Reclassifications from Accumulated Other Comprehensive Income (Loss) (AOCI) - Schedule of amounts reclassified from AOCI (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Mar. 31, 2021	Mar. 31, 2020	Mar. 31, 2021	Mar. 31, 2020
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Cost of sales			$ 1,029.1	$ 1,409.0
Net sales	$ 351.9	$ 585.4	1,054.0	1,743.8
Interest expense	8.9	4.9	23.5	15.6
(Loss) gain	(8.3)	(3.9)	(9.4)	(3.4)
(Loss) income before income taxes	(57.2)	49.9	(218.9)	154.5
Tax (expense)/benefit	16.7	(10.0)	46.4	(34.6)
Net (loss) income	(40.5)	39.9	(172.5)	119.9
Amount Reclassified from AOCI | Cash flow hedging items
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
(Loss) income before income taxes	1.5	2.4	6.9	10.7
Tax (expense)/benefit	(0.4)	(0.6)	(1.7)	(2.6)
Net (loss) income	1.1	1.8	5.2	8.1
Amount Reclassified from AOCI | Pension and other postretirement benefit plan items
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
(Loss) income before income taxes	(13.1)	(4.0)	(22.4)	(12.2)
Tax (expense)/benefit	1.4	0.9	3.5	3.1
Net (loss) income	(11.7)	(3.1)	(18.9)	(9.1)
Amount Reclassified from AOCI | Net actuarial loss
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
(Loss) gain	(4.7)	(4.5)	(15.1)	(13.5)
Amount Reclassified from AOCI | Prior service benefit
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
(Loss) gain	0.5	0.5	1.6	1.3
Amount Reclassified from AOCI | Settlement charge
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
(Loss) gain	(8.9)	0.0	(8.9)	0.0
Amount Reclassified from AOCI | Commodity contracts | Cash flow hedging items
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Cost of sales	1.4	2.2	6.6	9.7
Amount Reclassified from AOCI | Foreign exchange contracts | Cash flow hedging items
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Net sales	0.0	0.1	0.0	0.7
Amount Reclassified from AOCI | Forward interest rate swaps | Cash flow hedging items
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Interest expense	$ 0.1	$ 0.1	$ 0.3	$ 0.3