Consolidated Statements of Comprehensive Income (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Net income	$ 203,989	$ 200,904	$ 171,220
Other comprehensive income:
Foreign currency translation adjustments	(904)	(3,553)	1,172
Change in unrealized gain (loss) on investments, net	927	13,053	6,109
Income tax (expense) benefit related to unrealized gain (loss) on investments, net	(404)	(5,018)	(2,340)
Other comprehensive income (loss)	(381)	4,482	4,941
Comprehensive income	$ 203,608	$ 205,386	$ 176,161