Fair Value Measurements (Schedule of the Carrying Values and Fair Values of Financial Instruments) (Details) - USD ($) $ in Millions	Dec. 31, 2021	Sep. 30, 2021
Carrying Value
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term debt, including current portion and related party, carrying value	$ 7,265.1	$ 7,634.8
Fair Value
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term debt, including current portion and related party, fair value	7,421.1	7,812.2
Forward exchange contracts | Carrying Value
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Derivative assets	47.4	49.3
Derivative liabilities	71.8	88.8
Forward exchange contracts | Fair Value
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Derivative assets	47.4	49.3
Derivative liabilities	71.8	88.8
Interest Rate Management Contracts | Carrying Value
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Derivative assets	37.7	34.1
Derivative liabilities	56.0	32.7
Interest Rate Management Contracts | Fair Value
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Derivative assets	37.7	34.1
Derivative liabilities	$ 56.0	$ 32.7