Condensed Statements of Operations - USD ($) shares in Millions, $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Income Statement [Abstract]
Sales	$ 2,340.1	$ 1,437.6	$ 6,480.2	$ 4,103.9
Operating expenses:
Cost of goods sold	1,679.8	1,307.4	4,815.8	3,917.3
Selling and administration	107.2	112.7	314.7	309.1
Restructuring charges	3.6	1.3	24.5	4.7
Goodwill impairment	0.0	699.8	0.0	699.8
Other operating expense	0.5	0.2	0.0	0.1
Operating income (loss)	549.0	(683.8)	1,325.2	(827.1)
Interest expense	54.0	74.6	204.4	207.1
Interest income	0.1	0.1	0.2	0.4
Non-operating pension income	(9.2)	(4.9)	(26.7)	(14.4)
Income (loss) before taxes	504.3	(753.4)	1,147.7	(1,019.4)
Income tax provision (benefit)	113.6	(16.6)	157.6	(82.5)
Net income (loss)	$ 390.7	$ (736.8)	$ 990.1	$ (936.9)
Net income (loss) per common share:
Basic	$ 2.44	$ (4.67)	$ 6.21	$ (5.94)
Diluted	$ 2.38	$ (4.67)	$ 6.07	$ (5.94)
Average common shares outstanding:
Basic	160.1	157.9	159.4	157.8
Diluted	163.9	157.9	163.0	157.8