Fair Value of Investments - Quantitative information about the significant unobservable inputs of Level 3 investments (Details)
$ in Thousands

Jun. 30, 2025

USD ($)

Dec. 31, 2024

USD ($)

Quantitative information about the significant unobservable inputs of Level 3 investments

Fair Value

$ 2,653,666

^{[1],[2],[3],[4]}

$ 2,504,242

^[5],[6],[7]

Level 3

Quantitative information about the significant unobservable inputs of Level 3 investments

Fair value

2,520,501

2,391,216

Fair Value

2,520,501

2,391,216

First Lien Loans

Quantitative information about the significant unobservable inputs of Level 3 investments

Fair Value

2,335,714

2,209,392

First Lien Loans | Level 3

Quantitative information about the significant unobservable inputs of Level 3 investments

Fair Value

2,283,935

2,175,758

First Lien Loans | Level 3 | Discounted Cash Flow | Discount Rate

Quantitative information about the significant unobservable inputs of Level 3 investments

Fair Value

1,933,105

1,973,337

First Lien Loans | Level 3 | Market Transaction | Market Transaction

Quantitative information about the significant unobservable inputs of Level 3 investments

Fair Value

329,725

181,212

First Lien Loans | Level 3 | Recovery Analysis | Recovery Rate

Quantitative information about the significant unobservable inputs of Level 3 investments

Fair Value

$ 21,105

$ 21,207

Debt

6.5

First Lien Loans | Level 3 | Minimum [Member] | Discounted Cash Flow | Discount Rate

Quantitative information about the significant unobservable inputs of Level 3 investments

Debt

8.3

8.4

First Lien Loans | Level 3 | Minimum [Member] | Market Transaction | Market Transaction

Quantitative information about the significant unobservable inputs of Level 3 investments

Debt

98.5

98.5

First Lien Loans | Level 3 | Minimum [Member] | Recovery Analysis | Recovery Rate

Quantitative information about the significant unobservable inputs of Level 3 investments

Debt

5.3

First Lien Loans | Level 3 | Maximum [Member] | Discounted Cash Flow | Discount Rate

Quantitative information about the significant unobservable inputs of Level 3 investments

Debt

14.1

17.5

First Lien Loans | Level 3 | Maximum [Member] | Market Transaction | Market Transaction

Quantitative information about the significant unobservable inputs of Level 3 investments

Debt

100

99.5

First Lien Loans | Level 3 | Maximum [Member] | Recovery Analysis | Recovery Rate

Quantitative information about the significant unobservable inputs of Level 3 investments

Debt

5.3

First Lien Loans | Level 3 | Weighted Average [Member] | Discounted Cash Flow | Discount Rate

Quantitative information about the significant unobservable inputs of Level 3 investments

Debt

(9.6)

(10.1)

First Lien Loans | Level 3 | Weighted Average [Member] | Market Transaction | Market Transaction

Quantitative information about the significant unobservable inputs of Level 3 investments

Debt

(99.2)

(99)

First Lien Loans | Level 3 | Weighted Average [Member] | Recovery Analysis | Recovery Rate

Quantitative information about the significant unobservable inputs of Level 3 investments

Debt

(5.3)

Second Lien Loans

Quantitative information about the significant unobservable inputs of Level 3 investments

Fair Value

$ 149,799

$ 151,362

Second Lien Loans | Level 3

Quantitative information about the significant unobservable inputs of Level 3 investments

Fair Value

82,079

79,596

Second Lien Loans | Level 3 | Discounted Cash Flow | Discount Rate

Quantitative information about the significant unobservable inputs of Level 3 investments

Fair Value

$ 82,079

64,671

Second Lien Loans | Level 3 | Market Transaction | Market Transaction

Quantitative information about the significant unobservable inputs of Level 3 investments

Fair Value

$ 14,925

Debt

99.5

Second Lien Loans | Level 3 | Minimum [Member] | Discounted Cash Flow | Discount Rate

Quantitative information about the significant unobservable inputs of Level 3 investments

Debt

8.6

9

Second Lien Loans | Level 3 | Maximum [Member] | Discounted Cash Flow | Discount Rate

Quantitative information about the significant unobservable inputs of Level 3 investments

Debt

19.8

21.2

Second Lien Loans | Level 3 | Weighted Average [Member] | Discounted Cash Flow | Discount Rate

Quantitative information about the significant unobservable inputs of Level 3 investments

Debt

(12.6)

(14.1)

Unsecured Note

Quantitative information about the significant unobservable inputs of Level 3 investments

Fair Value

$ 112,475

$ 91,375

Unsecured Note | Level 3

Quantitative information about the significant unobservable inputs of Level 3 investments

Fair Value

103,973

87,940

Unsecured Note | Level 3 | Discounted Cash Flow | Discount Rate

Quantitative information about the significant unobservable inputs of Level 3 investments

Fair Value

$ 103,369

53,726

Unsecured Note | Level 3 | Market Transaction | Market Transaction

Quantitative information about the significant unobservable inputs of Level 3 investments

Fair Value

$ 34,215

Unsecured Note | Level 3 | Minimum [Member] | Discounted Cash Flow | Discount Rate

Quantitative information about the significant unobservable inputs of Level 3 investments

Debt

7

8

Unsecured Note | Level 3 | Minimum [Member] | Market Transaction | Market Transaction

Quantitative information about the significant unobservable inputs of Level 3 investments

Debt

98

Unsecured Note | Level 3 | Maximum [Member] | Discounted Cash Flow | Discount Rate

