Pension and Other Postretirement Benefits - Net Periodic Pension and Other Postretirement Costs (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Defined Benefit Pension Plan [Member] | U.S. Defined Benefit Pension Plans [Member] | U.S. [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost	$ 1,651	$ 1,714	$ 2,743
Interest cost	8,413	9,977	7,990
Expected return on plan assets	(12,503)	(13,424)	(10,996)
Amortization of prior service cost (credit)	52	44	371
Actuarial loss (gain)	4,111	3,324	5,440
Curtailment (gain) loss	0	(887)	1,303
Net cost	1,724	748	6,851
Defined Benefit Pension Plan [Member] | Foreign Pension Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost	150	314	0
Interest cost	1,845	2,250	2,394
Expected return on plan assets	(2,239)	(2,461)	(2,681)
Amortization of prior service cost (credit)	0	0	0
Actuarial loss (gain)	751	670	845
Curtailment (gain) loss	0	0	0
Net cost	507	773	558
Other Postretirement Benefit Plans [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost	492	504	384
Interest cost	571	722	474
Expected return on plan assets	0	0	0
Amortization of prior service cost (credit)	(1,607)	(1,277)	(672)
Actuarial loss (gain)	(24)	36	26
Curtailment (gain) loss	0	0	0
Net cost	$ (568)	$ (15)	$ 212