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Subsequent Events - Additional Information (Details) - USD ($) $ / shares in Units, $ in Thousands |  |  |  |  | 12 Months Ended |  |  |  |  |
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Feb. 27, 2025 | Jan. 24, 2025 | Jan. 18, 2025 | Jan. 14, 2025 | Dec. 31, 2024 | Dec. 31, 2023 | Dec. 31, 2022 | Dec. 31, 2021 | Feb. 13, 2025 | Feb. 06, 2025 | Feb. 05, 2025 | Jan. 07, 2025 | Jan. 06, 2025
Subsequent Event [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Investments at cost |  |  |  |  |  | $ 1,075,157 | [1],[2],[3] | $ 936,629 | [4],[5],[6] |  |  |  |  |  |  |
Investment, Type [Extensible Enumeration] |  |  |  |  |  | Pfanstiehl Inc [Member] |  | Pfanstiehl Inc [Member] |  |  |  |  |  |  |  |
Total net realized gain (loss) on investments |  |  |  |  |  | $ 11,585 |  | $ 24,071 |  | $ 65,635 | $ 65,635 |  |  |  |  |
Repayment of SBA debentures |  |  |  |  |  | $ 35,000 |  | $ 5,000 |  |  | $ 30,000 |  |  |  |  |
Weighted average interest rate |  |  |  |  |  | 4.599% |  | 4.346% |  | 4.037% |  |  |  |  |  |
SBA Debentures |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Subsequent Event [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Weighted average interest rate |  |  |  |  |  | 4.316% |  | 4.226% |  | 3.479% |  |  |  |  |  |
SBA Debentures | Subsequent Events |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Subsequent Event [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Repayment of SBA debentures |  | $ 12,500 |  |  |  |  |  |  |  |  |  |  |  |  |  |
Weighted average interest rate |  | 5.755% |  |  |  |  |  |  |  |  |  |  |  |  |  |
SBA Debentures | Subsequent Events | Minimum |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Subsequent Event [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Maturity date |  | 2032-03 |  |  |  |  |  |  |  |  |  |  |  |  |  |
SBA Debentures | Subsequent Events | Maximum |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Subsequent Event [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Maturity date |  | 2033-09 |  |  |  |  |  |  |  |  |  |  |  |  |  |
5.207% Fixed Interest Rate | SBA Debentures | Subsequent Events |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Subsequent Event [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Debt instrument issued amount |  |  |  |  |  |  |  |  |  |  |  |  | $ 5,000 |  |  |
Debt instrument interim interest rate |  |  |  |  |  |  |  |  |  |  |  |  | 5.207% |  |  |
5.217% Fixed Interest Rate | SBA Debentures | Subsequent Events |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Subsequent Event [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Debt instrument issued amount |  |  |  |  |  |  |  |  |  |  |  | $ 14,500 |  |  |  |
Debt instrument interim interest rate |  |  |  |  |  |  |  |  |  |  |  | 5.217% |  |  |  |
First Lien Debt |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Subsequent Event [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Investments at cost | [7] |  |  |  |  | $ 729,084 |  | $ 577,684 |  |  |  |  |  |  |  |
First Lien Debt | Subsequent Events |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Subsequent Event [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Investment, Type [Extensible Enumeration] |  |  |  |  |  |  |  |  |  |  |  |  |  | Fraser Steel LLC | Onsight Industries, LLC | Customer Expressions Corp
Common Equity | Subsequent Events |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Subsequent Event [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Investment, Type [Extensible Enumeration] |  |  |  |  |  |  |  |  |  |  |  |  |  | Fraser Steel LLC | Onsight Industries, LLC | Customer Expressions Corp
Preferred Equity [Member] | Subsequent Events |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Subsequent Event [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Investment, Type [Extensible Enumeration] |  |  |  |  |  |  |  |  |  |  |  |  |  | Fraser Steel LLC |  |
Customer Expressions Corp | First Lien Debt | Subsequent Events |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Subsequent Event [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Investments at cost |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | $ 15,000
Customer Expressions Corp | Common Equity | Subsequent Events |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Subsequent Event [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Investments at cost |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | $ 750
