Condensed Consolidated Statements of Operations (Unaudited) (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended		9 Months Ended		260 Months Ended
	Sep. 30, 2012	Sep. 30, 2011	Sep. 30, 2012	Sep. 30, 2011	Sep. 30, 2012
Condensed Consolidated Statements of Operations [Abstract]
Revenue	$ 35		$ 35	$ 50	$ 3,166
Operating expenses:
Research and development	25,453	23,132	76,247	79,717	1,442,298
General and administrative	10,069	9,641	37,262	30,293	417,493
In-process research and development costs					19,726
Goodwill impairment					151,428
Total operating expenses	35,522	32,773	113,509	110,010	2,030,945
Loss from operations	(35,487)	(32,773)	(113,474)	(109,960)	(2,027,779)
Other income (expense)	(2,651)	79	12,078	1,476	11,002
Interest expense on note payable to related party	(2,245)	(2,863)	(8,321)	(7,849)	(36,655)
Interest expense on senior convertible notes	(2,859)	(2,845)	(8,278)	(8,092)	(37,072)
Interest income			2	18	36,991
Loss before provision for income taxes	(43,242)	(38,402)	(117,993)	(124,407)	(2,053,513)
Income tax benefit	(408)		(408)		(382)
Net loss	(42,834)	(38,402)	(117,585)	(124,407)	(2,053,131)
Deemed dividend related to beneficial conversion feature of convertible preferred stock					(22,260)
Accretion on redeemable convertible preferred stock					(952)
Net loss applicable to common stockholders	$ (42,834)	$ (38,402)	$ (117,585)	$ (124,407)	$ (2,076,343)
Net loss per share applicable to common stockholders- basic and diluted	$ (0.22)	$ (0.31)	$ (0.71)	$ (1.02)
Shares used to compute basic and diluted net loss per share applicable to common stockholders	190,534	122,130	164,611	121,636