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, 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	9,804		0	9,804
Issuance of Common Stock in connection with exercise of stock options (shares)			396
Common Stock tendered upon exercise of stock options in connection with employee tax obligations	(3,085)		0	(3,085)
Common Stock tendered upon exercise of stock options in connection with employee tax obligations (in shares)			(17)
Issuance of Common Stock in connection with Company 401(k) Savings Plan contribution	0
Issuance of Common Stock in connection with Company 401(k) Savings Plan contribution (shares)			38
Conversion of Class A Stock to Common Stock (shares)		(11)	11
Stock-based compensation charges	53,555			53,555
Excess tax benefit from stock-based compensation	2,293			2,293
Net income	98,874
Other comprehensive income (loss)	(478)					(478)
Balance at Mar. 31, 2013	1,406,348	2	95	1,826,075	(418,180)	(1,644)
Balance (shares) at Mar. 31, 2013		2,058	95,651
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	97,667
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of Common Stock in connection with exercise of stock options	53,920		2	53,918
Issuance of Common Stock in connection with exercise of stock options (shares)			1,338
Common Stock tendered upon exercise of stock options in connection with employee tax obligations	(63,086)		0	(63,086)
Common Stock tendered upon exercise of stock options in connection with employee tax obligations (in shares)			(198)
Issuance of Common Stock in connection with Company 401(k) Savings Plan contribution	0
Issuance of Common Stock in connection with Company 401(k) Savings Plan contribution (shares)			21
Conversion of Class A Stock to Common Stock (shares)		(20)	20
Stock-based compensation charges	82,982			82,982
Excess tax benefit from stock-based compensation	117,260			117,260
Net income	65,443				65,443
Other comprehensive income (loss)	2,653					2,653
Balance at Mar. 31, 2014	$ 2,211,248	$ 2	$ 99	$ 2,236,931	$ (27,249)	$ 1,465
Balance (shares) at Mar. 31, 2014		2,000	98,848