Net Income (Loss) per Common Share -Computation of basic and diluted net income per common share (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended						9 Months Ended
	Sep. 30, 2021	Jun. 30, 2021	Mar. 31, 2021	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Sep. 30, 2021	Sep. 30, 2020
Basic- net (loss) income per share
Net income (loss)	$ (5,965)	$ (7,563)	$ 115,738	$ (20,552)	$ (24,226)	$ 8,817	$ 102,210	$ (35,961)
Less: Undistributed earnings to preferred stockholders							(1,636)
Net (loss) income attributable to common stockholders	$ (5,965)			$ (20,552)			$ 100,574	$ (35,961)
Denominator for basic net (loss) income per share	52,740			35,091			47,990	32,999
Basic net (loss) income per common share	$ (0.11)			$ (0.59)			$ 2.10	$ (1.09)
Diluted- net (loss) income per share
Net income (loss)	$ (5,965)	$ (7,563)	$ 115,738	$ (20,552)	$ (24,226)	$ 8,817	$ 102,210	$ (35,961)
Less: Warrant revaluation gain applicable to dilutive warrants							(6,983)
Less: Future tranche right revaluation gain applicable to dilutive future tranche rights							(118,803)
Numerator for diluted net (loss) income per share	$ (5,965)			$ (20,552)			$ (23,576)	$ (35,961)
Denominator for basic net (loss) income per share	52,740			35,091			47,990	32,999
Plus: Incremental shares underlying "in the money" warrants outstanding							223
Plus: Incremental shares underlying "in the money" future tranche rights outstanding							3,400
Denominator for diluted net (loss) income per share	52,740			35,091			51,613	32,999