v3.26.1
Significant Accounting Policies and Recent Accounting Updates (Details)
 3 Months Ended 9 Months Ended
Jun. 30, 2026
USD ($)
security
Jun. 30, 2025
USD ($)
Jun. 30, 2026
USD ($)
segment
security
Jun. 30, 2025
USD ($)
Sep. 30, 2025
USD ($)
security
Accounting Policies [Abstract]          
Amortization of deferred loan origination fees, net $ 1,618,000 $ 1,706,000 $ 4,696,000 $ 6,085,000  
Interest income, operating, accretion of discounts 1,663,000 1,285,000 5,171,000 3,722,000  
Payment-in-kind interest income 4,120,000 2,449,000 11,471,000 7,020,000  
Payment-in-kind interest capitalized 4,047,000 2,412,000 11,390,000 6,973,000  
Investment company, premium prepayment fees 52,000 127,000 179,000 151,000  
Interest and fee income 49,755,000 35,166,000 155,530,000 112,228,000  
Non-cash preferred dividends 228,000 179,000 711,000 387,000  
Dividend income, operating, paid in kind 228,000 179,000 711,000 387,000  
Proceeds from dividends received 111,000 0 111,000 170,000  
Dividend income received in cash 2,000 2,000 154,000 69,000  
Return of capital 0 1,000 32,000 91,000  
Loans on non-accrual status 347,000   347,000   $ 0
Preferred equity securities aggregate amount in nonaccrual status $ 567,000   $ 567,000    
Number of preferred equity security on non-accrual status | security 1   1   0
Excise tax $ 0 0 $ 0 0  
Deferred debt issuance cost 5,364,000   5,364,000   $ 8,281,000
Amortization of deferred debt issuance costs 983,000 1,149,000 $ 2,945,000 3,070,000  
Deferred offering cost, amortization duration (in years)     3 years    
Amortization of deferred offering costs $ 0 $ 0 $ 0 $ 68,000  
Number of operating segments | segment     1    
Number of reportable segments | segment     1