Reclassifications from Accumulated Other Comprehensive Loss - Schedule of amounts reclassified from AOCI (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2021	Dec. 31, 2020
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Interest expense, net	$ 10.1	$ 7.9	$ 20.3	$ 14.6
(Loss) gain	6.6	1.3	10.7	(1.1)
Total before tax	(35.0)	(95.6)	(60.2)	(161.7)
Tax (expense)/benefit	5.6	10.7	16.1	29.7
Net loss	(29.4)	(84.9)	(44.1)	(132.0)
Amount Reclassified from AOCI | Cash flow hedging items
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Total before tax	(0.9)	2.5	(2.7)	5.4
Tax (expense)/benefit	0.2	(0.5)	0.6	(1.3)
Net loss	(0.7)	2.0	(2.1)	4.1
Amount Reclassified from AOCI | Pension and other postretirement benefit plan items
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Total before tax	(1.5)	(4.7)	(3.0)	(9.4)
Tax (expense)/benefit	0.4	1.1	0.8	2.2
Net loss	(1.1)	(3.6)	(2.2)	(7.2)
Amount Reclassified from AOCI | Net actuarial loss
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
(Loss) gain	(1.9)	(5.2)	(3.8)	(10.4)
Amount Reclassified from AOCI | Prior service benefit
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
(Loss) gain	0.4	0.5	0.8	1.0
Commodity contracts | Amount Reclassified from AOCI | Cash flow hedging items
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Cost of sales	(1.0)	2.4	(2.9)	5.2
Forward interest rate swaps | Amount Reclassified from AOCI | Cash flow hedging items
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Interest expense, net	$ 0.1	$ 0.1	$ 0.2	$ 0.2