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Fair Value Measurements - Valuation Techniques and Significant Unobservable Inputs Used in Recurring Level 3 Fair Value Measurements of Assets and Liabilities (Details) $ in Thousands | Mar. 31, 2024 USD ($) | Dec. 31, 2023 USD ($)
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Fair Value Measurements |  |  |  |
Investments, at fair value | $ 500,889 | [1],[2] | $ 488,386 | [3],[4]
Investments at fair value where valuation (unadjusted) is obtained from third-party pricing service | 1,992 |  | 1,040 |
2026 Notes |  |  |  |
Fair Value Measurements |  |  |  |
Estimated fair value of notes | 120,792 |  | 121,145 |
Senior secured loans |  |  |  |
Fair Value Measurements |  |  |  |
Investments, at fair value | 404,051 |  | 388,882 |
Unitranche secured loans |  |  |  |
Fair Value Measurements |  |  |  |
Investments, at fair value | 6,091 |  | 13,877 |
Junior secured loans |  |  |  |
Fair Value Measurements |  |  |  |
Investments, at fair value | 27,427 |  | 26,594 |
Equity securities |  |  |  |
Fair Value Measurements |  |  |  |
Investments, at fair value | 30,330 |  | 25,911 |
Level 3 | Total Level 3 Assets |  |  |  |
Fair Value Measurements |  |  |  |
Investments, at fair value | 464,887 |  | 453,967 |
Level 3 | Senior secured loans | EBITDA multiples | Discounted cash flow |  |  |  |
Fair Value Measurements |  |  |  |
Investments, at fair value | $ 254,006 |  | $ 238,481 |
Level 3 | Senior secured loans | EBITDA multiples | Discounted cash flow | Weighted Average Mean |  |  |  |
Fair Value Measurements |  |  |  |
Investments, measurement input | 10.4 |  | 10.5 |
Level 3 | Senior secured loans | EBITDA multiples | Discounted cash flow | Minimum |  |  |  |
Fair Value Measurements |  |  |  |
Investments, measurement input | 4.8 |  | 5.0 |
Level 3 | Senior secured loans | EBITDA multiples | Discounted cash flow | Maximum |  |  |  |
Fair Value Measurements |  |  |  |
Investments, measurement input | 22.4 |  | 22.2 |
Level 3 | Senior secured loans | EBITDA multiples | Enterprise value |  |  |  |
Fair Value Measurements |  |  |  |
Investments, at fair value | $ 1,991 |  | $ 4,322 |
Level 3 | Senior secured loans | EBITDA multiples | Enterprise value | Weighted Average Mean |  |  |  |
Fair Value Measurements |  |  |  |
Investments, measurement input | 9.5 |  | 7.3 |
Level 3 | Senior secured loans | EBITDA multiples | Enterprise value | Minimum |  |  |  |
Fair Value Measurements |  |  |  |
Investments, measurement input | 9.5 |  | 5.3 |
Level 3 | Senior secured loans | EBITDA multiples | Enterprise value | Maximum |  |  |  |
Fair Value Measurements |  |  |  |
Investments, measurement input | 9.5 |  | 8.3 |
Level 3 | Senior secured loans | EBITDA Market yields | Discounted cash flow | Weighted Average Mean |  |  |  |
Fair Value Measurements |  |  |  |
Investments, measurement input | 0.131 |  | 0.132 |
Level 3 | Senior secured loans | EBITDA Market yields | Discounted cash flow | Minimum |  |  |  |
Fair Value Measurements |  |  |  |
Investments, measurement input | 0.089 |  | 0.090 |
Level 3 | Senior secured loans | EBITDA Market yields | Discounted cash flow | Maximum |  |  |  |
Fair Value Measurements |  |  |  |
Investments, measurement input | 0.245 |  | 0.245 |
Level 3 | Senior secured loans | Revenue Market yields | Discounted cash flow | Weighted Average Mean |  |  |  |
Fair Value Measurements |  |  |  |
Investments, measurement input | 0.117 |  | 0.119 |
