Consolidated Statement Of Stockholders' Equity (USD $) In Thousands, except Share data, unless otherwise specified	Total	Common Stock [Member]	Additional Paid-in Capital [Member]	Treasury Stock [Member]	Accumulated Other Comprehensive Income (Loss) [Member]	Accumulated Deficit [Member]	Comprehensive Income [Member]
Balance, value at Dec. 31, 2008	$ 1,568,770	$ 1,694	$ 4,539,154	$ 0	$ (24,350)	$ (2,947,728)
Balance, shares at Dec. 31, 2008		169,371,675
Comprehensive income:
Net income	145,913					145,913	145,913
Foreign currency translation adjustment	1,933				1,933		1,933
Change in unrealized gain (loss) on available-for-sale marketable securities, net of tax	11,735				11,735		11,735
Comprehensive income							159,581
Issuance of common stock upon the exercise of stock options and vesting of restricted and deferred stock units, shares		4,479,139
Issuance of common stock upon the exercise of stock options and vesting of restricted and deferred stock units, value	12,028	45	11,983
Issuance of common stock under employee stock purchase plan, shares		727,449
Issuance of common stock under employee stock purchase plan, value	9,801	7	9,794
Stock-based compensation	65,004		65,004
Common stock returned upon settlement of escrow claims related to prior business acquisitions, shares		(9,233)
Common stock returned upon settlement of escrow claims related to prior business acquisitions, value	(427)	0	(427)
Tax benefits (shortfall) from stock-based award activity, net	(9,880)		(9,880)
Stock-based compensation from awards issued to non-employees for services rendered	46		46
Issuance of common stock upon conversion of 1% convertible senior notes, shares		6,472
Issuance of common stock upon conversion of 1% convertible senior notes, value	100	0	100
Repurchases of common stock, shares		(3,327,146)
Repurchases of common stock, value	(66,301)			(66,301)
Balance, value at Dec. 31, 2009	1,738,722	1,746	4,615,774	(66,301)	(10,682)	(2,801,815)
Balance, shares at Dec. 31, 2009		171,248,356
Comprehensive income:
Net income	171,220					171,220	171,220
Foreign currency translation adjustment	1,172				1,172		1,172
Change in unrealized gain (loss) on available-for-sale marketable securities, net of tax	3,769				3,769		3,769
Comprehensive income							176,161
Issuance of common stock upon the exercise of stock options and vesting of restricted and deferred stock units, shares		4,413,894
Issuance of common stock upon the exercise of stock options and vesting of restricted and deferred stock units, value	33,625	44	33,581
Issuance of common stock under employee stock purchase plan, shares		474,242
Issuance of common stock under employee stock purchase plan, value	12,151	5	12,146
Stock-based compensation	84,268		84,268
Common stock returned upon settlement of escrow claims related to prior business acquisitions, shares		(9,612)
Common stock returned upon settlement of escrow claims related to prior business acquisitions, value	(430)	0	(430)
Tax benefits (shortfall) from stock-based award activity, net	25,303		25,303
Stock-based compensation from awards issued to non-employees for services rendered	10		10
Issuance of common stock upon conversion of 1% convertible senior notes, shares		12,929,095
Issuance of common stock upon conversion of 1% convertible senior notes, value	199,755	129	199,626
Repurchases of common stock, shares		(2,452,595)
Repurchases of common stock, value	(91,960)			(91,960)
Balance, value at Dec. 31, 2010	2,177,605	1,924	4,970,278	(158,261)	(5,741)	(2,630,595)
Balance, shares at Dec. 31, 2010		186,603,380
Comprehensive income:
Net income	200,904					200,904	200,904
Foreign currency translation adjustment	(3,553)				(3,553)		(3,553)
Change in unrealized gain (loss) on available-for-sale marketable securities, net of tax	8,035				8,035		8,035
Comprehensive income							205,386
Issuance of common stock upon the exercise of stock options and vesting of restricted and deferred stock units, shares		2,686,726
Issuance of common stock upon the exercise of stock options and vesting of restricted and deferred stock units, value	4,203	30	4,173
Issuance of common stock under employee stock purchase plan, shares		491,396
Issuance of common stock under employee stock purchase plan, value	12,656	5	12,651
Stock-based compensation	69,260		69,260
Tax benefits (shortfall) from stock-based award activity, net	11,855		11,855
Stock-based compensation from awards issued to non-employees for services rendered	18		18
Repurchases of common stock, shares		(12,276,878)
Repurchases of common stock, value	(324,733)			(324,733)
Balance, value at Dec. 31, 2011	$ 2,156,250	$ 1,959	$ 5,068,235	$ (482,994)	$ (1,259)	$ (2,429,691)
Balance, shares at Dec. 31, 2011		177,504,624