Portfolio Investments - Schedule of Composition of Investments (Details) - USD ($) $ in Thousands	Jun. 30, 2026	Sep. 30, 2025
Schedule of Investments [Line Items]
Fair Value	$ 6,761,703	$ 6,867,378
% of Debt Investments	100.00%	100.00%
Floating rate
Schedule of Investments [Line Items]
Fair Value	$ 6,354,247	$ 6,413,837
% of Debt Investments	93.97%	93.40%
Fixed rate
Schedule of Investments [Line Items]
Fair Value	$ 407,456	$ 453,541
% of Debt Investments	6.03%	6.60%