Portfolio Investments - Schedule of Balance Sheet Information (Details) € in Thousands, $ in Thousands	Jun. 30, 2026 USD ($)	Jun. 30, 2026 EUR (€)	Sep. 30, 2025 USD ($)
Investment Company, Nonconsolidated Subsidiary [Line Items]
Investment owned, fair value | $	$ 6,796,814		$ 6,899,031	[1]
Investment, cost | $	6,897,681		6,863,940	[1]
Cash and cash equivalents | $	157,145		215,962
Other assets | $	1,122		608
Total assets | $	7,194,665		7,282,434
Credit facilities payable | $	1,471,500		1,349,400
Total liabilities | $	2,917,021		2,740,629
Total liabilities and net assets | $	$ 7,194,665		$ 7,282,434
Equity investment in EDL JV
Investment Company, Nonconsolidated Subsidiary [Line Items]
Investment owned, fair value		€ 106,560
Investment, cost		106,433
Cash and cash equivalents		2,037
Other assets		950
Total assets		109,547
Credit facilities payable		62,976
Other liabilities		565
Total liabilities		63,541
Members' equity		46,006
Total liabilities and net assets		€ 109,547

[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 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.