Annual report [Section 13 and 15(d), not S-K Item 405]

INVESTMENTS - Investment Concentrations Narrative (Details)

v3.25.3
INVESTMENTS - Investment Concentrations Narrative (Details)
$ in Thousands
 12 Months Ended
Sep. 30, 2025
USD ($)
portfolioCompany
state
industry
Sep. 30, 2024
USD ($)
Summary of Investment Holdings [Line Items]    
Number of investment portfolio company | portfolioCompany 55  
Number of states which have invested in the company location | state 22  
Number of industries that have made investments | industry 16  
Fair Value $ 859,124 [1] $ 796,260 [2]
Weighted average investment owned, at cost, amount 15,900 15,700
Five Largest Portfolio Investments | Investment Portfolio Benchmark | Customer Concentration Risk    
Summary of Investment Holdings [Line Items]    
Fair Value $ 196,500 $ 232,700
Concentration risk, percentage 22.90% 29.20%
[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.
[2] Cumulative gross unrealized depreciation for federal income tax purposes is $66.1 million; cumulative gross unrealized appreciation for federal income tax purposes is $85.8 million. Cumulative net unrealized appreciation is $19.7 million, based on a tax cost of $776.5 million