Retirement Plans (Schedule of Benefit Obligations, Plan Assets and Funded Status of the Plans) (Details) - USD ($) $ in Millions	12 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2021
Change in projected benefit obligation
Plan settlements	$ (7.9)
Change in plan assets
Estimated fair value of plan assets at beginning of year	398.2
Estimated fair value of plan assets at end of year	363.9	$ 398.2
Pension plan
Change in projected benefit obligation
Benefit obligation at beginning of year	439.4	618.7
Service cost	1.9	3.8	$ 4.4
Interest cost	20.6	10.2	9.6
Actuarial gain	(12.9)	(141.1)
Benefits paid, net	(29.6)	(26.4)
Plan settlements	(21.9)	(4.3)
Expenses paid	0.0	0.0
Foreign currency exchange rate changes	7.4	(21.5)
Projected benefit obligation at end of year	404.9	439.4	618.7
Change in plan assets
Estimated fair value of plan assets at beginning of year	398.2	570.5
Actual return on plan assets	8.9	(121.0)
Company contributions	0.9	0.9
Plan settlements	(21.9)	(4.3)
Benefits paid	(29.6)	(26.4)
Expenses paid	0.0	0.0
Foreign currency exchange rate changes	8.2	(21.5)
Estimated fair value of plan assets at end of year	363.9	398.2	570.5
Funded status at end of year	(41.0)	(41.2)
Postretirement plan
Change in projected benefit obligation
Benefit obligation at beginning of year	4.1	5.5
Service cost	0.0	0.0	0.0
Interest cost	0.2	0.2	0.2
Actuarial gain	(0.1)	(0.9)
Benefits paid, net	(0.3)	(0.3)
Plan settlements	0.0	0.0
Expenses paid	0.0	0.0
Foreign currency exchange rate changes	0.0	(0.4)
Projected benefit obligation at end of year	3.9	4.1	5.5
Change in plan assets
Estimated fair value of plan assets at beginning of year	0.0	0.0
Actual return on plan assets	0.0	0.0
Company contributions	0.3	0.3
Plan settlements	0.0	0.0
Benefits paid	(0.3)	(0.3)
Expenses paid	0.0	0.0
Foreign currency exchange rate changes	0.0	0.0
Estimated fair value of plan assets at end of year	0.0	0.0	$ 0.0
Funded status at end of year	$ (3.9)	$ (4.1)