v3.26.1
Fair Value of Financial Instruments - Reconciliation of Liabilities Measured at Fair Value Using Significant Unobservable Inputs Level 3 (Details) - USD ($)
$ in Thousands
6 Months Ended
Mar. 31, 2026
Mar. 31, 2025
Fair Value Liabilities Measured On Recurring Basis Unobservable Input Reconciliation [Line Items]    
Net realized (gain) loss $ (6,079) $ 23,197
Level 3 | Long-Term Credit Facility    
Fair Value Liabilities Measured On Recurring Basis Unobservable Input Reconciliation [Line Items]    
Beginning balance (cost - $683,855 and $443,855, respectively) 683,837 443,880
Net change in unrealized (depreciation) appreciation included in earnings (4) (91)
Borrowings 141,500 235,001
Repayments (497,000) (405,000)
Ending balance (cost - $328,355 and $273,855, respectively) $ 328,333 $ 273,790