Net Loss Per Share - Summary of Basic and Diluted Net Loss Per Share of Common Stock (Detail) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015
Earnings Per Share [Abstract]
Net loss	$ (15,580)	$ (7,682)
Accretion of preferred stock to redemption value		(11,273)
Net loss attributable to common stockholders, basic and diluted	$ (15,580)	$ (18,955)
Weighted-average common shares outstanding, basic and diluted	40,547,669	12,642,188
Net loss per share attributable to common stockholders, basic and diluted	$ (0.38)	$ (1.50)