Pension and Other Postretirement Benefits - Schedule of Projected Benefit Obligations in Excess of Plan Assets and Accumulated Benefit Obligations in Excess of Plan Assets (Details) - USD ($) $ in Millions	Jun. 30, 2020	Jun. 30, 2019
Pension Benefits
Defined Benefit Plan Disclosure [Line Items]
Accumulated benefit obligation	$ 1,335.1	$ 1,331.5
Fair value of plan assets	923.3	964.7
Other Benefits
Defined Benefit Plan Disclosure [Line Items]
Accumulated benefit obligation	264.2	255.9
Fair value of plan assets	$ 112.8	$ 119.0