Reclassifications from Accumulated Other Comprehensive (Loss) Income - Schedule of Changes in AOCI by Component, Net of Tax (Details) - USD ($) $ in Millions	12 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2018
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Balances, beginning of period	$ 1,520.1	$ 1,485.9	$ 1,198.6
Balances, end of period	1,445.7	1,520.1	$ 1,485.9
Accounting Standards Update [Extensible List]			us-gaap:AccountingStandardsUpdate201712Member
Accumulated Other Comprehensive (Loss) Income
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Balances, beginning of period	(351.8)	(239.8)	$ (343.1)
Other comprehensive income (loss) before reclassifications	(48.9)	(112.9)
Amounts reclassified from AOCI	2.7	1.9
Net current-period other comprehensive income (loss)	(46.2)	(112.0)
Balances, end of period	(398.0)	(351.8)	(239.8)
Cash flow hedging items
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Balances, beginning of period	(14.8)	23.8	(2.3)
Other comprehensive income (loss) before reclassifications	13.3	(32.7)
Amounts reclassified from AOCI	(9.6)	(4.9)
Net current-period other comprehensive income (loss)	3.7	(38.6)
Balances, end of period	(11.1)	(14.8)	23.8
Pension and other postretirement benefit plan items
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Balances, beginning of period	(293.3)	(220.4)
Other comprehensive income (loss) before reclassifications	(53.3)	(79.7)
Amounts reclassified from AOCI	12.3	6.8
Net current-period other comprehensive income (loss)	(41.0)	(72.9)
Balances, end of period	(334.3)	(293.3)	(220.4)
Unrealized losses on available-for-sale securities
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Balances, beginning of period	0.0	(0.3)
Other comprehensive income (loss) before reclassifications		0.3
Amounts reclassified from AOCI	0.0	0.0
Net current-period other comprehensive income (loss)	0.0	0.3
Balances, end of period	0.0	0.0	(0.3)
Foreign currency items
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Balances, beginning of period	(43.7)	(42.9)
Other comprehensive income (loss) before reclassifications	(8.9)	(0.8)
Amounts reclassified from AOCI	0.0	0.0
Net current-period other comprehensive income (loss)	(8.9)	(0.8)
Balances, end of period	(52.6)	(43.7)	(42.9)
Cumulative Effect, Period of Adoption, Adjustment
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Balances, beginning of period		0.0
Balances, end of period			0.0
Cumulative Effect, Period of Adoption, Adjustment | Accumulated Other Comprehensive (Loss) Income
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Balances, beginning of period		(1.0)
Balances, end of period			(1.0)
Cumulative Effect, Period of Adoption, Adjustment | Cash flow hedging items
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Balances, beginning of period	$ 0.0	(1.0)	0.0
Balances, end of period		0.0	(1.0)
Cumulative Effect, Period of Adoption, Adjustment | Pension and other postretirement benefit plan items
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Balances, beginning of period		0.0
Balances, end of period			0.0
Cumulative Effect, Period of Adoption, Adjustment | Unrealized losses on available-for-sale securities
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Balances, beginning of period		0.0
Balances, end of period			0.0
Cumulative Effect, Period of Adoption, Adjustment | Foreign currency items
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Balances, beginning of period		$ 0.0
Balances, end of period			$ 0.0