CONSOLIDATED STATEMENTS OF STOCKHOLDERS' EQUITY (USD $) In Thousands, except Share data, unless otherwise specified	Total	Common Stock	Additional Paid-in Capital	Retained Earnings (Accumulated Deficit)	Treasury Stock	Accumulated Other Comprehensive Income (Loss)	Class A Stock Common Stock
Balance at Dec. 31, 2012	$ 1,245,385	$ 95	$ 1,763,508	$ (517,054)	$ 0	$ (1,166)	$ 2
Balance (shares) at Dec. 31, 2012		95,223,000			0		2,069,000
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of Common Stock in connection with exercise of stock options	30,498	2	30,496
Issuance of Common Stock in connection with exercise of stock options (shares)		1,661,000
Common Stock tendered upon exercise of stock options in connection with employee tax obligations	(73,137)	0	(73,137)
Common Stock tendered upon exercise of stock options in connection with employee tax obligations (in shares)		(290,000)
Issuance of Common Stock in connection with Company 401(k) Savings Plan contribution	0	0
Issuance of Common Stock in connection with Company 401(k) Savings Plan contribution (in shares)		38,000
Conversion of Class A Stock to Common Stock (in shares)		30,000					(30,000)
Stock-based compensation charges	98,728		98,728
Excess tax benefit from stock-based compensation	7,876		7,876
Net income	186,250			186,250
Other comprehensive income, net of tax	(2,263)					(2,263)
Balance at Jun. 30, 2013	1,493,337	97	1,827,471	(330,804)	0	(3,429)	2
Balance (shares) at Jun. 30, 2013		96,662,000			0		2,039,000
Balance at Dec. 31, 2013	1,952,076	97	2,045,857	(92,692)	0	(1,188)	2
Balance (shares) at Dec. 31, 2013		97,667,000			0		2,020,000
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of Common Stock in connection with exercise of stock options	62,117	2	62,115
Issuance of Common Stock in connection with exercise of stock options (shares)		1,514,000
Common Stock tendered upon exercise of stock options in connection with employee tax obligations	(64,990)	0	(64,990)
Common Stock tendered upon exercise of stock options in connection with employee tax obligations (in shares)		(205,000)
Issuance of Common Stock in connection with conversion of convertible senior notes	156,368	1	156,367
Issuance of Common Stock in connection with conversion of convertible senior notes (in shares)	521,876	522,000
Issuance of Common Stock in connection with Company 401(k) Savings Plan contribution	0	0
Issuance of Common Stock in connection with Company 401(k) Savings Plan contribution (in shares)		21,000
Issuance of restricted Common Stock under Long-Term Incentive Plan	0	0
Issuance of restricted Common Stock under Long-Term Incentive Plan (in shares)		5,000
Conversion of Class A Stock to Common Stock (in shares)		21,000					(21,000)
Stock-based compensation charges	155,137		155,137
Excess tax benefit from stock-based compensation	244,197		244,197
Acquisition of Common Stock in connection with exercise of convertible note hedges	0		43,848		(43,848)
Acquisition of Common Stock in connection with exercise of convertible note hedges (in shares)	(521,876)				(522,000)
Reduction of warrants in connection with conversion of senior notes	(143,041)		(143,041)
Reduction of equity component of convertible senior notes	(156,651)		(156,651)
Net income	158,178			158,178
Other comprehensive income, net of tax	5,451					5,451
Balance at Jun. 30, 2014	$ 2,368,842	$ 100	$ 2,342,839	$ 65,486	$ (43,848)	$ 4,263	$ 2
Balance (shares) at Jun. 30, 2014		99,545,000			(522,000)		1,999,000