Quarterly report pursuant to Section 13 or 15(d)

FAIR VALUE HIERARCHY FOR INVESTMENTS???PORTFOLIO COMPOSITION - Schedule of Fair Value Hierarchy (Details)

v3.23.3
FAIR VALUE HIERARCHY FOR INVESTMENTS—PORTFOLIO COMPOSITION - Schedule of Fair Value Hierarchy (Details) - USD ($)
$ in Thousands
Sep. 30, 2023
Dec. 31, 2022
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]    
Investments at fair value: $ 4,294,722 [1] $ 4,102,177 [2]
Fair Value, Recurring    
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]    
Investments at fair value: 4,294,722 4,102,177
Fair Value, Recurring | LMM portfolio investments    
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]    
Investments at fair value: 2,190,371 2,060,459
Fair Value, Recurring | Private Loan portfolio investments    
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]    
Investments at fair value: 1,543,958 1,471,466
Fair Value, Recurring | Middle Market portfolio investments    
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]    
Investments at fair value: 290,613 329,119
Fair Value, Recurring | Other Portfolio investments    
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]    
Investments at fair value: 123,649 116,299
Fair Value, Recurring | External Investment Manager    
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]    
Investments at fair value: 146,131 122,930
Fair Value, Recurring | Short-term portfolio investments    
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]    
Investments at fair value:   1,904
Quoted Prices in Active Markets for Identical Assets (Level 1) | Fair Value, Recurring    
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]    
Investments at fair value: 0 0
Quoted Prices in Active Markets for Identical Assets (Level 1) | Fair Value, Recurring | LMM portfolio investments    
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]    
Investments at fair value: 0 0
Quoted Prices in Active Markets for Identical Assets (Level 1) | Fair Value, Recurring | Private Loan portfolio investments    
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]    
Investments at fair value: 0 0
Quoted Prices in Active Markets for Identical Assets (Level 1) | Fair Value, Recurring | Middle Market portfolio investments    
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]    
Investments at fair value: 0 0
Quoted Prices in Active Markets for Identical Assets (Level 1) | Fair Value, Recurring | Other Portfolio investments    
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]    
Investments at fair value: 0 0
Quoted Prices in Active Markets for Identical Assets (Level 1) | Fair Value, Recurring | External Investment Manager    
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]    
Investments at fair value: 0 0
Quoted Prices in Active Markets for Identical Assets (Level 1) | Fair Value, Recurring | Short-term portfolio investments    
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]    
Investments at fair value:   0
Significant Other Observable Inputs (Level 2) | Fair Value, Recurring    
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]    
Investments at fair value: 0 1,904
Significant Other Observable Inputs (Level 2) | Fair Value, Recurring | LMM portfolio investments    
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]    
Investments at fair value: 0 0
Significant Other Observable Inputs (Level 2) | Fair Value, Recurring | Private Loan portfolio investments    
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]    
Investments at fair value: 0 0
Significant Other Observable Inputs (Level 2) | Fair Value, Recurring | Middle Market portfolio investments    
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]    
Investments at fair value: 0 0
Significant Other Observable Inputs (Level 2) | Fair Value, Recurring | Other Portfolio investments    
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]    
Investments at fair value: 0 0
Significant Other Observable Inputs (Level 2) | Fair Value, Recurring | External Investment Manager    
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]    
Investments at fair value: 0 0
Significant Other Observable Inputs (Level 2) | Fair Value, Recurring | Short-term portfolio investments    
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]    
Investments at fair value:   1,904
Significant Unobservable Inputs (Level 3)    
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]    
Investments at fair value: 4,294,722 4,100,273
Significant Unobservable Inputs (Level 3) | Fair Value, Recurring    
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]    
Investments at fair value: 4,294,722 4,100,273
Significant Unobservable Inputs (Level 3) | Fair Value, Recurring | LMM portfolio investments    
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]    
Investments at fair value: 2,190,371 2,060,459
Significant Unobservable Inputs (Level 3) | Fair Value, Recurring | Private Loan portfolio investments    
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]    
Investments at fair value: 1,543,958 1,471,466
Significant Unobservable Inputs (Level 3) | Fair Value, Recurring | Middle Market portfolio investments    
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]    
Investments at fair value: 290,613 329,119
Significant Unobservable Inputs (Level 3) | Fair Value, Recurring | Other Portfolio investments    
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]    
Investments at fair value: 123,649 116,299
Significant Unobservable Inputs (Level 3) | Fair Value, Recurring | External Investment Manager    
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]    
Investments at fair value: $ 146,131 122,930
Significant Unobservable Inputs (Level 3) | Fair Value, Recurring | Short-term portfolio investments    
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]    
Investments at fair value:   $ 0
[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.