Retirement Plans (Pension and Other Postretirement Benefits Activity in Accumulated Other Comprehensive Income) (Details) $ in Millions	12 Months Ended
	Sep. 30, 2020 USD ($)
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Prior year actuarial loss amortization to net periodic cost	$ 2.1
Other	2.1
Pension Plan, Defined Benefit [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Balance at beginning of year	78.4
Balance at beginning of year	78.4
Actuarial gain	(1.6)
Prior year service loss amortization to net periodic cost	(2.8)
Balance at end of year	$ 74.0