Level 3 | Senior secured loans | Revenue Market yields | Discounted cash flow | Minimum |  |  |  |
Fair Value Measurements |  |  |  |
Investments, measurement input | 0.092 |  | 0.090 |
Level 3 | Senior secured loans | Revenue Market yields | Discounted cash flow | Maximum |  |  |  |
Fair Value Measurements |  |  |  |
Investments, measurement input | 0.173 |  | 0.166 |
Level 3 | Senior secured loans | Revenue multiples | Discounted cash flow |  |  |  |
Fair Value Measurements |  |  |  |
Investments, at fair value | $ 112,692 |  | $ 112,213 |
Level 3 | Senior secured loans | Revenue multiples | Discounted cash flow | Weighted Average Mean |  |  |  |
Fair Value Measurements |  |  |  |
Investments, measurement input | 5.6 |  | 5.6 |
Level 3 | Senior secured loans | Revenue multiples | Discounted cash flow | Minimum |  |  |  |
Fair Value Measurements |  |  |  |
Investments, measurement input | 1.0 |  | 0.9 |
Level 3 | Senior secured loans | Revenue multiples | Discounted cash flow | Maximum |  |  |  |
Fair Value Measurements |  |  |  |
Investments, measurement input | 12.0 |  | 11.8 |
Level 3 | Senior secured loans | Revenue multiples | Enterprise value |  |  |  |
Fair Value Measurements |  |  |  |
Investments, at fair value | $ 8,813 |  | $ 7,054 |
Level 3 | Senior secured loans | Revenue multiples | Enterprise value | Weighted Average Mean |  |  |  |
Fair Value Measurements |  |  |  |
Investments, measurement input | 1.9 |  | 2.5 |
Level 3 | Senior secured loans | Revenue multiples | Enterprise value | Minimum |  |  |  |
Fair Value Measurements |  |  |  |
Investments, measurement input | 0.5 |  | 1.6 |
Level 3 | Senior secured loans | Revenue multiples | Enterprise value | Maximum |  |  |  |
Fair Value Measurements |  |  |  |
Investments, measurement input | 2.4 |  | 2.5 |
Level 3 | Senior secured loans | Book value multiples | Enterprise value |  |  |  |
Fair Value Measurements |  |  |  |
Investments, at fair value | $ 17,784 |  | $ 17,839 |
Level 3 | Senior secured loans | Book value multiples | Enterprise value | Weighted Average Mean |  |  |  |
Fair Value Measurements |  |  |  |
Investments, measurement input | 1.3 |  | 1.3 |
Level 3 | Senior secured loans | Book value multiples | Enterprise value | Minimum |  |  |  |
Fair Value Measurements |  |  |  |
Investments, measurement input | 1.3 |  | 1.3 |
Level 3 | Senior secured loans | Book value multiples | Enterprise value | Maximum |  |  |  |
Fair Value Measurements |  |  |  |
Investments, measurement input | 1.3 |  | 1.3 |
Level 3 | Senior secured loans | Probability weighting of alternative outcomes | Liquidation |  |  |  |
Fair Value Measurements |  |  |  |
Investments, at fair value | $ 8,138 |  | $ 8,352 |
Level 3 | Senior secured loans | Probability weighting of alternative outcomes | Liquidation | Weighted Average Mean |  |  |  |
Fair Value Measurements |  |  |  |
Investments, measurement input | 0.891 |  | 0.917 |
Level 3 | Senior secured loans | Probability weighting of alternative outcomes | Liquidation | Minimum |  |  |  |
Fair Value Measurements |  |  |  |
Investments, measurement input | 0.324 |  | 0.324 |
Level 3 | Senior secured loans | Probability weighting of alternative outcomes | Liquidation | Maximum |  |  |  |
Fair Value Measurements |  |  |  |
Investments, measurement input | 0.923 |  | 0.950 |
Level 3 | Unitranche secured loans | Market yields | Discounted cash flow |  |  |  |
Fair Value Measurements |  |  |  |
Investments, at fair value | $ 2,250 |  | $ 10,126 |
