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, 2013		178,580,696
Balance as of January 1, 2016 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	0	$ (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
Balance as of December 31, 2016 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
Balance as of December 31, 2016 at Dec. 31, 2015	3,120,878	$ 1,772	4,437,420	0	(41,453)	(1,276,861)
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)		2,194,699
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	(27,394)	$ 22	(27,416)
Issuance of common stock under employee stock purchase plan (in shares)		863,419
Issuance of common stock under employee stock purchase plan	39,914	$ 9	39,905
Stock-based compensation	166,987		166,987
Tax deficiency from stock-based award activity, net	(3,584)		(3,584)
Repurchases of common stock (in shares)		(7,015,502)
Repurchases of common stock	(373,794)			(373,794)
Treasury stock retirement	0	$ (70)	(373,724)	373,794
Net income	316,132					316,132
Foreign currency translation adjustments	(14,081)				(14,081)
Change in unrealized gain on investments, net of tax	(688)				(688)
Ending balance (in shares) at Dec. 31, 2016		173,254,797
Balance as of December 31, 2016 at Dec. 31, 2016	$ 3,224,370	$ 1,733	$ 4,239,588	$ 0	$ (56,222)	$ (960,729)