Statements of Operations and Comprehensive Income (Loss) (Unaudited) (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended		6 Months Ended		383 Months Ended
	Jun. 30, 2012	Jun. 30, 2011	Jun. 30, 2012	Jun. 30, 2011	Jun. 30, 2012
Statements of Operations and Comprehensive Income (loss) [Abstract]
Revenues from license fees, grants and research contracts	$ 11,207	$ 11,585	$ 22,419	$ 25,881	$ 158,638
Operating expenses:
Research and development	13,849	17,750	28,654	32,551	361,920
General and administrative	2,915	3,960	6,196	8,986	110,653
Acquired in-process research and development	0	0	0	0	29,461
Operating loss	(5,557)	(10,125)	(12,431)	(15,656)	(343,396)
Other income (loss):
Interest income and other, net	107	151	203	241	9,372
Gain (loss) on change in warrant valuation	13,488	11,253	2,562	18,527	27,532
Realized gain on sale of short-term securities-available-for-sale	0	0	0	0	3,863
Write-down of short-term securities-available-for-sale	0	0	0	0	(17,001)
Total other non operating income	13,595	11,404	2,765	18,768	23,766
Net income (loss)	8,038	1,279	(9,666)	3,112	(319,630)
Other comprehensive income (loss):
Write-down of short-term securities--available-for-sale	0	0	0	0	17,001
Realized gain on sale of short-term securities available-for-sale	0	0	0	0	(3,863)
Unrealized loss on short-term securities--available-for-sale	0	0	0	0	(13,138)
Total Other comprehensive income (loss)	0	0	0	0	0
Comprehensive income (loss)	$ 8,038	$ 1,279	$ (9,666)	$ 3,112	$ (319,630)
Net income (loss) per share - basic	$ 0.36	$ 0.06	$ (0.43)	$ 0.15
Net income (loss) per share - diluted	$ 0.35	$ 0.06	$ (0.43)	$ 0.14
Weighted average number of common shares outstanding for computing basic income (loss) per share (in thousands)	22,624	22,348	22,624	20,558
Weighted average number of common shares outstanding for computing diluted income (loss) per share (in thousands)	22,658	23,153	22,624	21,670