Level 3 | Unitranche secured loans | Market yields | Discounted cash flow | Weighted Average Mean |  |  |  |
Fair Value Measurements |  |  |  |
Investments, measurement input | 0.119 |  | 0.119 |
Level 3 | Unitranche secured loans | Market yields | Discounted cash flow | Minimum |  |  |  |
Fair Value Measurements |  |  |  |
Investments, measurement input | 0.119 |  | 0.119 |
Level 3 | Unitranche secured loans | Market yields | Discounted cash flow | Maximum |  |  |  |
Fair Value Measurements |  |  |  |
Investments, measurement input | 0.119 |  | 0.119 |
Level 3 | Unitranche secured loans | Revenue Market yields | Discounted cash flow | Weighted Average Mean |  |  |  |
Fair Value Measurements |  |  |  |
Investments, measurement input | 0.131 |  | 0.124 |
Level 3 | Unitranche secured loans | Revenue Market yields | Discounted cash flow | Minimum |  |  |  |
Fair Value Measurements |  |  |  |
Investments, measurement input | 0.121 |  | 0.119 |
Level 3 | Unitranche secured loans | Revenue Market yields | Discounted cash flow | Maximum |  |  |  |
Fair Value Measurements |  |  |  |
Investments, measurement input | 0.138 |  | 0.127 |
Level 3 | Unitranche secured loans | Revenue multiples | Discounted cash flow |  |  |  |
Fair Value Measurements |  |  |  |
Investments, at fair value | $ 3,841 |  | $ 3,751 |
Level 3 | Unitranche secured loans | Revenue multiples | Discounted cash flow | Weighted Average Mean |  |  |  |
Fair Value Measurements |  |  |  |
Investments, measurement input | 9.0 |  | 9.0 |
Level 3 | Unitranche secured loans | Revenue multiples | Discounted cash flow | Minimum |  |  |  |
Fair Value Measurements |  |  |  |
Investments, measurement input | 6.0 |  | 6.0 |
Level 3 | Unitranche secured loans | Revenue multiples | Discounted cash flow | Maximum |  |  |  |
Fair Value Measurements |  |  |  |
Investments, measurement input | 12.8 |  | 12.8 |
Level 3 | Junior secured loans | Market yields | Discounted cash flow |  |  |  |
Fair Value Measurements |  |  |  |
Investments, at fair value | $ 21,514 |  | $ 20,661 |
Level 3 | Junior secured loans | Market yields | Discounted cash flow | Weighted Average Mean |  |  |  |
Fair Value Measurements |  |  |  |
Investments, measurement input | 0.131 |  | 0.131 |
Level 3 | Junior secured loans | Market yields | Discounted cash flow | Minimum |  |  |  |
Fair Value Measurements |  |  |  |
Investments, measurement input | 0.127 |  | 0.124 |
Level 3 | Junior secured loans | Market yields | Discounted cash flow | Maximum |  |  |  |
Fair Value Measurements |  |  |  |
Investments, measurement input | 0.154 |  | 0.156 |
Level 3 | Junior secured loans | Revenue Market yields | Discounted cash flow | Weighted Average Mean |  |  |  |
Fair Value Measurements |  |  |  |
Investments, measurement input | 0.176 |  | 0.142 |
Level 3 | Junior secured loans | Revenue Market yields | Discounted cash flow | Minimum |  |  |  |
Fair Value Measurements |  |  |  |
Investments, measurement input | 0.160 |  | 0.133 |
Level 3 | Junior secured loans | Revenue Market yields | Discounted cash flow | Maximum |  |  |  |
Fair Value Measurements |  |  |  |
Investments, measurement input | 0.225 |  | 0.162 |
Level 3 | Junior secured loans | Revenue multiples | Discounted cash flow |  |  |  |
Fair Value Measurements |  |  |  |
Investments, at fair value | $ 2,391 |  | $ 1,419 |
Level 3 | Junior secured loans | Revenue multiples | Discounted cash flow | Weighted Average Mean |  |  |  |
Fair Value Measurements |  |  |  |
Investments, measurement input | 0.7 |  | 0.4 |
