Income Taxes - Schedule of current and deferred income tax expense (benefit) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Current:
Federal	$ 4,700	$ 8,452
State	1,423	1,218
Total current	6,123	9,670
Deferred:
Federal	26	(13,070)
State	(16)	(1,768)
Total deferred	10	(14,838)
Total expense	$ 6,133	$ (5,168)	$ 832