CONSOLIDATED STATEMENTS OF STOCKHOLDERS' EQUITY (USD $) In Thousands, except Share data, unless otherwise specified	Total	Class A Stock	Common Stock	Additional Paid-in Capital	Accumulated Deficit	Accumulated Other Comprehensive Income (Loss)
Balance at Dec. 31, 2010	$ 527,815	$ 2	$ 87	$ 1,575,780	$ (1,045,563)	$ (2,491)
Balance (shares) at Dec. 31, 2010		2,182,000	87,238,000
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of Common Stock in connection with exercise of stock options	43,615		4	43,611
Issuance of Common Stock in connection with exercise of stock options (shares)			3,770,000
Common Stock tendered upon exercise of stock options in connection with employee tax obligations	(22,440)		0	(22,440)
Common Stock tendered upon exercise of stock options in connection with employee tax obligations (in shares)			(446,000)
Issuance of Common Stock in connection with Company 401(k) Savings Plan contribution	6,979			6,979
Issuance of Common Stock in connection with Company 401(k) Savings Plan contribution (shares)			92,000
Issuance of restricted Common Stock under Long-Term Incentive Plan (shares)			16,000
Restricted Common Stock tendered upon vesting in connection with employee tax obligations	(2,638)			(2,638)
Restricted Common Stock rendered upon vesting in connection with employee tax obligations (in shares)			(51,000)
Conversion of Class A Stock to Common Stock (shares)		(73,000)	73,000
Stock-based compensation charges	56,609			56,609
Equity component of convertible senior notes, net of issuance costs	120,623			120,623
Purchase of convertible note hedges	(117,500)			(117,500)
Issuance of warrants in connection with issuance of convertible senior notes	93,800			93,800
Net income (loss)	(221,760)				(221,760)
Other comprehensive income (loss), net of tax	629					629
Balance at Dec. 31, 2011	485,732	2	91	1,754,824	(1,267,323)	(1,862)
Balance (shares) at Dec. 31, 2011		2,109,000	90,692,000
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of Common Stock in connection with exercise of stock options	67,174		5	67,169
Issuance of Common Stock in connection with exercise of stock options (shares)			5,086,000
Common Stock tendered upon exercise of stock options in connection with employee tax obligations	(112,834)		(1)	(112,833)
Common Stock tendered upon exercise of stock options in connection with employee tax obligations (in shares)			(878,000)
Issuance of Common Stock in connection with Company 401(k) Savings Plan contribution	6,325			6,325
Issuance of Common Stock in connection with Company 401(k) Savings Plan contribution (shares)			64,000
Issuance of restricted Common Stock under Long-Term Incentive Plan (shares)			501,000
Restricted Common Stock tendered upon vesting in connection with employee tax obligations	(50,466)			(50,466)
Restricted Common Stock rendered upon vesting in connection with employee tax obligations (in shares)			(282,000)
Conversion of Class A Stock to Common Stock (shares)		(40,000)	40,000
Stock-based compensation charges	94,181			94,181
Excess tax benefit from stock-based compensation	4,308			4,308
Net income (loss)	750,269				750,269
Other comprehensive income (loss), net of tax	696					696
Balance at Dec. 31, 2012	1,245,385	2	95	1,763,508	(517,054)	(1,166)
Balance (shares) at Dec. 31, 2012		2,069,000	95,223,000
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of Common Stock in connection with exercise of stock options	54,762		3	54,759
Issuance of Common Stock in connection with exercise of stock options (shares)			3,052,000
Common Stock tendered upon exercise of stock options in connection with employee tax obligations	(179,423)		(1)	(179,422)
Common Stock tendered upon exercise of stock options in connection with employee tax obligations (in shares)			(644,000)
Issuance of Common Stock in connection with Company 401(k) Savings Plan contribution	5,718			5,718
Issuance of Common Stock in connection with Company 401(k) Savings Plan contribution (shares)			38,000
Issuance of restricted Common Stock under Long-Term Incentive Plan (shares)			6,000
Restricted Common Stock tendered upon vesting in connection with employee tax obligations	(15,664)			(15,664)
Restricted Common Stock rendered upon vesting in connection with employee tax obligations (in shares)			(57,000)
Conversion of Class A Stock to Common Stock (shares)		(49,000)	49,000
Stock-based compensation charges	200,101			200,101
Excess tax benefit from stock-based compensation	216,857			216,857
Net income (loss)	424,362				424,362
Other comprehensive income (loss), net of tax	(22)					(22)
Balance at Dec. 31, 2013	$ 1,952,076	$ 2	$ 97	$ 2,045,857	$ (92,692)	$ (1,188)
Balance (shares) at Dec. 31, 2013		2,020,000	97,667,000