Debt (Summary of Outstanding Debt) (Details) - USD ($) $ in Millions	Sep. 30, 2025	Sep. 30, 2024
Debt Instrument [Line Items]
Short-term borrowings	$ 34.7	$ 83.5
Current portion of long-term debt	716.3	611.4
Total Debt	$ 17,698.4	$ 14,227.9
Short-term borrowings, weighted average interest rate	5.00%	4.00%
Nonrelated Party
Debt Instrument [Line Items]
Long-term debt	$ 16,769.9	$ 13,428.6
Related Party
Debt Instrument [Line Items]
Current portion of long-term debt	59.0	200.0
Long-term debt	$ 177.5	$ 104.4