FAIR VALUE MEASUREMENTS - Schedule of Valuation Techniques and Significant Unobservable Inputs Used in Level 3 Fair Value Measurements of Assets (Details) - Level 3	Jun. 30, 2024 USD ($)	Dec. 31, 2023 USD ($)
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Fair Value	$ 1,909,266,000	$ 1,597,257,000
First Lien Term Loans | Yield Method | Market Yield Discount Rates
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Fair Value	$ 1,490,410,000	$ 1,192,190,000
First Lien Term Loans | Yield Method | Low | Market Yield Discount Rates
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Measurement input	0.0609	0.0613
First Lien Term Loans | Yield Method | High | Market Yield Discount Rates
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Measurement input	0.2250	0.1873
First Lien Term Loans | Yield Method | Weighted Average | Market Yield Discount Rates
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Measurement input	0.1056	0.1063
First Lien Term Loans | Market Approach | EBITDA Multiple
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Fair Value	$ 21,236,000	$ 19,519,000
First Lien Term Loans | Market Approach | Low | EBITDA Multiple
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Measurement input	6.5	6.5
First Lien Term Loans | Market Approach | High | EBITDA Multiple
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Measurement input	13.5	9.25
First Lien Term Loans | Market Approach | Weighted Average | EBITDA Multiple
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Measurement input	9.31	7.21
First Lien Term Loans | Recent Transactions | Transaction Price
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Fair Value	$ 212,753,000	$ 181,302,000
First Lien Term Loans | Recent Transactions | Low | Transaction Price
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Measurement input	97.31	59.50
First Lien Term Loans | Recent Transactions | High | Transaction Price
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Measurement input	100.25	100.00
First Lien Term Loans | Recent Transactions | Weighted Average | Transaction Price
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Measurement input	99.34	97.52
Subordinated Debt | Yield Method | Market Yield Discount Rates
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Fair Value	$ 136,322,000	$ 162,646,000
Subordinated Debt | Yield Method | Low | Market Yield Discount Rates
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Measurement input	0.1225	0.0970
Subordinated Debt | Yield Method | High | Market Yield Discount Rates
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Measurement input	0.2491	0.2491
Subordinated Debt | Yield Method | Weighted Average | Market Yield Discount Rates
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Measurement input	0.1516	0.1444
Subordinated Debt | Market Approach | EBITDA Multiple
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Fair Value	$ 705,000
Subordinated Debt | Market Approach | Low | EBITDA Multiple
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Measurement input	9.93
Subordinated Debt | Market Approach | High | EBITDA Multiple
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Measurement input	9.93
Subordinated Debt | Market Approach | Weighted Average | EBITDA Multiple
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Measurement input	9.93
Subordinated Debt | Recent Transactions | Transaction Price
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Fair Value	$ 16,325,000	$ 12,050,000
Subordinated Debt | Recent Transactions | Low | Transaction Price
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Measurement input	90.25	84.75
Subordinated Debt | Recent Transactions | High | Transaction Price
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Measurement input	98.03	98.01
Subordinated Debt | Recent Transactions | Weighted Average | Transaction Price
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Measurement input	94.16	89.53
Subordinated Debt | Black-Scholes | EBITDA Multiple
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Fair Value	$ 1,340,000
Subordinated Debt | Black-Scholes | Low | EBITDA Multiple
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Measurement input	11.75
Subordinated Debt | Black-Scholes | High | EBITDA Multiple
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Measurement input	11.75
Subordinated Debt | Black-Scholes | Weighted Average | EBITDA Multiple
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Measurement input	11.75
Equity
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Investments valued using recent transactions	$ 2,001,000	$ 1,257,000
Equity | Yield Method | Market Yield Discount Rates
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Fair Value	$ 2,333,000	$ 158,000
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	0.1550	0.0836
Equity | Yield Method | Weighted Average | Market Yield Discount Rates
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Measurement input	0.1291	0.0836
Equity | Market Approach | EBITDA Multiple
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Fair Value	$ 27,842,000	$ 29,390,000
Equity | Market Approach | Blended EBITDA Multiple
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Fair Value		$ 2,000
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 | 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 | 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	12.01	10.96
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