Accrued Liabilities (Details) - USD ($) $ in Millions	Dec. 31, 2019	Jun. 30, 2019
Accrued Liabilities, Current [Abstract]
Accrued compensation and benefits	$ 51.1	$ 71.2
Accrued postretirement benefits	14.7	14.7
Deferred revenue	14.5	10.5
Derivative financial instruments	12.5	16.7
Current portion of lease liabilities	11.8
Accrued interest expense	10.4	10.4
Accrued pension liabilities	3.4	3.4
Accrued income taxes	0.6	4.2
Other	27.6	26.5
Total accrued liabilities	$ 146.6	$ 157.6