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

SUBSEQUENT EVENTS - Narrative (Details)

v3.25.3
SUBSEQUENT EVENTS - Narrative (Details) - USD ($)
$ in Thousands
 1 Months Ended 12 Months Ended
Nov. 17, 2025
Oct. 31, 2025
Sep. 30, 2025
Sep. 30, 2024
Sep. 30, 2023
Oct. 15, 2025
Aug. 31, 2023
Sep. 30, 2022
Sep. 30, 2021
Mar. 31, 2021
Dec. 31, 2020
Sep. 30, 2020
Sep. 30, 2019
Sep. 30, 2018
Sep. 30, 2017
Sep. 30, 2016
Subsequent Event [Line Items]                                
Purchase of investments     $ 396,796 $ 177,649 $ 175,477                      
Committed capital, unfunded     66,396 57,594                        
Investment owned, cost     876,614 [1] 771,011 [2]                        
Aggregate principal amount     $ 406,500 $ 257,000 $ 257,000     $ 200,000 $ 188,813     $ 96,313 $ 57,500 $ 0 $ 0 $ 0
Notes Payable | 7.75% Notes due 2028                                
Subsequent Event [Line Items]                                
Aggregate principal amount             $ 57,000                  
Notes Payable | 5.125% Notes due 2026                                
Subsequent Event [Line Items]                                
Aggregate principal amount                   $ 50,000 $ 100,000          
Subsequent Event | Notes Payable | 7.75% Notes due 2028                                
Subsequent Event [Line Items]                                
Aggregate principal amount           $ 57,000                    
Subsequent Event | Notes Payable | 5.125% Notes due 2026                                
Subsequent Event [Line Items]                                
Aggregate principal amount   $ 150,000                            
Total Access Elevator, LLC (“Total Access”) | Subsequent Event                                
Subsequent Event [Line Items]                                
Purchase of investments   11,000                            
Committed capital, unfunded   9,850                            
Leadpoint Business Services, LLC | Subsequent Event                                
Subsequent Event [Line Items]                                
Net proceeds from the sale of investments   28,100                            
Investment company, prepayment fee   300                            
Sokol | Subsequent Event                                
Subsequent Event [Line Items]                                
Investment owned, cost   500                            
Realized investment gains   1,800                            
Sea Link International IRB, Inc | Subsequent Event                                
Subsequent Event [Line Items]                                
Net proceeds from the sale of investments   17,800                            
Investment company exit fee   200                            
Turn Key Health Clinics, LLC | Subsequent Event                                
Subsequent Event [Line Items]                                
Purchase of investments $ 15,000                              
Committed capital, unfunded 5,000 $ 1,000                            
Sicilian Oven Holdings, LLC | Subsequent Event                                
Subsequent Event [Line Items]                                
Purchase of investments $ 26,600                              
[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