v3.25.2
Portfolio Investments - Schedule of Significant Unobservable Inputs for Level 3 Investments (Details)
$ in Thousands
Jun. 30, 2025
USD ($)
Sep. 30, 2024
USD ($)
Fair Value Measurement Inputs and Valuation Techniques [Line Items]    
Investment owned, fair value $ 6,362,926 [1] $ 4,576,233 [2]
Senior secured debt    
Fair Value Measurement Inputs and Valuation Techniques [Line Items]    
Investment owned, fair value 5,744,828 4,073,936
Level 3    
Fair Value Measurement Inputs and Valuation Techniques [Line Items]    
Investment owned, fair value 4,910,435 3,140,726
Level 3 | Senior secured debt    
Fair Value Measurement Inputs and Valuation Techniques [Line Items]    
Investment owned, fair value 4,535,534 2,890,580
Level 3 | Senior secured debt | Market Yield | Market Yield    
Fair Value Measurement Inputs and Valuation Techniques [Line Items]    
Investment owned, fair value $ 4,359,174 $ 2,693,219
Level 3 | Senior secured debt | Market Yield | Market Yield | Minimum    
Fair Value Measurement Inputs and Valuation Techniques [Line Items]    
Measurement input 0.060 0.057
Level 3 | Senior secured debt | Market Yield | Market Yield | Maximum    
Fair Value Measurement Inputs and Valuation Techniques [Line Items]    
Measurement input 0.240 0.220
Level 3 | Senior secured debt | Market Yield | Market Yield | Weighted Average    
Fair Value Measurement Inputs and Valuation Techniques [Line Items]    
Measurement input 0.097 0.101
Level 3 | Senior secured debt | Revenue Multiple | Enterprise Value    
Fair Value Measurement Inputs and Valuation Techniques [Line Items]    
Investment owned, fair value $ 10,751 $ 10,208
Level 3 | Senior secured debt | Revenue Multiple | Enterprise Value | Minimum    
Fair Value Measurement Inputs and Valuation Techniques [Line Items]    
Measurement input 2.1 1.9
Level 3 | Senior secured debt | Revenue Multiple | Enterprise Value | Maximum    
Fair Value Measurement Inputs and Valuation Techniques [Line Items]    
Measurement input 2.3 2.1
Level 3 | Senior secured debt | Revenue Multiple | Enterprise Value | Weighted Average    
Fair Value Measurement Inputs and Valuation Techniques [Line Items]    
Measurement input 2.2 2.0
Level 3 | Senior secured debt | EBITDA Multiple | Enterprise Value    
Fair Value Measurement Inputs and Valuation Techniques [Line Items]    
Investment owned, fair value $ 3,485 $ 2,391
Level 3 | Senior secured debt | EBITDA Multiple | Enterprise Value | Minimum    
Fair Value Measurement Inputs and Valuation Techniques [Line Items]    
Measurement input 7.2 6.5
Level 3 | Senior secured debt | EBITDA Multiple | Enterprise Value | Maximum    
Fair Value Measurement Inputs and Valuation Techniques [Line Items]    
Measurement input 9.2 8.5
Level 3 | Senior secured debt | EBITDA Multiple | Enterprise Value | Weighted Average    
Fair Value Measurement Inputs and Valuation Techniques [Line Items]    
Measurement input 8.2 7.5
Level 3 | Senior secured debt | Transaction Price | Transaction Precedent    
Fair Value Measurement Inputs and Valuation Techniques [Line Items]    
Investment owned, fair value $ 121,152 $ 92,340
Level 3 | Senior secured debt | Broker Quoted Price | Broker Quotations    
Fair Value Measurement Inputs and Valuation Techniques [Line Items]    
Investment owned, fair value 40,972 92,422
Level 3 | Subordinated debt | Market Yield | Market Yield    
Fair Value Measurement Inputs and Valuation Techniques [Line Items]    
Investment owned, fair value $ 239,261 $ 223,942
Level 3 | Subordinated debt | Market Yield | Market Yield | Minimum    
Fair Value Measurement Inputs and Valuation Techniques [Line Items]    
Measurement input 0.050 0.050
Level 3 | Subordinated debt | Market Yield | Market Yield | Maximum    
Fair Value Measurement Inputs and Valuation Techniques [Line Items]    
Measurement input 0.120 0.120
Level 3 | Subordinated debt | Market Yield | Market Yield | Weighted Average    
Fair Value Measurement Inputs and Valuation Techniques [Line Items]    
Measurement input 0.086 0.086
