Revenue from United States and European Union Governments Contracts and Other Revenue (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended		6 Months Ended		395 Months Ended
	Jun. 30, 2013	Jun. 30, 2012	Jun. 30, 2013	Jun. 30, 2012	Jun. 30, 2013
Accounts, Notes, Loans and Financing Receivable [Line Items]
U.S. and E.U. governments contract revenue	$ 2,951	$ 11,207	$ 7,425	$ 22,419	$ 180,973
July 2010 Contract (Ebola and Marburg IV)
Accounts, Notes, Loans and Financing Receivable [Line Items]
U.S. and E.U. governments contract revenue	2,076	11,171	4,690	22,334
August 2012 Contract (Intramuscular)
Accounts, Notes, Loans and Financing Receivable [Line Items]
U.S. and E.U. governments contract revenue	439		2,245
November 2012 SKIP-NMD Agreement (DMD)
Accounts, Notes, Loans and Financing Receivable [Line Items]
U.S. and E.U. governments contract revenue	9		63
Other Agreements
Accounts, Notes, Loans and Financing Receivable [Line Items]
U.S. and E.U. governments contract revenue	$ 427	$ 36	$ 427	$ 85