Segment Information (Details) $ in Millions	3 Months Ended	9 Months Ended
Sep. 30, 2017 USD ($)	Sep. 30, 2016 USD ($)	Sep. 30, 2017 USD ($) segment	Sep. 30, 2016 USD ($)	Dec. 31, 2016 USD ($)
Segment Reporting Information [Line Items]
Assets	$ 1,532.0		$ 1,532.0		$ 1,173.7
Number of operating segments \| segment			2
Number of reportable segments \| segment			2
Net Sales [Abstract]
Net sales	$ 257.8	$ 209.3	$ 746.4	$ 641.2
Percentage of Net Sales (in hundredths)	100.00%	100.00%	100.00%	100.00%
Operating Profit [Abstract]
Operating Profit	$ 38.5	$ 30.8	$ 104.6	$ 99.9
Operating Profit (in hundredths)	100.00%	100.00%	100.00%	100.00%
Operating Segments [Member] \| Engineered Papers [Member]
Segment Reporting Information [Line Items]
Assets	$ 523.0		$ 523.0		569.3
Net Sales [Abstract]
Net sales	$ 141.6	$ 136.8	$ 412.4	$ 425.7
Percentage of Net Sales (in hundredths)	54.90%	65.40%	55.30%	66.40%
Operating Profit [Abstract]
Operating Profit	$ 32.3	$ 32.0	$ 90.0	$ 103.4
Operating Profit (in hundredths)	83.90%	103.90%	86.00%	103.50%
Operating Segments [Member] \| Advanced Materials & Structures [Member]
Segment Reporting Information [Line Items]
Assets	$ 918.4		$ 918.4		505.1
Net Sales [Abstract]
Net sales	$ 116.2	$ 72.5	$ 334.0	$ 215.5
Percentage of Net Sales (in hundredths)	45.10%	34.60%	44.70%	33.60%
Operating Profit [Abstract]
Operating Profit	$ 15.4	$ 8.7	$ 40.9	$ 22.8
Operating Profit (in hundredths)	40.00%	28.20%	39.10%	22.80%
Unallocated [Member]
Segment Reporting Information [Line Items]
Assets	$ 90.6		$ 90.6		$ 99.3
Operating Profit [Abstract]
Operating Profit	$ (9.2)	$ (9.9)	$ (26.3)	$ (26.3)
Operating Profit (in hundredths)	(23.90%)	(32.10%)	(25.10%)	(26.30%)

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.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 944
-SubTopic 210
-Section S99
-Paragraph 1
-Subparagraph (SX 210.7-03(a)(12))
-URI http://asc.fasb.org/extlink&oid=6879938&loc=d3e572229-122910

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 210
-Section S99
-Paragraph 1
-Subparagraph (SX 210.9-03(11))
-URI http://asc.fasb.org/extlink&oid=6876686&loc=d3e534808-122878

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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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Aggregate revenue during the period from the sale of goods in the normal course of business, after deducting returns, allowances and discounts.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 225
-SubTopic 10
-Section S99
-Paragraph 2
-Subparagraph (SX 210.5-03.1(a))
-URI http://asc.fasb.org/extlink&oid=63488584&loc=d3e20235-122688

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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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