Pension and Other Postretirement Benefits - Schedule of Reconciliation of Benefit Obligations, Plan Assets and Funded Status of the Plans (Details) - USD ($) $ in Millions	12 Months Ended
Jun. 30, 2024	Jun. 30, 2023	Jun. 30, 2022
Change in plan assets:
Fair value of plan assets at beginning of year
Fair value of plan assets at end of year
Pension Benefits
Change in projected benefit obligation:
Projected benefit obligation at beginning of year	848.2	959.4
Service cost	8.2	8.1	$ 8.6
Interest cost	43.7	46.2	36.6
Benefits paid	(68.8)	(77.5)
Actuarial gain	(2.3)	(65.3)
Plan settlements	(147.2)	(23.3)
Other	0.9	0.6
Projected benefit obligation at end of year	682.7	848.2	959.4
Change in plan assets:
Fair value of plan assets at beginning of year	654.8	759.4
Actual return	18.5	(7.4)
Benefits paid	(68.8)	(77.5)
Contributions	14.5	3.6
Plan settlements	(147.2)	(23.3)
Fair value of plan assets at end of year	471.8	654.8	759.4
Funded status of the plans	(210.9)	(193.4)
Amounts recognized in the consolidated balance sheets:
Accrued liabilities - current	(3.3)	(3.3)
Accrued pension and postretirement benefits - noncurrent	(207.6)	(190.1)
Amounts recognized in the consolidated balance sheets	(210.9)	(193.4)
Other Benefits
Change in projected benefit obligation:
Projected benefit obligation at beginning of year	182.3	206.2
Service cost	1.5	1.8	2.4
Interest cost	10.2	10.0	7.4
Benefits paid	(12.3)	(13.5)
Actuarial gain	(8.9)	(22.2)
Plan settlements	0.0	0.0
Other	0.0	0.0
Projected benefit obligation at end of year	172.8	182.3	206.2
Change in plan assets:
Fair value of plan assets at beginning of year	120.4	114.7
Actual return	25.6	15.9
Benefits paid	(12.3)	(13.5)
Contributions	2.6	3.3
Plan settlements	0.0	0.0
Fair value of plan assets at end of year	136.3	120.4	$ 114.7
Funded status of the plans	(36.5)	(61.9)
Amounts recognized in the consolidated balance sheets:
Accrued liabilities - current	(15.4)	(16.1)
Accrued pension and postretirement benefits - noncurrent	(21.1)	(45.8)
Amounts recognized in the consolidated balance sheets	$ (36.5)	$ (61.9)

Amount of increase (decrease) in plan assets of defined benefit plan from actual return (loss) determined by change in fair value of plan assets adjusted for contributions, benefit payments, and other expenses.

Name:	us-gaap_DefinedBenefitPlanActualReturnOnPlanAssets
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Amount of gain (loss) from change in actuarial assumptions which (increases) decreases benefit obligation of defined benefit plan. Assumptions include, but are not limited to, interest, mortality, employee turnover, salary, and temporary deviation from substantive plan.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 715
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 1
-Subparagraph (a)(4)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147480506/715-20-50-1