Retirement Benefits (Amounts Recognized on Balance Sheet) (Details) - USD ($) $ in Millions	Sep. 30, 2024	Sep. 30, 2023
Defined Benefit Plan Disclosure [Line Items]
Noncurrent assets	$ 200.0	$ 120.0
Accrued liabilities	11.3	9.6
Defined Benefit Pension Plan | U.S.
Defined Benefit Plan Disclosure [Line Items]
Noncurrent assets	45.3	36.2
Accrued liabilities	7.3	5.3
Noncurrent liabilities	118.1	80.7
Net Liability Recognized	(80.1)	(49.8)
Defined Benefit Pension Plan | International
Defined Benefit Plan Disclosure [Line Items]
Noncurrent assets	154.7	83.8
Accrued liabilities	0.9	0.6
Noncurrent liabilities	118.0	111.6
Net Liability Recognized	$ 35.8	$ (28.4)