Net Loss Per Share - Reconciliation of Shares Used in Calculating Basic and Diluted Earnings Per Share (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended				6 Months Ended
	Jun. 30, 2021	Mar. 31, 2021	Jun. 30, 2020	Mar. 31, 2020	Jun. 30, 2021	Jun. 30, 2020
Earnings Per Share [Abstract]
Net loss (in thousands)	$ (21,119)	$ (21,195)	$ (18,627)	$ (37,001)	$ (42,314)	$ (55,628)
Weighted average number of shares outstanding, basic and diluted	69,057,129		65,650,782		68,482,653	65,023,302
Net loss per share, basic and diluted	$ (0.31)		$ (0.28)		$ (0.62)	$ (0.86)