Taxes and Distributions - Summary of Amounts Reclassified for Tax Purposes (Details) - USD ($) $ in Thousands	12 Months Ended
	Sep. 30, 2025	Sep. 30, 2024	Sep. 30, 2023
Income Tax Disclosure [Abstract]
Increase (Decrease) in paid-in capital	$ (3,462)	$ (2,800)	$ (1,703)
Increase (Decrease) in accumulated net realized gain	68	(11,993)	(1,494)
Increase in undistributed net investment income	$ 3,394	$ 14,793	$ 3,197