Accumulated Other Comprehensive Loss - Comprehensive income/loss (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Equity [Abstract]
Change in net unrealized gain (loss) on securities available for sale, before tax	$ 184	$ 1,515	$ (1,671)
Change in net unrealized loss on securities available for sale, tax effect	(591)	611	0
Change in net unrealized loss on securities available for sale, net of tax	775	904	(1,671)
Other comprehensive Income (loss), before tax	184	1,515	(1,671)
Other comprehensive income (loss), tax effect	(591)	611	0
Other comprehensive income (loss), net of tax	$ 775	$ 904	$ (1,671)