Restructuring - Additional Information (Detail) - USD ($)	1 Months Ended		12 Months Ended
	Apr. 30, 2017	Dec. 31, 2016	Dec. 31, 2017	Dec. 31, 2016
Restructuring Cost And Reserve [Line Items]
Restructuring expenses			$ 3,020,000	$ 4,562,000
Workforce Reduction [Member]
Restructuring Cost And Reserve [Line Items]
Cost incurred related to workforce reduction				$ 2,300,000
Workforce Reduction [Member] | Maximum [Member]
Restructuring Cost And Reserve [Line Items]
Cost incurred related to workforce reduction			$ 100,000
Corvallis Plan [Member]
Restructuring Cost And Reserve [Line Items]
Restructuring, initiation date			2016-03
Restructuring, completion date			Sep. 30, 2017
Minimum lease payment obligation			$ 4,900,000
Corvallis Plan [Member] | Workforce Reduction [Member]
Restructuring Cost And Reserve [Line Items]
Percentage of workforce reduced			19.00%
Corvallis Plan [Member] | Facility Closing [Member]
Restructuring Cost And Reserve [Line Items]
Restructuring expenses	$ 2,400,000	$ 1,600,000
Cambridge Plan [Member]
Restructuring Cost And Reserve [Line Items]
Restructuring, initiation date			2016-08
Restructuring, completion date			Oct. 31, 2016
Cambridge Plan [Member] | Workforce Reduction [Member]
Restructuring Cost And Reserve [Line Items]
Percentage of workforce reduced			6.00%
Restructuring expenses			$ 600,000