Federal Income Tax Matters - Schedule of Tax Character of Distributions Paid (Details) - USD ($) $ in Thousands	12 Months Ended
Sep. 30, 2022	Sep. 30, 2021	Sep. 30, 2020
Schedule of Investments [Abstract]
Ordinary Income	$ 204,806	$ 189,204	$ 190,874
Long-Term Capital Gains	0	5,648	4,691
Return of Capital	$ 0	$ 0	$ 6,625

Amount of distribution in excess of tax-basis earnings and profit of investment company.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 946
-SubTopic 20
-Section 50
-Paragraph 8
-URI https://asc.fasb.org/extlink&oid=66023616&loc=d3e9079-115832

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 946
-SubTopic 205
-Section 45
-Paragraph 3
-Subparagraph (c)
-URI https://asc.fasb.org/extlink&oid=118262037&loc=d3e9915-115836

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration