Accumulated Other Comprehensive Income (Loss) - Schedule of Accumulated Other Comprehensive Income (Loss) (Detail) - USD ($) $ in Thousands	3 Months Ended						9 Months Ended
	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Sep. 30, 2020	Sep. 30, 2019
Accumulated Other Comprehensive Income Loss [Line Items]
Beginning balance, Value	$ 1,736,233	$ 1,855,579	$ 1,975,430	$ 1,722,951	$ 1,741,729	$ 1,596,610	$ 1,975,430	$ 1,596,610
Other comprehensive income (loss), net of tax	31,328	17,685	(29,956)	(30,584)	(10,564)	6,977	19,057	(34,171)
Ending balance, Value	2,813,386	1,736,233	1,855,579	1,938,435	1,722,951	1,741,729	2,813,386	1,938,435
Foreign Currency Translation [Member]
Accumulated Other Comprehensive Income Loss [Line Items]
Beginning balance, Value			(126,214)				(126,214)
Other comprehensive income (loss) before reclassifications, net of tax							19,047
Other comprehensive income (loss), net of tax							19,047
Ending balance, Value	(107,167)						(107,167)
Unrealized Gains (Losses) on Available-For-Sale Marketable Debt Securities [Member]
Accumulated Other Comprehensive Income Loss [Line Items]
Beginning balance, Value			279				279
Other comprehensive income (loss) before reclassifications, net of tax							10
Other comprehensive income (loss), net of tax							10
Ending balance, Value	289						289
Accumulated Other Comprehensive Income (Loss) [Member]
Accumulated Other Comprehensive Income Loss [Line Items]
Beginning balance, Value	(138,206)	(155,891)	(125,935)	(122,026)	(111,462)	(118,439)	(125,935)	(118,439)
Other comprehensive income (loss) before reclassifications, net of tax							19,057
Other comprehensive income (loss), net of tax	31,328	17,685	(29,956)	(30,584)	(10,564)	6,977	19,057
Ending balance, Value	$ (106,878)	$ (138,206)	$ (155,891)	$ (152,610)	$ (122,026)	$ (111,462)	$ (106,878)	$ (152,610)