Quarterly report pursuant to Section 13 or 15(d)

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

v3.22.2.2
FAIR VALUE HIERARCHY FOR INVESTMENTS—PORTFOLIO COMPOSITION - Fair Value Hierarchy (Details) - USD ($)
$ in Thousands
Sep. 30, 2022
Dec. 31, 2021
Sep. 30, 2021
 [2],[4],[5]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]      
Investments at fair value: $ 3,973,490 $ 3,561,831 [1],[2],[3] $ 3,973,490
Fair Value, Recurring      
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]      
Investments at fair value: 3,973,490 3,561,831  
Fair Value, Recurring | LMM portfolio investments      
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]      
Investments at fair value: 1,910,915 1,716,415  
Fair Value, Recurring | Private Loan portfolio investments      
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]      
Investments at fair value: 1,476,934 1,141,772  
Fair Value, Recurring | Middle Market portfolio investments      
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]      
Investments at fair value: 354,286 395,167  
Fair Value, Recurring | Other Portfolio investments      
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]      
Investments at fair value: 117,010 166,083  
Fair Value, Recurring | External Investment Manager investments      
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]      
Investments at fair value: 112,490 140,400  
Fair Value, Recurring | Short-term portfolio investments      
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]      
Investments at fair value: 1,855 1,994  
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 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 | Short-term 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      
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]      
Investments at fair value: 1,855 1,994  
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 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 | Short-term portfolio investments      
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]      
Investments at fair value: 1,855 1,994  
Significant Unobservable Inputs (Level 3)      
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]      
Investments at fair value: 3,971,635 3,559,837  
Significant Unobservable Inputs (Level 3) | Fair Value, Recurring      
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]      
Investments at fair value: 3,971,635 3,559,837  
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: 1,910,915 1,716,415  
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: 1,476,934 1,141,772  
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: 354,286 395,167  
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: 117,010 166,083  
Significant Unobservable Inputs (Level 3) | Fair Value, Recurring | External Investment Manager investments      
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]      
Investments at fair value: 112,490 140,400  
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 $ 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.
[2] 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 Credit Facility or in support of the SBA-guaranteed debentures issued by the Funds.
[3] All portfolio company headquarters are based in the United States, unless otherwise noted.
[4] 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.
[5] All portfolio company headquarters are based in the United States, unless otherwise noted.