Retirement and Postretirement Benefit Plans (Schedule of Fair Value Measurements of Plan Assets) (Details) - USD ($)	Sep. 30, 2021	Sep. 30, 2020
Pension Plan [Member] | Cash [Member]
Defined Benefit Plan Disclosure [Line Items]
Assets for Plan Benefits, Defined Benefit Plan	$ 3,200,000	$ 2,100,000
Fair Value Measured at Net Asset Value Per Share [Member]
Defined Benefit Plan Disclosure [Line Items]
Assets for Plan Benefits, Defined Benefit Plan	298,700,000	289,600,000
Fair Value Measured at Net Asset Value Per Share [Member] | Fixed income securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Assets for Plan Benefits, Defined Benefit Plan	197,200,000	191,000,000.0
Fair Value Measured at Net Asset Value Per Share [Member] | U.S. companies [Member] | Equity Funds [Member]
Defined Benefit Plan Disclosure [Line Items]
Assets for Plan Benefits, Defined Benefit Plan	52,000,000.0	49,700,000
Fair Value Measured at Net Asset Value Per Share [Member] | International companies [Member] | Equity Funds [Member]
Defined Benefit Plan Disclosure [Line Items]
Assets for Plan Benefits, Defined Benefit Plan	$ 49,500,000	$ 48,900,000