Note 3 - Procurement Contracts and Research Agreements (Details Textual) $ in Thousands		1 Months Ended		3 Months Ended		107 Months Ended
	May 20, 2019 USD ($) shares	Jul. 31, 2019 USD ($)	Aug. 31, 2018 USD ($)	Mar. 31, 2020 USD ($)	Mar. 31, 2019 USD ($)	Mar. 31, 2020 USD ($)	Feb. 29, 2020 USD ($)	Sep. 10, 2018	May 13, 2011 USD ($)
Contract with Customer, Liability, Revenue Recognized				$ 100
The 19C BARDA Contract [Member]
Number of Courses to Be Delivered								1,488,000
Number of Courses Stored As Vendor Managed Inventory								212,000
Government Contract, Value of Award				602,500		$ 602,500
Government Contract, Base Period, Value of Award for Delivery and Support Activities				$ 51,700		51,700
Base Period of Performance (Year)				5 years
Government Contract, Value, Payments Remaining Related to Exercised Options				$ 127,100		127,100
Government Contract, Value, Payments Currently Specified as Unexercised Options				$ 423,700		423,700
Base Period of Performance, Exercise of Options, Term (Year)				10 years
Number of Courses Divided into Procurement-Related Options	363,070
Number of Procurement-related Options, Conversion of Option, Manufacture and Delivery of Courses (in shares) | shares	4
Payments to be Received, Procurement-related Options Providing for Payment for Procurement of Raw Materials	$ 11,200
Number of Procurement-related Options Specifying Delivery of Courses for Consideration (in shares) | shares	3
Courses to be Delivered, Procurement-related Options Specifying Delivery of Courses for Consideration	121,000
Payments to be Received, Procurement-related Options Specifying Delivery of Courses for Consideration	$ 33,800
Payments to be Received, Procurement-related Options	$ 112,500
Government Contract, Base Period, Value of Award for Delivery and Support Activities, Delivery of Courses				$ 11,100		$ 11,100
Government Contract, Base Period, Number of Deliveries				35,700		35,700
Government Contract, Base Period, Value of Award for Delivery and Support Activities, Manufacture of Courses				$ 8,000		$ 8,000
Government Contract, Base Period, Value of Award for Delivery and Support Activities, Advanced Development				32,000		32,000
Government Contract, Base Period, Value of Award for Delivery and Support Activities, Supportive Procurement Activities				600		600
Proceeds from Delivery of Courses				$ 11,100
Number of Courses Delivered				35,700
Proceeds from Other Base Period Activities				$ 4,700
Contract with Customer, Liability, Total				11,200		11,200
Government Contract, Value, Payments Related to Exercised Options, Procurement of Raw Materials				11,200
Government Contract, Value, Payments Related to Exercised Options, Funding of Post-Marketing Activities				14,600		14,600
Proceeds for the Funding of Post-marketing Activities				2,300
Government Contract, Value, Payments Related to Unexercised Options, Funding of Post-Marketing Activities				3,600		3,600
Government Contract, Value of Unexercised Options, Supportive Procurement Activities				5,600		$ 5,600
Number of Procurement-related Options Providing for Payment for Procurement of Raw Materials (in shares) | shares	1
The 19C BARDA Contract [Member] | Transferred over Time [Member]
Contract with Customer, Liability, Revenue Recognized				2,100	$ 1,300
The 19C BARDA Contract [Member] | Transferred at Point in Time [Member]
Contract with Customer, Liability, Revenue Recognized				$ 0	7,100
The 19C BARDA Contract [Member] | IV TPOXX [Member]
Government Contract, Base Period, Number of Courses Manufactured				20,000		20,000
Government Contract, Value, Payments Currently Specified as Unexercised Options, Delivery of Courses				$ 337,700		$ 337,700
Government Contract, Unexercised Options, Number of Deliveries				1,089,000		1,089,000
Number of Manufacturing Steps				2		2
The 19C BARDA Contract [Member] | IV BDS [Member]
Government Contract, Base Period, Value of Award for Delivery and Support Activities, Manufacture of Courses				$ 3,200		$ 3,200
Proceeds from the Manufacture of Courses				3,200
Contract with Customer, Liability, Total				3,200	3,200	3,200
Government Contract, Value, Payments Currently Specified as Unexercised Options, Manufacture of Courses				$ 30,700		$ 30,700
Government Contract, Number of Options for Manufacture of Product				3		3
Government Contract, Courses Manufactured Upon Exercise of Options				64,000		64,000
The 19C BARDA Contract [Member] | Oral TPOXX [Member]
Proceeds from Delivery of Courses				$ 101,300
Number of Courses Delivered				363,070
The 19C BARDA Contract [Member] | IV FDP [Member]
Government Contract, Value, Payments Currently Specified as Unexercised Options, Manufacture of Courses				$ 76,800		$ 76,800
Government Contract, Value, Unexercised Options, Manufacture of Courses				192,000		192,000
Government Contract, Number of Options for Manufacture of Product				3		3
Government Contract, Courses Manufactured Upon Exercise of Options				64,000		64,000
The 2011 BARDA Contract [Member]
Number of Courses to Be Delivered									1,700,000
Government Contract, Value of Award									$ 508,400
Government Contract, Value, Payments Remaining Related to Exercised Options				$ 72,700		$ 72,700
Number of Courses Delivered						1,700,000
Number of Additional Courses to be Delivered at No Additional Cost									300,000
Proceeds from the Manufacture and Delivery of Courses						$ 459,800
Proceeds from Reimbursements in Connection with Development and Supportive Activities						45,100
Amount Eligible to be Received for Reimbursements of Development and Supportive Activities				3,500		3,500
Proceeds from Government Contract Options, Exercised			$ 50,000
Government Contract, Increase (Decrease) in Value of Award, FDA Approval			$ 50,000
Government Contract, Value, Payments Related to Exercised Options, Development and Supportive Activities				58,300		58,300
Government Contract, Value, Payments Related to Exercised Options, Production-related Activities				14,400		14,400
The 2011 BARDA Contract [Member] | Transferred over Time [Member]
Contract with Customer, Liability, Revenue Recognized				100	100
The 2011 BARDA Contract [Member] | Transferred at Point in Time [Member]
Contract with Customer, Liability, Revenue Recognized				0	0
The IV Formulation R & D Contract with BARDA [Member]
Government Contract, Future Aggregate Research and Development Funding				2,600		2,600
The IV Formulation R & D Contract with BARDA [Member] | Transferred over Time [Member]
Contract with Customer, Liability, Revenue Recognized				400	$ 1,900
The PEP Label Expansion R & D Contract with the Department of Defense [Member]
Grants Receivable		$ 19,500					$ 19,500
Government Contract, Initial Award		$ 12,400		19,200		$ 19,200
Government Contract, Term (Year)		5 years
The PEP Label Expansion R & D Contract with the Department of Defense [Member] | Transferred over Time [Member]
Contract with Customer, Liability, Revenue Recognized				$ 100