U.S. Government Contracts (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2012	Sep. 30, 2011	Sep. 30, 2012	Sep. 30, 2011
Revenue for U.S Government Contract
U.S. government contract revenue	$ 7,574	$ 7,524	$ 29,993	$ 33,405
July 2010 Agreement (Ebola and Marburg) [Member]
Revenue for U.S Government Contract
U.S. government contract revenue	7,511	7,290	29,844	29,780
August 2012 Agreement (Intramuscular) [Member]
Revenue for U.S Government Contract
U.S. government contract revenue	50		50
June 2010 Agreement (H1N1) [Member]
Revenue for U.S Government Contract
U.S. government contract revenue		183		3,390
Other Agreements [Member]
Revenue for U.S Government Contract
U.S. government contract revenue	$ 13	$ 51	$ 99	$ 235