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, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning Balance			$ 979,248
Other comprehensive (loss) income before reclassifications	$ (15,719)	$ (212)	(20,488)	$ 2,042
Income tax effect	102	1,492	1,659	(1,762)
Cash flow hedges	17	(2,664)	(1,395)	(6,990)
Amortization of prior service credit	(142)	(142)	(283)	(283)
Amortization of actuarial losses	10,937	11,687	21,869	23,357
Income tax effect	(3,866)	(3,032)	(7,203)	(5,611)
Other comprehensive (loss) income	(8,671)	7,129	(5,841)	10,753
Ending Balance	1,048,437		1,048,437
Cumulative Currency Translation Adjustment [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning Balance	(24,788)	(2,699)	(22,034)	9,059
Other comprehensive (loss) income before reclassifications	(20,641)	9,845	(23,395)	(1,913)
Other comprehensive (loss) income	(20,641)	9,845	(23,395)	(1,913)
Ending Balance	(45,429)	7,146	(45,429)	7,146
Changes in the Fair Value of Derivatives and Unrealized Gains (Losses) [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning Balance	71	7,450	3,454	4,762
Other comprehensive (loss) income before reclassifications	(312)	(3,800)	(4,356)	4,946
Income tax effect	102	1,492	1,659	(1,762)
Cash flow hedges	17	(2,664)	(1,395)	(6,990)
Income tax effect	(12)	1,072	504	2,594
Other comprehensive (loss) income	(205)	(3,900)	(3,588)	(1,212)
Ending Balance	(134)	3,550	(134)	3,550
Unrecognized Postretirement Benefit Plans [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning Balance	(482,220)	(531,729)	(491,187)	(544,423)
Other comprehensive (loss) income before reclassifications	5,234	(6,257)	7,263	(991)
Amortization of prior service credit	(142)	(142)	(283)	(283)
Amortization of actuarial losses	10,937	11,687	21,869	23,357
Income tax effect	(3,854)	(4,104)	(7,707)	(8,205)
Other comprehensive (loss) income	12,175	1,184	21,142	13,878
Ending Balance	(470,045)	(530,545)	(470,045)	(530,545)
Cumulative Other Comprehensive Income (Loss) [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning Balance	(506,937)	(526,978)	(509,767)	(530,602)
Ending Balance	$ (515,608)	$ (519,849)	$ (515,608)	$ (519,849)