Level 3 | Subordinated debt | Transaction Price | Transaction Precedent    
Fair Value Measurement Inputs and Valuation Techniques [Line Items]    
Investment owned, fair value $ 85,710  
Level 3 | Subordinated debt | Broker Quoted Price | Broker Quotations    
Fair Value Measurement Inputs and Valuation Techniques [Line Items]    
Investment owned, fair value 17,914  
Level 3 | Common equity and warrants & preferred equity | Market Yield | Market Yield    
Fair Value Measurement Inputs and Valuation Techniques [Line Items]    
Investment owned, fair value $ 22,582  
Level 3 | Common equity and warrants & preferred equity | Market Yield | Market Yield | Minimum    
Fair Value Measurement Inputs and Valuation Techniques [Line Items]    
Measurement input 0.120  
Level 3 | Common equity and warrants & preferred equity | Market Yield | Market Yield | Maximum    
Fair Value Measurement Inputs and Valuation Techniques [Line Items]    
Measurement input 0.180  
Level 3 | Common equity and warrants & preferred equity | Market Yield | Market Yield | Weighted Average    
Fair Value Measurement Inputs and Valuation Techniques [Line Items]    
Measurement input 0.143  
Level 3 | Common equity and warrants & preferred equity | Revenue Multiple | Enterprise Value    
Fair Value Measurement Inputs and Valuation Techniques [Line Items]    
Investment owned, fair value $ 7,212 $ 18,187
Level 3 | Common equity and warrants & preferred equity | Revenue Multiple | Enterprise Value | Minimum    
Fair Value Measurement Inputs and Valuation Techniques [Line Items]    
Measurement input 1.9 0.5
Level 3 | Common equity and warrants & preferred equity | Revenue Multiple | Enterprise Value | Maximum    
Fair Value Measurement Inputs and Valuation Techniques [Line Items]    
Measurement input 5.0 7.2
Level 3 | Common equity and warrants & preferred equity | Revenue Multiple | Enterprise Value | Weighted Average    
Fair Value Measurement Inputs and Valuation Techniques [Line Items]    
Measurement input 2.2 2.0
Level 3 | Common equity and warrants & preferred equity | EBITDA Multiple | Enterprise Value    
Fair Value Measurement Inputs and Valuation Techniques [Line Items]    
Investment owned, fair value $ 2,222 $ 8,017
Level 3 | Common equity and warrants & preferred equity | EBITDA Multiple | Enterprise Value | Minimum    
Fair Value Measurement Inputs and Valuation Techniques [Line Items]    
Measurement input 6.5 7.3
Level 3 | Common equity and warrants & preferred equity | EBITDA Multiple | Enterprise Value | Maximum    
Fair Value Measurement Inputs and Valuation Techniques [Line Items]    
Measurement input 11.8 15.0
Level 3 | Common equity and warrants & preferred equity | EBITDA Multiple | Enterprise Value | Weighted Average    
Fair Value Measurement Inputs and Valuation Techniques [Line Items]    
Measurement input 10.4 13.5
[1] Non-Control/Non-Affiliate Investments are investments that are neither Control Investments nor Affiliate Investments. Control Investments generally are defined by the Investment Company Act of 1940, as amended (the “Investment Company Act”), as investments in companies in which the Company owns more than 25% of the voting securities and/or has the power to exercise control over the management or policies of the company. Affiliate Investments generally are defined by the Investment Company Act as investments in companies in which the Company owns between 5% and 25% of the voting securities.
[2] Non-Control/Non-Affiliate Investments are investments that are neither Control Investments nor Affiliate Investments. Control Investments generally are defined by the Investment Company Act, as investments in companies in which the Company owns more than 25% of the voting securities and/or has the power to exercise control over the management or policies of the company. Affiliate Investments generally are defined by the Investment Company Act as investments in companies in which the Company owns between 5% and 25% of the voting securities.