Restructuring - Additional Information (Detail) - USD ($) $ in Thousands	1 Months Ended			12 Months Ended
	Jun. 30, 2018	Apr. 30, 2017	Dec. 31, 2016	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Restructuring Cost And Reserve [Line Items]
Restructuring expenses				$ (2,222)	$ 3,020	$ 4,562
Relieved cease-use liability				(2,222)
Selling, General And Administrative Expenses [Member]
Restructuring Cost And Reserve [Line Items]
Restructuring expenses				$ (2,222)	$ 2,832	$ 2,549
Corvallis Plan [Member]
Restructuring Cost And Reserve [Line Items]
Restructuring, initiation date				2016-03
Restructuring, completion date				Dec. 31, 2017
Corvallis Plan [Member] | Oregon [Member] | Selling, General And Administrative Expenses [Member]
Restructuring Cost And Reserve [Line Items]
Relieved cease-use liability	$ (2,200)
Corvallis Plan [Member] | Oregon [Member] | Facility Closing [Member]
Restructuring Cost And Reserve [Line Items]
Restructuring expenses		$ 2,300	$ 1,500