Consolidated Statements of Comprehensive Income - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Statement of Comprehensive Income [Abstract]
Net income	$ 298,373	$ 222,766	$ 320,727
Other comprehensive income (loss):
Foreign currency translation adjustments	(27,585)	36,151	(14,815)
Change in unrealized gain (loss) on investments, net of income tax (provision) benefit of $(200), $245 and $432 for the years ended December 31, 2018, 2017 and 2016, respectively	603	(406)	(688)
Other comprehensive (loss) income	(26,982)	35,745	(15,503)
Comprehensive income	$ 271,391	$ 258,511	$ 305,224