Net Loss Per Common Share - Diluted Net Loss Per Common Share (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2020	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Computation of basic and diluted net loss per share [Abstract]
Net loss available to common stockholders									$ (83,328)	$ (25,580)	$ (29,979)
Dividends on Series B Convertible Preferred Stock									34,044	0	0
Numerator - net loss available to common stockholders adjusted for hypothetical conversion of Series B Convertible Preferred Stock									$ (83,328)	$ (25,580)	$ (29,979)
Denominator - weighted average common shares outstanding adjusted for potential common shares (in shares)									108,257,112	106,946,384	105,596,256
Diluted net loss per common share (in dollars per share)	$ (0.17)	$ (0.48)	$ (0.08)	$ (0.04)	$ (0.07)	$ 0.11	$ (0.16)	$ (0.12)	$ (0.77)	$ (0.24)	$ (0.28)
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Potential common shares (in shares)									15,687,044	2,135,806	3,538,921
Convertible preferred stock Series B
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Potential common shares (in shares)									12,987,013	0	0
Restricted stock awards
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Potential common shares (in shares)									1,299,770	1,157,563	365,978
Outstanding stock options
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Potential common shares (in shares)									752,499	978,243	3,172,943
Restricted stock unit awards
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Potential common shares (in shares)									616,141	0	0
Performance stock unit awards
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Potential common shares (in shares)									31,621	0	0