Formation and Business of the Company - Additional Information (Detail) - USD ($) $ in Thousands	3 Months Ended		12 Months Ended
	Mar. 31, 2016	Mar. 31, 2015	Dec. 31, 2015
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Net loss	$ (9,288)	$ (14,060)	$ (67,400)
Cash used in operations	(30,265)	$ (16,829)	(100,400)
Accumulated deficit	$ (198,696)		$ (189,408)