Pensions and Postretirement Benefits Other than Pensions - Components of Net Periodic Benefit Costs (Detail) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Pension Plan
Defined Benefit Plan Disclosure [Line Items]
Plan amendment			$ 2,582
Other Postretirement Benefits
Defined Benefit Plan Disclosure [Line Items]
Service cost	$ 360	$ 393	720	$ 787
Interest cost	1,830	2,472	3,660	4,944
Amortization of actuarial (gain) loss	(106)	0	(212)	0
Amortization of prior service cost (credit)	(22)	(102)	(44)	(204)
Net periodic benefit cost	2,062	2,763	4,124	5,527
United States | Pension Plan
Defined Benefit Plan Disclosure [Line Items]
Service cost	2,551	2,244	5,048	4,488
Interest cost	8,278	9,875	16,586	19,749
Expected return on plan assets	(13,807)	(12,042)	(28,001)	(24,022)
Amortization of actuarial (gain) loss	8,104	8,284	15,325	16,568
Amortization of prior service cost (credit)	353	0	545	0
Net periodic benefit cost	5,479	8,361	9,503	16,783
International | Pension Plan
Defined Benefit Plan Disclosure [Line Items]
Interest cost	2,036	2,768	4,135	5,575
Expected return on plan assets	(2,151)	(2,898)	(4,369)	(5,836)
Amortization of actuarial (gain) loss	1,003	931	2,037	1,876
Amortization of prior service cost (credit)	64	0	130	0
Net periodic benefit cost	$ 952	$ 801	$ 1,933	$ 1,615