Net Loss Per Share (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
Numerator:
Net loss attributable to common stockholders	$ (14,635)	$ (6,398)
Denominator:
Weighted-average common shares outstanding- basic and diluted (in shares)	46,598,797	40,626,729
Basic and diluted net loss (in dollars per share)	$ (0.31)	$ (0.16)