Statements of Operations and Comprehensive Income (Loss) (Unaudited) (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended		9 Months Ended		386 Months Ended
	Sep. 30, 2012	Sep. 30, 2011	Sep. 30, 2012	Sep. 30, 2011	Sep. 30, 2012
Statements of Operations and Comprehensive Income (loss) [Abstract]
Revenues from license fees, grants and research contracts	$ 7,574	$ 7,524	$ 29,993	$ 33,405	$ 166,212
Operating expenses:
Research and development	10,914	15,610	39,568	48,161	372,834
General and administrative	3,565	3,185	9,761	12,171	114,218
Acquired in-process research and development	0	0	0	0	29,461
Operating loss	(6,905)	(11,271)	(19,336)	(26,927)	(350,301)
Other income (loss):
Interest income and other, net	67	199	270	440	9,439
Gain (loss) on change in warrant valuation	(42,716)	7,052	(40,154)	25,579	(15,184)
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	(42,649)	7,251	(39,884)	26,019	(18,883)
Net income (loss)	(49,554)	(4,020)	(59,220)	(908)	(369,184)
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)	$ (49,554)	$ (4,020)	$ (59,220)	$ (908)	$ (369,184)
Net income (loss) per share - basic	$ (2.17)	$ (0.18)	$ (2.61)	$ (0.04)
Net income (loss) per share - diluted	$ (2.17)	$ (0.18)	$ (2.61)	$ (0.04)
Weighted average number of common shares outstanding for computing basic income (loss) per share (in thousands)	22,824	22,623	22,691	21,254
Weighted average number of common shares outstanding for computing diluted income (loss) per share (in thousands)	22,824	22,623	22,691	21,254