Onsight Industries, LLC | First Lien Debt | Subsequent Events |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Subsequent Event [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Investments at cost |  |  |  |  |  |  |  |  |  |  |  |  |  |  | $ 19,000 |
Onsight Industries, LLC | Common Equity | Subsequent Events |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Subsequent Event [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Investments at cost |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 380 |
Onsight Industries, LLC | Revolving Loan | Subsequent Events | Maximum |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Subsequent Event [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Investment commitment amount |  |  |  |  |  |  |  |  |  |  |  |  |  |  | $ 2,280 |
Healthfuse, LLC | Subsequent Events |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Subsequent Event [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Investment, Type [Extensible Enumeration] |  |  |  |  | Preferred Equity [Member] |  |  |  |  |  |  |  |  |  |  |
Total net realized gain (loss) on investments |  |  |  |  | $ 3,171 |  |  |  |  |  |  |  |  |  |  |
Medsurant Holdings, LLC | Subsequent Events |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Subsequent Event [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Total net realized gain (loss) on investments |  |  | $ 8,216 |  |  |  |  |  |  |  |  |  |  |  |  |
Fraser Steel LLC | First Lien Debt | Subsequent Events |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Subsequent Event [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Investments at cost |  |  |  |  |  |  |  |  |  |  |  |  |  | $ 14,000 |  |
Fraser Steel LLC | Common Equity | Subsequent Events |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Subsequent Event [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Investments at cost |  |  |  |  |  |  |  |  |  |  |  |  |  | 500 |  |
Fraser Steel LLC | Revolving Loan | Subsequent Events | Maximum |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Subsequent Event [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Investment commitment amount |  |  |  |  |  |  |  |  |  |  |  |  |  | 2,000 |  |
Fraser Steel LLC | Preferred Equity [Member] | Subsequent Events |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Subsequent Event [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Investments at cost |  |  |  |  |  |  |  |  |  |  |  |  |  | $ 140 |  |
Regular Dividends | Subsequent Events |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Subsequent Event [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Dividends to stockholders |  |  |  | $ 0.43 |  |  |  |  |  |  |  |  |  |  |  |
Supplemental Dividends | Subsequent Events |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Subsequent Event [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Dividends to stockholders |  |  |  | $ 0.11 |  |  |  |  |  |  |  |  |  |  |  |
Quarterly Dividends | Subsequent Events |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Subsequent Event [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Dividend payable date |  |  |  | Mar. 27, 2025 |  |  |  |  |  |  |  |  |  |  |  |
Dividend record date |  |  |  | Mar. 20, 2025 |  |  |  |  |  |  |  |  |  |  |  |
[1] | (a) See Note 3 to the consolidated financial statements for portfolio composition by geographic location.
[2] | (b) Equity ownership may be held in shares or units of companies related to the portfolio companies. The Company’s investments are generally classified as “restricted securities”, unless otherwise noted, as such term is defined under Regulation S-X Rule 6-03(f) or Securities Act Rule 144. As of December 31, 2024, the Company held restricted securities with an aggregate fair value of $1,090,506, or 166% of the Company's net assets.
[3] | (c) All debt investments are income producing, unless otherwise indicated. Equity investments are non-income producing unless otherwise noted.
[4] | (a) See Note 3 to the consolidated financial statements for portfolio composition by geographic location.
[5] | (b) Equity ownership may be held in shares or units of companies related to the portfolio companies.
[6] | (c) All debt investments are income producing, unless otherwise indicated. Equity investments are non-income producing unless otherwise noted.
[7] | Includes unitranche investments, which account for 39.9% and 40.4% of our portfolio on a fair value and cost basis as of December 31, 2024, respectively. Includes unitranche investments, which account for 37.6% and 38.5% of our portfolio on a fair value and cost basis as of December 31, 2023, respectively.

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