Retirement Plans Schedule of Amounts Expected to Amortize from AOCI to net income in the coming year (Details) - USD ($) $ in Millions	12 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2018
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Amortization of Gain (Loss)		$ (2.8)	$ (1.9)	$ (3.2)
Forecast [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Amortization of Gain (Loss)	$ (2.5)