Net Loss Per Share - Schedule of Earnings Per Share (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Numerators:
Net loss	$ (175,552)	$ (31,868)	$ (9,740)	$ (14,648)	$ (14,336)	$ (4,019)	$ 2,742	$ (3,492)	$ (231,808)	$ (19,105)	$ (84,850)
Less: Income attributable to unvested restricted stock awards									0	0	0
Numerator for basic net loss per share									(231,808)	(19,105)	(84,850)
Less: Income attributable to unvested restricted stock awards									0	0	0
Numerator for basic net loss per share									(231,808)	(19,105)	(84,850)
Effect of dilutive securities:
Unvested restricted stock awards									0	0	0
Numerator for diluted net loss per share									$ (231,808)	$ (19,105)	$ (84,850)
Denominators:
Weighted average number of common shares outstanding (in shares)									60,424	59,680	51,253
Less: Weighted average number of unvested restricted stock awards outstanding (in shares)									(1,045)	(968)	(1,114)
Denominator for basic and diluted net loss per share (in shares)									59,379	58,712	50,139
Net loss per share:
Basic (in dollars per share)									$ (3.90)	$ (0.33)	$ (1.69)
Diluted (in dollars per share)									$ (3.90)	$ (0.33)	$ (1.69)