Level 3 | Junior secured loans | Revenue multiples | Discounted cash flow | Minimum |  |  |  |
Fair Value Measurements |  |  |  |
Investments, measurement input | 0.2 |  | 0.2 |
Level 3 | Junior secured loans | Revenue multiples | Discounted cash flow | Maximum |  |  |  |
Fair Value Measurements |  |  |  |
Investments, measurement input | 1.0 |  | 0.9 |
Level 3 | Junior secured loans | Revenue multiples | Enterprise value |  |  |  |
Fair Value Measurements |  |  |  |
Investments, at fair value | $ 331 |  | $ 2,340 |
Level 3 | Junior secured loans | Revenue multiples | Enterprise value | Weighted Average Mean |  |  |  |
Fair Value Measurements |  |  |  |
Investments, measurement input | 1.7 |  | 1.6 |
Level 3 | Junior secured loans | Revenue multiples | Enterprise value | Minimum |  |  |  |
Fair Value Measurements |  |  |  |
Investments, measurement input | 1.7 |  | 1.6 |
Level 3 | Junior secured loans | Revenue multiples | Enterprise value | Maximum |  |  |  |
Fair Value Measurements |  |  |  |
Investments, measurement input | 1.7 |  | 1.6 |
Level 3 | Junior secured loans | Probability weighting of alternative outcomes | Liquidation |  |  |  |
Fair Value Measurements |  |  |  |
Investments, at fair value | $ 2,246 |  | $ 2,174 |
Level 3 | Junior secured loans | Probability weighting of alternative outcomes | Liquidation | Weighted Average Mean |  |  |  |
Fair Value Measurements |  |  |  |
Investments, measurement input | 2.698 |  | 2.608 |
Level 3 | Junior secured loans | Probability weighting of alternative outcomes | Liquidation | Minimum |  |  |  |
Fair Value Measurements |  |  |  |
Investments, measurement input | 0.000 |  | 0 |
Level 3 | Junior secured loans | Probability weighting of alternative outcomes | Liquidation | Maximum |  |  |  |
Fair Value Measurements |  |  |  |
Investments, measurement input | 2.698 |  | 2.608 |
Level 3 | Equity securities | EBITDA multiples | Discounted cash flow |  |  |  |
Fair Value Measurements |  |  |  |
Investments, at fair value |  |  | $ 1,380 |
Level 3 | Equity securities | EBITDA multiples | Discounted cash flow | Weighted Average Mean |  |  |  |
Fair Value Measurements |  |  |  |
Investments, measurement input |  |  | 6.0 |
Level 3 | Equity securities | EBITDA multiples | Discounted cash flow | Minimum |  |  |  |
Fair Value Measurements |  |  |  |
Investments, measurement input |  |  | 6.0 |
Level 3 | Equity securities | EBITDA multiples | Discounted cash flow | Maximum |  |  |  |
Fair Value Measurements |  |  |  |
Investments, measurement input |  |  | 6.0 |
Level 3 | Equity securities | EBITDA multiples | Enterprise value |  |  |  |
Fair Value Measurements |  |  |  |
Investments, at fair value | $ 20,905 |  | $ 18,994 |
Level 3 | Equity securities | EBITDA multiples | Enterprise value | Weighted Average Mean |  |  |  |
Fair Value Measurements |  |  |  |
Investments, measurement input | 8.7 |  | 8.8 |
Level 3 | Equity securities | EBITDA multiples | Enterprise value | Minimum |  |  |  |
Fair Value Measurements |  |  |  |
Investments, measurement input | 5.4 |  | 4.9 |
Level 3 | Equity securities | EBITDA multiples | Enterprise value | Maximum |  |  |  |
Fair Value Measurements |  |  |  |
Investments, measurement input | 20.0 |  | 20.5 |
Level 3 | Equity securities | Market yields | Discounted cash flow |  |  |  |
Fair Value Measurements |  |  |  |
Investments, at fair value | $ 842 |  |  |
Level 3 | Equity securities | Market yields | Discounted cash flow | Weighted Average Mean |  |  |  |
Fair Value Measurements |  |  |  |
