Separation Benefits - Schedule of Accrued Separation Benefits (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016
Termination Benefits [Abstract]
Beginning balance	$ 255	$ 1,665
Provision for separation benefits	8,916	435
Separation benefits paid	(602)	(1,845)
Ending balance	$ 8,569	$ 255