Note 3 - Fair Value Measurements - Fair Value Hierarchy on a Recurring Basis (Details) - USD ($) $ in Thousands	Jun. 30, 2022	Dec. 31, 2021
Derivative liability - Warrants	$ 547	$ 899
Fair Value, Recurring [Member]
Derivative liability - Warrants	899
Total liabilities	899
Fair Value, Recurring [Member] | Fair Value, Inputs, Level 1 [Member]
Derivative liability - Warrants	0
Total liabilities	0
Fair Value, Recurring [Member] | Fair Value, Inputs, Level 2 [Member]
Derivative liability - Warrants	0
Total liabilities	0
Fair Value, Recurring [Member] | Fair Value, Inputs, Level 3 [Member]
Derivative liability - Warrants	899
Total liabilities	$ 899