Statements Of Operations And Comprehensive Income (Loss) (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended		380 Months Ended
	Mar. 31, 2012	Mar. 31, 2011	Mar. 31, 2012
Statements Of Operations And Comprehensive Income (Loss) [Abstract]
Revenues from license fees, grants and research contracts	$ 11,212	$ 14,296	$ 147,431
Operating expenses:
Research and development	14,805	14,801	348,071
General and administrative	3,281	5,026	107,738
Acquired in-process research and development	0	0	29,461
Operating loss	(6,874)	(5,531)	(337,839)
Other income (loss):
Interest income and other, net	96	90	9,265
Gain (loss) on change in warrant valuation	(10,926)	7,274	14,044
Realized gain on sale of short-term securities- available-for-sale	0	0	3,863
Write-down of short-term securities- available-for-sale	0	0	(17,001)
Total other non operating income	(10,830)	7,364	10,171
Net income (loss)	(17,704)	1,833	(327,668)
Other comprehensive income (loss):
Write-down of short-term securities-available-for-sale	0	0	17,001
Realized gain on sale of short-term securities-available-for-sale	0	0	(3,863)
Unrealized loss on short-term securities-available-for-sale	0	0	(13,138)
Other comprehensive income (loss)
Comprehensive income (loss)	$ (17,704)	$ 1,833	$ (327,668)
Net income (loss) per share - basic	$ (0.13)	$ 0.02
Net income (loss) per share - diluted	$ (0.13)	$ 0.02
Weighted average number of common shares outstanding for computing basic income (loss) per share (in thousands)	135,743	112,482
Weighted average number of common shares outstanding for computing diluted income (loss) per share (in thousands)	135,743	121,285