Note 7 - Embedded Derivatives Liabilities - Schedule of Shares Issued Upon Exercise of Warrants (Details) - $ / shares		9 Months Ended
		Sep. 30, 2020		Aug. 31, 2020	Aug. 25, 2020	Jul. 31, 2020	Jul. 06, 2020	Dec. 31, 2019
Shares Underlying Warrants (in shares)		2,734,198						56,033,028
Series D Warrants (in shares)		53,298,830
Series D Warrants [Member]
Warrant, Issuance Date		Dec. 11, 2015
Warrants, Expiration date		Dec. 11, 2020
Warrant Exercise Price (in dollars per share)		$ 40
Shares Underlying Warrants (in shares)		47						25,125
Series D Warrants (in shares)		25,078
Series F Warrants [Member]
Warrant, Issuance Date		Apr. 01, 2016
Warrants, Expiration date		Apr. 01, 2021
Warrant Exercise Price (in dollars per share)		$ 40
Shares Underlying Warrants (in shares)		14,041						25,733
Series D Warrants (in shares)		11,692
Series I Warrants [Member]
Warrant, Issuance Date		Sep. 13, 2016
Warrants, Expiration date		Sep. 13, 2021
Warrant Exercise Price (in dollars per share)		$ 220
Shares Underlying Warrants (in shares)		35,368						35,368
Series D Warrants (in shares)
Series K Warrants [Member]
Warrant, Issuance Date		Feb. 17, 2017
Warrants, Expiration date		Feb. 17, 2022
Warrant Exercise Price (in dollars per share)		$ 2
Shares Underlying Warrants (in shares)		2,576						311,236
Series D Warrants (in shares)		308,660
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)		2,682,166	[1]			30,000,000		30,000,000	[1]
Series D Warrants (in shares)	[1]	27,317,834
Series 2020 B Warrants [Member]
Warrant, Issuance Date	[1]	Jul. 06, 2020
Warrants, Expiration date	[1]	Jul. 06, 2025
Warrant Exercise Price (in dollars per share)	[1]	$ 0.01
Shares Underlying Warrants (in shares)			[1]			9,103,334	30,000,000	9,103,334	[1]
Series D Warrants (in shares)	[1]	9,103,334
Series 2020C Warrants [Member]
Warrant, Issuance Date	[1]	Aug. 25, 2020
Warrants, Expiration date	[1]	Aug. 25, 2025
Warrant Exercise Price (in dollars per share)		$ 0.01	[1]		$ 0.01
Shares Underlying Warrants (in shares)			[1]	16,532,232	16,532,232			16,532,232	[1]
Series D Warrants (in shares)	[1]	16,532,232

[1] The Series 2020-A, Series 2020-B and Series 2020-C Warrants are equity-classified warrants.