Retirement and Postretirement Benefit Plans (Schedule of Fair Value Measurements of Plan Assets) (Details) - Fair Value Measured at Net Asset Value Per Share [Member] - USD ($)	Sep. 30, 2019	Sep. 30, 2018
Defined Benefit Plan Disclosure [Line Items]
Assets for Plan Benefits, Defined Benefit Plan	$ 306,400,000	$ 275,800,000
Fixed income securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Assets for Plan Benefits, Defined Benefit Plan	206,600,000	179,400,000
U.S. companies [Member] | Equity Funds [Member]
Defined Benefit Plan Disclosure [Line Items]
Assets for Plan Benefits, Defined Benefit Plan	49,600,000	50,000,000.0
International companies [Member] | Equity Funds [Member]
Defined Benefit Plan Disclosure [Line Items]
Assets for Plan Benefits, Defined Benefit Plan	$ 50,200,000	$ 46,400,000