Condensed Consolidated Statements of Comprehensive Loss (Unaudited) (USD $) In Thousands, except Share data, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2012	Jun. 30, 2011	Jun. 30, 2012	Jun. 30, 2011
Condensed Consolidated Statements of Comprehensive Loss (Unaudited) [Abstract]
Contract revenue	$ 2,992	$ 4,263	$ 6,011	$ 8,582
Operating expenses:
Research and development	4,230	4,328	7,450	9,373
General and administrative	875	1,127	1,820	2,154
Total operating expenses	5,105	5,455	9,270	11,527
Loss from operations	(2,113)	(1,192)	(3,259)	(2,945)
Other income (expense):
Interest income, net	12	12	19	27
Other income (expense), net	21		30
Net loss	(2,080)	(1,180)	(3,210)	(2,918)
Other comprehensive income (loss):
Net unrealized gains (losses) on marketable securities	11	(2)	13	2
Comprehensive loss	$ (2,069)	$ (1,182)	$ (3,197)	$ (2,916)
Basic and diluted net loss per common share	$ (0.28)	$ (0.17)	$ (0.44)	$ (0.43)
Weighted average common shares outstanding used to calculate basic and diluted net loss per common share	7,347,051	6,872,531	7,276,462	6,813,824