CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
CONDENSED CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME
Net income, as reported	$ 546,733	$ 483,185	$ 338,661
Other comprehensive (loss) income:
Change in foreign currency translation adjustment, net of tax	(10,425)	(10,220)	(1,782)
Available-for-sale investments:
Reclassification adjustment for net gains included in net income			(1,525)
Net change in available-for-sale investments			(1,525)
Other comprehensive (loss) income	(10,425)	(10,220)	(3,307)
Comprehensive income	$ 536,308	$ 472,965	$ 335,354