Consolidated Statements of Operations - USD ($) $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2020	Oct. 01, 2020	Jul. 02, 2020	Apr. 02, 2020	Dec. 31, 2019	Sep. 26, 2019	Jun. 27, 2019	Mar. 28, 2019	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Income Statement [Abstract]
Net revenues	$ 876.6	$ 806.3	$ 644.6	$ 1,077.3	$ 1,959.3	$ 1,919.9	$ 2,016.1	$ 1,967.8	$ 3,404.8	$ 7,863.1	$ 7,222.0
Operating costs and expenses
Cost of sales									3,845.5	6,786.4	6,135.9
Selling, general and administrative									237.4	261.4	210.4
Unusual or Infrequent Item, or Both, Net of Insurance Proceeds									0.0	0.0	(10.0)
Restructuring Charges	4.6	19.5	6.3	42.6					73.0	0.0	0.0
Research and development									38.8	54.5	42.5
Gain (Loss) on Disposition of Property Plant Equipment			(22.9)						22.9	0.0	0.0
Total operating costs and expenses									4,217.6	7,102.3	6,378.8
Operating (loss) income	(101.4)	(176.9)	(367.0)	(167.5)	95.7	206.1	226.0	233.0	(812.8)	760.8	843.2
Interest expense and financing fee amortization									(195.3)	(91.9)	(80.0)
Other expense, net									77.8	5.8	7.0
(Loss) income before income taxes and equity in net (loss) income of affiliates									(1,085.9)	663.1	756.2
Income tax benefit (provision)									220.2	(132.8)	(139.8)
(Loss) income before equity in net (loss) income of affiliates									(865.7)	530.3	616.4
Equity in net (loss) income of affiliates									(4.6)	(0.2)	0.6
Net (loss) income	$ (295.9)	$ (155.5)	$ (255.9)	$ (163.0)	$ 67.7	$ 131.3	$ 168.0	$ 163.1	$ (870.3)	$ 530.1	$ 617.0
(Loss) earnings per share
Basic (in dollars per share)	$ (2.85)	$ (1.50)	$ (2.46)	$ (1.57)	$ 0.65	$ 1.27	$ 1.62	$ 1.57	$ (8.38)	$ 5.11	$ 5.71
Earnings Per Share, Diluted	(2.85)	(1.50)	(2.46)	(1.57)	0.65	1.26	1.61	1.55	(8.38)	5.06	5.65
Common Stock, Dividends, Per Share, Declared	$ 0.01	$ 0.01	$ 0.01	$ 0.01	$ 0.12	$ 0.12	$ 0.12	$ 0.12	$ 0.04	$ 0.48	$ 0.46