Net Loss Per Share (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
Earnings Per Share [Abstract]
Net loss	$ (14,739)	$ (15,034)	$ (26,362)	$ (24,955)
Weighted average common shares outstanding (in shares)	82,012	67,784	81,241	63,962
Net loss per share, basic and diluted (in dollars per share)	$ (0.18)	$ (0.22)	$ (0.32)	$ (0.39)