Note 6 - Fair Value (Details Textual) - USD ($) $ / shares in Units, $ in Thousands			9 Months Ended	12 Months Ended
	Feb. 24, 2020	Apr. 28, 2017	Sep. 30, 2021	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019	Mar. 31, 2020
Business Combination, Contingent Consideration Arrangements, Change in Amount of Contingent Consideration, Liability				$ (1,565)	$ 2,924	$ (9,553)
Number of Units Sold (in shares)		24,900,000
Number of Shares in Each Unit (in shares)		0.077
Shares Issued, Price Per Share (in dollars per share)		$ 1.00
Stock issued During Period, Value, Exchange of Shares for Warrants					$ 2,470
Share-based Compensation Arrangement by Share-based Payment Award, Non-Option Equity Instruments, Outstanding, Number, Ending Balance (in shares)					46,498,909
Fair Value Adjustment of Warrants			$ 2,000	$ 1,981	$ 336	$ (2,248)
Series A Warrant [Member]
Class of Warrant or Right, Number of Securities Called by Each Warrant or Right (in shares)		0.077
Class of Warrant or Right, Exercise Price of Warrants or Rights (in dollars per share)		$ 13.00
Series B Warrant [Member]
Class of Warrant or Right, Number of Securities Called by Each Warrant or Right (in shares)		0.058
Class of Warrant or Right, Exercise Price of Warrants or Rights (in dollars per share)	$ 0.35	$ 13.00		$ 0.35			$ 0.35
Class of Warrant or Right, Outstanding (in shares)	3,638,780			567,660
Share-based Compensation Arrangement by Share-based Payment Award, Non-Option Equity Instruments, Outstanding, Number, Ending Balance (in shares)					567,660
Series B Warrant [Member] | Exchange Agreement [Member]
Class of Warrant or Right, Number of Securities Called by Each Warrant or Right (in shares)	0.61
Class of Warrant or Right, Outstanding (in shares)	3,373,900
Stock issued During Period, Shares, Exchange of Shares for Warrants (in shares)	2,040,757
Stock issued During Period, Value, Exchange of Shares for Warrants	$ 2,500