Earnings Per Share - Schedule of Computation of Basic and Diluted Earnings Per Share (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Basic and diluted
Net (loss) income	$ (171,064)	$ (25,195)	$ (8,196)	$ (18,904)	$ (3,094)	$ (13,032)	$ (18,957)	$ (520)	$ (223,359)	$ (34,618)	$ 11,058
Weighted average common shares outstanding used in computing net (loss) income per share—basic									45,999	45,259	42,230
Plus: net effect of dilutive stock options and unvested restricted common shares											1,391
Weighted average common shares outstanding used in computing net (loss) income per share—diluted									45,999	45,259	43,621
Net (loss) income per share—basic									$ (4.86)	$ (0.76)	$ 0.26
Net (loss) income per share—diluted									$ (4.86)	$ (0.76)	$ 0.25