Accumulated Other Comprehensive Loss - Accumulated Comprehensive Loss (Activity) (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Beginning balance	$ 67,690	$ 65,930
Net current period change	7,955	(9,581)
Reclassification adjustments for losses reclassified into income	(345)	390
Ending balance	74,742	67,690
Foreign currency items
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Beginning balance	(24,313)	(21,079)
Net current period change	7,141	(3,234)
Reclassification adjustments for losses reclassified into income	0	0
Ending balance	(17,172)	(24,313)
Pension and postretirement benefits plans
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Beginning balance	(24,532)	(18,575)
Net current period change	814	(6,347)
Reclassification adjustments for losses reclassified into income	(345)	390
Ending balance	(24,063)	(24,532)
Accumulated other comprehensive loss
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Beginning balance	(48,845)	(39,654)
Ending balance	$ (41,235)	$ (48,845)