Note 6 - Fair Value Measurements (Details Textual) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2022 USD ($)	Jun. 30, 2021 USD ($)	Jun. 30, 2022 USD ($)	Jun. 30, 2021 USD ($)
Asset Impairment Charges, Total	$ 0	$ 0	$ 0	$ 0
Fair Value, Inputs, Level 3 [Member] | Measurement Input, Share Price [Member]
Warrants and Rights Outstanding, Measurement Input	2.43		2.43
Fair Value, Inputs, Level 3 [Member] | Measurement Input, Risk Free Interest Rate [Member]
Warrants and Rights Outstanding, Measurement Input	0.0301		0.0301
Fair Value, Inputs, Level 3 [Member] | Measurement Input, Expected Term [Member]
Warrants and Rights Outstanding, Measurement Input	5.0		5.0
Fair Value, Inputs, Level 3 [Member] | Measurement Input, Price Volatility [Member]
Warrants and Rights Outstanding, Measurement Input	0.83		0.83