Pension and Other Postretirement Benefits - Net Periodic Pension and Other Postretirement Costs (Detail) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Defined Benefit Pension Plan [Member] | U.S. Defined Benefit Pension Plans [Member] | U.S. [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost	$ 335	$ 411
Interest cost	2,040	2,098
Expected return on plan assets	(3,284)	(3,127)
Amortization of prior service cost (credit)	13	13
Amortization of actuarial (gain) loss	475	936
Net benefit (income) cost	(421)	331
Defined Benefit Pension Plan [Member] | Foreign Defined Benefits Pension Plans [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost	111	90
Interest cost	364	445
Expected return on plan assets	(672)	(538)
Amortization of prior service cost (credit)	(88)	0
Amortization of actuarial (gain) loss	194	181
Net benefit (income) cost	(91)	178
Other Postretirement Benefit Plans [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost	102	172
Interest cost	125	172
Amortization of prior service cost (credit)	(402)	(405)
Amortization of actuarial (gain) loss	(62)	8
Net benefit (income) cost	$ (237)	$ (53)