Net Loss Per Share - Computation of Net Loss Per Share (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended				6 Months Ended
	Jun. 30, 2020	Mar. 31, 2020	Jun. 30, 2019	Mar. 31, 2019	Jun. 30, 2020	Jun. 30, 2019
Earnings Per Share [Abstract]
Weighted average shares outstanding - basic and diluted (shares)	112,615,744		110,345,135		112,199,229	109,744,405
Net loss	$ (32,085)	$ (40,572)	$ (28,395)	$ (19,259)	$ (72,657)	$ (47,654)
Net loss per share - basic and diluted ($ per share)	$ (0.28)		$ (0.26)		$ (0.65)	$ (0.43)