Pensions and Postretirement Benefits Other than Pensions - Components of Net Periodic Benefit Costs (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Pension Plan
Defined Benefit Plan Disclosure [Line Items]
Service cost	$ 9,946	$ 8,906
Interest cost	41,560	50,560
Other Postretirement Benefits
Defined Benefit Plan Disclosure [Line Items]
Service cost	1,439	1,573	$ 1,948
Interest cost	7,320	9,887	9,251
Amortization of actuarial (gain) loss	(422)	0	0
Amortization of prior service cost (credit)	(89)	(409)	(541)
Net periodic benefit cost	8,248	11,051	10,658
United States | Pension Plan
Defined Benefit Plan Disclosure [Line Items]
Service cost	9,946	8,906	10,363
Interest cost	33,143	39,499	36,840
Expected return on plan assets	(55,410)	(48,034)	(54,035)
Amortization of actuarial (gain) loss	31,533	32,432	32,939
Amortization of prior service cost (credit)	1,251	703	0
Net periodic benefit cost	20,463	33,506	26,107
International | Pension Plan
Defined Benefit Plan Disclosure [Line Items]
Service cost	0	0
Interest cost	8,417	11,061	11,161
Expected return on plan assets	(8,892)	(11,554)	(12,073)
Amortization of actuarial (gain) loss	4,146	3,411	4,264
Amortization of prior service cost (credit)	267	309	0
Effect of settlements	4,155	4,262	0
Net periodic benefit cost	$ 8,093	$ 7,489	$ 3,352