Earnings (Loss) Per Share - Schedule of Computation of Basic and Diluted Earnings (Loss) Per Share (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Basic and diluted
Net income (loss)	$ 46,197	$ (8,196)	$ 37,998	$ (27,099)
Weighted average common shares outstanding used in computing net income (loss) per share—basic	46,799	45,943	46,546	45,876
Plus: net effect of dilutive stock options and restricted common shares	402		428
Weighted average common shares outstanding used in computing net income (loss) per share—diluted	47,201	45,943	46,974	45,876
Net income (loss) per share—basic	$ 0.99	$ (0.18)	$ 0.82	$ (0.59)
Net income (loss) per share—diluted	$ 0.98	$ (0.18)	$ 0.81	$ (0.59)