Restructuring Program and Other Separation Costs - Schedule of Restructuring Program Activity (Detail) - Severance and Other Employment Expenses [Member] - 2017 Restructuring Program [Member] $ in Thousands	3 Months Ended
	Mar. 31, 2018 USD ($)
Restructuring Cost And Reserve [Line Items]
Liability, beginning balance	$ 1,234
Payments made	(495)
Liability, ending balance	$ 739