Changes in Accumulated Other Comprehensive Loss by Component - Changes in Accumulated Other Comprehensive Loss by Component (Detail) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning Balance	$ 1,185,756
Other comprehensive income (loss) before reclassifications	21,571	$ 12,128
Foreign currency translation effect	(2,900)	(865)
Income tax effect	(416)	149
Amount reclassified from accumulated other comprehensive loss
Cash flow hedges	1,493	(10)
Amortization of prior service credit	(135)	(141)
Amortization of actuarial loss	9,345	10,591
Income tax effect	(2,382)	(3,715)
Other comprehensive income	26,576	18,137
Ending Balance	1,204,026
Cumulative Translation Adjustment
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning Balance	(39,940)	(75,415)
Other comprehensive income (loss) before reclassifications	20,925	12,517
Amount reclassified from accumulated other comprehensive loss
Other comprehensive income	20,925	12,517
Ending Balance	(19,015)	(62,898)
Derivative Instruments
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning Balance	349	1,967
Other comprehensive income (loss) before reclassifications	646	(389)
Income tax effect	(416)	149
Amount reclassified from accumulated other comprehensive loss
Cash flow hedges	1,493	(10)
Income tax effect	(172)	4
Other comprehensive income	1,551	(246)
Ending Balance	1,900	1,721
Post-retirement Benefits
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning Balance	(438,887)	(471,703)
Other comprehensive income (loss) before reclassifications		0
Foreign currency translation effect	(2,900)	(865)
Income tax effect		0
Amount reclassified from accumulated other comprehensive loss
Amortization of prior service credit	(135)	(141)
Amortization of actuarial loss	9,345	10,591
Income tax effect	(2,210)	(3,719)
Other comprehensive income	4,100	5,866
Ending Balance	(434,787)	(465,837)
Total
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning Balance	(478,478)	(545,151)
Amount reclassified from accumulated other comprehensive loss
Ending Balance	$ (451,902)	$ (527,014)