Retirement and Postretirement Benefit Plans (Schedule of Obligations and Funded Status) (Details) - USD ($) $ in Millions	12 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2018
Change in benefit obligation:
Benefit obligation at beginning of year	$ 380.4
Benefit obligation at end of year	371.8	$ 380.4
Change in plan assets:
Fair value of plan assets at beginning of year	310.6
Fair value of plan assets at end of year	291.7	310.6
Amounts recorded in the Consolidated Balance Sheets:
Accrued pension benefits, long-term	(89.3)	(80.8)
Pension Plan [Member]
Change in benefit obligation:
Benefit obligation at beginning of year	380.4	334.6
Service cost	5.2	4.5
Interest cost	8.7	12.5	$ 11.0
Actuarial loss	28.7	43.4
Defined Benefit Plan, Benefit Obligation, Benefits Paid	12.6	13.3
Defined Benefit Plan, Benefit Obligation, Business Combination	3.5	0.0
Defined Benefit Plan, Benefit Obligation, Payment for Settlement	(44.2)
Defined Benefit Plan, Benefit Obligation, Special and Contractual Termination Benefits	0.5
Exchange rate loss (gain)	1.6	(1.3)
Benefit obligation at end of year	371.8	380.4	334.6
Change in plan assets:
Fair value of plan assets at beginning of year	310.6	279.8
Actual return on plan assets	33.4	35.1
Employer contributions	1.0	9.0
Defined Benefit Plan, Plan Assets, Benefits Paid	12.6	13.3
Defined Benefit Plan, Plan Assets, Business Combination	(3.5)
Defined Benefit Plan, Plan Assets, Payment for Settlement	(44.2)
Fair value of plan assets at end of year	291.7	310.6	$ 279.8
Funded status and net amounts recognized	(80.1)	(69.8)
Amounts recorded in the Consolidated Balance Sheets:
Accrued pension benefits, current portion	(1.5)	(1.2)
Accrued pension benefits, long-term	(78.6)	(68.6)
Net amount recognized	$ (80.1)	$ (69.8)