FAIR VALUE MEASUREMENTS - Unobservable Inputs (Details) $ in Thousands	Jun. 30, 2025 USD ($) investment	Dec. 31, 2024 USD ($) investment
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Fair Value	$ 3,785,496	$ 3,791,494
Level 3
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Fair Value	3,726,935	3,686,956
Level 3 | First Lien Debt
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Fair Value	3,630,247	3,603,209
Level 3 | First Lien Debt | Yield Analysis | Discount Rate
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Fair Value	$ 3,602,320	$ 3,597,236
Level 3 | First Lien Debt | Yield Analysis | Low | Discount Rate
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Measurement input	0.0709	0.0805
Level 3 | First Lien Debt | Yield Analysis | Low | EBITDA Multiple
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Measurement input	0.075
Level 3 | First Lien Debt | Yield Analysis | High | Discount Rate
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Measurement input	0.9146	0.3406
Level 3 | First Lien Debt | Yield Analysis | High | EBITDA Multiple
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Measurement input	0.10
Level 3 | First Lien Debt | Yield Analysis | Weighted Average | Discount Rate
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Measurement input	0.1007	0.1031
Level 3 | First Lien Debt | Market Approach | EBITDA Multiple
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Fair Value	$ 27,927	$ 5,973
Level 3 | First Lien Debt | Market Approach | Weighted Average | EBITDA Multiple
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Measurement input	0.0853	0.065
Level 3 | Second Lien Debt
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Fair Value	$ 49,743	$ 33,351
Level 3 | Second Lien Debt | Yield Analysis | Discount Rate
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Fair Value	$ 46,640	$ 33,351
Level 3 | Second Lien Debt | Yield Analysis | Low | Discount Rate
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Measurement input	0.1034	0.1018
Level 3 | Second Lien Debt | Yield Analysis | High | Discount Rate
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Measurement input	0.2030	0.1641
Level 3 | Second Lien Debt | Yield Analysis | Weighted Average | Discount Rate
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Measurement input	0.1871	0.1509
Level 3 | Second Lien Debt | Market Approach | EBITDA Multiple
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Fair Value	$ 3,103
Level 3 | Second Lien Debt | Market Approach | Weighted Average | EBITDA Multiple
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Measurement input	0.0825
Level 3 | Other Debt Investments
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Fair Value	$ 9,773	$ 9,198
Level 3 | Other Debt Investments | Yield Analysis
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Fair Value	$ 1,200
Investment owned, transitions, number | investment	1
Level 3 | Other Debt Investments | Yield Analysis | Discount Rate
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Fair Value	$ 8,637	$ 8,313
Level 3 | Other Debt Investments | Yield Analysis | Low | Discount Rate
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Measurement input	0.1445	0.0942
Level 3 | Other Debt Investments | Yield Analysis | High | Discount Rate
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Measurement input	0.1520	0.1490
Level 3 | Other Debt Investments | Yield Analysis | Weighted Average | Discount Rate
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Measurement input	0.1462	0.1074
Level 3 | Other Debt Investments | Market Approach
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Fair Value	$ 27,900
Investment owned, transitions, number | investment	3
Level 3 | Other Debt Investments | Market Approach | EBITDA Multiple
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Fair Value	$ 1,136	$ 885
Level 3 | Other Debt Investments | Market Approach | Low | EBITDA Multiple
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Measurement input	8.25
Level 3 | Other Debt Investments | Market Approach | High | EBITDA Multiple
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Measurement input	9
Level 3 | Other Debt Investments | Market Approach | Weighted Average | EBITDA Multiple
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Measurement input	8.3	9
Level 3 | Preferred equity | Income Approach | Discount Rate
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Fair Value	$ 18,879	$ 22,694
Level 3 | Preferred equity | Income Approach | Low | Discount Rate
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Measurement input	0.1184	0.1215
Level 3 | Preferred equity | Income Approach | High | Discount Rate
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Measurement input	0.1626	0.1750
Level 3 | Preferred equity | Income Approach | Weighted Average | Discount Rate
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Measurement input	0.1443	0.1371
Level 3 | Preferred equity | Market Approach
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Fair Value	$ 3,200
Investment owned, transitions, number | investment	2
Level 3 | Preferred equity | Market Approach | EBITDA Multiple
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Fair Value	$ 3,893	$ 923
Level 3 | Preferred equity | Market Approach | Low | EBITDA Multiple
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Measurement input	8.25
Level 3 | Preferred equity | Market Approach | High | EBITDA Multiple
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Measurement input	14.75
Level 3 | Preferred equity | Market Approach | Weighted Average | EBITDA Multiple
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Measurement input	13.13	8.5
Level 3 | Common equity | Market Approach | EBITDA Multiple
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Fair Value	$ 11,541	$ 14,442
Level 3 | Common equity | Market Approach | Revenue Multiple
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Fair Value	$ 2,859	$ 3,139
Level 3 | Common equity | Market Approach | Low | EBITDA Multiple
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Measurement input	1.5	3.9
Level 3 | Common equity | Market Approach | Low | Revenue Multiple
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Measurement input	9	7.6
Level 3 | Common equity | Market Approach | High | EBITDA Multiple
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Measurement input	19	18.7
Level 3 | Common equity | Market Approach | High | Revenue Multiple
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Measurement input	22.25	12.7
Level 3 | Common equity | Market Approach | Weighted Average | EBITDA Multiple
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Measurement input	11.62	13.47
Level 3 | Common equity | Market Approach | Weighted Average | Revenue Multiple
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Measurement input	12.44	8.8
Level 3 | Unsecured Debt | Yield Analysis
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Fair Value		$ 2,010
Investment owned, transitions, number | investment		1