Condensed Statements of Operations - USD ($) shares in Millions, $ in Millions	3 Months Ended				6 Months Ended		55 Months Ended
	Jun. 30, 2019	Mar. 31, 2019	Jun. 30, 2018	Mar. 31, 2018	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019
Income Statement [Abstract]
Sales	$ 1,592.9		$ 1,728.4		$ 3,146.3	$ 3,438.7
Operating expenses:
Cost of goods sold	1,463.7		1,460.7		2,811.0	2,989.4
Selling and administration	97.0		110.3		204.0	210.8
Restructuring charges	3.8	$ 4.0	6.4	$ 4.0	7.8	10.4	$ 189.8
Acquisition-related costs	0.0		0.3		0.0	0.6
Other operating income	0.1		0.0		0.2	8.1
Operating income	28.5		150.7		123.7	235.6
Losses of non-consolidated affiliates	0.0		(21.1)		0.0	(20.6)
Interest expense	57.9		61.1		115.3	124.8
Interest income	0.3		0.4		0.5	0.8
Non-operating pension income	4.2		5.4		8.1	10.8
Other income	0.0		0.0		11.2	0.0
Income (loss) before taxes	(24.9)		74.3		28.2	101.8
Income tax (benefit) provision	(4.9)		15.7		6.5	22.3
Net (loss) income	$ (20.0)	$ 41.7	$ 58.6	$ 20.9	$ 21.7	$ 79.5
Net (loss) income per common share:
Basic	$ (0.12)		$ 0.35		$ 0.13	$ 0.48
Diluted	$ (0.12)		$ 0.35		$ 0.13	$ 0.47
Average common shares outstanding:
Basic	164.6		167.1		164.8	167.1
Diluted	164.6		168.8		165.7	169.1