Pension and Other Postretirement Benefits - Narrative (Details) - USD ($) $ in Millions	12 Months Ended
	Jun. 30, 2024	Jun. 30, 2023	Jun. 30, 2022
Defined Benefit Plan Disclosure [Line Items]
Settlement charge	$ 51.9	$ 0.0	$ 0.0
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	$ 5.4
Change in plan experience	3.1	9.2
Mortality update	4.9	13.8
Settlement charge	51.9	0.0	0.0
Employer contributions	14.5	3.6
Pension Benefits | Qualified Plan
Defined Benefit Plan Disclosure [Line Items]
Employer contributions	11.3	0.0	0.7
Expected contributions for next fiscal year	26.3
Pension Benefits | Nonqualified Plan
Defined Benefit Plan Disclosure [Line Items]
Employer contributions	3.2	3.6	3.1
Other Benefits
Defined Benefit Plan Disclosure [Line Items]
Mortality update	2.1	70.9
Settlement charge	0.0	0.0	0.0
Employer contributions	$ 2.6	3.3
Other Benefits | Equity securities
Defined Benefit Plan Disclosure [Line Items]
Plan's current allocation policy	95.00%
Other Benefits | Short-term investments
Defined Benefit Plan Disclosure [Line Items]
Plan's current allocation policy	5.00%
Defined Contribution Retirement and Savings Plans
Defined Benefit Plan Disclosure [Line Items]
Contributions to defined contribution retirement and savings plans	$ 26.5	$ 23.3	$ 21.0