Items to be Recognized in 2018 as Component of Net Periodic Cost (Detail) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Foreign Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Accumulated benefit obligations in excess of plan assets, projected benefit obligation	$ 101,200	$ 71,000
Pension Benefits [Member]
Items to be recognized in 2018 as a component of net periodic cost
Net actuarial loss (gain)	7,169
Prior service cost (credit)	173
Net periodic cost (credit) to be recorded in 2018	7,342
Other Postretirement Benefits [Member]
Items to be recognized in 2018 as a component of net periodic cost
Net actuarial loss (gain)	(474)
Prior service cost (credit)	(2,602)
Net periodic cost (credit) to be recorded in 2018	$ (3,076)