Pension and Other Postretirement Benefits - Narrative (Details) - USD ($) $ in Millions	12 Months Ended
Jun. 30, 2026	Jun. 30, 2025	Jun. 30, 2024
Defined Benefit Plan Disclosure [Line Items]
Pension settlement charge	$ 0.3	$ 0.0	$ 51.9
Plan's current allocation policy	95.00%
Percentage increase in funding level to shift assets from return seeking to liability hedging	5.00%
Return Seeking Asset
Defined Benefit Plan Disclosure [Line Items]
Plan's current allocation policy	75.00%
Liability Matching Assets
Defined Benefit Plan Disclosure [Line Items]
Plan's current allocation policy	25.00%
Pension Benefits
Defined Benefit Plan Disclosure [Line Items]
Change in discount rate	$ 17.0	(8.3)
Change in plan experience	0.4	(0.4)
Pension settlement charge	0.3	0.0	51.9
Contributions	27.0	67.9
Pension Benefits \| Qualified Plan
Defined Benefit Plan Disclosure [Line Items]
Contributions	23.8	64.8	11.3
Expected contributions for next fiscal year	25.5
Pension Benefits \| Nonqualified Plan
Defined Benefit Plan Disclosure [Line Items]
Contributions	3.2	3.2	3.2
Other Postretirement Plans
Defined Benefit Plan Disclosure [Line Items]
Change in plan experience		2.2
Mortality update	4.4	(3.0)
Demographic update	0.6	0.6
Pension settlement charge	0.0	0.0	0.0
Contributions	$ 4.0	3.6
Other Postretirement Plans \| Domestic and international equities
Defined Benefit Plan Disclosure [Line Items]
Plan's current allocation policy	100.00%
Defined Contribution Retirement and Savings Plans
Defined Benefit Plan Disclosure [Line Items]
Contributions to defined contribution retirement and savings plans	$ 28.6	$ 27.6	$ 26.5

Defined Benefit Plan, Benefit Obligation, Actuarial Gain (Loss), Change In Discount Rate

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