CONSOLIDATED STATEMENTS OF INCOME - USD ($) shares in Millions, $ in Millions	3 Months Ended		6 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2015	Dec. 31, 2014
Income Statement [Abstract]
Net sales	$ 443.8	$ 548.4	$ 899.4	$ 1,098.2
Cost of sales	377.5	463.4	764.5	944.1
Gross profit	66.3	85.0	134.9	154.1
Selling, general and administrative expenses	44.5	40.0	87.8	86.9
Restructuring charges	0.0	0.0	0.4	0.0
Operating income	21.8	45.0	46.7	67.2
Interest expense	(7.0)	(6.8)	(13.6)	(13.8)
Other income (expense), net	0.3	0.0	(1.9)	4.8
Income before income taxes	15.1	38.2	31.2	58.2
Income tax expense	3.6	14.1	10.8	20.6
Net income	$ 11.5	$ 24.1	$ 20.4	$ 37.6
EARNINGS PER COMMON SHARE:
Basic (in dollars per share)	$ 0.23	$ 0.45	$ 0.41	$ 0.70
Diluted (in dollars per share)	$ 0.23	$ 0.45	$ 0.41	$ 0.70
WEIGHTED AVERAGE COMMON SHARES OUTSTANDING:
Basic (in shares)	48.8	53.4	49.3	53.5
Diluted (in shares)	48.9	53.6	49.4	53.7
Cash dividends per common share (in dollars per share)	$ 0.18	$ 0.18	$ 0.36	$ 0.36