Accrued Liabilities - Schedule of Accrued Liabilities (Details) - USD ($) $ in Millions	Dec. 31, 2023	Jun. 30, 2023
Accrued Liabilities, Current [Abstract]
Accrued compensation and benefits	$ 68.0	$ 92.4
Accrued interest expense	18.5	18.5
Accrued postretirement benefits	16.1	16.1
Contract liabilities	13.5	14.0
Derivative financial instruments	10.2	6.4
Current portion of lease liabilities	8.6	9.1
Accrued taxes	4.1	4.9
Accrued pension liabilities	3.3	3.3
Accrued income taxes	1.2	2.5
Other	14.9	14.1
Total accrued liabilities	$ 158.4	$ 181.3