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, 2020	Dec. 31, 2019
2020 Restructuring Program [Member]
Restructuring Cost And Reserve [Line Items]
Costs incurred	$ 2,658
Payments made	(2,513)
Liability, ending balance	$ 145
2018 Restructuring Program [Member]
Restructuring Cost And Reserve [Line Items]
Liability, beginning balance		$ 537
Payments made		$ (537)