Accumulated Other Comprehensive Income - Changes in Accumulated Other Comprehensive Income (Loss) (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning Balance	$ (242,563)
Ending Balance	(197,631)	$ (242,563)
Cumulative currency translation adjustment [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning Balance	(143,481)	(130,661)
Other comprehensive income (loss) before reclassifications	47,996	(12,820)
Amounts reclassified from accumulated other comprehensive income (loss)	0	0
Ending Balance	(95,485)	(143,481)
Benefit plan liabilities [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning Balance	(97,612)	(84,124)
Other comprehensive income (loss) before reclassifications	(11,000)	(14,757)
Amounts reclassified from accumulated other comprehensive income (loss)	7,863	1,269
Ending Balance	(100,749)	(97,612)
Fair value change of derivatives [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning Balance	(1,470)	(2,280)
Other comprehensive income (loss) before reclassifications	784	(3,676)
Amounts reclassified from accumulated other comprehensive income (loss)	(711)	4,486
Ending Balance	(1,397)	(1,470)
Accumulated other comprehensive loss [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning Balance	(242,563)	(217,065)
Other comprehensive income (loss) before reclassifications	37,780	(31,253)
Amounts reclassified from accumulated other comprehensive income (loss)	7,152	5,755
Ending Balance	$ (197,631)	$ (242,563)