Retirement Plans (Amounts Recognized for Pension and Other Postretirement Benefit Plans) (Details) - USD ($) $ in Millions	12 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2016
Projected benefit obligations:
Service cost	$ 1.8	$ 2.0	$ 1.7
Interest cost	14.3	14.3	18.9
Plan assets:
Beginning of year	366.3
Defined Benefit Plan, Plan Assets, Contributions by Employer	0.0	35.0
Settlement			(58.5)
End of year	343.4	366.3
Recognized in accumulated other comprehensive loss, before tax:
Other	(0.2)	(0.1)
Pension Plan, Defined Benefit [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Other current liabilities	(1.1)	(1.1)
Projected benefit obligations:
Beginning of year	380.5	403.1
Service cost	1.8	2.0
Interest cost	14.3	14.3
Actuarial loss (gain)	(38.6)	(14.5)
Benefits paid	(24.3)	(24.8)
Currency translation	(0.3)	0.4
Decrease in obligation due to curtailment / settlement	0.0	0.0
End of year	333.4	380.5	403.1
Accumulated benefit obligation at end of year	333.4	380.5
Plan assets:
Beginning of year	366.3	340.0
Actual return on plan assets	2.0	15.8
Currency translation	(0.3)	0.4
Benefits paid	(24.3)	(24.8)
End of year	343.5	366.3	$ 340.0
Accrued benefit cost at end of year:
Unfunded status	10.1	(14.2)
Recognized on balance sheet:
Other noncurrent assets	11.2	1.1
Other noncurrent liabilities	0.0	(14.2)
Amount recognized on balance sheet	10.1	(14.2)
Recognized in accumulated other comprehensive loss, before tax:
Prior year service cost (gain)	0.0	0.0
Net actuarial loss (gain)	66.0	93.4
Recognized in accumulated other comprehensive loss, before tax	$ 66.0	$ 93.4