Net Loss Per Share (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Numerator:
Net loss available for common shareholders - basic and diluted	$ (7,132)	$ (5,949)
Denominator:
Weighted-average shares outstanding - basic and diluted	78,610	68,113
Net loss per share - basic and diluted	$ (0.09)	$ (0.09)