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, 2024 USD ($)	Dec. 31, 2023 USD ($)
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Fair value	$ 1,793,812	$ 1,403,905
First-Lien Debt | Yield Method | Market Yield Discount Rates
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Fair value	$ 1,584,187	$ 1,192,190
First-Lien Debt | Yield Method | Low | Market Yield Discount Rates
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Measurement input	0.0609	0.0613
First-Lien Debt | Yield Method | High | Market Yield Discount Rates
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Measurement input	0.2250	0.1873
First-Lien Debt | Yield Method | Weighted Average | Market Yield Discount Rates
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Measurement input	0.0948	0.1063
First-Lien Debt | Market Approach | EBITDA Multiple
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Fair value	$ 19,979	$ 19,519
First-Lien Debt | Market Approach | Low | EBITDA Multiple
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Measurement input	6.5	6.5
First-Lien Debt | Market Approach | High | EBITDA Multiple
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Measurement input	12	9.25
First-Lien Debt | Market Approach | Weighted Average | EBITDA Multiple
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Measurement input	9.15	7.21
First-Lien Debt | Recent Transactions
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Investments valued using recent transactions	$ 187,405	$ 181,302
Subordinated Debt | Yield Method | Market Yield Discount Rates
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Fair value	$ 152,687	$ 162,646
Subordinated Debt | Yield Method | Low | Market Yield Discount Rates
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Measurement input	0.1146	0.0970
Subordinated Debt | Yield Method | High | Market Yield Discount Rates
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Measurement input	0.2541	0.2491
Subordinated Debt | Yield Method | Weighted Average | Market Yield Discount Rates
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Measurement input	0.1500	0.1444
Subordinated Debt | Market Approach | EBITDA Multiple
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Fair value	$ 1,800
Subordinated Debt | Market Approach | Low | EBITDA Multiple
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Measurement input	8.63
Subordinated Debt | Market Approach | High | EBITDA Multiple
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Measurement input	8.63
Subordinated Debt | Market Approach | Weighted Average | EBITDA Multiple
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Measurement input	8.63
Subordinated Debt | Black-Scholes | EBITDA Multiple
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Fair value	$ 1,825
Subordinated Debt | Black-Scholes | Low | EBITDA Multiple
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Measurement input	11.25
Subordinated Debt | Black-Scholes | High | EBITDA Multiple
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Measurement input	11.25
Subordinated Debt | Black-Scholes | Weighted Average | EBITDA Multiple
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Measurement input	11.25
Subordinated Debt | Recent Transactions
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Investments valued using recent transactions	$ 13,143	$ 12,050
Equity | Yield Method | Market Yield Discount Rates
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Fair value	$ 168	$ 158
Equity | Yield Method | Low | Market Yield Discount Rates
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Measurement input	0.0836	0.0836
Equity | Yield Method | High | Market Yield Discount Rates
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Measurement input	0.0836	0.0836
Equity | Yield Method | Weighted Average | Market Yield Discount Rates
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Measurement input	0.0836	0.0836
Equity | Market Approach | EBITDA Multiple
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Fair value	$ 33,160	$ 29,390
Equity | Market Approach | Revenue Multiple
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Fair value	$ 6
Equity | Market Approach | Blended EBITDA Multiple
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Fair value		$ 2
Equity | Market Approach | Low | EBITDA Multiple
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Measurement input	5.75	6.5
Equity | Market Approach | Low | Revenue Multiple
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Measurement input	0.85
Equity | Market Approach | Low | Blended EBITDA Multiple
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Measurement input		13.25
Equity | Market Approach | Low | Blended Revenue Multiple
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Measurement input		1.4
Equity | Market Approach | High | EBITDA Multiple
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Measurement input	20.5	19.5
Equity | Market Approach | High | Revenue Multiple
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Measurement input	0.85
Equity | Market Approach | High | Blended EBITDA Multiple
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Measurement input		13.25
Equity | Market Approach | High | Blended Revenue Multiple
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Measurement input		1.4
Equity | Market Approach | Weighted Average | EBITDA Multiple
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Measurement input	11.85	10.96
Equity | Market Approach | Weighted Average | Revenue Multiple
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Measurement input	0.85
Equity | Market Approach | Weighted Average | Blended EBITDA Multiple
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Measurement input		13.25
Equity | Market Approach | Weighted Average | Blended Revenue Multiple
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Measurement input		1.4
Equity | Recent Transactions
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Investments valued using recent transactions	$ 491	$ 1,257