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, 2018	Jun. 30, 2017
Pension Benefits
Defined Benefit Plan Disclosure [Line Items]
Accumulated benefit obligation	$ 1,257.7	$ 1,362.7
Fair value of plan assets	972.4	987.4
Other Benefits
Defined Benefit Plan Disclosure [Line Items]
Accumulated benefit obligation	241.5	255.1
Fair value of plan assets	$ 117.9	$ 117.0