Consolidated Statements of Operations and Comprehensive Loss (USD $) In Thousands, except Per Share data, unless otherwise specified	12 Months Ended			389 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2012
Revenues from license fees, grants and research contracts	$ 37,329	$ 46,990	$ 29,420	$ 173,548
Operating expenses:
Research and development	52,402	66,862	35,972	385,668
General and administrative	14,630	16,055	14,382	119,087
Acquired in-process research and development	0	0	0	29,461
Operating loss	(29,703)	(35,927)	(20,934)	(360,668)
Other non-operating income (loss):
Interest income and other, net	354	587	259	9,523
Gain (loss) on change in warrant valuation	(91,938)	33,022	(11,502)	(66,968)
Realized gain on sale of short-term securities-available-for-sale	0	0	0	3,863
Write-down of short-term securities-available-for-sale	0	0	0	(17,001)
Nonoperating Income (Expense), Total	(91,584)	33,609	(11,243)	(70,583)
Net income (loss)	(121,287)	(2,318)	(32,177)	(431,251)
Other comprehensive income (loss):
Write-down of short-term securities-available-for-sale	0	0	0	17,001
Realized gain on sale of short-term securities-available-for-sale	0	0	0	(3,863)
Unrealized loss on short-term securities available-for-sale	0	0	0	(13,138)
Other Comprehensive Income (Loss), Net of Tax, Total	0	0	0	0
Comprehensive loss	$ (121,287)	$ (2,318)	$ (32,177)	$ (431,251)
Net loss per share-basic and diluted	$ (5.14)	$ (0.11)	$ (1.74)
Weighted average number of common shares outstanding for computing basic and diluted loss per share (in thousands)	23,602	21,599	18,539