Note 6 - Fair Value Measurements - Carrying Amount of Assets and Liabilities (Details) - Fair Value, Recurring [Member] - USD ($) $ in Thousands	Mar. 31, 2022	Dec. 31, 2021
Balance	$ 5,410	$ 12,818
Derivative Warrant Liability [Member]
Liability	5,410	12,818
Fair Value, Inputs, Level 1 [Member]
Balance	0	0
Fair Value, Inputs, Level 1 [Member] | Derivative Warrant Liability [Member]
Liability	0	0
Fair Value, Inputs, Level 2 [Member]
Balance	0	0
Fair Value, Inputs, Level 2 [Member] | Derivative Warrant Liability [Member]
Liability	0	0
Fair Value, Inputs, Level 3 [Member]
Balance	5,410	12,818
Fair Value, Inputs, Level 3 [Member] | Derivative Warrant Liability [Member]
Liability	$ 5,410	$ 12,818