Consolidated Statements of Operations - USD ($) shares in Millions, $ in Millions	1 Months Ended	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2017	Dec. 31, 2016	Nov. 30, 2015
Income Statement [Abstract]
Net sales	$ 96.3	$ 1,877.2	$ 1,761.3	$ 1,708.3
Operating costs and expenses:
Cost of sales (exclusive of items shown separately below)	75.4	1,615.4	1,527.4	1,459.5
AR1 research and development	0.0	0.0	0.0	32.1
Selling, general and administrative expense	2.8	67.0	53.6	49.0
Depreciation and amortization	5.1	72.6	64.9	65.1
Other expense, net:
Legal settlement	0.0	0.0	0.0	50.0
Other	0.2	7.9	19.8	16.5
Total operating costs and expenses	83.5	1,762.9	1,665.7	1,672.2
Operating income	12.8	114.3	95.6	36.1
Non-operating (income) expense:
Loss on debt	0.0	0.0	34.5	1.9
Interest income	0.0	(3.5)	(0.6)	(0.3)
Interest expense	3.8	30.9	32.5	50.4
Total non-operating expense, net	3.8	27.4	66.4	52.0
Income (loss) before income taxes	9.0	86.9	29.2	(15.9)
Income tax provision	2.0	96.1	11.2	0.3
Net (loss) income	$ 7.0	$ (9.2)	$ 18.0	$ (16.2)
Basic:
Net income (loss) income per share (in USD per share)	$ 0.11	$ (0.13)	$ 0.27	$ (0.27)
Diluted:
Net income (loss) per share (in USD per share)	$ 0.10	$ (0.13)	$ 0.27	$ (0.27)
Weighted average shares of common stock outstanding, basic (in shares)	62.9	73.0	65.6	61.1
Weighted average shares of common stock outstanding, diluted (in shares)	72.5	73.0	65.7	61.1