Condensed Consolidated Statements of Operations - USD ($) shares in Millions, $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Income Statement [Abstract]
Net sales	$ 320.3	$ 378.7	$ 630.6	$ 919.7
Cost of sales	258.4	323.8	515.6	723.9
Gross margin	61.9	54.9	115.0	195.8
Selling, general and administrative expenses	31.1	24.1	70.7	70.6
Research and technology expenses	11.5	11.3	23.1	25.3
Other operating expense	3.1	13.1	15.2	27.8
Operating income	16.2	6.4	6.0	72.1
Interest expense, net	9.3	10.7	19.6	22.7
Income (loss) before income taxes, and equity in earnings from affiliated companies	6.9	(4.3)	(13.6)	49.4
Income tax expense (benefit)	4.0	(3.6)	(3.5)	8.2
Income (loss) before equity in earnings from affiliated companies	2.9	(0.7)	(10.1)	41.2
Equity in (losses) earnings from affiliated companies	(0.7)	(0.3)	(1.7)	0.2
Net income (loss)	$ 2.2	$ (1.0)	$ (11.8)	$ 41.4
Basic net income (loss) per common share	$ 0.03	$ (0.01)	$ (0.14)	$ 0.49
Diluted net income (loss) per common share	$ 0.03	$ (0.01)	$ (0.14)	$ 0.49
Weighted-average common shares:
Basic	84.1	83.7	84.0	83.7
Diluted	84.7	83.7	84.0	84.1