Statements Of Operations (USD $) In Thousands, except Per Share data	3 Months Ended		9 Months Ended		379 Months Ended
	Sep. 30, 2011	Sep. 30, 2010	Sep. 30, 2011	Sep. 30, 2010	Sep. 30, 2011
Statements Of Operations [Abstract]
Revenues from license fees, grants and research contracts	$ 7,524	$ 8,702	$ 33,405	$ 13,903	$ 122,634
Operating expenses:
Research and development	15,610	9,059	48,161	22,080	314,565
General and administrative	3,185	3,440	12,171	11,017	100,573
Acquired in-process research and development					29,461
Operating loss	(11,271)	(3,797)	(26,927)	(19,194)	(321,965)
Other non-operating (loss) income:
Interest (expense) income and other, net	199	82	440	170	9,022
(Increase) decrease on warrant valuation	7,052	(3,578)	25,579	(5,509)	17,527
Realized gain on sale of short-term securities-available-for-sale					3,863
Write-down of short-term securities-available-for-sale					(17,001)
Total other non operating income	7,251	(3,496)	26,019	(5,339)	13,411
Net loss and comprehensive loss	$ (4,020)	$ (7,293)	$ (908)	$ (24,533)	$ (308,554)
Net loss per share-basic and diluted	$ (0.03)	$ (0.07)	$ (0.01)	$ (0.22)
Weighted average number of common shares outstanding for computing basic and diluted loss per share (in thousands)	135,738	111,767	127,523	110,863