CONSOLIDATED STATEMENTS OF OPERATIONS - USD ($) shares in Thousands, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014
Revenue:
Government contracts	$ 6,307	$ 7,504	$ 29,273	$ 20,217
Research and development collaborations	218	710	1,124	3,718
Total revenue	6,525	8,214	30,397	23,935
Costs and expenses:
Cost of government contracts revenue	2,747	4,027	8,054	12,150
Research and development	27,917	19,219	78,686	48,940
General and administrative	9,060	4,757	21,991	14,871
Total costs and expenses	39,724	28,003	108,731	75,961
Loss from operations	(33,199)	(19,789)	(78,334)	(52,026)
Other income (expense):
Investment income	194	128	450	160
Interest expense	(64)	(47)	(126)	(150)
Other expense	(51)	(19)	(121)	0
Realized gains on marketable securities	0	0	0	615
Net loss	$ (33,120)	$ (19,727)	$ (78,131)	$ (51,401)
Basic and diluted net loss per share	$ (0.12)	$ (0.08)	$ (0.30)	$ (0.23)
Basic and diluted weighted average number of common shares outstanding (in shares)	269,554	238,304	259,703	221,578