Description of Business and Basis of Presentation (Net Income (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
Numerator
Net loss	$ (13,860)	$ (6,855)	$ (34,377)	$ (11,536)
Denominator
Basic and diluted (in shares)	37,008	31,989	34,929	31,828
Net loss per share
Basic and diluted (in dollars per share)	$ (0.37)	$ (0.21)	$ (0.98)	$ (0.36)