Quarterly report [Sections 13 or 15(d)]

SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES (Details)

v3.25.1
SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES (Details)
$ in Thousands
 3 Months Ended 6 Months Ended
Apr. 04, 2024
Mar. 31, 2025
USD ($)
investment
loan
Mar. 31, 2024
USD ($)
Mar. 31, 2025
USD ($)
investment
loan
Mar. 31, 2024
USD ($)
Sep. 30, 2024
USD ($)
investment
loan
Schedule of Investments [Line Items]            
Reverse stock split, conversion ratio 0.5          
Money market funds   $ 2,400   $ 2,400   $ 2,200
Cost   789,193   789,193   771,011 [1]
Fair Value   762,636   762,636   796,260 [1]
Total interest income (excluding PIK interest income)   20,438 $ 22,330 40,995 $ 43,918  
PIK interest income   900 1,385 1,663 2,793  
OID            
Schedule of Investments [Line Items]            
Fair Value   $ 400   $ 400   $ 600
Number of loans | loan   2   2   2
Total interest income (excluding PIK interest income)   $ 100 100 $ 200 100  
PIK            
Schedule of Investments [Line Items]            
Number of investments | investment   7   7   8
Proceeds from interest received   $ 2,600 $ 0 $ 7,200 $ 0  
B+T Group Acquisition, Inc., Edge Adhesives Holdings, Inc,. And WB Xcel Holdings, LLC            
Schedule of Investments [Line Items]            
Cost   $ 53,700   $ 53,700   $ 28,300
Cost percentage   7.50%   7.50%   4.10%
Fair Value   $ 29,800   $ 29,800   $ 12,800
Fair value percentage   4.30%   4.30%   1.90%
[1] 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.