Net Loss per Share - Schedule of Basic and Diluted Net Loss per Share (Detail) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
Numerator:
Net loss	$ (23,879)	$ (16,815)
Net loss:	$ (23,879)	$ (16,815)
Denominator:
Weighted average common shares outstanding, basic and diluted	31,704	21,570
Net loss per share, basic and diluted	$ (0.75)	$ (0.78)