Quarterly report [Sections 13 or 15(d)]

INVESTMENTS - Schedule of Fair Value Measurements Using Significant Unobservable Inputs (Details)

v3.25.2
INVESTMENTS - Schedule of Fair Value Measurements Using Significant Unobservable Inputs (Details) - USD ($)
$ in Thousands
 3 Months Ended 9 Months Ended
Jun. 30, 2025
Jun. 30, 2024
Jun. 30, 2025
Jun. 30, 2024
Total        
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]        
Beginning balance $ 757,625 $ 791,324 $ 796,222 $ 704,562
New investments, repayments and settlements:        
Issuances/originations 74,031 47,846 268,103 153,183
Settlements/repayments (80,934) (85,084) (238,417) (121,397)
Net proceeds from sales (731) (1,434) (89,564) (2,663)
Transfers 0   0  
Ending balance 746,214 757,535 746,214 757,535
Total | Net realized gain (loss)        
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]        
Total gain (loss) (3,708) 1,415 61,718 1,893
Total | Net unrealized appreciation (depreciation) and Reversal of prior period net depreciation (appreciation) on realization        
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]        
Total gain (loss) (6,417) 3,559 3,659 22,063
Reversal of prior period net depreciation (appreciation) on realization 6,348 (91) (55,507) (106)
Secured First Lien Debt        
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]        
Beginning balance 541,524 563,849 554,937 510,701
New investments, repayments and settlements:        
Issuances/originations 73,889 26,964 212,754 106,939
Settlements/repayments (80,193) (41,749) (221,130) (73,555)
Net proceeds from sales 0 50 0 50
Transfers (8,500)   (8,500)  
Ending balance 529,149 542,283 529,149 542,283
Secured First Lien Debt | Net realized gain (loss)        
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]        
Total gain (loss) (4,439) (50) (8,513) (50)
Secured First Lien Debt | Net unrealized appreciation (depreciation) and Reversal of prior period net depreciation (appreciation) on realization        
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]        
Total gain (loss) 815 (6,748) (10,011) (1,750)
Reversal of prior period net depreciation (appreciation) on realization 6,053 (33) 9,612 (52)
Secured second lien debt        
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]        
Beginning balance 144,970 140,409 113,716 127,854
New investments, repayments and settlements:        
Issuances/originations 130 20,132 47,827 35,494
Settlements/repayments (741) (43,335) (17,287) (47,842)
Net proceeds from sales 0 0 0 0
Transfers 0   0  
Ending balance 144,299 117,875 144,299 117,875
Secured second lien debt | Net realized gain (loss)        
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]        
Total gain (loss) 0 0 0 0
Secured second lien debt | Net unrealized appreciation (depreciation) and Reversal of prior period net depreciation (appreciation) on realization        
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]        
Total gain (loss) (355) 727 (252) 2,270
Reversal of prior period net depreciation (appreciation) on realization 295 (58) 295 99
Unsecured debt        
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]        
Beginning balance 335 33 32 24
New investments, repayments and settlements:        
Issuances/originations 12 0 345 0
Settlements/repayments 0 0 0 0
Net proceeds from sales 0 0 0 0
Transfers 0   0  
Ending balance 354 33 354 33
Unsecured debt | Net realized gain (loss)        
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]        
Total gain (loss) 0 0 0 0
Unsecured debt | Net unrealized appreciation (depreciation) and Reversal of prior period net depreciation (appreciation) on realization        
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]        
Total gain (loss) 7 0 (23) 9
Reversal of prior period net depreciation (appreciation) on realization 0 0 0 0
Preferred Equity        
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]        
Beginning balance 25,031 32,598 31,346 26,855
New investments, repayments and settlements:        
Issuances/originations 0 0 6,262 10,000
Settlements/repayments 0 0 0 0
Net proceeds from sales 0 0 (19,404) (969)
Transfers 0   0  
Ending balance 25,717 32,965 25,717 32,965
Preferred Equity | Net realized gain (loss)        
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]        
Total gain (loss) 0 0 5,404 219
Preferred Equity | Net unrealized appreciation (depreciation) and Reversal of prior period net depreciation (appreciation) on realization        
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]        
Total gain (loss) 686 367 7,513 (3,270)
Reversal of prior period net depreciation (appreciation) on realization 0 0 (5,404) 130
Common Equity/ Equivalents        
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]        
Beginning balance 45,765 54,435 96,191 39,128
New investments, repayments and settlements:        
Issuances/originations 0 750 915 750
Settlements/repayments 0 0 0 0
Net proceeds from sales (731) (1,484) (70,160) (1,744)
Transfers 8,500   8,500  
Ending balance 46,695 64,379 46,695 64,379
Common Equity/ Equivalents | Net realized gain (loss)        
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]        
Total gain (loss) 731 1,465 64,827 1,724
Common Equity/ Equivalents | Net unrealized appreciation (depreciation) and Reversal of prior period net depreciation (appreciation) on realization        
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]        
Total gain (loss) (7,570) 9,213 6,432 24,804
Reversal of prior period net depreciation (appreciation) on realization $ 0 $ 0 $ (60,010) $ (283)