Consolidated Statements Of Stockholders' Equity (USD $) In Thousands, except Share data	Preferred Stock [Member]	Common Stock [Member] USD ($)	Treasury Shares [Member] USD ($)	Additional Paid-In Capital [Member] USD ($)	Accumulated Other Comprehensive Income (Loss) [Member] USD ($)	Retained Earnings [Member] USD ($)	Total USD ($)
Balance, value at Dec. 31, 2010		$ 156		$ 717,375	$ (258)	$ 173,862	$ 891,135
Balance, shares at Dec. 31, 2010		78,141,000
Exercise of common stock options, shares		514,000
Exercise of common stock options, value		1		3,847			3,848
Employee stock purchase plan, shares		38,000					16,991
Employee stock purchase plan, value				452			452
Share-based compensation, shares
Share-based compensation, value				10,871			10,871
Unrealized gains on available for sale securities, net					12		12
Cumulative translation adjustment, net					(649)		(649)
Repurchase of shares, shares		(8,151,000)	8,151,000
Repurchase of shares, value			(148,884)				(148,884)
Stock option tax benefits				1,216			1,216
Net income						87,481	87,481
Balance, value at Sep. 30, 2011		$ 157	$ (148,884)	$ 733,761	$ (895)	$ 261,343	$ 845,482
Balance, shares at Sep. 30, 2011		70,542,000	8,151,000