Consolidated Statements Of Stockholders' Equity - USD ($) $ in Thousands	Total	Common Stock	Additional Paid-in Capital	Treasury Stock	Accumulated Other Comprehensive Loss	Accumulated Deficit
Beginning balance (in shares) at Dec. 31, 2012		177,782,814
Beginning balance at Dec. 31, 2012	$ 2,345,754	$ 2,015	$ 5,195,543	$ (624,462)	$ (1,640)	$ (2,225,702)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
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 (in shares)		4,050,525
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	(168)	$ 50	(218)
Issuance of common stock under employee stock purchase plan (in shares)		644,639
Issuance of common stock under employee stock purchase plan	22,092	$ 6	22,086
Stock-based compensation	107,882		107,882
Tax benefits from stock-based award activity, net	20,926		20,926
Stock-based compensation from awards issued to non-employees for services rendered	327		327
Repurchases of common stock (in shares)		(3,897,282)
Repurchases of common stock	(160,418)			(160,418)
Treasury stock retirement		$ (263)	(784,617)	784,880
Net income	293,487					293,487
Foreign currency translation adjustments	(4,361)				(4,361)
Change in unrealized gain on investments, net of tax	3,910				3,910
Ending balance (in shares) at Dec. 31, 2013		178,580,696
Ending balance at Dec. 31, 2013	2,629,431	$ 1,808	4,561,929	0	(2,091)	(1,932,215)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
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 (in shares)		3,648,994
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	6,458	$ 14	6,444
Issuance of common stock under employee stock purchase plan (in shares)		700,879
Issuance of common stock under employee stock purchase plan	29,271	$ 7	29,264
Stock-based compensation	127,222		127,222
Tax benefits from stock-based award activity, net	26,867		26,867
Equity component of convertible senior notes, net of issuance costs of $1,649	99,627		99,627
Issuance costs of convertible senior notes	1,649
Issuance of warrants related to convertible senior notes	77,970		77,970
Purchase of note hedge related to convertible senior notes	(101,292)		(101,292)
Repurchases of common stock (in shares)		(4,629,966)
Repurchases of common stock	(268,647)			(268,647)
Treasury stock retirement		$ (46)	(268,601)	268,647
Net income	333,948					333,948
Foreign currency translation adjustments	(15,349)				(15,349)
Change in unrealized gain on investments, net of tax	(171)				(171)
Ending balance (in shares) at Dec. 31, 2014		178,300,603
Ending balance at Dec. 31, 2014	2,945,335	$ 1,783	4,559,430	0	(17,611)	(1,598,267)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
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 (in shares)		2,756,357
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	(27,670)	$ 27	(27,697)
Issuance of common stock under employee stock purchase plan (in shares)		668,654
Issuance of common stock under employee stock purchase plan	34,841	$ 7	34,834
Stock-based compensation	144,544		144,544
Tax benefits from stock-based award activity, net	28,870		28,870
Repurchases of common stock (in shares)		(4,513,433)
Repurchases of common stock	(302,606)			(302,606)
Treasury stock retirement	0	$ (45)	(302,561)	302,606
Net income	321,406					321,406
Foreign currency translation adjustments	(22,872)				(22,872)
Change in unrealized gain on investments, net of tax	(970)				(970)
Ending balance (in shares) at Dec. 31, 2015		177,212,181
Ending balance at Dec. 31, 2015	$ 3,120,878	$ 1,772	$ 4,437,420	$ 0	$ (41,453)	$ (1,276,861)