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]
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
Foreign currency translation adjustments	1,172				1,172
Change in unrealized gain (loss) on available-for-sale marketable securities, net of tax	3,769				3,769
Issuance of common stock upon the exercise of stock options and vesting of restricted and deferred stock units, net of shares withheld for employee taxes, shares		4,413,894
Issuance of common stock upon the exercise of stock options and vesting of restricted and deferred stock units, net of shares withheld for employee taxes, 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 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
Foreign currency translation adjustments	(3,553)				(3,553)
Change in unrealized gain (loss) on available-for-sale marketable securities, net of tax	8,035				8,035
Issuance of common stock upon the exercise of stock options and vesting of restricted and deferred stock units, net of shares withheld for employee taxes, shares		2,686,726
Issuance of common stock upon the exercise of stock options and vesting of restricted and deferred stock units, net of shares withheld for employee taxes, 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 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
Comprehensive income:
Net income	203,989					203,989
Foreign currency translation adjustments	(904)				(904)
Change in unrealized gain (loss) on available-for-sale marketable securities, net of tax	523				523
Issuance of common stock upon the exercise of stock options and vesting of restricted and deferred stock units, net of shares withheld for employee taxes, shares		3,961,440
Issuance of common stock upon the exercise of stock options and vesting of restricted and deferred stock units, net of shares withheld for employee taxes, value	(6,853)	49	(6,902)
Issuance of common stock under employee stock purchase plan, shares		676,853
Issuance of common stock under employee stock purchase plan, value	16,823	7	16,816
Stock-based compensation	99,038		99,038
Tax benefits from stock-based award activity, net	17,533		17,533
Stock-based compensation from awards issued to non-employees for services rendered	823		823
Repurchases of common stock, shares		(4,360,103)
Repurchases of common stock, value	(141,468)			(141,468)
Balance, value at Dec. 31, 2012	$ 2,345,754	$ 2,015	$ 5,195,543	$ (624,462)	$ (1,640)	$ (2,225,702)
Balance, shares at Dec. 31, 2012		177,782,814