Revenue from United States and European Union Governments Contracts and Other Revenue (Detail) (USD $)	3 Months Ended		9 Months Ended
	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013
Revenue [Line Items]
U.S. and E.U. governments contract revenue	$ 1,059,000	$ 4,168,000	$ 9,730,000	$ 11,593,000
July 2010 Agreement (Ebola and Marburg IV) [Member]
Revenue [Line Items]
U.S. and E.U. governments contract revenue	1,043,000	2,444,000	6,816,000	7,134,000
August 2012 Agreement (Intramuscular) [Member]
Revenue [Line Items]
U.S. and E.U. governments contract revenue		514,000		2,759,000
European Union SKIP-NMD Agreement (DMD) [Member]
Revenue [Line Items]
U.S. and E.U. governments contract revenue	16,000	536,000	1,405,000	599,000
July 2013 Children's National Medical Center Agreement (DMD) [Member]
Revenue [Line Items]
U.S. and E.U. governments contract revenue	0	674,000	659,000	674,000
Carolinas Medical Center Agreement (DMD) [Member]
Revenue [Line Items]
U.S. and E.U. governments contract revenue	0		850,000
Other Agreements [Member]
Revenue [Line Items]
U.S. and E.U. governments contract revenue				$ 427,000