Annual report pursuant to Section 13 and 15(d)

FAIR VALUE HIERARCHY FOR INVESTMENTS???PORTFOLIO COMPOSITION - Schedule of Investments (Details)

v3.24.0.1
FAIR VALUE HIERARCHY FOR INVESTMENTS—PORTFOLIO COMPOSITION - Schedule of Investments (Details)
$ in Thousands
 12 Months Ended
Dec. 31, 2023
USD ($)
company
Dec. 31, 2022
USD ($)
company
Summary of Investment Holdings [Line Items]    
Fair value $ 4,286,271 [1] $ 4,102,177 [2]
Cost $ 3,725,960 [3] $ 3,773,752 [4]
Investment Owned, At Cost | Investment Type Concentration Risk    
Summary of Investment Holdings [Line Items]    
Concentration risk (as a percent) 100.00% 100.00%
Investment Owned, At Cost | Non-accrual Status | Investment Type Concentration Risk    
Summary of Investment Holdings [Line Items]    
Concentration risk (as a percent) 2.30% 3.70%
Equity investments | Investment Owned, At Cost | Investment Type Concentration Risk    
Summary of Investment Holdings [Line Items]    
Concentration risk (as a percent) 16.80% 14.20%
First lien debt | Investment Owned, At Cost | Investment Type Concentration Risk    
Summary of Investment Holdings [Line Items]    
Concentration risk (as a percent) 82.70% 85.00%
LMM portfolio investments    
Summary of Investment Holdings [Line Items]    
Number of portfolio companies | company 80 78
Fair value $ 2,273,000 $ 2,060,500
Cost $ 1,782,900 $ 1,719,900
Weighted-average annual effective yield 13.00% 12.30%
Average EBITDA $ 8,200 $ 8,000
Diluted equity ownership (as a percent) 40.00% 41.00%
Investment company, number of companies within portfolio excluded from EBITDA calculation | company 2 3
LMM portfolio investments | Non-accrual Status    
Summary of Investment Holdings [Line Items]    
Weighted-average annual effective yield (as a percent) 12.90% 11.60%
LMM portfolio investments | Debt investments | Investment Owned, At Cost | Investment Type Concentration Risk    
Summary of Investment Holdings [Line Items]    
Concentration risk (as a percent) 72.00% 73.70%
LMM portfolio investments | Equity investments | Investment Owned, At Cost | Investment Type Concentration Risk    
Summary of Investment Holdings [Line Items]    
Concentration risk (as a percent) 28.00% 26.30%
LMM portfolio investments | First lien debt | Investment Owned, At Cost | Investment Type Concentration Risk    
Summary of Investment Holdings [Line Items]    
Concentration risk (as a percent) 99.20% 99.10%
Private Loan portfolio investments    
Summary of Investment Holdings [Line Items]    
Number of portfolio companies | company 87 85
Fair value $ 1,453,500 $ 1,471,500
Cost $ 1,470,100 $ 1,500,300
Weighted-average annual effective yield 12.90% 11.60%
Average EBITDA $ 27,200 $ 38,100
Investment company, number of companies within portfolio excluded from EBITDA calculation | company 2 2
Private Loan portfolio investments | Non-accrual Status    
Summary of Investment Holdings [Line Items]    
Weighted-average annual effective yield (as a percent) 12.50% 11.20%
Private Loan portfolio investments | Debt investments | Investment Owned, At Cost | Investment Type Concentration Risk    
Summary of Investment Holdings [Line Items]    
Concentration risk (as a percent) 94.70% 97.10%
Private Loan portfolio investments | Equity investments | Investment Owned, At Cost | Investment Type Concentration Risk    
Summary of Investment Holdings [Line Items]    
Concentration risk (as a percent) 5.30% 2.90%
Private Loan portfolio investments | First lien debt | Investment Owned, At Cost | Investment Type Concentration Risk    
Summary of Investment Holdings [Line Items]    
Concentration risk (as a percent) 100.00% 99.60%
Middle Market portfolio investments    
Summary of Investment Holdings [Line Items]    
Number of portfolio companies | company 23 31
Fair value $ 243,700 $ 329,100
Cost $ 294,400 $ 401,700
Weighted-average annual effective yield 12.50% 11.00%
Average EBITDA $ 64,200 $ 68,700
Middle Market portfolio investments | Non-accrual Status    
Summary of Investment Holdings [Line Items]    
Weighted-average annual effective yield (as a percent) 10.80% 10.30%
Middle Market portfolio investments | Debt investments | Investment Owned, At Cost | Investment Type Concentration Risk    
Summary of Investment Holdings [Line Items]    
Concentration risk (as a percent) 91.40% 93.80%
Middle Market portfolio investments | Equity investments | Investment Owned, At Cost | Investment Type Concentration Risk    
Summary of Investment Holdings [Line Items]    
Concentration risk (as a percent) 8.60% 6.20%
Middle Market portfolio investments | First lien debt | Investment Owned, At Cost | Investment Type Concentration Risk    
Summary of Investment Holdings [Line Items]    
Concentration risk (as a percent) 99.10% 98.80%
[1] Investment fair value was determined using significant unobservable inputs, unless otherwise noted. See Note C — Fair Value Hierarchy for Investments — Portfolio Composition for further discussion. Negative fair value is the result of the capitalized discount on the loan or the unfunded commitment being valued below par.
[2] Investment fair value was determined using significant unobservable inputs, unless otherwise noted. See Note C — Fair Value Hierarchy for Investments — Portfolio Composition for further discussion. Negative fair value is the result of the capitalized discount on the loan or the unfunded commitment being valued below par.
[3] Principal is net of repayments. Cost is net of repayments and accumulated unearned income. Negative cost is the result of the capitalized discount being greater than the principal amount outstanding on the loan.
[4] Principal is net of repayments. Cost is net of repayments and accumulated unearned income. Negative cost is the result of the capitalized discount being greater than the principal amount outstanding on the loan.