Components of Net Periodic Pension Cost (Detail) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
UNITED STATES
Defined Benefit Plan Disclosure [Line Items]
Interest cost	$ 345	$ 434	$ 691	$ 867
Return on assets (expected)	(62)	(224)	(124)	(448)
Amortization of net actuarial loss(gain)	253	138	506	276
Net periodic pension cost	536	348	1,073	695
Non-U.S. Pension Plans
Defined Benefit Plan Disclosure [Line Items]
Service cost	158	154	317	308
Interest cost	101	113	202	226
Return on assets (expected)	(68)	(75)	(137)	(150)
Net periodic pension cost	$ 191	$ 192	$ 382	$ 384