CONDENSED STATEMENTS OF STOCKHOLDERS' EQUITY (Unaudited) (USD $) In Thousands	Total	Class A Stock [Member]	Common Stock [Member]	Additional Paid-in Capital [Member]	Accumulated Deficit [Member]	Accumulated Other Comprehensive Income (Loss) [Member]	Comprehensive Loss [Member]
Balance at Dec. 31, 2009	$ 396,762	$ 2	$ 79	$ 1,336,732	$ (941,095)	$ 1,044
Balance (in shares) at Dec. 31, 2009		2,245	78,861
Increase (decrease) in stockholders' equity [Roll Forward]
Issuance of Common Stock in connection with exercise of stock options, net of shares tendered	11,392		1	11,391
Issuance of Common Stock in connection with exercise of stock options, net of shares tendered (in shares)			878
Issuance of Common Stock in connection with Company 401(k) Savings Plan contribution	2,867			2,867
Issuance of Common Stock in connection with Company 401(k) Savings Plan contribution (in shares)			111
Issuance of restricted Common Stock under Long-Term Incentive Plan (in shares)			10
Conversion of Class A Stock to Common Stock (in shares)		(63)	63
Stock-based compensation charges	17,541			17,541
Net loss	(55,996)				(55,996)		(55,996)
Change in net unrealized gain (loss) on marketable securities	(1,350)					(1,350)	(1,350)
Total comprehensive loss	(57,346)
Balance at Jun. 30, 2010	371,216	2	80	1,368,531	(997,091)	(306)	(57,346)
Balance (in shares) at Jun. 30, 2010		2,182	79,923
Balance at Dec. 31, 2010	527,815	2	87	1,575,780	(1,045,563)	(2,491)
Balance (in shares) at Dec. 31, 2010		2,182	87,238
Increase (decrease) in stockholders' equity [Roll Forward]
Issuance of Common Stock in connection with exercise of stock options, net of shares tendered	23,794		2	23,792
Issuance of Common Stock in connection with exercise of stock options, net of shares tendered (in shares)			2,026
Issuance of Common Stock in connection with Company 401(k) Savings Plan contribution	3,405			3,405
Issuance of Common Stock in connection with Company 401(k) Savings Plan contribution (in shares)			92
Issuance of restricted Common Stock under Long-Term Incentive Plan (in shares)			5
Conversion of Class A Stock to Common Stock (in shares)		(55)	55
Stock-based compensation charges	27,385			27,385
Net loss	(105,952)				(105,952)		(105,952)
Change in net unrealized gain (loss) on marketable securities	1,587					1,587	1,587
Total comprehensive loss	(104,365)
Balance at Jun. 30, 2011	$ 478,034	$ 2	$ 89	$ 1,630,362	$ (1,151,515)	$ (904)	$ (104,365)
Balance (in shares) at Jun. 30, 2011		2,127	89,416