Segment Information (Details) $ in Millions	3 Months Ended	9 Months Ended
Sep. 30, 2019 USD ($)	Sep. 30, 2018 USD ($)	Sep. 30, 2019 USD ($) segment	Sep. 30, 2018 USD ($)	Dec. 31, 2018 USD ($)
Segment Reporting Information [Line Items]
Number of operating segments \| segment			2
Number of reportable segments \| segment			2
Net Sales [Abstract]
Net Sales	$ 256.4	$ 260.3	$ 784.3	$ 792.6
Percentage of Net Sales (in hundredths)	100.00%	100.00%	100.00%	100.00%
Operating Profit [Abstract]
Operating Profit	$ 34.6	$ 31.1	$ 109.2	$ 108.2
Operating Profit (in hundredths)	100.00%	100.00%	100.00%	100.00%
Assets	$ 1,450.2		$ 1,450.2		$ 1,466.5
Advanced Materials & Structures
Net Sales [Abstract]
Net Sales	$ 126.1	$ 120.8	$ 373.3	$ 360.1
Percentage of Net Sales (in hundredths)	49.20%	46.40%	47.60%	45.40%
Engineered Papers
Net Sales [Abstract]
Net Sales	$ 130.3	$ 139.5	$ 411.0	$ 432.5
Percentage of Net Sales (in hundredths)	50.80%	53.60%	52.40%	54.60%
Operating Segments \| Advanced Materials & Structures
Operating Profit [Abstract]
Operating Profit	$ 19.3	$ 11.9	$ 54.6	$ 39.5
Operating Profit (in hundredths)	55.80%	38.30%	50.00%	36.50%
Assets	$ 765.3		$ 765.3		796.1
Operating Segments \| Engineered Papers
Operating Profit [Abstract]
Operating Profit	$ 27.3	$ 27.5	$ 88.5	$ 94.7
Operating Profit (in hundredths)	78.90%	88.40%	81.00%	87.50%
Assets	$ 502.5		$ 502.5		527.4
Unallocated
Operating Profit [Abstract]
Operating Profit	$ (12.0)	$ (8.3)	$ (33.9)	$ (26.0)
Operating Profit (in hundredths)	(34.70%)	(26.70%)	(31.00%)	(24.00%)
Assets	$ 182.4		$ 182.4		$ 143.0

The percentage of segment operating profit contribution to total operating profit.

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The percentage of net product revenue to total net revenue from the sale of goods.

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Segment Net Sales [Abstract]

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Segment Operating Profit [Abstract]

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- Definition

Sum of the carrying amounts as of the balance sheet date of all assets that are recognized. Assets are probable future economic benefits obtained or controlled by an entity as a result of past transactions or events.

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Number of operating segments. An operating segment is a component of an enterprise: (a) that engages in business activities from which it may earn revenues and incur expenses (including revenues and expenses relating to transactions with other components of the same enterprise), (b) whose operating results are regularly reviewed by the enterprise's chief operating decision maker to make decisions about resources to be allocated to the segment and assess its performance, and (c) for which discrete financial information is available. An operating segment may engage in business activities for which it has yet to earn revenues, for example, start-up operations may be operating segments before earning revenues.

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Number of segments reported by the entity. A reportable segment is a component of an entity for which there is an accounting requirement to report separate financial information on that component in the entity's financial statements.

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The net result for the period of deducting operating expenses from operating revenues.

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Amount, excluding tax collected from customer, of revenue from satisfaction of performance obligation by transferring promised good or service to customer. Tax collected from customer is tax assessed by governmental authority that is both imposed on and concurrent with specific revenue-producing transaction, including, but not limited to, sales, use, value added and excise.

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Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

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