Investments, measurement input | 0.163 |  |  |
Level 3 | Equity securities | Market yields | Discounted cash flow | Minimum |  |  |  |
Fair Value Measurements |  |  |  |
Investments, measurement input | 0.163 |  |  |
Level 3 | Equity securities | Market yields | Discounted cash flow | Maximum |  |  |  |
Fair Value Measurements |  |  |  |
Investments, measurement input | 0.163 |  |  |
Level 3 | Equity securities | EBITDA Market yields | Discounted cash flow | Weighted Average Mean |  |  |  |
Fair Value Measurements |  |  |  |
Investments, measurement input |  |  | 0.190 |
Level 3 | Equity securities | EBITDA Market yields | Discounted cash flow | Minimum |  |  |  |
Fair Value Measurements |  |  |  |
Investments, measurement input |  |  | 0.163 |
Level 3 | Equity securities | EBITDA Market yields | Discounted cash flow | Maximum |  |  |  |
Fair Value Measurements |  |  |  |
Investments, measurement input |  |  | 0.275 |
Level 3 | Equity securities | Revenue multiples | Enterprise value |  |  |  |
Fair Value Measurements |  |  |  |
Investments, at fair value | $ 4,895 |  | $ 2,701 |
Level 3 | Equity securities | Revenue multiples | Enterprise value | Weighted Average Mean |  |  |  |
Fair Value Measurements |  |  |  |
Investments, measurement input | 3.2 |  | 3.7 |
Level 3 | Equity securities | Revenue multiples | Enterprise value | Minimum |  |  |  |
Fair Value Measurements |  |  |  |
Investments, measurement input | 1.7 |  | 0.9 |
Level 3 | Equity securities | Revenue multiples | Enterprise value | Maximum |  |  |  |
Fair Value Measurements |  |  |  |
Investments, measurement input | 12.0 |  | 11.8 |
Level 3 | Equity securities | Volatility | Option pricing model |  |  |  |
Fair Value Measurements |  |  |  |
Investments, at fair value | $ 2,248 |  | $ 2,160 |
Level 3 | Equity securities | Volatility | Option pricing model | Weighted Average Mean |  |  |  |
Fair Value Measurements |  |  |  |
Investments, measurement input | 0.579 |  | 0.590 |
Level 3 | Equity securities | Volatility | Option pricing model | Minimum |  |  |  |
Fair Value Measurements |  |  |  |
Investments, measurement input | 0.250 |  | 0.350 |
Level 3 | Equity securities | Volatility | Option pricing model | Maximum |  |  |  |
Fair Value Measurements |  |  |  |
Investments, measurement input | 0.725 |  | 0.700 |
[1] | All of the Company’s investments are issued by eligible portfolio companies, as defined in the Investment Company Act of 1940 (the “1940 Act”), unless otherwise noted. All of the Company’s investments are issued by U.S. portfolio companies unless otherwise noted.
[2] | Because there is no readily available market value for these investments, the fair value of these investments is determined in good faith using significant unobservable inputs by the Valuation Designee. (See Note 4 in the accompanying notes to the consolidated financial statements).
[3] | All of the Company's investments are issued by eligible portfolio companies, as defined in the Investment Company Act of 1940 (the “1940 Act”), unless otherwise noted. All of the Company's investments are issued by U.S. portfolio companies unless otherwise noted.
[4] | Because there is no readily available market value for these investments, the fair value of these investments is determined in good faith using significant unobservable inputs by the Valuation Designee. (See Note 4 in the accompanying notes to the consolidated financial statements.)

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