Taxes and Distributions - Summary of Tax Characteristics of Distributions Declared (Details) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Sep. 30, 2025	Sep. 30, 2024	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2021
Income Tax Disclosure [Abstract]
Ordinary income (including short-term gains, if any)	$ 62,684	$ 57,420	$ 49,571
Long-term capital gain	0	0	0
Total distributions	62,684	57,432	49,571
Total distributions	$ 62,684	$ 57,420	$ 49,571
Total distributions declared per share	$ 0.96	$ 0.88	$ 0.76	$ 0.56	$ 0.48