Quantitative information about the significant unobservable inputs of Level 3 investments

Debt

15.5

16.1

Unsecured Note | Level 3 | Maximum [Member] | Market Transaction | Market Transaction

Quantitative information about the significant unobservable inputs of Level 3 investments

Debt

100

Unsecured Note | Level 3 | Weighted Average [Member] | Discounted Cash Flow | Discount Rate

Quantitative information about the significant unobservable inputs of Level 3 investments

Debt

(11.4)

(12.7)

Unsecured Note | Level 3 | Weighted Average [Member] | Market Transaction | Market Transaction

Quantitative information about the significant unobservable inputs of Level 3 investments

Debt

(98.9)

Unsecured Notes | Level 3 | Market Transaction | Market Transaction

Quantitative information about the significant unobservable inputs of Level 3 investments

Fair Value

$ 604

Unsecured Notes | Level 3 | Minimum [Member] | Market Transaction | Market Transaction

Quantitative information about the significant unobservable inputs of Level 3 investments

Debt

20,939.7

Unsecured Notes | Level 3 | Maximum [Member] | Market Transaction | Market Transaction

Quantitative information about the significant unobservable inputs of Level 3 investments

Debt

20,939.7

Unsecured Notes | Level 3 | Weighted Average [Member] | Market Transaction | Market Transaction

Quantitative information about the significant unobservable inputs of Level 3 investments

Debt

(20,939.7)

Preferred Equity

Quantitative information about the significant unobservable inputs of Level 3 investments

Fair Value

$ 38,583

$ 36,226

Preferred Equity | Level 3

Quantitative information about the significant unobservable inputs of Level 3 investments

Fair Value

38,583

36,226

Preferred Equity | Level 3 | Discounted Cash Flow | Discount Rate

Quantitative information about the significant unobservable inputs of Level 3 investments

Fair Value

35,441

33,086

Preferred Equity | Level 3 | Enterprise Value Analysis | EBITDA Multiple

Quantitative information about the significant unobservable inputs of Level 3 investments

Fair Value

$ 3,142

$ 3,140

Equity investments

19.5

20.5

Preferred Equity | Level 3 | Minimum [Member] | Discounted Cash Flow | Discount Rate

Quantitative information about the significant unobservable inputs of Level 3 investments

Equity investments

13.1

13.2

Preferred Equity | Level 3 | Maximum [Member] | Discounted Cash Flow | Discount Rate

Quantitative information about the significant unobservable inputs of Level 3 investments

Equity investments

15

15

Preferred Equity | Level 3 | Weighted Average [Member] | Discounted Cash Flow | Discount Rate

Quantitative information about the significant unobservable inputs of Level 3 investments

Equity investments

(14.3)

(14.4)

Common Equity & Warrants

Quantitative information about the significant unobservable inputs of Level 3 investments

Fair Value

$ 17,095

$ 15,887

Common Equity & Warrants | Level 3 | Enterprise Value Analysis | EBITDA Multiple

Quantitative information about the significant unobservable inputs of Level 3 investments

Fair Value

$ 11,931

$ 11,696

Common Equity & Warrants | Level 3 | Minimum [Member] | Enterprise Value Analysis | EBITDA Multiple

Quantitative information about the significant unobservable inputs of Level 3 investments

Equity investments

7

25

Common Equity & Warrants | Level 3 | Maximum [Member] | Enterprise Value Analysis | EBITDA Multiple

Quantitative information about the significant unobservable inputs of Level 3 investments

Equity investments

22.5

6.5

Common Equity & Warrants | Level 3 | Weighted Average [Member] | Enterprise Value Analysis | EBITDA Multiple

Quantitative information about the significant unobservable inputs of Level 3 investments

Equity investments

(17.5)

(18.3)

[1]	All investments were qualifying assets as defined under Section 55(a) of the Investment Company Act of 1940 except for ALP CFO LP 2024-1, Barings Middle Market CLO Ltd., Best Egg Asset Structured Pass Through Master Trust, Churchill Middle Market CLO Ltd., Claros Mortgage Trust, Inc., Exeter Short Term Funding LLC, Imagine Software Inc, Ivy Hill Asset Management, L.P., Ivy Hill Middle Market Credit XII Ltd, LD Holdings Grouup LLC., New Mountain Capital LLC, and Syntax Systems Limited.
[2]	All of the Company’s investments are domiciled in the United States except for Barings Middle Market CLO Ltd., New Mountain Guardian, and Syntax Systems Limited, which are domiciled in the Cayman Islands, Bermuda, and Canada, respectively.
[3]	As of June 30, 2025, all investments are pledged as collateral unless otherwise stated.
[4]	Unless otherwise indicated, all securities are valued using significant unobservable inputs, which are categorized as Level 3 assets under the definition of ASC 820 fair value hierarchy.
[5]	All investments were qualifying assets as defined under Section 55(a) of the Investment Company Act of 1940 except for Ardonagh Finco B.V., New Mountain Guardian, Syntax Systems Limited, Exeter Short Term Funding LLC, and ALP CFO 2024, L.P
[6]	All of the Company's investments are domiciled in the United States except for Ardonagh Finco B.V., New Mountain Guardian, and Syntax Systems Limited, which are domiciled in the United Kingdom, Bermuda, and Canada, respectively.
[7]	Unless otherwise indicated, all securities are valued using significant unobservable inputs, which are categorized as Level 3 assets under the definition of ASC 820 fair value hierarchy.