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						9 Months Ended
	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Sep. 30, 2019	Sep. 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	$ (16,868)	$ (7,361)	7,145	$ (5,778)	$ (28,706)	$ 21,571
Foreign currency translation effect	2,201	1,429	(1,460)	559	4,082	(2,900)	2,170	$ 1,365
Income tax effect	476	226	245	140	(285)	(416)
Amount reclassified from accumulated other comprehensive income (loss)	(888)	(853)	62	(1,792)	(1,592)	1,493
Income tax effect	(1,987)	(1,917)	(1,953)	(1,732)	(2,080)	(2,382)
Other comprehensive (loss) income	(7,991)	637	13,170	537	(19,396)	26,576
Ending balance	1,209,110						1,209,110
Total
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance	(447,782)	(448,419)	(461,589)	(471,298)	(451,902)	(478,478)	(461,589)	(478,478)
Ending balance	(455,773)	(447,782)	(448,419)	(470,761)	(471,298)	(451,902)	(455,773)	(470,761)
Cumulative Translation Adjustment
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance	(60,799)	(53,805)	(62,133)	(49,783)	(19,015)	(39,940)	(62,133)	(39,940)
Other comprehensive (loss) income before reclassifications	(15,704)	(6,994)	8,328	(5,823)	(30,768)	20,925
Other comprehensive (loss) income	(15,704)	(6,994)	8,328	(5,823)	(30,768)	20,925
Ending balance	(76,503)	(60,799)	(53,805)	(55,606)	(49,783)	(19,015)	(76,503)	(55,606)
Derivative Instruments
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance	492	1,362	2,150	2,212	1,901	349	2,150	349
Other comprehensive (loss) income before reclassifications	(1,164)	(367)	(1,183)	45	2,062	646
Income tax effect	476	226	245	140	(285)	(416)
Amount reclassified from accumulated other comprehensive income (loss)	(888)	(853)	62	(1,792)	(1,592)	1,493
Income tax effect	54	124	88	289	126	(171)
Other comprehensive (loss) income	(1,522)	(870)	(788)	(1,318)	311	1,552
Ending balance	(1,030)	492	1,362	894	2,212	1,901	(1,030)	894
Post- retirement Benefits
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance	(387,475)	(395,976)	(401,606)	(423,727)	(434,788)	(438,887)	(401,606)	(438,887)
Foreign currency translation effect	2,201	1,429	(1,460)	559	4,082	(2,900)
Income tax effect	(2,041)	(2,041)	(2,041)	(2,021)	(2,206)	(2,211)
Other comprehensive (loss) income	9,235	8,501	5,630	7,678	11,061	4,099
Ending balance	(378,240)	(387,475)	(395,976)	(416,049)	(423,727)	(434,788)	$ (378,240)	$ (416,049)
Net Prior Service
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Amount reclassified from accumulated other comprehensive income (loss)	(102)	(102)	(102)	(135)	(135)	(135)
Actuarial Gain (Loss)
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Amount reclassified from accumulated other comprehensive income (loss)	$ 9,177	$ 9,215	$ 9,233	$ 9,275	$ 9,320	$ 9,345