Note 17 - Equity Offerings - Summary of Sales Under Offering (Details) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Apr. 28, 2017
Average price per share (in dollars per share)			$ 1.00
Net Proceeds	$ 13,478	$ 0
The 2019 ATM Offering [Member]
Total shares of common stock sold (in shares)	6,687,846	1,374,686
Average price per share (in dollars per share)	$ 1.73	$ 5.23
Gross proceeds	$ 11,558	$ 7,193
Commissions earned by Cantor	347	212
Net Proceeds	$ 11,211	$ 6,981
The 2020 ATM Offering [Member]
Total shares of common stock sold (in shares)	16,320,793
Average price per share (in dollars per share)	$ 0.58
Gross proceeds	$ 9,264
Commissions earned by Cantor	278
Net Proceeds	$ 8,986