Contract Revenue - Additional Information (Detail) (USD $)	3 Months Ended		6 Months Ended		395 Months Ended	1 Months Ended	6 Months Ended	3 Months Ended		6 Months Ended			1 Months Ended	3 Months Ended		6 Months Ended
	Jun. 30, 2013	Jun. 30, 2012	Jun. 30, 2013	Jun. 30, 2012	Jun. 30, 2013	Nov. 30, 2012 European Union Agreement	Jun. 30, 2013 European Union Agreement	Jun. 30, 2013 July 2010 Contract (Ebola and Marburg IV)	Jun. 30, 2012 July 2010 Contract (Ebola and Marburg IV)	Jun. 30, 2013 July 2010 Contract (Ebola and Marburg IV) Segment	Jun. 30, 2012 July 2010 Contract (Ebola and Marburg IV)	Jun. 30, 2013 Phase two three four Marburg	Aug. 29, 2012 August 2012 Contract (Intramuscular administration)	Jun. 30, 2013 Other Agreements	Jun. 30, 2012 Other Agreements	Jun. 30, 2013 Other Agreements	Jun. 30, 2012 Other Agreements
Accounts, Notes, Loans and Financing Receivable [Line Items]
Number of segments										4
Period of performance spanning								4 years		4 years
Estimated funding												$ 84,400,000
Advance payments received on contracts awarded							1,300,000						3,900,000
U.S. governments contract revenue	2,951,000	11,207,000	7,425,000	22,419,000	180,973,000			2,076,000	11,171,000	4,690,000	22,334,000			427,000	36,000	427,000	85,000
Aggregate amount for research granted						2,500,000	64,000
Aggregate potential funding period						3 years
Deferred revenue							$ 1,200,000