Employee Benefit Plans - Components of Net Periodic Benefit Cost (Detail) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Pension Plan | UNITED STATES
Net periodic benefit cost
Service cost	$ 87	$ 86	$ 261	$ 258
Interest cost	333	356	999	1,068
Expected return on plan assets	(445)	(433)	(1,335)	(1,299)
Net amortization/deferrals	243	248	729	744
Net periodic benefit cost (credit)	218	257	$ 654	$ 771
Assumptions
Discount Rate			3.56%	3.95%
Expected long-term rate of return			5.15%	4.95%
Rate of compensation increase			3.00%	3.00%
Pension Plan | Foreign Plan
Net periodic benefit cost
Service cost	691	614	$ 2,073	$ 1,842
Interest cost	1,834	1,677	5,502	5,031
Expected return on plan assets	(3,466)	(2,910)	(10,398)	(8,730)
Net amortization/deferrals	554	685	1,662	2,055
Net periodic benefit cost (credit)	(387)	66	$ (1,161)	$ 198
Assumptions
Discount Rate			2.40%	2.51%
Expected long-term rate of return			5.10%	4.93%
Rate of compensation increase			2.60%	2.54%
Other Postretirement Benefit Plan | UNITED STATES
Net periodic benefit cost
Service cost	1	1	$ 3	$ 3
Interest cost	81	88	243	264
Net amortization/deferrals	(76)	(73)	(228)	(219)
Net periodic benefit cost (credit)	6	16	$ 18	$ 48
Assumptions
Discount Rate			3.43%	3.76%
Other Postretirement Benefit Plan | Foreign Plan
Net periodic benefit cost
Service cost	8	7	$ 24	$ 21
Interest cost	26	24	78	72
Net amortization/deferrals	(4)	(7)	(12)	(21)
Net periodic benefit cost (credit)	$ 30	$ 24	$ 90	$ 72
Assumptions
Discount Rate			3.21%	3.46%