Reclassifications from Accumulated Other Comprehensive Loss - Schedule of changes in AOCI by component, net of tax (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2021	Dec. 31, 2020
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Balances at the beginning of the period	$ 1,367.6	$ 1,407.5	$ 1,392.3	$ 1,445.7
Other comprehensive gain (loss) before reclassifications	0.0	15.7	(2.4)	31.8
Amounts reclassified from AOCI	1.8	1.6	4.3	3.1
Other comprehensive income, net of tax	1.8	17.3	1.9	34.9
Balances at the end of the period	1,333.1	1,332.9	1,333.1	1,332.9
AOCI Attributable to Parent
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Balances at the beginning of the period	(192.2)	(380.4)	(192.3)	(398.0)
Balances at the end of the period	(190.4)	(363.1)	(190.4)	(363.1)
Cash flow hedging items
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Balances at the beginning of the period	8.0	(2.8)	6.9	(11.1)
Other comprehensive gain (loss) before reclassifications	1.0	6.9	0.7	17.3
Amounts reclassified from AOCI	0.7	(2.0)	2.1	(4.1)
Other comprehensive income, net of tax	1.7	4.9	2.8	13.2
Balances at the end of the period	9.7	2.1	9.7	2.1
Pension and other postretirement benefit plan items
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Balances at the beginning of the period	(158.0)	(330.7)	(159.1)	(334.3)
Other comprehensive gain (loss) before reclassifications	(0.3)	0.0	(0.3)	0.0
Amounts reclassified from AOCI	1.1	3.6	2.2	7.2
Other comprehensive income, net of tax	0.8	3.6	1.9	7.2
Balances at the end of the period	(157.2)	(327.1)	(157.2)	(327.1)
Foreign currency items
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Balances at the beginning of the period	(42.2)	(46.9)	(40.1)	(52.6)
Other comprehensive gain (loss) before reclassifications	(0.7)	8.8	(2.8)	14.5
Amounts reclassified from AOCI	0.0	0.0	0.0	0.0
Other comprehensive income, net of tax	(0.7)	8.8	(2.8)	14.5
Balances at the end of the period	$ (42.9)	$ (38.1)	$ (42.9)	$ (38.1)