Net Loss Per Share (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014
Earnings Per Share [Abstract]
Net loss	$ (11,105)	$ (13,640)	$ (37,467)	$ (38,595)
Weighted average common shares outstanding (in shares)	82,417	76,880	81,637	68,315
Net loss per share, basic and diluted (in dollars per share)	$ (0.13)	$ (0.18)	$ (0.46)	$ (0.56)