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, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
Other Postretirement Benefits
Defined Benefit Plan Disclosure [Line Items]
Service cost	$ 393	$ 487	$ 787	$ 974
Interest cost	2,472	2,313	4,944	4,625
Amortization of prior service cost	(102)	(135)	(204)	(270)
Net periodic benefit cost	2,763	2,665	5,527	5,329
United States | Pension Plan
Defined Benefit Plan Disclosure [Line Items]
Service cost	2,244	2,580	4,488	5,160
Interest cost	9,875	9,210	19,749	18,419
Expected return on plan assets	(12,042)	(13,508)	(24,022)	(27,017)
Amortization of actuarial loss	8,284	8,235	16,568	16,471
Net periodic benefit cost	8,361	6,517	16,783	13,033
International | Pension Plan
Defined Benefit Plan Disclosure [Line Items]
Service cost	0	0	0	0
Interest cost	2,768	2,840	5,575	5,746
Expected return on plan assets	(2,898)	(3,073)	(5,836)	(6,216)
Amortization of actuarial loss	931	1,085	1,876	2,195
Net periodic benefit cost	$ 801	$ 852	$ 1,615	$ 1,725