Note 13 - Fair Value Measurement - Fair Value of Liabilities on Recurring Basis (Details) - Fair Value, Recurring [Member] - USD ($) $ in Thousands	Mar. 31, 2022	Dec. 31, 2021
Total liabilities at fair value as of March 31, 2022 - Derivative warrant liability	$ 429
Total liabilities at fair value as of December 31, 2021 - Derivative warrant liability		$ 258
Fair Value, Inputs, Level 1 [Member]
Total liabilities at fair value as of March 31, 2022 - Derivative warrant liability	0
Total liabilities at fair value as of December 31, 2021 - Derivative warrant liability		0
Fair Value, Inputs, Level 2 [Member]
Total liabilities at fair value as of March 31, 2022 - Derivative warrant liability	0
Total liabilities at fair value as of December 31, 2021 - Derivative warrant liability		0
Fair Value, Inputs, Level 3 [Member]
Total liabilities at fair value as of March 31, 2022 - Derivative warrant liability	$ 429
Total liabilities at fair value as of December 31, 2021 - Derivative warrant liability		$ 258