Pension and Other Postretirement Benefits - Narrative (Details) - USD ($) $ in Millions	12 Months Ended
	Jun. 30, 2023	Jun. 30, 2022	Jun. 30, 2021
Defined Benefit Plan Disclosure [Line Items]
Settlement charge	$ 0.0	$ 0.0	$ (11.4)
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	$ 70.9
Change in plan experience	9.2
Mortality update		41.9
Settlement charge	0.0	0.0	(11.4)
Employer contributions	3.6	3.8
Pension Benefits | Qualified Plan
Defined Benefit Plan Disclosure [Line Items]
Employer contributions	0.0	0.7	19.9
Expected contributions for next fiscal year	11.5
Pension Benefits | Nonqualified Plan
Defined Benefit Plan Disclosure [Line Items]
Employer contributions	3.6	3.1	3.8
Other Benefits
Defined Benefit Plan Disclosure [Line Items]
Mortality update	13.8	225.2
Settlement charge	0.0	0.0	0.0
Employer contributions	$ 3.3	1.6
Other Benefits | Equity securities
Defined Benefit Plan Disclosure [Line Items]
Plan's current allocation policy	85.00%
Other Benefits | Short-term investments
Defined Benefit Plan Disclosure [Line Items]
Plan's current allocation policy	15.00%
Defined Contribution Retirement and Savings Plans
Defined Benefit Plan Disclosure [Line Items]
Contributions to defined contribution retirement and savings plans	$ 23.3	$ 21.0	$ 19.2