Note 3 - Collaborative and Other Research and Development Contracts (Details Textual) - USD ($)				1 Months Ended			9 Months Ended	52 Months Ended	54 Months Ended
	Sep. 06, 2018	Jun. 16, 2015	Feb. 28, 2006	Sep. 30, 2013	Jun. 30, 2006	Jun. 30, 2000	Sep. 30, 2019	Sep. 30, 2019	Sep. 30, 2019	Mar. 31, 2015	Nov. 11, 2011
Centers for Disease Control and Prevention [Member]
Collaborative Agreement Contract Value	$ 34,660
Contract Term	5 years
CSL Limited [Member
Proceeds from License Fees Received		$ 33,740,000
Milestone Payment Received								$ 12,000,000
Royalty Term		10 years
Base Contract [Member]
Government Contract Receivable										$ 16,265,000
Additional Development Options [Member]
Government Contract Receivable										22,855,000
ASPRBARDA Contract [Member]
Government Contract Receivable										$ 39,120,000
Proceeds from awards for Research and Development Contracts									$ 20,574,000
Green Cross Corporation [Member]
Proceeds from License Fees Received					$ 250,000
Mundipharma [Member]
Upfront Payments Receivable Amount			$ 10,000,000
Potential Milestone Payments Receivable											$ 15,000,000
AECOM and IRL [Member]
Milestone Payment Minimum						$ 1,400,000
Milestone Payment Maximum						4,000,000
Annual License Fee Minimum						150,000
Annual License Fee Maximum						$ 500,000
Advance Notice Period for Termination of Agreement						60 days
National Institute of Allergy and Infectious Diseases [Member]
Collaborative Agreement Contract Value				$ 5,000,000
Expected Receivable From Awards for Research and Development Contracts							$ 43,035,000
UAB [Member]
Period of Agreement							25 years
Renewable Period of Agreement							5 years