CONSOLIDATED STATEMENTS OF OPERATIONS - USD ($) shares in Millions, $ in Millions	3 Months Ended		9 Months Ended
	Mar. 31, 2021	Mar. 31, 2020	Mar. 31, 2021	Mar. 31, 2020
Income Statement [Abstract]
Net sales	$ 351.9	$ 585.4	$ 1,054.0	$ 1,743.8
Cost of sales	336.5	475.9	1,029.1	1,409.0
Cost of sales - inventory write-downs from restructuring	2.6	0.0	2.6	0.0
Gross profit	12.8	109.5	22.3	334.8
Selling, general and administrative expenses	47.8	50.8	132.3	159.0
Restructuring and asset impairment charges	5.0	0.0	15.0	2.3
Goodwill impairment		0.0	52.8	0.0
Operating (loss) income	(40.0)	58.7	(177.8)	173.5
Interest expense, net	(8.9)	(4.9)	(23.5)	(15.6)
Debt extinguishment losses, net	0.0	0.0	(8.2)	0.0
Other expense, net	(8.3)	(3.9)	(9.4)	(3.4)
(Loss) income before income taxes	(57.2)	49.9	(218.9)	154.5
Income tax (benefit) expense	(16.7)	10.0	(46.4)	34.6
Net (loss) income	$ (40.5)	$ 39.9	$ (172.5)	$ 119.9
(LOSS) EARNINGS PER COMMON SHARE:
Basic (in dollars per share)	$ (0.84)	$ 0.82	$ (3.58)	$ 2.47
Diluted (in dollars per share)	$ (0.84)	$ 0.82	$ (3.58)	$ 2.46
WEIGHTED AVERAGE COMMON SHARES OUTSTANDING:
Basic (in shares)	48.3	48.1	48.3	48.0
Diluted (in shares)	48.3	48.3	48.3	48.4