Severance and Other Separation Costs - Schedule of Restructuring Program Activity (Detail) - Severance and Other Employment Expenses [Member] - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
2017 Restructuring Program [Member]
Restructuring Cost And Reserve [Line Items]
Liability, beginning balance		$ 1,234
Payments made		(1,234)
2018 Restructuring Program [Member]
Restructuring Cost And Reserve [Line Items]
Liability, beginning balance	$ 537
Costs incurred		5,548
Payments made	$ (537)	(5,011)
Liability, ending balance		$ 537