Other Real Estate Owned - Change in OREO (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Changes in the balance for OREO
Balance at the beginning of year, gross	$ 281	$ 998
Transfers between loans and other real estate owned	208	618	$ 824
Capitalized expenses		21
Charge-offs	(29)	(106)
Sales proceeds	(245)	(1,384)
Gain on disposition	10	134	242
Balance at the end of year, gross	225	281	998
Less allowance for losses	(57)	(86)	$ (56)	$ (29)
Balance at the end of the year, net	$ 168	$ 195