Goodwill and Purchased Intangible Assets - Schedule of Gross Goodwill and Other Purchased Intangible Assets (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Changes in the carrying amount of gross goodwill and other purchased intangibles
Balance at the beginning of the period	$ 148.7	$ 72.2
Amortization expense	(2.9)	(1.0)
Additions		70.1
Currency translation adjustments and other	(3.5)	7.4
Balance at the end of the period	142.3	148.7
Composite Materials
Changes in the carrying amount of gross goodwill and other purchased intangibles
Balance at the beginning of the period	103.7	56.1
Amortization expense	(2.0)	(1.0)
Additions		41.2
Currency translation adjustments and other	(3.5)	7.4
Balance at the end of the period	98.2	103.7
Engineered Products
Changes in the carrying amount of gross goodwill and other purchased intangibles
Balance at the beginning of the period	45.0	16.1
Amortization expense	(0.9)
Additions		28.9
Balance at the end of the period	$ 44.1	$ 45.0