Condensed Consolidated Statements of Operations and Comprehensive Loss (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended		392 Months Ended
	Mar. 31, 2013	Mar. 31, 2012	Mar. 31, 2013
Revenues from license fees, grants and research contracts	$ 4,474	$ 11,212	$ 178,022
Operating expenses:
Research and development	13,762	14,805	399,430
General and administrative	6,127	3,281	125,214
Acquired in-process research and development			29,461
Operating loss	(15,415)	(6,874)	(376,083)
Other non-operating income (loss):
Interest income and other, net	237	96	9,760
Loss on change in warrant liability	(26,906)	(10,926)	(93,874)
Realized gain on sale of short-term securities - available-for-sale			3,863
Write-down of short-term securities - available-for-sale			(17,001)
Non-operating Income (Expense), Total	(26,669)	(10,830)	(97,252)
Net loss	(42,084)	(17,704)	(473,335)
Other comprehensive income (loss):
Write-down of short-term securities - available-for-sale			17,001
Realized gain on sale of short-term securities - available-for-sale			(3,863)
Unrealized loss on short-term securities - available-for-sale			(13,138)
Other Comprehensive Income (Loss), Net of Tax, Total
Comprehensive loss	$ (42,084)	$ (17,704)	$ (473,335)
Net loss per share - basic and diluted	$ (1.32)	$ (0.78)
Weighted average number of common shares outstanding for computing basic and diluted net loss per share	31,813	22,624