Retirement Plans (Amounts Recognized for Pension and Other Postretirement Benefit Plans) (Details) - USD ($) $ in Millions	12 Months Ended
Sep. 30, 2024	Sep. 30, 2023	Sep. 30, 2022
Projected benefit obligations:
Service cost	$ 0.6	$ 0.8	$ 1.3
Interest cost	13.9	13.9	9.8
Plan assets:
Beginning of year	239.8
End of year	261.4	239.8
Recognized on balance sheet:
Pension asset	13.5	6.6
Pension Plan, Defined Benefit [Member]
Projected benefit obligations:
Beginning of year	233.2	251.2
Service cost	0.6	0.8
Interest cost	13.9	13.9
Actuarial loss (gain)	22.2	(10.4)
Benefits paid	(22.0)	(22.3)
End of year	247.9	233.2	251.2
Plan assets:
Beginning of year	239.8	251.8
Actual return on plan assets	43.6	10.3
Benefits paid	(22.0)	(22.3)
End of year	261.4	239.8	$ 251.8
Accrued benefit cost at end of year:
Funded (unfunded) status	13.5	6.6
Recognized on balance sheet:
Pension asset	13.5	6.6
Recognized in accumulated other comprehensive loss, before tax:
Net actuarial loss (gain)	$ 56.6	$ 68.2

No definition available.

Name:	us-gaap_DefinedBenefitPlanAccumulatedOtherComprehensiveIncomeBeforeTaxAbstract
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

Amount, before tax, of accumulated other comprehensive income (loss) for gain (loss) of defined benefit plan, that has not been recognized in net periodic benefit (cost) credit.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Name Accounting Standards Codification
-Topic 220
-SubTopic 10
-Section 45
-Paragraph 14A
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482790/220-10-45-14A

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Topic 715
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 1
-Subparagraph (j)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147480506/715-20-50-1