Fair Value Measurements - Schedule of Fair Value of Assets and Liabilities Measured on Recurring Basis (Details) - USD ($) $ in Thousands	Sep. 30, 2025		Sep. 30, 2024
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Fair value	$ 845,821	[1]	$ 689,946	[2]
Money market funds	7,714		5,658
Total assets, at fair value:	853,535		695,604
Debt investments
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Fair value	823,219	[1]	674,121	[2]
Equity Investments
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Fair value	22,602	[1],[3],[4]	15,825	[2],[5],[6]
Level 1
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Money market funds	7,714		5,658
Total assets, at fair value:	7,714		5,658
Level 1 | Debt investments
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Fair value	0		0
Level 1 | Equity Investments
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Fair value	0		0
Level 2
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Money market funds	0		0
Total assets, at fair value:	0		0
Level 2 | Debt investments
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Fair value	0		0
Level 2 | Equity Investments
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Fair value	0		0
Level 3
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Money market funds	0		0
Total assets, at fair value:	845,821		689,946
Level 3 | Debt investments
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Fair value	823,219		674,121
Level 3 | Equity Investments
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Fair value	$ 22,602		$ 15,825

[1] The fair values of investments were valued using significant unobservable inputs, unless otherwise noted. See Note 6. The fair value of loan investments may include the impact of the unfunded commitment being valued below par.

[2] The fair values of investments were valued using significant unobservable inputs, unless otherwise noted. See Note 6. The fair value of loan investments may include the impact of the unfunded commitment being valued below par.

[3] Equity investments are non-income producing securities, unless otherwise noted.

[4] Ownership of certain equity investments occurs through a holding company or partnership.

[5] Equity investments are non-income producing securities, unless otherwise noted.

[6] Ownership of certain equity investments occurs through a holding company or partnership.