Pension and Other Postretirement Benefits - Schedule of Fair Values of Pension Plan by Assets Category (Details) - USD ($) $ in Millions	Jun. 30, 2023	Jun. 30, 2022	Jun. 30, 2021
Defined Benefit Plan Disclosure [Line Items]
Fair value of pension plan assets
Pension Benefits
Defined Benefit Plan Disclosure [Line Items]
Fair value of pension plan assets	$ 654.8	759.4	$ 999.4
Pension Benefits | Short-term investments
Defined Benefit Plan Disclosure [Line Items]
Fair value of pension plan assets	6.7	25.5
Pension Benefits | Commingled trust funds
Defined Benefit Plan Disclosure [Line Items]
Fair value of pension plan assets	646.8	732.8
Pension Benefits | Mortgage/asset backed securities and other
Defined Benefit Plan Disclosure [Line Items]
Fair value of pension plan assets	1.3	1.1
Pension Benefits | Level 1
Defined Benefit Plan Disclosure [Line Items]
Fair value of pension plan assets	6.7	25.5
Pension Benefits | Level 1 | Short-term investments
Defined Benefit Plan Disclosure [Line Items]
Fair value of pension plan assets	6.7	25.5
Pension Benefits | Level 1 | Commingled trust funds
Defined Benefit Plan Disclosure [Line Items]
Fair value of pension plan assets	0.0	0.0
Pension Benefits | Level 1 | Mortgage/asset backed securities and other
Defined Benefit Plan Disclosure [Line Items]
Fair value of pension plan assets	0.0	0.0
Pension Benefits | Level 2
Defined Benefit Plan Disclosure [Line Items]
Fair value of pension plan assets	1.3	1.1
Pension Benefits | Level 2 | Short-term investments
Defined Benefit Plan Disclosure [Line Items]
Fair value of pension plan assets	0.0	0.0
Pension Benefits | Level 2 | Commingled trust funds
Defined Benefit Plan Disclosure [Line Items]
Fair value of pension plan assets	0.0	0.0
Pension Benefits | Level 2 | Mortgage/asset backed securities and other
Defined Benefit Plan Disclosure [Line Items]
Fair value of pension plan assets	1.3	1.1
Pension Benefits | Net Asset Value
Defined Benefit Plan Disclosure [Line Items]
Fair value of pension plan assets	646.8	732.8
Pension Benefits | Net Asset Value | Short-term investments
Defined Benefit Plan Disclosure [Line Items]
Fair value of pension plan assets	0.0	0.0
Pension Benefits | Net Asset Value | Commingled trust funds
Defined Benefit Plan Disclosure [Line Items]
Fair value of pension plan assets	646.8	732.8
Pension Benefits | Net Asset Value | Mortgage/asset backed securities and other
Defined Benefit Plan Disclosure [Line Items]
Fair value of pension plan assets	$ 0.0	$ 0.0