Segment Information - Schedule of Operating Segment Reporting Information (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Segment Reporting Information [Line Items]
Total sales	$ 320.3	$ 378.7	$ 630.6	$ 919.7
Other operating expense	3.1	13.1	15.2	27.8
Operating income (loss)	16.2	6.4	6.0	72.1
Depreciation and amortization	34.2	34.9	68.7	70.4
Stock-based compensation	4.3	(1.7)	13.3	12.7
Accrual basis additions to capital expenditures	3.8	11.5	7.8	33.4
Corporate & Other and Intersegment Elimination
Segment Reporting Information [Line Items]
Total sales	(15.4)	(15.8)	(29.2)	(41.1)
Other operating expense	0.1	2.2	0.2	16.0
Operating income (loss)	(14.2)	(13.2)	(36.5)	(45.5)
Depreciation and amortization	0.1	0.1	0.1	0.1
Stock-based compensation	3.4	(1.3)	11.6	7.2
Composite Materials
Segment Reporting Information [Line Items]
Total sales	240.9	306.2	478.1	744.7
Composite Materials | Intersegment Elimination
Segment Reporting Information [Line Items]
Total sales	14.6	15.4	27.8	40.2
Composite Materials | Operating Segments
Segment Reporting Information [Line Items]
Total sales	255.5	321.6	505.9	784.9
Other operating expense	2.8	8.5	15.5	9.1
Operating income (loss)	24.5	20.1	31.9	111.6
Depreciation and amortization	30.5	30.8	61.3	62.6
Stock-based compensation	0.8	(0.3)	1.4	4.4
Accrual basis additions to capital expenditures	3.4	10.5	7.0	30.7
Engineered Products
Segment Reporting Information [Line Items]
Total sales	79.4	72.5	152.5	175.0
Engineered Products | Intersegment Elimination
Segment Reporting Information [Line Items]
Total sales	0.8	0.4	1.4	0.9
Engineered Products | Operating Segments
Segment Reporting Information [Line Items]
Total sales	80.2	72.9	153.9	175.9
Other operating expense	0.2	2.4	(0.5)	2.7
Operating income (loss)	5.9	(0.5)	10.6	6.0
Depreciation and amortization	3.6	4.0	7.3	7.7
Stock-based compensation	0.1	(0.1)	0.3	1.1
Accrual basis additions to capital expenditures	$ 0.4	$ 1.0	$ 0.8	$ 2.7