Quarterly report [Sections 13 or 15(d)]

BORROWINGS - Schedule of Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation (Details)

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BORROWINGS - Schedule of Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation (Details) - USD ($)
$ in Thousands
 3 Months Ended 9 Months Ended
Jun. 30, 2026
Jun. 30, 2025
Jun. 30, 2026
Jun. 30, 2025
Sep. 30, 2025
Debt Instrument [Line Items]          
Credit Facility $ 177,500   $ 177,500   $ 0
Significant Unobservable Inputs (Level 3) | Fair Value, Recurring          
Debt Instrument [Line Items]          
Credit Facility 177,500   177,500   $ 0
Significant Unobservable Inputs (Level 3) | Fair Value, Recurring | Long-Term Debt          
Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis, Unobservable Input Reconciliation [Roll Forward]          
Beginning balance 199,800 $ 25,149 0 $ 70,600  
Borrowings 97,000 63,500 381,000 212,000  
Repayments (119,300) (61,100) (203,500) (255,100)  
Net unrealized appreciation 0 (49) 0 0  
Ending balance $ 177,500 $ 27,500 $ 177,500 $ 27,500