Net Loss Per Share (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended				6 Months Ended
	Jun. 30, 2019	Mar. 31, 2019	Jun. 30, 2018	Mar. 31, 2018	Jun. 30, 2019	Jun. 30, 2018
Earnings Per Share [Abstract]
Net loss	$ (24,060)	$ (14,365)	$ (6,622)	$ (9,055)	$ (38,425)	$ (15,677)
Weighted average common shares outstanding (in shares)	105,485		101,150		105,139	100,862
Net loss per share, basic and diluted (in dollars per share)	$ (0.23)		$ (0.07)		$ (0.37)	$ (0.16)