v3.26.1
Borrowings - 2026-B Debt Securitization - Narrative (Details)
3 Months Ended 9 Months Ended
Jan. 14, 2026
USD ($)
Jun. 30, 2026
USD ($)
portfolio_company
Jun. 30, 2026
USD ($)
portfolio_company
Jun. 30, 2025
USD ($)
Sep. 30, 2025
USD ($)
[2]
Debt Instrument [Line Items]          
Repayments of debt     $ 2,899,787,000 $ 2,110,736,000  
Fair value   $ 9,616,525,000 [1] $ 9,616,525,000 [1]   $ 8,555,251,000
2026-B Debt Securitization          
Debt Instrument [Line Items]          
Aggregate principal amount $ 400,150,000        
Debt instrument, basis spread on variable rate     3.70%    
Repayments of debt   0 $ 0    
Restricted cash and cash equivalent   $ 43,758,000 $ 43,758,000    
Number of investment portfolio company | portfolio_company   120 120    
Fair value   $ 342,299,000 $ 342,299,000    
2026-B Debt Securitization | Class A-1 2026-B Notes          
Debt Instrument [Line Items]          
Aggregate principal amount $ 264,000,000        
Debt instrument, basis spread on variable rate 1.05%        
2026-B Debt Securitization | Class A-2 2026-B Notes          
Debt Instrument [Line Items]          
Aggregate principal amount $ 8,000,000        
Debt instrument, basis spread on variable rate 1.30%        
2026-B Debt Securitization | Class B 2026-B Notes          
Debt Instrument [Line Items]          
Aggregate principal amount $ 35,000,000        
Debt instrument, basis spread on variable rate 1.45%        
2026-B Debt Securitization | Class C 2026-B Notes          
Debt Instrument [Line Items]          
Aggregate principal amount $ 28,000,000        
Debt instrument, basis spread on variable rate 1.70%        
2026-B Debt Securitization | Subordinated Notes          
Debt Instrument [Line Items]          
Aggregate principal amount $ 65,150,000        
[1] The fair values of investments were valued using significant unobservable inputs, unless otherwise noted. See Note 6. The fair value of loan investments may include the impact of the unfunded commitment being valued below par.
[2] The fair values of investments were valued using significant unobservable inputs, unless otherwise noted. See Note 6. The fair value of loan investments may include the impact of the unfunded commitment being valued below par.