Statements of Operations (USD $) In Thousands, except Share data, unless otherwise specified	12 Months Ended			96 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2012
Statements of Operations
Grant revenue			$ 650	$ 650
Operating expenses:
Research and development	10,149	12,407	17,064	71,407
Acquired in-process research and development				5,500
Selling, general and administrative	10,884	9,416	4,772	34,899
Total operating expenses	21,033	21,823	21,836	111,806
Loss from operations	(21,033)	(21,823)	(21,186)	(111,156)
Interest income	23	72	47	669
Interest expense	(1,579)	(1,483)	(3,718)	(9,402)
Change in fair value of warrants	(1,287)			(1,287)
Loss on debt extinguishment	(799)			(799)
Loss before tax benefit	(24,675)	(23,234)	(24,857)	(121,975)
Income tax benefit	141	47	500	839
Net loss	(24,534)	(23,187)	(24,357)	(121,136)
Deemed dividend-beneficial conversion feature	(13,250)			(13,250)
Accretion of redeemable convertible preferred stock			(2,533)
Net loss applicable to common stockholders	$ (37,784)	$ (23,187)	$ (26,890)
Basic and diluted net loss per common share (in dollars per share)	$ (2.48)	$ (1.58)	$ (4.39)
Weighted average basic and diluted common shares outstanding (in shares)	15,210,047	14,630,125	6,126,123