Accrued Liabilities (Details) - USD ($) $ in Millions	Mar. 31, 2021	Jun. 30, 2020
Accrued Liabilities, Current [Abstract]
Accrued compensation and benefits	$ 65.9	$ 50.4
Accrued postretirement benefits	14.0	14.0
Current portion of lease liabilities	9.3	11.5
Contract liabilities	6.9	12.3
Accrued interest expense	6.4	10.4
Accrued pension liabilities	3.5	20.2
Derivative financial instruments	3.0	11.1
Accrued income taxes	0.5	1.0
Other	24.7	27.0
Total accrued liabilities	$ 134.2	$ 157.9