Restructuring and Other Separation Costs - Schedule of Restructuring Program Activity (Detail) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Restructuring Cost And Reserve [Line Items]
Costs incurred	$ 1,207	$ 3,866	$ 3,839	$ 16,392
2019 Restructuring and Other Separation Costs [Member] | Severance and Other Employment Expenses [Member]
Restructuring Cost And Reserve [Line Items]
Costs incurred			3,839
Payments made			(2,669)
Liability, ending balance	$ 1,170		1,170
2018 Restructuring Program [Member] | Severance and Other Employment Expenses [Member]
Restructuring Cost And Reserve [Line Items]
Liability, beginning balance			537
Payments made			$ (537)