Condensed Consolidated 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]
Net sales	$ 286.9	$ 572.5	$ 1,206.6	$ 1,791.4
Cost of sales	273.4	414.6	997.3	1,297.5
Gross margin	13.5	157.9	209.3	493.9
Selling, general and administrative expenses	24.6	33.8	95.2	122.8
Research and technology expenses	10.7	14.2	36.0	43.3
Other operating expense	15.8		43.6
Operating income (loss)	(37.6)	109.9	34.5	327.8
Interest expense, net	9.7	11.0	32.4	34.9
Income (loss) before income taxes, and equity in earnings from affiliated companies	(47.3)	98.9	2.1	292.9
Provision for (benefit from) income taxes	(56.9)	18.2	(48.7)	62.4
Income before equity in earnings from affiliated companies	9.6	80.7	50.8	230.5
Equity in earnings (loss) from affiliated companies	0.1	(0.4)	0.3	2.9
Net income	$ 9.7	$ 80.3	$ 51.1	$ 233.4
Basic net income per common share	$ 0.12	$ 0.94	$ 0.61	$ 2.74
Diluted net income per common share	$ 0.12	0.93	0.61	2.71
Dividends per share		$ 0.17	$ 0.17	$ 0.47
Weighted-average common shares:
Basic	83.8	85.1	83.7	85.1
Diluted	84.0	86.1	84.0	86.1