Restructuring - Additional Information (Detail) $ in Thousands	3 Months Ended
	Mar. 31, 2017 USD ($)
Restructuring Cost and Reserve [Line Items]
Restructuring benefits	$ (800)
Restructuring liability	$ 17,200
Restructuring liability, expected paid out period	5 years 2 months 12 days
Research and Development [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring benefits	$ (900)
General and Administrative [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring charges	$ 100