Note 2 - Liquidity (Details Textual) - USD ($)		1 Months Ended	9 Months Ended	12 Months Ended
	Mar. 05, 2021	Mar. 31, 2019	Sep. 30, 2020	Dec. 31, 2019	Dec. 31, 2020
Retained Earnings (Accumulated Deficit), Ending Balance				$ (86,938,163)	$ (102,148,817)
Working Capital					19,400,000
Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents, Ending Balance					22,400,000
Subsequent Event [Member] | Public Offering [Member]
Stock Issued During Period, Shares, New Issues (in shares)	7,875,000
Shares Issued, Price Per Share (in dollars per share)	$ 8
Proceeds from Issuance of Common Stock	$ 63,000,000
Sale of Stock, Option to Purchase Shares (in shares)	1,181,250
JMP Securities, Inc [Member]
Distribution Agreement, Aggregate Sales Price		$ 12,500,000
Distribution Agreement, Amount Available for Sale					$ 10,200,000
Stock Issued During Period, Shares, New Issues (in shares)			0	398,709
Proceeds from Issuance of Common Stock				$ 2,300,000