Consolidated Statements of Comprehensive Income - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014
Statement of Comprehensive Income [Abstract]
Net income	$ 88,040	$ 91,155	$ 232,986	$ 236,841
Other comprehensive loss:
Foreign currency translation adjustments	(9,261)	(10,763)	(17,069)	(7,937)
Change in unrealized gain (loss) on investments, net of income tax (provision) benefit of $(73), $715, $(647) and $324 for the three and nine months ended September 30, 2015 and 2014, respectively	121	(1,279)	1,161	483
Other comprehensive loss	(9,140)	(12,042)	(15,908)	(7,454)
Comprehensive income	$ 78,900	$ 79,113	$ 217,078	$ 229,387