v3.26.3
Portfolio Investments - Fair Value of Investments (Details) - USD ($)
$ in Thousands
Sep. 30, 2026
Jun. 30, 2026
Sep. 30, 2025
Jun. 30, 2025
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]        
Investments at fair value $ 5,944,478 [1] $ 6,342,558 [2]    
Derivative Instruments        
Derivative Assets, at fair value (Note 6) 14,373 18,900    
Total Foreign currency forward contracts - Assets 14,373 18,900    
Total Foreign currency forward contracts - Liabilities 0 0    
Investment , cost 5,944,319 6,315,369    
Foreign Exchange Forward        
Derivative Instruments        
Derivative Assets, at fair value (Note 6) 14,373 18,900    
Foreign currency forward contracts - Liabilities 0 0    
Level 1        
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]        
Investments at fair value 0 0    
Derivative Instruments        
Total Foreign currency forward contracts - Assets 0 0    
Total Foreign currency forward contracts - Liabilities 0 0    
Level 1 | Foreign Exchange Forward        
Derivative Instruments        
Derivative Assets, at fair value (Note 6) 0 0    
Foreign currency forward contracts - Liabilities 0 0    
Level 2        
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]        
Investments at fair value 1,124 1,233    
Derivative Instruments        
Total Foreign currency forward contracts - Assets 14,373 18,900    
Total Foreign currency forward contracts - Liabilities 0 0    
Level 2 | Foreign Exchange Forward        
Derivative Instruments        
Derivative Assets, at fair value (Note 6) 14,373 18,900    
Foreign currency forward contracts - Liabilities 0 0    
Level 3        
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]        
Investments at fair value 5,943,354 6,341,325    
Derivative Instruments        
Total Foreign currency forward contracts - Assets 0 0    
Total Foreign currency forward contracts - Liabilities 0 0    
Level 3 | Foreign Exchange Forward        
Derivative Instruments        
Derivative Assets, at fair value (Note 6) 0 0    
Foreign currency forward contracts - Liabilities 0 0    
First Lien Revolving Line of Credit        
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]        
Investments at fair value 82,317 72,378    
First Lien Revolving Line of Credit | Level 1        
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]        
Investments at fair value 0 0    
First Lien Revolving Line of Credit | Level 2        
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]        
Investments at fair value 0 0    
First Lien Revolving Line of Credit | Level 3        
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]        
Investments at fair value 82,317 72,378    
First Lien Debt        
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]        
Investments at fair value 3,952,018 4,216,556    
First Lien Debt | Level 1        
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]        
Investments at fair value 0 0    
First Lien Debt | Level 2        
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]        
Investments at fair value 1,124 1,192    
First Lien Debt | Level 3        
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]        
Investments at fair value 3,950,894 4,215,364    
First Lien, Unitranche        
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]        
Investments at fair value 58,579 155,717 $ 146,873 $ 166,464
Derivative Instruments        
Investment , cost 63,005 219,582 $ 202,687 $ 201,585
Second Lien Revolving Line of Credit        
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]        
Investments at fair value 5,284 1,854    
Second Lien Revolving Line of Credit | Level 1        
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]        
Investments at fair value 0 0    
Second Lien Revolving Line of Credit | Level 2        
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]        
Investments at fair value 0 0    
Second Lien Revolving Line of Credit | Level 3        
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]        
Investments at fair value 5,284 1,854    
Second Lien Debt        
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]        
Investments at fair value 568,779 577,354    
Second Lien Debt | Level 1        
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]        
Investments at fair value 0 0    
Second Lien Debt | Level 2        
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]        
Investments at fair value 0 41    
Second Lien Debt | Level 3        
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]        
Investments at fair value 568,779 577,313    
Unsecured Debt        
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]        
Investments at fair value 5,213 5,195    
Unsecured Debt | Level 1        
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]        
Investments at fair value 0 0    
Unsecured Debt | Level 2        
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]        
Investments at fair value 0 0    
Unsecured Debt | Level 3        
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]        
Investments at fair value 5,213 5,195    
Subordinated Structured Notes        
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]        
Investments at fair value 0 2,794    
Subordinated Structured Notes | Level 1        
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]        
Investments at fair value 0 0    
Subordinated Structured Notes | Level 2        
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]        
Investments at fair value 0 0    
Subordinated Structured Notes | Level 3        
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]        
Investments at fair value 0 2,794    
Equity        
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]        
Investments at fair value 1,330,867 1,466,427    
Equity | Level 1        
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]        
Investments at fair value 0 0    
Equity | Level 2        
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]        
Investments at fair value 0 0    
Equity | Level 3        
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]        
Investments at fair value $ 1,330,867 $ 1,466,427    
[1] Fair value is determined by or under the direction of our Board of Directors. Unless otherwise indicated by endnote 42 below, all of our investments are valued using significant unobservable inputs. In accordance with ASC 820, such investments are classified as Level 3 within the fair value hierarchy. See Notes 2 and 3 within the accompanying notes to consolidated financial statements for further discussion.
[2] Fair value is determined by or under the direction of our Board of Directors. Unless otherwise indicated by endnote 42 below, all of our investments are valued using significant unobservable inputs. In accordance with ASC 820, such investments are classified as Level 3 within the fair value hierarchy. See Notes 2 and 3 within the accompanying notes to consolidated financial statements for further discussion.