CONSOLIDATED STATEMENTS OF OPERATIONS - USD ($) shares in Millions	12 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2019
Income Statement [Abstract]
Net sales	$ 1,475,600,000	$ 2,181,100,000	$ 2,380,200,000
Cost of sales	1,470,400,000	1,822,400,000	1,935,400,000
Cost of sales - inventory write-downs from restructuring	4,200,000	29,300,000	0
Gross profit	1,000,000.0	329,400,000	444,800,000
Selling, general and administrative expenses	180,200,000	201,000,000.0	203,400,000
Restructuring and asset impairment charges	16,600,000	68,500,000	0
Goodwill impairment	52,800,000	34,600,000	0
Operating (loss) income	(248,600,000)	25,300,000	241,400,000
Interest expense, net	32,700,000	19,800,000	26,000,000.0
Debt extinguishment losses, net	8,200,000	(0.0)	0
Other expense (income), net	8,400,000	(600,000)	(600,000)
(Loss) income before income taxes	(297,900,000)	6,100,000	216,000,000.0
Income tax (benefit) expense	(68,300,000)	4,600,000	49,000,000.0
Net (loss) income	$ (229,600,000)	$ 1,500,000	$ 167,000,000.0
(LOSS) EARNINGS PER COMMON SHARE:
Basic (in dollars per share)	$ (4.76)	$ 0.02	$ 3.46
Diluted (in dollars per share)	$ (4.76)	$ 0.02	$ 3.43
WEIGHTED AVERAGE COMMON SHARES OUTSTANDING:
Basic (in shares)	48.3	48.1	47.7
Diluted (in shares)	48.3	48.2	48.1