Share Data and Net Assets - Schedule of Basic and Diluted Earnings Per Share (Details) - USD ($) $ / shares in Units, $ in Thousands		3 Months Ended
		Dec. 31, 2022	Dec. 31, 2021
Earnings (loss) per common share — basic and diluted:
Net increase (decrease) in net assets resulting from operations		$ 13,172	$ 39,408
Weighted average common shares outstanding - basic (shares)	[1]	61,142,000	60,127,000
Weighted average common shares outstanding - diluted (shares)	[1]	61,142,000	60,127,000
Earnings (loss) per common share - basic (dollars per share)	[1]	$ 0.22	$ 0.66
Earnings (loss) per common share - diluted (dollars per share)	[1]	$ 0.22	$ 0.66

[1] (1) As discussed in Note 2, the Company completed a 1-for-3 reverse stock split on January 20, 2023, effective as of the commencement of trading on January 23, 2023. The weighted average common shares outstanding and per share information reflect the reverse stock split on a retroactive basis.