Reclassifications from Accumulated Other Comprehensive Loss - Schedule of Changes in AOCI by Component, Net of Tax (Details) - USD ($) $ in Millions	12 Months Ended
	Jun. 30, 2025	Jun. 30, 2024	Jun. 30, 2023
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Balances, beginning of period	$ 1,628.8	$ 1,396.1	$ 1,330.5
Other comprehensive (loss) income before reclassifications	19.0	(1.7)
Amounts reclassified from AOCI	7.0	50.8
Net other comprehensive income	26.0	49.1	30.5
Balances, end of period	1,887.0	1,628.8	1,396.1
Accumulated Other Comprehensive (Loss) Income
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Balances, beginning of period	(93.9)	(143.0)	(173.5)
Balances, end of period	(67.9)	(93.9)	(143.0)
Cash flow hedging items
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Balances, beginning of period	(5.9)	(7.0)	5.5
Other comprehensive (loss) income before reclassifications	(1.5)	(7.3)
Amounts reclassified from AOCI	3.2	8.4
Net other comprehensive income	1.7	1.1
Balances, end of period	(4.2)	(5.9)	(7.0)
Pension and other postretirement benefit plan items
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Balances, beginning of period	(44.3)	(95.5)
Other comprehensive (loss) income before reclassifications	13.1	8.8
Amounts reclassified from AOCI	3.8	42.4
Net other comprehensive income	16.9	51.2
Balances, end of period	(27.4)	(44.3)	(95.5)
Foreign currency items
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Balances, beginning of period	(43.7)	(40.5)
Other comprehensive (loss) income before reclassifications	7.4	(3.2)
Amounts reclassified from AOCI	0.0	0.0
Net other comprehensive income	7.4	(3.2)
Balances, end of period	$ (36.3)	$ (43.7)	$ (40.5)