Consolidated Statements of Comprehensive Income - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015
Statement of Comprehensive Income [Abstract]
Net income	$ 73,635	$ 67,200	$ 148,493	$ 144,946
Other comprehensive (loss) income:
Foreign currency translation adjustments	(3,728)	607	5,925	(7,808)
Change in unrealized gain (loss) on investments, net of income tax (provision) benefit of $(529), $639, $(2,311) and $(574) for the three and six months ended June 30, 2016 and 2015, respectively	904	(1,073)	3,912	1,040
Other comprehensive (loss) income	(2,824)	(466)	9,837	(6,768)
Comprehensive income	$ 70,811	$ 66,734	$ 158,330	$ 138,178