Income Taxes - Schedule Reconciles United States Statutory Federal Rate to Income Tax Provision (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Effective Income Tax Rate Reconciliation, Amount [Abstract]
Tax at U.S. statutory rate	$ 74,585	$ 68,166	$ 53,546
State and local taxes	1,177	2,564	3,441
Tax credits	(11,436)	(10,348)	(8,139)
Effect of foreign tax rates	(23,158)	(19,600)	(6,465)
Nonrecurring permanent items	(13,947)	0	(11,300)
Effective Income Tax Rate Reconciliation, Nondeductible Expense, Share-based Compensation Cost, Amount	(3,563)	(5,305)	0
Other changes in tax reserves	730	116	(368)
Valuation allowance	25,761	9,112	11,638
Income tax provision	$ 74,527	$ 54,321	$ 41,218
Effective income tax rate	35.00%	27.90%	26.90%
U.S. Tax and Jobs Act [Member]
Effective Income Tax Rate Reconciliation, Amount [Abstract]
Changes in tax law	$ 33,493	$ 0	$ 0
Other legislation [Member]
Effective Income Tax Rate Reconciliation, Amount [Abstract]
Changes in tax law	7,279	8,813	3,630
Other Adjustments [Member]
Effective Income Tax Rate Reconciliation, Amount [Abstract]
Effective Income Tax Rate Reconciliation, Other Adjustments, Amount	(6,025)	803	(4,765)
Outside Basis Difference [Member]
Effective Income Tax Rate Reconciliation, Amount [Abstract]
Effective Income Tax Rate Reconciliation, Other Adjustments, Amount	9,562	0	0
Capital Loss [Member]
Effective Income Tax Rate Reconciliation, Amount [Abstract]
Effective Income Tax Rate Reconciliation, Other Adjustments, Amount	$ (19,931)	$ 0	$ 0