Retirement Benefits (Amounts Recognized on Balance Sheet) (Details) - USD ($) $ in Millions	Sep. 30, 2019	Sep. 30, 2018
Defined Benefit Plan Disclosure [Line Items]
Noncurrent assets	$ 28.7	$ 131.7
Accrued liabilities	26.0	34.1
Defined Benefit Pension Plan | U.S.
Defined Benefit Plan Disclosure [Line Items]
Noncurrent assets	17.3	28.2
Accrued liabilities	18.3	23.5
Noncurrent liabilities	448.2	242.6
Net Liability Recognized	449.2	237.9
Defined Benefit Pension Plan | International
Defined Benefit Plan Disclosure [Line Items]
Noncurrent assets	11.4	103.5
Accrued liabilities	0.0	1.2
Noncurrent liabilities	203.0	174.6
Net Liability Recognized	$ 191.6	$ 72.3