Retirement Benefits (Amounts Recognized on Balance Sheet) (Details) - USD ($) $ in Millions	Sep. 30, 2023	Sep. 30, 2022
Defined Benefit Plan Disclosure [Line Items]
Noncurrent assets	$ 120.0	$ 133.9
Accrued liabilities	9.6	11.1
Defined Benefit Pension Plan | U.S.
Defined Benefit Plan Disclosure [Line Items]
Noncurrent assets	36.2	36.4
Accrued liabilities	5.3	5.8
Noncurrent liabilities	80.7	77.4
Net Liability Recognized	(49.8)	(46.8)
Defined Benefit Pension Plan | International
Defined Benefit Plan Disclosure [Line Items]
Noncurrent assets	83.8	97.5
Accrued liabilities	0.6	0.4
Noncurrent liabilities	111.6	112.6
Net Liability Recognized	$ (28.4)	$ (15.5)