v3.26.1
Portfolio Investments - Schedule of Summarized Balance Sheet Information (Details) - USD ($)
 9 Months Ended 12 Months Ended
Jun. 30, 2026
Sep. 30, 2025
Investment Company, Nonconsolidated Subsidiary [Line Items]    
Investments at fair value $ 2,741,814,000 $ 2,847,782,000
Cash and cash equivalents 39,921,000 79,630,000
Restricted cash 0 0
Receivables from unsettled transactions 36,627,000 4,949,000
Other assets 997,000 1,495,000
Total assets 2,858,192,000 3,002,991,000
Senior credit facility payable 501,000,000 545,000,000
Payables from unsettled transactions 4,943,000 15,011,000
Other liabilities 1,957,000 1,569,000
Total liabilities 1,475,137,000 1,537,178,000
Additional paid-in-capital 2,858,192,000 3,002,991,000
Investment owned, at cost 2,996,697,000 3,075,122,000
SLF JV I    
Investment Company, Nonconsolidated Subsidiary [Line Items]    
Investments at fair value 391,910,000 384,364,000
Cash and cash equivalents 13,734,000 58,556,000
Restricted cash 2,879,000 2,023,000
Other assets 20,523,000 2,456,000
Total assets 429,046,000 447,399,000
Senior credit facility payable 272,500,000 252,500,000
Notes payable at fair value 96,560,000 128,750,000
Other liabilities 27,187,000 52,496,000
Total liabilities 396,247,000 433,746,000
Members' equity 32,799,000 13,653,000
Additional paid-in-capital 429,046,000 447,399,000
Investment owned, at cost 409,871,000 403,332,000
Net proceeds 96,560,000 128,750,000
Glick JV LLC    
Investment Company, Nonconsolidated Subsidiary [Line Items]    
Investments at fair value 132,082,000 128,651,000
Cash and cash equivalents 4,165,000 18,752,000
Restricted cash 929,000 650,000
Receivables from unsettled transactions 4,267,000 0
Other assets 1,093,000 1,070,000
Total assets 142,536,000 149,123,000
Senior credit facility payable 90,000,000 80,500,000
Notes payable at fair value 47,219,000 52,640,000
Payables from unsettled transactions 3,708,000 14,002,000
Other liabilities 1,609,000 1,981,000
Total liabilities 142,536,000 149,123,000
Members' equity 0 0
Additional paid-in-capital 142,536,000 149,123,000
Investment owned, at cost 138,309,000 135,083,000
Net proceeds $ 66,685,000 $ 66,685,000