Note 14 - Warrant Liabilities - Warrant Liabilities (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022	Jun. 30, 2023	Dec. 31, 2022	Jun. 30, 2022	Dec. 31, 2021
Warrant liabilities as of the closing date	$ 0	$ 1,280	$ 0	$ 1,280	$ 13	$ 185	$ 257	$ 2,039
Change in fair value of warrants	(13)	1,023	(185)	(759)
Investor Warrants Issued in Connection with 2021 Financing [Member]
Warrant liabilities as of the closing date	0	782	0	782	12	86	167	964
Change in fair value of warrants	(12)	615	(86)	(182)
Placement Agent Warrants Issued in Connection with 2021 Financing [Member]
Warrant liabilities as of the closing date	0	106	0	106	1	9	22	132
Change in fair value of warrants	(1)	84	(9)	(26)
Investor Warrants Issued in Connection with 2020 Financing [Member]
Warrant liabilities as of the closing date	0	328	0	328	0	76	57	795
Change in fair value of warrants	0	271	(76)	(467)
Placement Agent Warrants Issued in Connection with 2020 Financing [Member]
Warrant liabilities as of the closing date	0	64	0	64	$ 0	$ 14	$ 11	$ 148
Change in fair value of warrants	$ 0	$ 53	$ (14)	$ (84)