Reclassifications from Accumulated Other Comprehensive (Loss) Income - Schedule of Amounts Reclassified from AOCI (Details) - USD ($) $ in Millions	3 Months Ended								12 Months Ended
	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2016
Amount reclassified from AOCI
Cost of sales									$ 1,775.5	$ 1,513.3	$ 1,535.0
Net sales	$ 618.0	$ 572.2	$ 487.8	$ 479.8	$ 507.7	$ 473.6	$ 427.4	$ 389.0	2,157.7	1,797.6	1,813.4
Interest expense									28.3	29.8	28.0
Income before income taxes									160.2	70.2	21.5
Tax (expense) benefit									28.3	(23.2)	(10.2)
Net income	$ 42.8	$ 30.2	$ 92.1	$ 23.4	$ 25.5	$ 20.7	$ 7.0	$ (6.2)	188.5	47.0	$ 11.3
Cash flow hedging items
Amount reclassified from AOCI
Net of tax									0.8	(13.8)
Cash flow hedging items | Amount Reclassified from AOCI
Amount reclassified from AOCI
Income before income taxes									1.2	(21.9)
Tax (expense) benefit									(0.4)	8.1
Net income									0.8	(13.8)
Cash flow hedging items | Amount Reclassified from AOCI | Commodity contracts
Amount reclassified from AOCI
Cost of sales									1.8	(22.8)
Cash flow hedging items | Amount Reclassified from AOCI | Foreign exchange contracts
Amount reclassified from AOCI
Net sales									(1.0)	0.5
Cash flow hedging items | Amount Reclassified from AOCI | Forward interest rate swaps
Amount reclassified from AOCI
Interest expense									0.4	0.4
Net actuarial loss
Amount reclassified from AOCI
Net actuarial loss									(16.4)	(41.0)
Prior service cost
Amount reclassified from AOCI
Net actuarial loss									3.1	4.7
Amortization of pension and other postretirement benefit plan items
Amount reclassified from AOCI
Net actuarial loss									(13.3)	(36.3)
Tax benefit									4.4	13.4
Net of tax									$ (8.9)	$ (22.9)