CONSOLIDATED STATEMENTS OF INCOME (Unaudited) - USD ($) shares in Millions, $ in Millions	3 Months Ended		6 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2018	Dec. 31, 2017
Income Statement [Abstract]
Net sales	$ 556.5	$ 487.8	$ 1,128.9	$ 967.5
Cost of sales	449.5	402.1	930.2	796.2
Gross profit	107.0	85.7	198.7	171.3
Selling, general and administrative expenses	51.6	44.3	98.3	87.7
Operating income	55.4	41.4	100.4	83.6
Interest expense	(7.0)	(7.3)	(13.2)	(14.5)
Other expense, net	(3.2)	(0.4)	(1.7)	(0.2)
Income before income taxes	45.2	33.7	85.5	68.9
Income tax expense (benefit)	9.7	(58.4)	18.5	(46.6)
Net income	$ 35.5	$ 92.1	$ 67.0	$ 115.5
EARNINGS PER COMMON SHARE:
Basic (in dollars per share)	$ 0.73	$ 1.93	$ 1.39	$ 2.43
Diluted (in dollars per share)	$ 0.73	$ 1.92	$ 1.38	$ 2.41
WEIGHTED AVERAGE COMMON SHARES OUTSTANDING:
Basic (in shares)	47.7	47.2	47.7	47.1
Diluted (in shares)	48.0	47.6	48.1	47.5
Cash dividends per common share (in dollars per share)	$ 0.20	$ 0.18	$ 0.40	$ 0.36