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Note 2 - Basis of Presentation and Significant Accounting Policies (Details Textual) - USD ($) $ / shares in Units, $ in Thousands |  |  | 6 Months Ended | 12 Months Ended | 44 Months Ended |  |  |
--- | --- | --- | --- | --- | --- | --- | --- | ---
Jun. 02, 2023 | Mar. 14, 2022 | Dec. 31, 2024 | Dec. 31, 2024 | Dec. 31, 2023 | Dec. 31, 2022 | Dec. 31, 2024 | Apr. 26, 2024 | Sep. 22, 2023 | Aug. 02, 2021
Investments, Nonaccrual, Interest Income |  |  | $ 200 |  | $ 0 | $ 0 |  |  |  |
Investment, Income Attributable to Non-cash Paid-in-Kind Interest, Percent |  |  |  | 3.30% | 7.40% |  |  |  |  |
Interest Income, Operating, Paid in Kind |  |  |  | $ 3,261 | $ 8,433 | $ (0) |  |  |  |
Investment, Nonaccrual, Income Not Received in Cash, Percent |  |  |  | 5.60% | 4.20% | 7.40% |  |  |  |
Debt Issuance Costs, Net |  |  | 8,900 | $ 8,900 | $ 5,800 |  | $ 8,900 |  |  |
Accumulated Amortization, Debt Issuance Costs |  |  | $ 7,200 | 7,200 | 6,900 |  | $ 7,200 |  |  |
Amortization of Debt Issuance Costs |  |  |  | 1,783 | 1,852 | $ 1,604 |  |  |  |
Adjustments to Additional Paid in Capital, Non-deductible Excise Taxes Paid |  |  |  | $ 1,500 | 1,500 | 700 |  |  |  |
Federal Excise Tax, Percent |  |  | 4.00% | 4.00% |  |  | 4.00% |  |  |
Excise and Sales Taxes |  |  |  | $ 1,500 | 1,500 | 700 |  |  |  |
Unrecognized Tax Benefits, Ending Balance |  |  | $ 0 | $ 0 | 0 |  | $ 0 |  |  |
Open Tax Year |  |  |  | 2024 2023 2022 2021 |  |  |  |  |  |
Proceeds from Issuance of Common Stock |  |  |  | $ 66,353 | $ 65,093 | $ 84,603 |  |  |  |
Share Repurchase Program, Remaining Authorized, Amount |  |  |  |  |  |  |  | $ 5,000 |  |
Stock Repurchased During Period, Shares (in shares) |  |  |  | 0 | 0 | 0 | 167,465 |  |  |
Stock Repurchased During Period, Per Share (in dollars per share) |  |  |  |  |  |  | $ 11.22 |  |  |
Stock Repurchased During Period, Value |  |  |  |  |  |  | $ 1,900 |  |  |
The 2021 Equity Distribution Agreement [Member] |  |  |  |  |  |  |  |  |  |
Equity Sales Agreement, Maximum Value |  |  |  |  |  |  |  |  |  | $ 100,000
Equity Sales Agreement, Remaining Amount Available for Issuance |  |  |  |  |  |  |  |  | $ 0 |
Stock Issued During Period, Shares, New Issues (in shares) |  |  |  |  |  | 3,982,684 |  |  |  |
Proceeds from Issuance of Common Stock |  |  |  |  |  | $ 50,300 |  |  |  |
Payments of Stock Issuance Costs |  |  |  |  |  | $ 1,000 |  |  |  |
The 2023 Equity Distribution Agreement [Member] |  |  |  |  |  |  |  |  |  |
Equity Sales Agreement, Maximum Value |  |  |  |  |  |  |  |  | $ 150,000 |
Equity Sales Agreement, Remaining Amount Available for Issuance |  |  | 79,000 | $ 79,000 |  |  | 79,000 |  |  |
Stock Issued During Period, Shares, New Issues (in shares) |  |  |  | 6,300,095 |  |  |  |  |  |
Proceeds from Issuance of Common Stock |  |  |  | $ 66,400 |  |  |  |  |  |
Payments of Stock Issuance Costs |  |  |  | 1,400 |  |  |  |  |  |
The 2023 and 2021 Equity Distribution Agreements [Member] |  |  |  |  |  |  |  |  |  |
Stock Issued During Period, Shares, New Issues (in shares) |  |  |  |  | 2,248,830 |  |  |  |  |
Proceeds from Issuance of Common Stock |  |  |  |  | $ 26,200 |  |  |  |  |
Payments of Stock Issuance Costs |  |  |  |  | 700 |  |  |  |  |
Public Offering [Member] |  |  |  |  |  |  |  |  |  |
Stock Issued During Period, Shares, New Issues (in shares) | 3,250,000 | 2,500,000 |  |  |  |  |  |  |  |
Proceeds from Issuance of Common Stock | $ 38,900 | $ 34,300 |  |  |  |  |  |  |  |
Shares Issued, Price Per Share (in dollars per share) | $ 12.5 | $ 14.35 |  |  |  |  |  |  |  |
Four Investments [Member] |  |  |  |  |  |  |  |  |  |
Investments, Cost, Nonaccrual Status |  |  | 44,800 | 44,800 | 72,500 |  | 44,800 |  |  |
Investments, Fair Value, Nonaccrual Status |  |  | $ 10,500 | 10,500 | 27,600 |  | $ 10,500 |  |  |
Two Investments [Member] |  |  |  |  |  |  |  |  |  |
Interest Income, Operating, Paid in Kind |  |  |  | $ 1,800 | $ 3,900 |  |  |  |  |

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