CONDENSED CONSOLIDATED STATEMENTS OF STOCKHOLDERS' EQUITY (USD $) In Thousands, unless otherwise specified	Total	Class A Stock	Common Stock	Additional Paid-in Capital	Accumulated Deficit	Accumulated Other Comprehensive Income (Loss)
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	90,692
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of Common Stock in connection with exercise of stock options	48,440		4	48,436
Issuance of Common Stock in connection with exercise of stock options (shares)			3,773
Common Stock tendered upon exercise of stock options in connection with employee tax obligations	(71,475)		(1)	(71,474)
Common Stock tendered upon exercise of stock options in connection with employee tax obligations (shares)			(639)
Issuance of Common Stock in connection with Company 401(k) Savings Plan contribution
Issuance of Common Stock in connection with Company 401(k) Savings Plan contribution (shares)			64
Issuance of restricted Common Stock under Long-Term Incentive Plan (shares)			500
Conversion of Class A Stock to Common Stock (shares)		(20)	20
Stock-based compensation charges	63,507			63,507
Net income	279,862				279,862
Other comprehensive income (loss)	(42)					(42)
Balance at Sep. 30, 2012	806,024	2	94	1,795,293	(987,461)	(1,904)
Balance (shares) at Sep. 30, 2012		2,089	94,410
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	95,223
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of Common Stock in connection with exercise of stock options	42,625		3	42,622
Issuance of Common Stock in connection with exercise of stock options (shares)			2,641
Common Stock tendered upon exercise of stock options in connection with employee tax obligations	(166,358)		(1)	(166,357)
Common Stock tendered upon exercise of stock options in connection with employee tax obligations (shares)			(597)
Issuance of Common Stock in connection with Company 401(k) Savings Plan contribution
Issuance of Common Stock in connection with Company 401(k) Savings Plan contribution (shares)			38
Issuance of restricted Common Stock under Long-Term Incentive Plan (shares)			6
Conversion of Class A Stock to Common Stock (shares)		(40)	40
Stock-based compensation charges	144,808			144,808
Excess tax benefit from stock-based compensation	97,840			97,840
Net income	327,556				327,556
Other comprehensive income (loss)	(1,685)					(1,685)
Balance at Sep. 30, 2013	$ 1,690,171	$ 2	$ 97	$ 1,882,421	$ (189,498)	$ (2,851)
Balance (shares) at Sep. 30, 2013		2,029	97,351