Employee Benefit Plans - Summary of Fair Value of Plan Assets, Accumulated Benefit Obligation and Projected Benefit Obligation (Detail) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	$ 728,281	$ 646,119
Accumulated benefit obligation	763,831	718,821
Projected benefit obligation	763,831	718,821
U.S. Pension Plans [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	24,644	22,161
Accumulated benefit obligation	35,376	33,868
Projected benefit obligation	35,376	33,868
Non-U.S. Pension Plans [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	703,637	623,958
Accumulated benefit obligation	728,455	684,953
Projected benefit obligation	$ 728,455	$ 684,953