Fair Value Measurements (Schedule of the Carrying Values and Fair Values of Financial Instruments) (Details) - USD ($) $ in Millions	Mar. 31, 2024	Sep. 30, 2023
Carrying Value
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term debt, including current portion and related party, carrying value	$ 13,437.4	$ 10,046.3
Fair Value
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term debt, including current portion and related party, fair value	12,936.0	9,173.5
Forward exchange contracts | Carrying Value
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Derivative assets	72.2	76.4
Derivative liabilities	87.3	124.4
Forward exchange contracts | Fair Value
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Derivative assets	72.2	76.4
Derivative liabilities	87.3	124.4
Interest Rate Management Contracts | Carrying Value
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Derivative assets	193.0	317.7
Derivative liabilities	65.2	87.0
Interest Rate Management Contracts | Fair Value
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Derivative assets	193.0	317.7
Derivative liabilities	$ 65.2	$ 87.0