Accounting Policies - Reclassifications Out of Accumulated Other Comprehensive Loss (Detail) - USD ($) $ in Thousands	3 Months Ended				6 Months Ended
	Jun. 30, 2019	Mar. 31, 2019	Jun. 30, 2018	Mar. 31, 2018	Jun. 30, 2019	Jun. 30, 2018
Reclassification Adjustment Out Of Accumulated Other Comprehensive Income On Derivatives [Line Items]
Other income (expense), net	$ 2,177		$ 2,171		$ (6,051)	$ 4,757
Income tax expense	(41,400)		(10,503)		(59,923)	(36,627)
Interest expense, net	(58,560)		(31,920)		(103,129)	(52,204)
Net income	102,854	$ (4,013)	83,271	$ 87,457	98,841	170,728
Reclassification out of Accumulated Other Comprehensive Income | Pension and post retirement benefit plans
Reclassification Adjustment Out Of Accumulated Other Comprehensive Income On Derivatives [Line Items]
Other income (expense), net	726		718		1,452	1,435
Income tax expense	(176)		(198)		(351)	(396)
Net income	550		520		1,101	1,039
Reclassification out of Accumulated Other Comprehensive Income | Amortization of initial net obligation and prior service cost
Reclassification Adjustment Out Of Accumulated Other Comprehensive Income On Derivatives [Line Items]
Other income (expense), net	(366)		(375)		(732)	(751)
Reclassification out of Accumulated Other Comprehensive Income | Amortization of net loss
Reclassification Adjustment Out Of Accumulated Other Comprehensive Income On Derivatives [Line Items]
Other income (expense), net	$ 1,092		1,093		$ 2,184	2,186
Reclassification out of Accumulated Other Comprehensive Income | Derivative contracts
Reclassification Adjustment Out Of Accumulated Other Comprehensive Income On Derivatives [Line Items]
Income tax expense			(42)			(276)
Interest expense, net			176			855
Net income			$ 134			$ 579