Government Contracts - Additional Information (Detail) (USD $)	3 Months Ended								12 Months Ended			0 Months Ended	1 Months Ended
	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012	Aug. 29, 2012	Nov. 30, 2012	Jul. 31, 2013
Contract Revenue [Line Items]
Agreement revenue	$ 27,000	$ 1,059,000	$ 2,583,000	$ 6,088,000	$ 2,626,000	$ 4,168,000	$ 2,951,000	$ 4,474,000	$ 9,757,000	$ 14,219,000	$ 37,329,000
July 2010 Agreement (Ebola and Marburg Intravenous Administration) [Member]
Contract Revenue [Line Items]
Number of segments									4
Period of performance spanning									4 years
Agreement revenue									6,816,000	9,064,000	36,557,000
Marburg [Member]
Contract Revenue [Line Items]
Remaining portion of contract, expiration date									2014-07
June 2010 Agreement (H1N1/Influenza) [Member]
Contract Revenue [Line Items]
Indirect rate adjustment										400,000
August 2012 Agreement (Intramuscular administration) [Member]
Contract Revenue [Line Items]
Agreement revenue										2,791,000	673,000
Advance payments received on contracts awarded												3,900,000
European Union SKIP-NMD Agreement (DMD) [Member]
Contract Revenue [Line Items]
Agreement revenue									1,432,000	1,263,000
Agreement amount													2,500,000
Children's National Medical Center Agreement (DMD) [Member]
Contract Revenue [Line Items]
Agreement revenue									659,000	674,000
Agreement amount														1,300,000
Carolinas Medical Center Agreement (DMD) [Member]
Contract Revenue [Line Items]
Agreement revenue									$ 850,000