Goodwill - Reportable Segment (Details) - USD ($) $ in Millions	3 Months Ended	12 Months Ended
Mar. 31, 2015	Dec. 31, 2019	Dec. 31, 2018
Goodwill [Roll Forward]
Goodwill beginning balance		$ 338.1	$ 341.3
Foreign currency translation adjustments	$ (0.7)		(3.2)
Goodwill ending balance		337.4	338.1
Advanced Materials & Structures
Goodwill [Roll Forward]
Goodwill beginning balance		333.1	336.1
Foreign currency translation adjustments		(0.6)	(3.0)
Goodwill ending balance		332.5	333.1
Engineered Papers
Goodwill [Roll Forward]
Goodwill beginning balance		5.0	5.2
Foreign currency translation adjustments	$ (0.1)		(0.2)
Goodwill ending balance		$ 4.9	$ 5.0

Amount after accumulated impairment loss of an asset representing future economic benefits arising from other assets acquired in a business combination that are not individually identified and separately recognized.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 350
-SubTopic 20
-Section 45
-Paragraph 5
-URI http://asc.fasb.org/extlink&oid=77989000&loc=SL49117168-202975

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 350
-SubTopic 20
-Section 45
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=99380562&loc=d3e13770-109266

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- Definition

Amount of foreign currency translation gain (loss) which increases (decreases) an asset representing future economic benefits from other assets acquired in a business combination that are not individually identified and separately recognized.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 350
-SubTopic 20
-Section 50
-Paragraph 1
-Subparagraph (f)
-URI http://asc.fasb.org/extlink&oid=108376223&loc=d3e13816-109267

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- Definition

A roll forward is a reconciliation of a concept from the beginning of a period to the end of a period.

+ References

No definition available.

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