Net Loss Per Share (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Earnings Per Share [Abstract]
Net loss	$ (9,519)	$ (7,436)	$ (24,374)	$ (33,758)
Weighted average common shares outstanding (in shares)	98,665	84,822	93,108	84,075
Net loss per share, basic and diluted (in dollars per share)	$ (0.10)	$ (0.09)	$ (0.26)	$ (0.40)