Consolidated Statements of Comprehensive Income (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2014	Mar. 31, 2013
Statement of Comprehensive Income [Abstract]
Net income	$ 72,800	$ 71,487
Other comprehensive income (loss):
Foreign currency translation adjustments	1,367	(4,014)
Change in unrealized (loss) gain on investments, net of income tax benefit (provision) of $123 and $(10) for the three months ended March 31, 2014 and 2013, respectively	(913)	71
Other comprehensive income (loss)	454	(3,943)
Comprehensive income	$ 73,254	$ 67,544