Quarterly report [Sections 13 or 15(d)]

FAIR VALUE HIERARCHY FOR INVESTMENTS???PORTFOLIO COMPOSITION - Narrative (Details)

v3.25.1
FAIR VALUE HIERARCHY FOR INVESTMENTS—PORTFOLIO COMPOSITION - Narrative (Details)
$ in Thousands
 3 Months Ended 12 Months Ended
Mar. 31, 2025
USD ($)
company
investmentManager
investment
entity
Mar. 31, 2024
USD ($)
Mar. 31, 2025
USD ($)
company
investmentManager
investment
entity
Dec. 31, 2024
USD ($)
entity
investment
investmentManager
company
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]        
Expenses allocated $ 5,336 $ 5,559    
Annualized total return on investments (as a percent) 0.160 0.167    
Achieved total return on investments (as a percent)       0.179
Fair value $ 5,054,139 [1],[2],[3]   $ 5,054,139 [1],[2],[3] $ 4,932,669 [4],[5]
Cost $ 4,295,736 [1],[3],[6]   $ 4,295,736 [1],[3],[6] $ 4,237,312 [4],[5]
Investment Owned, At Fair Value | Investment Type Concentration Risk        
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]        
Concentration risk (as a percent) 100.00%     100.00%
Investment Owned, At Cost | Investment Type Concentration Risk        
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]        
Concentration risk (as a percent) 100.00%     100.00%
External Investment Manager | Affiliated Entity        
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]        
Expenses allocated $ 5,300 $ 5,600    
Short-term portfolio investments        
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]        
Number of portfolio investments | investment 0   0 0
Short-term portfolio investments | Maximum | Debt        
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]        
Investment term (in years) 1 year      
LMM portfolio investments        
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]        
Number of portfolio companies | company 86   86 84
Fair value $ 2,611,000   $ 2,611,000 $ 2,502,900
Cost $ 1,996,200   $ 1,996,200 $ 1,937,800
LMM portfolio investments | Investment Owned, At Fair Value | Investment Type Concentration Risk        
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]        
Concentration risk (as a percent) 20.00% 24.00% 91.00%  
LMM portfolio investments | Debt | Investment Owned, At Cost | Investment Type Concentration Risk        
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]        
Concentration risk (as a percent) 70.70%     70.80%
LMM portfolio investments | Minimum        
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]        
Annual revenues $ 10,000      
Investments $ 5,000   $ 5,000  
LMM portfolio investments | Minimum | Debt        
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]        
Investment term (in years) 5 years      
LMM portfolio investments | Maximum        
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]        
Annual revenues $ 150,000      
Investments $ 125,000   $ 125,000  
LMM portfolio investments | Maximum | Debt        
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]        
Investment term (in years) 7 years      
Private Loan portfolio investments        
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]        
Number of portfolio companies | company 90   90 91
Fair value $ 1,942,200   $ 1,942,200 $ 1,904,300
Cost $ 1,986,000   $ 1,986,000 $ 1,952,500
Private Loan portfolio investments | Investment Owned, At Fair Value | Investment Type Concentration Risk        
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]        
Concentration risk (as a percent) 26.00% 27.00% 89.00%  
Private Loan portfolio investments | Debt | Investment Owned, At Cost | Investment Type Concentration Risk        
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]        
Concentration risk (as a percent) 94.70%     95.40%
Private Loan portfolio investments | Minimum        
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]        
Annual revenues $ 25,000      
Investments $ 10,000   $ 10,000  
Private Loan portfolio investments | Minimum | Debt        
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]        
Investment term (in years) 3 years      
Private Loan portfolio investments | Maximum        
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]        
Annual revenues $ 500,000      
Investments $ 100,000   $ 100,000  
Private Loan portfolio investments | Maximum | Debt        
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]        
Investment term (in years) 7 years      
Middle Market portfolio investments        
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]        
Number of portfolio companies | company 13   13 15
Fair value $ 128,300   $ 128,300 $ 155,300
Cost $ 151,400   151,400 $ 195,000
Middle Market portfolio investments | Investment Owned, At Fair Value | Investment Type Concentration Risk        
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]        
Concentration risk (as a percent) 2.50%     3.10%
Middle Market portfolio investments | Investment Owned, At Cost | Investment Type Concentration Risk        
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]        
Concentration risk (as a percent) 3.50%     4.60%
Middle Market portfolio investments | Minimum        
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]        
Investments $ 3,000   3,000  
Middle Market portfolio investments | Minimum | Debt        
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]        
Investment term (in years) 3 years      
Middle Market portfolio investments | Maximum        
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]        
Investments $ 25,000   25,000  
Middle Market portfolio investments | Maximum | Debt        
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]        
Investment term (in years) 7 years      
Other Portfolio investments        
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]        
Fair value $ 134,500   134,500 $ 124,100
Cost $ 132,700   $ 132,700 $ 122,500
Number of portfolio investments in entities | entity 31   31 31
Number of investment managers | investmentManager 12   12 12
Other Portfolio investments | Investment Owned, At Fair Value | Investment Type Concentration Risk        
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]        
Concentration risk (as a percent) 2.70%     2.50%
Other Portfolio investments | Investment Owned, At Cost | Investment Type Concentration Risk        
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]        
Concentration risk (as a percent) 3.10%     2.90%
Other Portfolio investments | Minimum | Debt        
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]        
Investment term (in years) 5 years      
Other Portfolio investments | Maximum | Debt        
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]        
Investment term (in years) 10 years      
External Investment Manager        
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]        
Fair value $ 238,200   $ 238,200 $ 246,000
Cost $ 29,500   $ 29,500 $ 29,500
External Investment Manager | Investment Owned, At Fair Value | Investment Type Concentration Risk        
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]        
Concentration risk (as a percent) 4.70%     5.00%
External Investment Manager | Investment Owned, At Cost | Investment Type Concentration Risk        
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]        
Concentration risk (as a percent) 0.70%     0.70%
[1] All portfolio company headquarters are based in the United States, unless otherwise noted.
[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] All investments are Lower Middle Market portfolio investments, unless otherwise noted. See Note C — Fair Value Hierarchy for Investments — Portfolio Composition for a description of Lower Middle Market portfolio investments. All of the Company’s investments, unless otherwise noted, are encumbered either as security for the Company’s Corporate Facility or SPV Facility (each as defined in Note B.5. — Summary of Significant Accounting Policies —Deferred Financing Costs, and together the “Credit Facilities”) or in support of the SBA-guaranteed debentures issued by the Funds.
[4] All portfolio company headquarters are based in the United States, unless otherwise noted.
[5] All investments are Lower Middle Market portfolio investments, unless otherwise noted. See Note C — Fair Value Hierarchy for Investments — Portfolio Composition for a description of Lower Middle Market portfolio investments. All of the Company’s investments, unless otherwise noted, are encumbered either as security for the Company’s Corporate Facility or SPV Facility (each as defined in Note B.5. — Summary of Significant Accounting Policies —Deferred Financing Costs, and together the “Credit Facilities”) or in support of the SBA-guaranteed debentures issued by the Funds.
[6] 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.