Accrued Liabilities (Details) - USD ($) $ in Millions	Mar. 31, 2018	Jun. 30, 2017
Accrued Liabilities, Current [Abstract]
Accrued compensation and benefits	$ 65.7	$ 59.1
Accrued postretirement benefits	15.5	15.5
Deferred revenue	12.1	9.8
Accrued interest expense	5.6	11.2
Derivative financial instruments	1.2	13.1
Other	28.3	31.2
Total accrued liabilities	$ 128.4	$ 139.9