FAIR VALUE MEASUREMENTS - Schedule of Valuation Techniques and Significant Unobservable Inputs Used in Level 3 Fair Value Measurements of Assets (Details) - Level 3 $ in Thousands	Sep. 30, 2025 USD ($)	Dec. 31, 2024 USD ($)
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Fair value	$ 1,914,067	$ 1,880,503
First-Lien Debt | Yield Method | Market Yield Discount Rates
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Fair value	$ 1,722,303	$ 1,680,013
First-Lien Debt | Yield Method | Low | Market Yield Discount Rates
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Measurement input	0.0737	0.0583
First-Lien Debt | Yield Method | High | Market Yield Discount Rates
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Measurement input	0.2150	0.2050
First-Lien Debt | Yield Method | Weighted Average | Market Yield Discount Rates
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Measurement input	0.0941	0.1013
First-Lien Debt | Market Approach | EBITDA Multiple
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Fair value	$ 11,079	$ 16,215
First-Lien Debt | Market Approach | Revenue Multiple
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Fair value	$ 3,082
First-Lien Debt | Market Approach | Low | EBITDA Multiple
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Measurement input	6.25	6.5
First-Lien Debt | Market Approach | Low | Revenue Multiple
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Measurement input	1.5
First-Lien Debt | Market Approach | High | EBITDA Multiple
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Measurement input	20.2	15.5
First-Lien Debt | Market Approach | High | Revenue Multiple
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Measurement input	1.5
First-Lien Debt | Market Approach | Weighted Average | EBITDA Multiple
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Measurement input	12.22	7.32
First-Lien Debt | Market Approach | Weighted Average | Revenue Multiple
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Measurement input	1.5
First-Lien Debt | Recent Transactions
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Investments valued using recent transactions	$ 23,595	$ 110,622
Subordinated Debt | Yield Method | Market Yield Discount Rates
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Fair value	$ 135,453	$ 143,952
Subordinated Debt | Yield Method | Low | Market Yield Discount Rates
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Measurement input	0.1143	0.1200
Subordinated Debt | Yield Method | High | Market Yield Discount Rates
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Measurement input	0.2700	0.2641
Subordinated Debt | Yield Method | Weighted Average | Market Yield Discount Rates
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Measurement input	0.1515	0.1546
Subordinated Debt | Market Approach | EBITDA Multiple
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Fair value	$ 5,073	$ 2,032
Subordinated Debt | Market Approach | Revenue Multiple
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Fair value	$ 1,941
Subordinated Debt | Market Approach | Low | EBITDA Multiple
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Measurement input	8.75	5.25
Subordinated Debt | Market Approach | Low | Revenue Multiple
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Measurement input	1.2
Subordinated Debt | Market Approach | High | EBITDA Multiple
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Measurement input	8.75	14
Subordinated Debt | Market Approach | High | Revenue Multiple
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Measurement input	1.2
Subordinated Debt | Market Approach | Weighted Average | EBITDA Multiple
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Measurement input	8.75	12.85
Subordinated Debt | Market Approach | Weighted Average | Revenue Multiple
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Measurement input	1.2
Subordinated Debt | Black-Scholes | EBITDA Multiple
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Fair value	$ 2,317	$ 1,896
Subordinated Debt | Black-Scholes | Low | EBITDA Multiple
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Measurement input	6.11	0.11
Subordinated Debt | Black-Scholes | High | EBITDA Multiple
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Measurement input	10.5	0.11
Subordinated Debt | Black-Scholes | Weighted Average | EBITDA Multiple
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Measurement input	8.47	0.11
Subordinated Debt | Recent Transactions
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Investments valued using recent transactions	$ 7,994	$ 2,899
Equity | Yield Method | Market Yield Discount Rates
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Fair value	$ 1,439	$ 1,224
Equity | Yield Method | Low | Market Yield Discount Rates
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Measurement input	0.0836	0.0800
Equity | Yield Method | High | Market Yield Discount Rates
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Measurement input	0.1641	0.0925
Equity | Yield Method | Weighted Average | Market Yield Discount Rates
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Measurement input	0.1521	0.0907
Equity | Market Approach | EBITDA Multiple
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Fair value	$ 31,380	$ 35,147
Equity | Market Approach | Revenue Multiple
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Fair value		$ 24
Equity | Market Approach | Low | EBITDA Multiple
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Measurement input	6.11	5.25
Equity | Market Approach | Low | Revenue Multiple
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Measurement input		0.95
Equity | Market Approach | High | EBITDA Multiple
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Measurement input	20.2	19.5
Equity | Market Approach | High | Revenue Multiple
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Measurement input		0.95
Equity | Market Approach | Weighted Average | EBITDA Multiple
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Measurement input	12.58	11.18
Equity | Market Approach | Weighted Average | Revenue Multiple
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Measurement input		0.95
Equity | Recent Transactions
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Investments valued using recent transactions	$ 1,598	$ 203