Accrued Liabilities (Details) - USD ($) $ in Millions	Dec. 31, 2020	Jun. 30, 2020
Accrued Liabilities, Current [Abstract]
Accrued compensation and benefits	$ 44.7	$ 50.4
Accrued pension liabilities	34.8	20.2
Accrued interest expense	15.6	10.4
Accrued postretirement benefits	14.0	14.0
Current portion of lease liabilities	10.7	11.5
Derivative financial instruments	7.2	11.1
Contract liabilities	5.5	12.3
Accrued income taxes	0.8	1.0
Other	24.1	27.0
Total accrued liabilities	$ 157.4	$ 157.9