Revenue from United States and European Union Governments Contracts and Other Revenue (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended		9 Months Ended		398 Months Ended
	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013
Accounts, Notes, Loans and Financing Receivable [Line Items]
U.S. and E.U. governments contract revenue	$ 4,168	$ 7,574	$ 11,593	$ 29,993	$ 185,141
July 2010 Contract (Ebola and Marburg IV)
Accounts, Notes, Loans and Financing Receivable [Line Items]
U.S. and E.U. governments contract revenue	2,444	7,511	7,134	29,844
August 2012 Contract (Intramuscular)
Accounts, Notes, Loans and Financing Receivable [Line Items]
U.S. and E.U. governments contract revenue	514	50	2,759	50
November 2012 EU-SKIP-NMD Agreement (DMD)
Accounts, Notes, Loans and Financing Receivable [Line Items]
U.S. and E.U. governments contract revenue	536		599
Children's National Medical Center
Accounts, Notes, Loans and Financing Receivable [Line Items]
U.S. and E.U. governments contract revenue	674		674
Other Agreements
Accounts, Notes, Loans and Financing Receivable [Line Items]
U.S. and E.U. governments contract revenue		$ 13	$ 427	$ 99