Net Loss Per Share - Computation of Net Loss Per Share (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Earnings Per Share [Abstract]
Weighted average shares outstanding - basic and diluted (shares)	109,552,602	100,809,853
Net loss	$ (19,155)	$ (15,816)
Net loss per share – basic and diluted ($ per share)	$ (0.17)	$ (0.16)