Accrued Liabilities (Details) - USD ($) $ in Millions	Sep. 30, 2017	Jun. 30, 2017
Accrued Liabilities, Current [Abstract]
Accrued compensation and benefits	$ 43.3	$ 59.1
Accrued postretirement benefits	15.5	15.5
Deferred revenue	10.2	9.8
Derivative financial instruments	5.8	13.1
Accrued interest expense	5.6	11.2
Accrued income taxes	4.8	5.1
Accrued pension liabilities	3.3	3.3
Other	22.3	22.8
Total accrued liabilities	$ 110.8	$ 139.9