Net (Loss) Income Per Share - Computation of Basic and Dilutive Net Loss per Share (Details) - USD ($) $ / shares in Units, $ 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
Earnings Per Share [Abstract]
Net (loss) income	$ (7,476)	$ 12,379	$ (17,210)	$ (13,273)	$ (36,224)	$ (178)	$ 1,804	$ 4,619	$ (25,580)	$ (29,979)	$ 64,727
Denominator for basic earnings (loss) per share - weighted average shares (in shares)									106,946,384	105,596,256	106,121,810
Effect of dilutive securities: Stock options and restricted stock (in shares)									2,135,806	3,538,921	9,991,926
Denominator for diluted (loss) earnings per share - weighted average shares adjusted for dilutive securities (in shares)									106,946,384	105,596,256	116,113,736
(Loss) income per common share - basic (in dollars per share)	$ (0.07)	$ 0.12	$ (0.16)	$ (0.12)	$ (0.34)	$ 0.00	$ 0.02	$ 0.04	$ (0.24)	$ (0.28)	$ 0.61
(Loss) income per common share - diluted (in dollars per share)	$ (0.07)	$ 0.11	$ (0.16)	$ (0.12)	$ (0.34)	$ 0.00	$ 0.02	$ 0.04	$ (0.24)	$ (0.28)	$ 0.56