U.S. Government Agreement and Collaborations (Details) (USD $)	12 Months Ended			1 Months Ended	12 Months Ended	1 Months Ended	12 Months Ended	23 Months Ended		1 Months Ended	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010	Feb. 28, 2011 HHS BARDA Contract Award [Member]	Dec. 31, 2012 HHS BARDA Contract Award [Member]	Feb. 28, 2011 HHS BARDA Option for Additional Period [Member]	Dec. 31, 2012 HHS BARDA Option for Additional Period [Member]	Dec. 31, 2012 HHS BARDA Option for Additional Period [Member]	Feb. 28, 2011 License Agreement with LG Life Sciences, Ltd. [Member]	Jul. 31, 2012 PATH Vaccine Solutions [Member]	Dec. 31, 2012 PATH Vaccine Solutions [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Contract receivable				$ 97,000,000		$ 82,000,000
Contract term				3 years		2 years
Research and development collaborations	1,405,000									2,000,000	1,300,000
Expected costs					3,100,000
Trial costs incurred					3,000,000
Upfront license payment									2,500,000
Royalty payments, percent									10.00%
Potential funding of external clinical development costs										50.00%
Government contracts	$ 20,671,000	$ 14,688,000	$ 343,000				$ 20,100,000	$ 34,800,000