Restructuring Programs - Schedule of Restructuring Program Activity (Detail) - USD ($) $ in Thousands	3 Months Ended	9 Months Ended
	Sep. 30, 2017	Sep. 30, 2017	Sep. 30, 2016
Restructuring Cost And Reserve [Line Items]
Restructuring and other related costs	$ 5,100	$ 5,100	$ 112
Severance and Other Employment Expenses [Member]
Restructuring Cost And Reserve [Line Items]
Liability, beginning balance		7,842
Restructuring and other related costs		5,100
Reduction in estimated expenses		(572)
Payments made		(6,941)
Liability, ending balance	5,429	5,429
Severance and Other Employment Expenses [Member] | 2016 Restructuring Program [Member]
Restructuring Cost And Reserve [Line Items]
Liability, beginning balance		7,842
Reduction in estimated expenses		(572)
Payments made		(6,941)
Liability, ending balance	329	329
Severance and Other Employment Expenses [Member] | 2017 Restructuring Program [Member]
Restructuring Cost And Reserve [Line Items]
Restructuring and other related costs		5,100
Liability, ending balance	$ 5,100	$ 5,100