Net Loss per Share - Computation of Basic and Diluted Net Loss per Share (Detail) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
Earnings Per Share [Abstract]
Net loss	$ (9,300)	$ (13,075)	$ (31,504)	$ (23,766)
Weighted-average common shares outstanding:
Basic and Diluted	32,239,877	27,282,863	29,783,424	27,271,226
Net loss per share, Basic and Diluted	$ (0.29)	$ (0.48)	$ (1.06)	$ (0.87)