v3.26.1
FAIR VALUE HIERARCHY FOR INVESTMENTS—PORTFOLIO COMPOSITION - Narrative (Details)
$ in Thousands
 3 Months Ended 12 Months Ended
Mar. 31, 2026
USD ($)
company
investmentManager
investment
entity
Mar. 31, 2025
USD ($)
Mar. 31, 2026
USD ($)
company
investmentManager
investment
entity
Dec. 31, 2025
USD ($)
company
investmentManager
investment
entity
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]        
Expenses allocated $ 5,466 $ 5,336    
Annualized total return on investments (as a percent) 0.089 0.160    
Achieved total return on investments (as a percent)       0.164
Investments at fair value: $ 5,674,751 [1],[2],[3]   $ 5,674,751 [1],[2],[3] $ 5,518,117 [4],[5],[6]
Cost $ 4,933,484 [1],[3],[7]   $ 4,933,484 [1],[3],[7] $ 4,724,528 [4],[6],[8]
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 $ 5,500 $ 5,300    
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]        
Investments at fair value: $ 3,227,400   $ 3,227,400 $ 3,057,000
Cost $ 2,577,000   $ 2,577,000 $ 2,419,300
Number of portfolio companies | company 93   93 92
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) 25.00% 20.00% 86.00%  
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) 72.00%     71.20%
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]        
Investments at fair value: $ 1,993,900   1,993,900 $ 1,988,400
Cost $ 2,057,000   $ 2,057,000 $ 2,014,100
Number of portfolio companies | company 85   85 86
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) 24.00% 26.00% 84.00%  
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) 94.50%     93.50%
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]        
Investments at fair value: $ 81,900   81,900 $ 83,500
Cost $ 121,400   $ 121,400 $ 120,100
Number of portfolio companies | company 11   11 11
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) 1.40%     1.50%
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) 2.50%     2.50%
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]        
Number of portfolio investments in entities | entity 34   34 33
Number of investment managers | investmentManager 13   13 13
Investments at fair value: $ 138,500   $ 138,500 $ 134,100
Cost $ 148,500   148,500 $ 141,600
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) 2.40%     2.40%
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) 3.00%     3.00%
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]        
Investments at fair value: $ 233,100   233,100 $ 255,000
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) 4.10%     4.60%
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) 0.60%     0.60%
[1] All portfolio company headquarters are based in the U.S., 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 LMM (as defined below) portfolio investments, unless otherwise noted. See Note C — Fair Value Hierarchy for Investments — Portfolio Composition for a description of LMM portfolio investments. All of the Company’s investments, unless otherwise noted, are encumbered either as security for
the Corporate Facility or SPV Facility (each as defined below) or in support of the debentures guaranteed by the SBA (as defined below) and issued by the Funds (as defined below).
[4] All portfolio company headquarters are based in the U.S., unless otherwise noted.
[5] 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.
[6] All investments are LMM portfolio investments, unless otherwise noted. See Note C — Fair Value Hierarchy for Investments — Portfolio Composition for a description of LMM portfolio investments. All of the Company’s investments, unless otherwise noted, are encumbered either as security for the Corporate Facility or SPV Facility or in support of the debentures guaranteed by the SBA and issued by the Funds.
[7] 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.
[8] 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.