Segment Information (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014	Jun. 30, 2013
Segment information
Total sales	$ 470.1	$ 422.6	$ 931.8	$ 839.1
Operating income	75.1	71.9	149.7	134.9
Other operating expense	6.0		6.0
Depreciation and amortization	17.7	13.8	34.8	28.1
Stock-based compensation expense	2.7	3.3	11.5	12.0
Accrual basis additions to capital expenditures	64.8	40.7	104.8	82.1
Composite Materials
Segment information
Total sales	379.8	342.7	754.6	684.2
Operating income	79.8	71.2	155.7	139.1
Depreciation and amortization	16.3	12.6	31.9	25.7
Stock-based compensation expense	0.1	1.3	3.4	3.3
Accrual basis additions to capital expenditures	62.6	38.0	101.0	76.4
Engineered Products
Segment information
Total sales	109.0	98.4	214.5	190.7
Operating income	17.6	15.1	34.0	28.5
Depreciation and amortization	1.4	1.1	2.8	2.3
Stock-based compensation expense		0.2	0.7	0.7
Accrual basis additions to capital expenditures	2.2	2.7	3.8	5.7
Corporate and Other
Segment information
Total sales	(18.7)	(18.5)	(37.3)	(35.8)
Operating income	(22.3)	(14.4)	(40.0)	(32.7)
Other operating expense	6.0		6.0
Depreciation and amortization		0.1	0.1	0.1
Stock-based compensation expense	2.6	1.8	7.4	8.0
Operating Segments
Segment information
Total sales	470.1	422.6	931.8	839.1
Operating Segments | Composite Materials
Segment information
Total sales	361.6	324.7	717.9	649.5
Operating Segments | Engineered Products
Segment information
Total sales	108.5	97.9	213.9	189.6
Intersegment Elimination | Composite Materials
Segment information
Total sales	18.2	18.0	36.7	34.7
Intersegment Elimination | Engineered Products
Segment information
Total sales	0.5	0.5	0.6	1.1
Intersegment Elimination | Corporate and Other
Segment information
Total sales	$ (18.7)	$ (18.5)	$ (37.3)	$ (35.8)