Changes in Accumulated Other Comprehensive (Loss) Income by Component - Cumulative Other Comprehensive Loss in Accompanying Consolidated Statements of Equity (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance	$ 1,264,625
Other comprehensive (loss) income before reclassifications	(32,187)	$ (11,542)
Foreign currency translation loss	(4,611)	(2,668)	$ (264)
Income tax effect	9,879	804
Pension settlement charges	4,155	4,262	0
Prior service effect of plan amendment	(2,581)	(3,069)	(3,704)
Income tax effect	(11,314)	(9,083)
Other comprehensive (loss) income	671	14,009
Ending balance	1,388,899	1,264,625
Total
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance	(447,580)	(461,589)
Ending balance	(446,909)	(447,580)	(461,589)
Cumulative Translation Adjustment
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance	(58,186)	(62,133)
Other comprehensive (loss) income before reclassifications	14,865	3,947
Other comprehensive (loss) income	14,865	3,947
Ending balance	(43,321)	(58,186)	(62,133)
Derivative Instruments
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance	(549)	2,150
Other comprehensive (loss) income before reclassifications	(9,073)	(2,612)
Income tax effect	2,022	804
Amount reclassified from accumulated other comprehensive income (loss)	644	(1,141)
Income tax effect	184	250
Other comprehensive (loss) income	(6,223)	(2,699)
Ending balance	(6,772)	(549)	2,150
Post- retirement Benefits
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance	(388,845)	(401,606)
Other comprehensive (loss) income before reclassifications	(37,979)	(12,877)
Foreign currency translation loss	(4,611)	(2,668)
Income tax effect	7,857	0
Pension settlement charges	4,155	4,262
Prior service effect of plan amendment	(2,581)	(3,069)
Income tax effect	(11,498)	(9,333)
Other comprehensive (loss) income	(7,971)	12,761
Ending balance	(396,816)	(388,845)	$ (401,606)
Net Prior Service
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Amount reclassified from accumulated other comprehensive income (loss)	1,429	603
Actuarial Loss
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Amount reclassified from accumulated other comprehensive income (loss)	$ 35,257	$ 35,843