v3.25.1
FAIR VALUE HIERARCHY FOR INVESTMENTS—PORTFOLIO COMPOSITION - Narrative (Details)
$ in Thousands
 3 Months Ended 12 Months Ended
Mar. 31, 2025
USD ($)
investmentManager
company
entity
Mar. 31, 2024
Mar. 31, 2025
USD ($)
investmentManager
company
entity
Dec. 31, 2024
USD ($)
company
entity
investmentManager
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]        
Annualized total return on investments 0.106 0.118    
Achieved total return on investments       0.124
Fair value $ 1,260,853 [1]   $ 1,260,853 [1] $ 1,177,507 [2]
Cost $ 1,203,330 [3]   $ 1,203,330 [3] $ 1,138,745 [4]
Concentration risk, percentage (as a percent) 100.00%     100.00%
Investment Owned, At Fair Value | Investment Type Concentration Risk        
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]        
Concentration risk, percentage (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, percentage (as a percent) 100.00%     100.00%
Private Loan portfolio investments        
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]        
Number of portfolio companies | company 84   84 84
Fair value $ 767,800   $ 767,800 $ 677,900
Cost $ 790,000   $ 790,000 $ 697,500
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, percentage (as a percent) 26.00% 21.00% 88.00%  
Private Loan portfolio investments | Debt investments | Investment Owned, At Cost | Investment Type Concentration Risk        
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]        
Concentration risk, percentage (as a percent) 93.50%     93.90%
Private Loan portfolio investments | Minimum        
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]        
Annual revenues $ 25,000      
Investments $ 1,000   $ 1,000  
Private Loan portfolio investments | Minimum | Debt investments        
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]        
Investment, term 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 $ 30,000   $ 30,000  
Private Loan portfolio investments | Maximum | Debt investments        
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]        
Investment, term 7 years      
LMM portfolio investments        
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]        
Number of portfolio companies | company 57   57 57
Fair value $ 439,700   $ 439,700 $ 436,100
Cost $ 356,300   $ 356,300 $ 357,100
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, percentage (as a percent) 26.00% 26.00% 95.00%  
LMM portfolio investments | Debt investments | Investment Owned, At Cost | Investment Type Concentration Risk        
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]        
Concentration risk, percentage (as a percent) 67.70%     67.80%
LMM portfolio investments | Minimum        
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]        
Annual revenues $ 10,000      
Investments $ 1,000   $ 1,000  
LMM portfolio investments | Minimum | Debt investments        
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]        
Investment, term 5 years      
LMM portfolio investments | Maximum        
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]        
Annual revenues $ 150,000      
Investments $ 30,000   $ 30,000  
LMM portfolio investments | Maximum | Debt investments        
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]        
Investment, term 7 years      
Middle Market portfolio investments        
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]        
Number of portfolio companies | company 8   8 10
Fair value $ 30,800   $ 30,800 $ 39,400
Cost $ 40,600   40,600 $ 66,300
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, percentage (as a percent) 2.40%     3.30%
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, percentage (as a percent) 3.40%     5.80%
Middle Market portfolio investments | Minimum        
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]        
Investments $ 1,000   1,000  
Middle Market portfolio investments | Minimum | Debt investments        
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]        
Investment, term 3 years      
Middle Market portfolio investments | Maximum        
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]        
Investments $ 20,000   $ 20,000  
Middle Market portfolio investments | Maximum | Debt investments        
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]        
Investment, term 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 6   6 6
Number of portfolio investments with investments managers | investmentManager 4   4 4
Fair value $ 22,600   $ 22,600 $ 24,100
Cost $ 16,500   $ 16,500 $ 17,900
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, percentage (as a percent) 1.80%     2.00%
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, percentage (as a percent) 1.40%     1.60%
Other Portfolio investments | Minimum | Debt investments        
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]        
Investment, term 5 years      
Other Portfolio investments | Maximum | Debt investments        
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]        
Investment, term 10 years      
[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.