Taxable/Distributable Income - Narrative (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Jun. 30, 2026	Jun. 30, 2025	Jun. 30, 2026	Jun. 30, 2025	Sep. 30, 2025
Tax Credit Carryforward [Line Items]
Deferred income tax expense (benefit)			$ 37	$ 27
Cost of investments					$ 6,736,200
Unrealized appreciation					169,400
Unrealized depreciation					170,600
Net unrealized depreciation					$ 1,200
Income Statement Location [Axis]: us-gaap:NetInvestmentIncome
Tax Credit Carryforward [Line Items]
Current income tax expense	$ 400	$ 100	1,200	800
Deferred income tax expense (benefit)	$ (100)	$ (100)	$ 100	$ (100)