Income Taxes - Summary of components of income tax expense (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Income Taxes
Corporate tax rate	21.00%	34.00%
One time income tax expense due to the Tax Reform Act		$ 600
Current income tax (benefit) expense:
Federal	$ (1,191)	328
State	57	143
Total current tax expense	(1,134)	471
Deferred income tax benefits:
Federal	1,228	443
State	36	(1)
Total deferred tax expense	1,264	442
Income tax expense (benefit)	$ 130	$ 913