Benefits Expected to Be Paid from Pension and Other Postretirement Benefit Plans, Which Reflect Future Years of Services (Detail) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Foreign Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Benefit obligation discount rate	2.10%	1.90%
Pension Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
2018	$ 39,502
2019	39,285
2020	40,842
2021	42,365
2022	43,434
2023-2027	231,373
Defined Benefit Plan Expected Future Benefit Payments	436,801
Other Postretirement Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
2018	2,083
2019	1,870
2020	1,545
2021	1,484
2022	1,427
2023-2027	6,373
Defined Benefit Plan Expected Future Benefit Payments	$ 14,782