Note 16 - The Financing and Warrant Liabilities - Warrant Liabilities (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020		Dec. 31, 2019		Dec. 14, 2020		Dec. 31, 2018
Proceeds allocated to warrant liabilities	$ 1,505		$ 107		$ 2,051		$ 606
Change in fair value of warrants	(653)		(499)
Investor Warrants Issued in Connection with 2020 Financing [Member]
Proceeds allocated to warrant liabilities	1,279			[1]	1,746			[1]
Change in fair value of warrants	(467)			[1]
Placement Agent Warrants Issued in Connection with 2020 Financing [Member]
Proceeds allocated to warrant liabilities	224			[1]	305			[1]
Change in fair value of warrants	(81)			[1]
Investor Warrants Issued in Connection with 2018 Financing [Member]
Proceeds allocated to warrant liabilities		[2]	71			[1]	503
Change in fair value of warrants	(71)		(432)
Placement Agent Warrants Issued in Connection with 2018 Financing [Member]
Proceeds allocated to warrant liabilities	2	[3]	36				$ 103
Change in fair value of warrants	$ (34)		$ (67)

[1] Not applicable.

[2] The investor warrants issued in the 2018 Financing had expired during the year ended December 31, 2020.

[3] The placement agent warrants issued in the 2018 Financing with an original termination date on January 18, 2021 was subsequently extended to July 18, 2021 on January 18, 2021.