Income Taxes - Schedule of Provision for Taxes on Income and Other Related Income Before Taxes (Detail) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Federal
Current									$ (296)	$ 32,299	$ 18,811
Deferred									9,314	(1,744)	(3,192)
State
Current									2,095	1,764	2,273
Deferred									1,892	192	(1,171)
Foreign
Current									14,510	13,077	14,960
Deferred									(342)	2,102	(4,063)
Total									27,173	47,690	27,618
Income before Taxes
Domestic									88,522	72,662	64,675
Foreign									51,401	66,575	49,141
Income Before Provision for Income Taxes	$ 34,519	$ 25,243	$ 42,497	$ 37,664	$ 28,532	$ 29,312	$ 37,063	$ 44,330	$ 139,923	$ 139,237	$ 113,816