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Note 2 - Summary of Significant Accounting Policies (Details Textual) - USD ($) $ in Thousands | 3 Months Ended |  |
--- | --- | --- | ---
Jun. 30, 2024 | Dec. 31, 2023 | Dec. 31, 2022
Investment Plan, Maximum Amount. Approved |  |  | $ 20,000
Inventory, Net | $ 462 | $ 439 |
Equipment Constructed for Resale [Member] |  |  |
Inventory, Net | 197 | 207 |
Spare Parts [Member] |  |  |
Inventory, Net | 265 | 232 |
In Process Equipment [Member] |  |  |
Inventory, Net | $ 613 | $ 618 |
Minimum [Member] |  |  |
Debt Securities, Held-to-maturity, Maturity Term (Month) | 3 months |  |
Maximum [Member] |  |  |
Debt Securities, Held-to-maturity, Maturity Term (Month) | 36 months |  |
Asset Pledged as Collateral [Member] | Letter of Credit [Member] |  |  |
Restricted Cash and Investments | $ 720 |  |
Asset Pledged as Collateral [Member] | Letter of Credit [Member] | Varying Maturity Dates Expiring No Later Than June 30, 2025 [Member] |  |  |
Restricted Cash and Investments | 347 |  |
Asset Pledged as Collateral [Member] | Letter of Credit [Member] | Varying Maturity Dates Expiring No Later Than February 9, 2026 [Member] |  |  |
Restricted Cash and Investments | $ 373 |  |

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