Note 7 - Embedded Derivatives Liabilities - Schedule of Shares Issued Upon Exercise of Warrants (Details) - $ / shares		9 Months Ended
		Sep. 30, 2021	Dec. 31, 2019
Shares Underlying Warrants (in shares)		97,734	30,315,986
Shares Issued (in shares)		30,218,252
Series K Warrants [Member]
Warrant, Issuance Date		Feb. 17, 2017
Warrants, Expiration date		Feb. 17, 2022
Warrant Exercise Price (in dollars per share)		$ 2.00
Shares Underlying Warrants (in shares)		7,126	315,986
Shares Issued (in shares)		308,860
The Series 2020 A Warrants [Member]
Warrant, Issuance Date	[1]	Jul. 06, 2020
Warrants, Expiration date	[1]	Jul. 06, 2025
Warrant Exercise Price (in dollars per share)	[1]	$ 0.60
Shares Underlying Warrants (in shares)	[1]	90,608	30,000,000
Shares Issued (in shares)	[1]	29,909,392

[1] The Series 2020-A Warrants are equity-classified warrants.