Government Contracts - Additional Information (Detail) (USD $) In Millions, unless otherwise specified	12 Months Ended	1 Months Ended	12 Months Ended		12 Months Ended	0 Months Ended	1 Months Ended	12 Months Ended
	Dec. 31, 2013 July 2010 Agreement (Ebola and Marburg IV) Segment	Jul. 31, 2013 Children's National Medical Center	Dec. 31, 2013 Children's National Medical Center	Dec. 31, 2013 Phase two three four Marburg	Dec. 31, 2013 June 2010 Agreement (H1N1/Influenza)	Aug. 29, 2012 August 2012 Agreement (Intramuscular administration)	Nov. 30, 2012 November 2012 SKIP-NMD Agreement (DMD)	Dec. 31, 2013 November 2012 SKIP-NMD Agreement (DMD)
Accounts, Notes, Loans and Financing Receivable [Line Items]
Number of segments	4
Period of performance spanning	4 years
Estimated funding				$ 84.4
Indirect rate adjustment					0.4
Advance payments received on contracts awarded						3.9		1.3
Agreement amount		1.3					2.5
Agreement revenue			$ 0.7