MIDDLE MARKET CREDIT FUND, LLC - Summary of Portfolio (Details) $ in Thousands	3 Months Ended	12 Months Ended
	Mar. 31, 2024 USD ($) loan financial_institution	Dec. 31, 2023 USD ($) financial_institution loan
Schedule of Investments [Line Items]
Fair value of loans on non-accrual status	$ 3,792	$ 38,061
Fair value of loans with PIK provisions	279,267	337,061
Credit Fund
Schedule of Investments [Line Items]
Senior secured loans	$ 738,811	$ 803,541
Number of portfolio companies in Credit Fund | financial_institution	36	38
Average amount per portfolio company	$ 20,523	$ 21,146
Number of loans on non-accrual status | loan	3	3
Fair value of loans on non-accrual status	$ 13,554	$ 13,263
Percentage of portfolio at floating interest rates	100.00%	100.00%
Fair value of loans with PIK provisions	$ 1,322	$ 36,481
Investments at fair value | Investment type concentration
Schedule of Investments [Line Items]
Percentage of portfolio with PIK provisions	100.00%	100.00%
Investments at fair value | Investment type concentration | PIK loan
Schedule of Investments [Line Items]
Percentage of portfolio with PIK provisions	15.60%	18.30%
Investments at fair value | Investment type concentration | Credit Fund | PIK loan
Schedule of Investments [Line Items]
Percentage of portfolio with PIK provisions	0.20%	4.80%