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SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - Narrative (Details) $ in Millions | 3 Months Ended | 12 Months Ended | 49 Months Ended
--- | --- | --- | ---
Mar. 31, 2025 USD ($) company segment | Mar. 31, 2024 company | Mar. 31, 2025 USD ($) company | Dec. 31, 2024 USD ($) | Mar. 31, 2025 USD ($)
Schedule of Investments [Line Items] |  |  |  |  |
Concentration risk, percentage (as a percent) | 100.00% |  |  | 100.00% |
Cash equivalents | $ | $ 15.5 |  | $ 15.5 | $ 14.4 | $ 15.5
Cash balances exceeded federal deposit insurance corporation insurance protection levels | $ | $ 22.8 |  | $ 22.8 | $ 13.5 | $ 22.8
Percentage of total investment income, attributable to noncash paid-in-kind interest income (as a percent) | 5.80% | 4.50% |  |  |
Percentage of total investment income, attributable to noncash cumulative dividend income (as a percent) | 0.20% | 0.10% |  |  |
Percentage of total investment income, attributable to interest income, debt investments, net (as a percent) | 2.30% | 2.50% |  |  |
Number of reportable segments | segment | 1 |  |  |  |
Investment Owned, At Fair Value | Investment Type Concentration Risk |  |  |  |  |
Schedule of Investments [Line Items] |  |  |  |  |
Concentration risk, percentage (as a percent) | 100.00% |  |  | 100.00% |
Investment Owned, At Fair Value | Investment Type Concentration Risk | Nonperforming Financial Instruments |  |  |  |  |
Schedule of Investments [Line Items] |  |  |  |  |
Concentration risk, percentage (as a percent) | 2.80% |  |  | 1.50% |
Investment Owned, At Cost | Investment Type Concentration Risk |  |  |  |  |
Schedule of Investments [Line Items] |  |  |  |  |
Concentration risk, percentage (as a percent) | 100.00% |  |  | 100.00% |
Investment Owned, At Cost | Investment Type Concentration Risk | Nonperforming Financial Instruments |  |  |  |  |
Schedule of Investments [Line Items] |  |  |  |  |
Concentration risk, percentage (as a percent) | 6.10% |  |  | 5.60% |
Private Loan portfolio investments |  |  |  |  |
Schedule of Investments [Line Items] |  |  |  |  |
Consultation period subsequent to initial investment | 12 months |  |  |  |
Investment company, number of portfolio companies with annual third-party appraisal was obtained, reviewed and certified | company | 13 | 14 | 63 |  |
Percentage of portfolio with annual third-party appraisal was obtained, reviewed and certified (as a percent) |  |  |  |  | 96.00%
Private Loan portfolio investments | Investment Owned, At Fair Value | Investment Type Concentration Risk |  |  |  |  |
Schedule of Investments [Line Items] |  |  |  |  |
Concentration risk, percentage (as a percent) | 26.00% | 21.00% | 88.00% |  |
LMM portfolio investments |  |  |  |  |
Schedule of Investments [Line Items] |  |  |  |  |
Consultation period subsequent to initial investment | 12 months |  |  |  |
Investment company, number of portfolio companies with annual third-party appraisal was obtained, reviewed and certified | company | 12 | 12 | 48 |  |
Percentage of portfolio with annual third-party appraisal was obtained, reviewed and certified (as a percent) |  |  | 99.00% |  |
LMM portfolio investments | Investment Owned, At Fair Value | Investment Type Concentration Risk |  |  |  |  |
Schedule of Investments [Line Items] |  |  |  |  |
Concentration risk, percentage (as a percent) | 26.00% | 26.00% | 95.00% |  |
Middle Market portfolio investments |  |  |  |  |
Schedule of Investments [Line Items] |  |  |  |  |
Percentage of portfolio investments containing limited consultation with financial advisory services firm (as a percent) | 91.00% |  | 91.00% | 93.00% | 91.00%
Middle Market portfolio investments | Investment Owned, At Fair Value | Investment Type Concentration Risk |  |  |  |  |
Schedule of Investments [Line Items] |  |  |  |  |
Concentration risk, percentage (as a percent) | 2.40% |  |  | 3.30% |
Middle Market portfolio investments | Investment Owned, At Cost | Investment Type Concentration Risk |  |  |  |  |
Schedule of Investments [Line Items] |  |  |  |  |
Concentration risk, percentage (as a percent) | 3.40% |  |  | 5.80% |
Other Portfolio investments | Investment Owned, At Fair Value | Investment Type Concentration Risk |  |  |  |  |
Schedule of Investments [Line Items] |  |  |  |  |
Concentration risk, percentage (as a percent) | 1.80% |  |  | 2.00% |
Other Portfolio investments | Investment Owned, At Cost | Investment Type Concentration Risk |  |  |  |  |
Schedule of Investments [Line Items] |  |  |  |  |
Concentration risk, percentage (as a percent) | 1.40% |  |  | 1.60% |

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