Retirement and Postretirement Benefit Plans (Schedule of Accumulated Benefit Obligation) (Details) - USD ($) $ in Millions	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2018
Defined Benefit Plan Disclosure [Line Items]
PBO	$ 371.8	$ 380.4
ABO	352.1	362.9
Plan Assets	291.7	310.6
Pension Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
PBO	371.8	380.4	$ 334.6
Plan Assets	291.7	310.6	$ 279.8
Domestic Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
PBO	343.2	353.4
ABO	325.7	338.0
Plan Assets	291.7	310.5
Foreign Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
PBO	23.0	21.7
ABO	20.8	19.6
Plan Assets	0.0	0.1
Supplemental Executive Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
PBO	5.6	5.3
ABO	5.6	5.3
Plan Assets	$ 0.0	$ 0.0