Quarterly Results of Operations (Unaudited) (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2017	Dec. 31, 2016
Quarterly Financial Information Disclosure [Abstract]
Interest income	$ 3,466	$ 3,434	$ 3,383	$ 3,324	$ 3,343	$ 3,318	$ 3,269	$ 3,351	$ 13,607	$ 13,281
Interest expense	460	499	487	491	509	526	536	552	1,937	2,123
Net interest income	3,006	2,935	2,896	2,833	2,834	2,792	2,733	2,799	11,670	11,158
Provision for credit losses	93	78	(30)	195	635	116		117	336	868
Net securities gains			1		1			1	1	2
Income before income taxes	565	512	401	346	289	60	352	317	1,824	1,018
Net income	$ (152)	$ 411	$ 338	$ 316	$ 395	$ 115	$ 308	$ 283	$ 911	$ 1,101
Net income per share (basic and diluted) (in dollars per share)	$ (0.05)	$ 0.15	$ 0.12	$ 0.11	$ 0.15	$ 0.04	$ 0.11	$ 0.10	$ 0.33	$ 0.40