Retirement and Postretirement Benefit Plans (Schedule of Accumulated Benefit Obligation) (Details) - USD ($) $ in Millions	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2017
Defined Benefit Plan Disclosure [Line Items]
PBO	$ 380.4	$ 334.6
ABO	362.9	316.1
Plan Assets	310.6	279.8
Pension Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
PBO	380.4	334.6	$ 345.8
Plan Assets	310.6	279.8	$ 284.4
Domestic Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
PBO	353.4	309.5
ABO	338.0	292.7
Plan Assets	310.5	279.6
Foreign Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
PBO	21.7	20.5
ABO	19.6	18.8
Plan Assets	0.1	0.2
Supplemental Executive Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
PBO	5.3	4.6
ABO	5.3	4.6
Plan Assets	$ 0.0	$ 0.0