Portfolio Investments - Narrative (Details) $ in Thousands	Dec. 31, 2023 USD ($) borrower		Sep. 30, 2023 USD ($) borrower
Schedule of Investments [Abstract]
Fair value | $	$ 2,857,808	[1]	$ 1,927,237	[2]
Number of borrowers | borrower	143		123

[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 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.