Allowance for loan losses [Roll Forward]
Balance, beginning of period	70	86	76	96
Provision charged to expenses	95	(6)	102	(3)
Losses charged off	(88)	(30)	(109)	(84)
Recoveries	4	44	12	85
Balance, end of period	81	94	81	94
Agricultural [Member]
Allowance for loan losses [Roll Forward]
Balance, beginning of period	52	61	53	60
Provision charged to expenses	2	113	1	114
Losses charged off	0	0	0	0
Recoveries	0	0	0	0
Balance, end of period	54	174	54	174
Other [Member]
Allowance for loan losses [Roll Forward]
Balance, beginning of period	1	4	1	5
Provision charged to expenses	52	21	76	48
Losses charged off	(81)	(37)	(142)	(98)
Recoveries	32	15	69	48
Balance, end of period	$ 4	$ 3	$ 4	$ 3