Changes in Accumulated Other Comprehensive Income (Loss) by Component - Cumulative Other Comprehensive Loss in Accompanying Consolidated Statements of Equity (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
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance		$ 1,172,043			$ 1,172,043
Other comprehensive (loss) income before reclassifications	$ (7,361)	7,145	$ (28,706)	$ 21,571
Foreign currency translation effect	1,429	(1,460)	4,082	(2,900)	(31)	$ 1,180
Income tax effect	226	245	(285)	(416)
Amount reclassified from accumulated other comprehensive income (loss)	(853)	62	(1,592)	1,493
Income tax effect	(1,917)	(1,953)	(2,080)	(2,382)
Other comprehensive (loss) income	637	13,170	(19,396)	26,576
Ending balance	1,192,349				1,192,349
Total
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance	(448,419)	(461,589)	(451,902)	(478,478)	(461,589)	(478,478)
Ending balance	(447,782)	(448,419)	(471,298)	(451,902)	(447,782)	(471,298)
Cumulative Translation Adjustment
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance	(53,805)	(62,133)	(19,015)	(39,940)	(62,133)	(39,940)
Other comprehensive (loss) income before reclassifications	(6,994)	8,328	(30,768)	20,925
Other comprehensive (loss) income	(6,994)	8,328	(30,768)	20,925
Ending balance	(60,799)	(53,805)	(49,783)	(19,015)	(60,799)	(49,783)
Derivative Instruments
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance	1,362	2,150	1,900	349	2,150	349
Other comprehensive (loss) income before reclassifications	(367)	(1,183)	2,062	646
Income tax effect	226	245	(285)	(416)
Amount reclassified from accumulated other comprehensive income (loss)	(853)	62	(1,592)	1,493
Income tax effect	124	88	126	(172)
Other comprehensive (loss) income	(870)	(788)	311	1,551
Ending balance	492	1,362	2,211	1,900	492	2,211
Post- retirement Benefits
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance	(395,976)	(401,606)	(434,787)	(438,887)	(401,606)	(438,887)
Foreign currency translation effect	1,429	(1,460)	4,082	(2,900)
Income tax effect	(2,041)	(2,041)	(2,206)	(2,210)
Other comprehensive (loss) income	8,501	5,630	11,061	4,100
Ending balance	(387,475)	(395,976)	(423,726)	(434,787)	$ (387,475)	$ (423,726)
Net Prior Service
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Amount reclassified from accumulated other comprehensive income (loss)	(102)	(102)	(135)	(135)
Actuarial Gain (Loss)
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Amount reclassified from accumulated other comprehensive income (loss)	$ 9,215	$ 9,233	$ 9,320	$ 9,345