COMPREHENSIVE INCOME (Details) (USD $)	3 Months Ended		6 Months Ended
	Jun. 30, 2011	Jun. 30, 2010	Jun. 30, 2011	Jun. 30, 2010	Dec. 31, 2010
Components of comprehensive income:
Net income, as reported	$ 84,248,000	$ 63,838,000	$ 139,291,000	$ 96,401,000
Other comprehensive income (loss):
Change in unrealized loss on available-for-sale securities, net of tax	1,377,000	331,000	1,478,000	3,149,000
Foreign currency translation adjustments	(483,000)	(2,352,000)	245,000	(2,667,000)
Comprehensive income	85,142,000	61,817,000	141,014,000	96,883,000
Components of accumulated other comprehensive income:
Accumulated net unrealized loss on available-for-sale securities, net of tax benefit $1.0 million as of December 31, 2010					(1,478,000)
Tax benefit					1,000,000
Foreign currency translation adjustments	2,004,000		2,004,000		1,759,000
Total accumulated other comprehensive income	$ 2,004,000		$ 2,004,000		$ 281,000