Stock Based Compensation - Warrants Activity (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	9 Months Ended	12 Months Ended
	Sep. 30, 2018	Dec. 31, 2017
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Outstanding at the ending of the period (in shares)	1,019
Warrants
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Outstanding at the beginning of the period (in shares)	1,019
Granted (in shares)	0
Forfeited (in shares)	0
Expired (in shares)	0
Outstanding at the ending of the period (in shares)	1,019	1,019
Outstanding at the beginning of the period (in dollars per share)	$ 3.79
Granted (in dollars per share)	0
Forfeited (in dollars per share)	0
Expired (in dollars per share)	0
Outstanding at the ending of the period (in shares)	$ 3.79	$ 3.79
Weighted average remaining contractual term (in years)		4 years 8 months 12 days
Outstanding and Vested, September 30, 2018	3 years 10 months 24 days
Aggregate intrinsic value (in dollars)		$ 0
Outstanding and Vested, September 30, 2018	$ 0