Restructuring - Additional Information (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2015
Restructuring Cost and Reserve [Line Items]
Total restructuring charge	$ 1,900
Q2 2015 Restructuring Plan [Member]
Restructuring Cost and Reserve [Line Items]
Total restructuring charge	900
Restructuring liability	$ 19,388	$ 20,808	$ 21,837	$ 25,089	$ 26,406
Restructuring liability, expected paid out period	5 years 4 months 24 days
Research and Development [Member]
Restructuring Cost and Reserve [Line Items]
Total restructuring charge	$ 100
General and Administrative [Member]
Restructuring Cost and Reserve [Line Items]
Total restructuring charge	$ 1,800