Changes in Accumulated Other Comprehensive Loss by Component - Changes in Accumulated Other Comprehensive Loss by Component (Detail) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning Balance			$ 1,076,014
Amount reclassified from accumulated other comprehensive income (loss)
Amortization of prior service credit	$ (142)	$ (142)	(283)	$ (283)
Amortization of actuarial loss	10,631	10,937	21,222	21,869
Ending Balance	1,135,187		1,135,187
Cumulative Translation Adjustment
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning Balance	(62,898)	(24,788)	(75,415)	(22,034)
Other comprehensive income (loss) before reclassifications	12,876	(20,641)	25,393	(23,395)
Amount reclassified from accumulated other comprehensive income (loss)
Other comprehensive income (loss)	12,876	(20,641)	25,393	(23,395)
Ending Balance	(50,022)	(45,429)	(50,022)	(45,429)
Derivative Instruments
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning Balance	1,721	71	1,967	3,454
Other comprehensive income (loss) before reclassifications	(2,335)	(312)	(2,724)	(4,356)
Income tax effect	759	102	908	1,659
Amount reclassified from accumulated other comprehensive income (loss)
Cash flow hedges	(343)	17	(353)	(1,395)
Income tax effect	199	(12)	203	504
Other comprehensive income (loss)	(1,720)	(205)	(1,966)	(3,588)
Ending Balance	1	(134)	1	(134)
Post-retirement Benefits
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning Balance	(465,837)	(482,220)	(471,703)	(491,187)
Other comprehensive income (loss) before reclassifications	0	0	0	0
Foreign currency translation effect	(3,702)	5,234	(4,567)	7,263
Income tax effect	0		0
Amount reclassified from accumulated other comprehensive income (loss)
Amortization of prior service credit	(142)	(142)	(283)	(283)
Amortization of actuarial loss	10,631	10,937	21,222	21,869
Income tax effect	(3,725)	(3,854)	(7,444)	(7,707)
Other comprehensive income (loss)	3,062	12,175	8,928	21,142
Ending Balance	(462,775)	(470,045)	(462,775)	(470,045)
Total
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning Balance	(527,014)	(506,937)	(545,151)	(509,767)
Other comprehensive income (loss) before reclassifications	10,541	(20,953)	22,669	(27,751)
Foreign currency translation effect	(3,702)	5,234	(4,567)	7,263
Income tax effect	759	102	908	1,659
Amount reclassified from accumulated other comprehensive income (loss)
Cash flow hedges	(343)	17	(353)	(1,395)
Amortization of prior service credit	(142)	(142)	(283)	(283)
Amortization of actuarial loss	10,631	10,937	21,222	21,869
Income tax effect	(3,526)	(3,866)	(7,241)	(7,203)
Other comprehensive income (loss)	14,218	(8,671)	32,355	(5,841)
Ending Balance	$ (512,796)	$ (515,608)	$ (512,796)	$ (515,608)