Quarterly report [Sections 13 or 15(d)]

INVESTMENTS - Narrative (Details)

v3.26.1
INVESTMENTS - Narrative (Details)
$ in Thousands
 9 Months Ended 12 Months Ended
Jun. 30, 2026
USD ($)
portfolioCompany
state
industry
Sep. 30, 2025
USD ($)
Summary of Investment Holdings [Line Items]    
Number of investment portfolio company | portfolioCompany 59  
Number of states which have invested in the company location | state 24  
Number of industries that have made investments | industry 17  
Investments, at fair value $ 953,326 $ 859,124 [1]
Weighted average investment owned, at cost, amount $ 16,400 15,900
Uncollectible receivables allowance, minimum required day for uncollectible adjustment 90 days  
Gross receivables from portfolio companies $ 2,600 2,400
Allowance for uncollectible receivables 81 52
Five Largest Portfolio Investments | Investment Portfolio Benchmark | Customer Concentration Risk    
Summary of Investment Holdings [Line Items]    
Investments, at fair value $ 203,400 $ 196,500
Concentration risk, percentage 21.30% 22.90%
[1] Cumulative gross unrealized depreciation for federal income tax purposes is $59.7 million; cumulative gross unrealized appreciation for federal income tax purposes is $34.1 million. Cumulative net unrealized depreciation is $25.5 million, based on a tax cost of $884.7 million.