Changes in Accumulated Other Comprehensive (Loss) Income by Component - Cumulative Other Comprehensive Loss in Accompanying Consolidated Statements of Equity (Detail) - USD ($) $ in Thousands	3 Months Ended				6 Months Ended
	Jun. 30, 2020	Mar. 31, 2020	Jun. 30, 2019	Mar. 31, 2019	Jun. 30, 2020	Jun. 30, 2019
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance		$ 1,264,625			$ 1,264,625
Other comprehensive (loss) income before reclassifications	$ 3,156	(84,089)	$ (7,361)	$ 7,145
Foreign currency translation effect	91	4,708	1,429	(1,460)	4,799	$ (31)
Income tax effect	616	8,841	226	245
Income tax effect	(1,886)	(1,765)	(1,917)	(1,953)
Other comprehensive (loss) income	10,855	(64,430)	637	13,170
Ending balance	1,178,782				1,178,782
Total
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance	(512,010)	(447,580)	(448,419)	(461,589)	(447,580)	(461,589)
Ending balance	(501,155)	(512,010)	(447,782)	(448,419)	(501,155)	(447,782)
Cumulative Translation Adjustment
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance	(107,184)	(58,186)	(53,805)	(62,133)	(58,186)	(62,133)
Other comprehensive (loss) income before reclassifications	5,650	(48,998)	(6,994)	8,328
Other comprehensive (loss) income	5,650	(48,998)	(6,994)	8,328
Ending balance	(101,534)	(107,184)	(60,799)	(53,805)	(101,534)	(60,799)
Derivative Instruments
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance	(3,623)	(549)	1,362	2,150	(549)	2,150
Other comprehensive (loss) income before reclassifications	(2,494)	(3,601)	(367)	(1,183)
Income tax effect	616	984	226	245
Amount reclassified from accumulated other comprehensive income (loss)	(518)	(510)	(853)	62
Income tax effect	192	53	124	88
Other comprehensive (loss) income	(2,204)	(3,074)	(870)	(788)
Ending balance	(5,827)	(3,623)	492	1,362	(5,827)	492
Post- retirement Benefits
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance	(401,203)	(388,845)	(395,976)	(401,606)	(388,845)	(401,606)
Other comprehensive (loss) income before reclassifications		(31,490)
Foreign currency translation effect	91	4,708	1,429	(1,460)
Income tax effect		7,857
Income tax effect	(2,078)	(1,818)	(2,041)	(2,041)
Other comprehensive (loss) income	7,409	(12,358)	8,501	5,630
Ending balance	(393,794)	(401,203)	(387,475)	(395,976)	$ (393,794)	$ (387,475)
Net Prior Service
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Amount reclassified from accumulated other comprehensive income (loss)	395	236	(102)	(102)
Actuarial Loss
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Amount reclassified from accumulated other comprehensive income (loss)	$ 9,001	$ 8,149	$ 9,215	$ 9,233