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, 2024	Jun. 30, 2023
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Balances, beginning of period	$ 1,396.1	$ 1,330.5
Other comprehensive (loss) income before reclassifications	(1.7)	31.8
Amounts reclassified from AOCI	50.8	(1.3)
Net current-period other comprehensive income (loss)	49.1	30.5
Balances, end of period	1,628.8	1,396.1
Accumulated Other Comprehensive (Loss) Income
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Balances, beginning of period	(143.0)	(173.5)
Balances, end of period	(93.9)	(143.0)
Cash flow hedging items
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Balances, beginning of period	(7.0)	5.5
Other comprehensive (loss) income before reclassifications	(7.3)	(6.7)
Amounts reclassified from AOCI	8.4	(5.8)
Net current-period other comprehensive income (loss)	1.1	(12.5)
Balances, end of period	(5.9)	(7.0)
Pension and other postretirement benefit plan items
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Balances, beginning of period	(95.5)	(132.9)
Other comprehensive (loss) income before reclassifications	8.8	32.9
Amounts reclassified from AOCI	42.4	4.5
Net current-period other comprehensive income (loss)	51.2	37.4
Balances, end of period	(44.3)	(95.5)
Foreign currency items
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Balances, beginning of period	(40.5)	(46.1)
Other comprehensive (loss) income before reclassifications	(3.2)	5.6
Amounts reclassified from AOCI	0.0	0.0
Net current-period other comprehensive income (loss)	(3.2)	5.6
Balances, end of period	$ (43.7)	$ (40.5)