Taxable/Distributable Income and Dividend Distributions - Schedule of Reconciliation of Net Increase (Decrease) in Net Assets Resulting from Operations (Details) - USD ($) $ in Thousands	12 Months Ended
	Sep. 30, 2025	Sep. 30, 2024	Sep. 30, 2023
Income Tax Disclosure [Abstract]
Net increase (decrease) in net assets resulting from operations	$ 33,920	$ 57,905	$ 117,331
Net unrealized (appreciation) depreciation	101,229	(19,101)	28,555
Book/tax difference due to capital losses suspended (utilized)	3,890	137,723	34,607
Other book/tax differences	2,563	(24,729)	(14,691)
Taxable/Distributable Income	$ 141,602	$ 151,798	$ 165,802