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, 2019	Jun. 30, 2018
Pension Benefits
Defined Benefit Plan Disclosure [Line Items]
Accumulated benefit obligation	$ 1,331.5	$ 1,257.7
Fair value of plan assets	964.7	972.4
Other Benefits
Defined Benefit Plan Disclosure [Line Items]
Accumulated benefit obligation	255.9	241.5
Fair value of plan assets	$ 119.0	$ 117.9