Other Real Estate Owned - Changes in the Allowance for OREO Losses (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Change in the allowance for OREO losses
Balance at the beginning of year	$ 86	$ 56	$ 29
Provision for losses		135	90
Charge-offs, net	(29)	(105)	(63)
Balance at the end of year	57	86	56
OREO, expenses other than provision for losses	$ (72)	$ (22)	$ 19