Note 7 - Property and Equipment, Net (Details Textual) - USD ($) $ in Millions  | 
3 Months Ended | 6 Months Ended | ||
|---|---|---|---|---|
Jun. 30, 2022  | 
Jun. 30, 2021  | 
Jun. 30, 2022  | 
Jun. 30, 2021  | 
|
| Depreciation, Total | $ 0.1 | $ 0.3 | $ 0.2 | $ 0.5 | 
| X | ||||||||||
- Definition The amount of expense recognized in the current period that reflects the allocation of the cost of tangible assets over the assets' useful lives. Includes production and non-production related depreciation. Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef 
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