Amounts Included in Accumulated Other Comprehensive Loss, Net of Tax (Detail) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Other Comprehensive Income (Loss) [Roll Forward]
Balance at December 31, 2017			$ (188,973)
Other comprehensive loss before reclassifications			(21,630)
Amounts reclassified from accumulated other comprehensive loss			1,640
Other comprehensive loss	$ (34,256)	$ 30,971	(19,990)	$ 38,717
Balance at June 30, 2018	(208,963)	$ (185,139)	(208,963)	$ (185,139)
Unrecognized Net Defined Benefit Plan Costs [Member]
Other Comprehensive Income (Loss) [Roll Forward]
Balance at December 31, 2017			(104,822)
Other comprehensive loss before reclassifications			0
Amounts reclassified from accumulated other comprehensive loss			1,634
Other comprehensive loss			1,634
Balance at June 30, 2018	(103,188)		(103,188)
Change in Fair Value of Derivatives [Member]
Other Comprehensive Income (Loss) [Roll Forward]
Balance at December 31, 2017			(89)
Other comprehensive loss before reclassifications			191
Amounts reclassified from accumulated other comprehensive loss			6
Other comprehensive loss			197
Balance at June 30, 2018	108		108
Foreign Currency Translation [Member]
Other Comprehensive Income (Loss) [Roll Forward]
Balance at December 31, 2017			(84,062)
Other comprehensive loss before reclassifications			(21,821)
Amounts reclassified from accumulated other comprehensive loss			0
Other comprehensive loss			(21,821)
Balance at June 30, 2018	$ (105,883)		$ (105,883)