Accrued Liabilities (Details) - USD ($) $ in Millions	Mar. 31, 2019	Jun. 30, 2018
Accrued Liabilities, Current [Abstract]
Accrued compensation and benefits	$ 56.3	$ 83.3
Derivative financial instruments	17.3	0.0
Accrued postretirement benefits	15.4	15.4
Deferred revenue	12.3	10.4
Accrued income taxes	4.3	1.4
Accrued interest expense	3.9	10.4
Accrued pension liabilities	3.3	3.3
Other	25.6	24.4
Total accrued liabilities	$ 138.4	$ 148.6