Pensions and Postretirement Benefits Other than Pensions - Components of Net Periodic Benefit Costs (Detail) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Other Postretirement Benefits
Defined Benefit Plan Disclosure [Line Items]
Service cost	$ 372	$ 360
Interest cost	1,342	1,830
Amortization of actuarial loss	(429)	(106)
Amortization of prior service cost	0	(22)
Net periodic benefit cost	1,285	2,062
United States | Pension Plan
Defined Benefit Plan Disclosure [Line Items]
Service cost	2,745	2,497
Interest cost	6,595	8,308
Expected return on plan assets	(13,169)	(14,194)
Amortization of actuarial loss	6,978	7,221
Amortization of prior service cost	353	192
Net periodic benefit cost	3,502	4,024
International | Pension Plan
Defined Benefit Plan Disclosure [Line Items]
Interest cost	1,568	2,099
Expected return on plan assets	(1,890)	(2,218)
Amortization of actuarial loss	1,422	1,034
Amortization of prior service cost	76	66
Net periodic benefit cost	$ 1,176	$ 981