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Note 9 - Shareholders' Equity (Details Textual) - USD ($) $ / shares in Units, $ in Thousands |  | 3 Months Ended | 6 Months Ended
--- | --- | --- | ---
Apr. 06, 2022 | Jun. 30, 2022 | Jun. 30, 2022 | Jun. 30, 2021
Proceeds from Issuance of Common Stock |  |  | $ 30,000 | $ 0
Stock Issued During Period, Exercise Of Warrants, Shares (in shares) |  | 520,335 |  |
HGC NEXT INV LLC [Member] |  |  |  |
Stock Issued During Period, Shares, New Issues (in shares) | 4,618,226 |  |  |
Share Price (in dollars per share) | $ 6.496 |  |  |
Proceeds from Issuance of Common Stock | $ 30,000 |  |  |

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