Net (Loss) Income per Share - EPS (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Numerator (basic and diluted):
Net (loss) income, basic	$ (8,104)	$ 10,416	$ (25,612)	$ (36,704)
Net (loss) income, diluted	$ (8,065)	$ 10,416	$ (25,573)	$ (36,704)
Denominator (basic):
Weighted average shares of common stock outstanding	20,691,112	19,217,623	20,520,357	18,989,334
Denominator (diluted):
Weighted average shares of common stock outstanding	20,691,112	19,217,623	20,520,357	18,989,334
Effect of potential dilutive securities:
Weighted average dilutive effect of contingently issuable shares		273,886
Weighted average shares of common stock outstanding, diluted	20,691,112	22,288,873	20,520,357	18,989,334
Net (loss) income per share, basic (in dollars per share)	$ (0.39)	$ 0.54	$ (1.25)	$ (1.93)
Net (loss) income per share, diluted (in dollars per share)	$ (0.39)	$ 0.47	$ (1.25)	$ (1.93)
Stock options
Effect of potential dilutive securities:
Weighted average dilutive effect of share-based awards		1,898,543
Restricted stock
Effect of potential dilutive securities:
Weighted average dilutive effect of share-based awards		898,821