Condensed Statements of Operations - USD ($) shares in Millions, $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Income Statement [Abstract]
Sales	$ 1,437.6	$ 1,576.6	$ 4,103.9	$ 4,722.9
Operating expenses:
Cost of goods sold	1,307.4	1,357.6	3,917.3	4,168.6
Selling and administration	112.7	110.8	309.1	314.8
Restructuring charges	1.3	4.9	4.7	12.7
Goodwill impairment	699.8	0.0	699.8	0.0
Other operating (expense) income	(0.2)	0.1	(0.1)	0.3
Operating (loss) income	(683.8)	103.4	(827.1)	227.1
Interest expense	74.6	63.9	207.1	179.2
Interest income	0.1	0.2	0.4	0.7
Non-operating pension income	(4.9)	(4.1)	(14.4)	(12.2)
Other income	0.0	0.0	0.0	11.2
Income (loss) before taxes	(753.4)	43.8	(1,019.4)	72.0
Income tax (benefit) provision	(16.6)	(0.4)	(82.5)	6.1
Net (loss) income	$ (736.8)	$ 44.2	$ (936.9)	$ 65.9
Net (loss) income per common share:
Basic	$ (4.67)	$ 0.27	$ (5.94)	$ 0.40
Diluted	$ (4.67)	$ 0.27	$ (5.94)	$ 0.40
Average common shares outstanding:
Basic	157.9	161.9	157.8	163.7
Diluted	157.9	162.8	157.8	164.5