Revenue Recognition (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Revenue from External Customer [Line Items]
Revenue from Contract with Customer, Including Assessed Tax	$ 261.9	$ 233.3
Product Revenues [Member]
Revenue from External Customer [Line Items]
Revenue from Contract with Customer, Including Assessed Tax	229.2	204.6
Material Conversion Revenues [Member]
Revenue from External Customer [Line Items]
Revenue from Contract with Customer, Including Assessed Tax	30.9	27.2
Other Revenues [Member]
Revenue from External Customer [Line Items]
Revenue from Contract with Customer, Including Assessed Tax	1.8	1.5
Advanced Materials & Structures Segment [Member]
Revenue from External Customer [Line Items]
Revenue from Contract with Customer, Including Assessed Tax	115.3	100.0
Advanced Materials & Structures Segment [Member] | Product Revenues [Member]
Revenue from External Customer [Line Items]
Revenue from Contract with Customer, Including Assessed Tax	108.4	91.3
Advanced Materials & Structures Segment [Member] | Material Conversion Revenues [Member]
Revenue from External Customer [Line Items]
Revenue from Contract with Customer, Including Assessed Tax	6.2	8.2
Advanced Materials & Structures Segment [Member] | Other Revenues [Member]
Revenue from External Customer [Line Items]
Revenue from Contract with Customer, Including Assessed Tax	0.7	0.5
Engineered Papers Segment [Member]
Revenue from External Customer [Line Items]
Revenue from Contract with Customer, Including Assessed Tax	146.6	133.3
Engineered Papers Segment [Member] | Product Revenues [Member]
Revenue from External Customer [Line Items]
Revenue from Contract with Customer, Including Assessed Tax	120.8	113.3
Engineered Papers Segment [Member] | Material Conversion Revenues [Member]
Revenue from External Customer [Line Items]
Revenue from Contract with Customer, Including Assessed Tax	24.7	19.0
Engineered Papers Segment [Member] | Other Revenues [Member]
Revenue from External Customer [Line Items]
Revenue from Contract with Customer, Including Assessed Tax	1.1	1.0
UNITED STATES
Revenue from External Customer [Line Items]
Revenue from Contract with Customer, Including Assessed Tax	127.8	115.0
UNITED STATES | Advanced Materials & Structures Segment [Member]
Revenue from External Customer [Line Items]
Revenue from Contract with Customer, Including Assessed Tax	78.1	68.7
UNITED STATES | Engineered Papers Segment [Member]
Revenue from External Customer [Line Items]
Revenue from Contract with Customer, Including Assessed Tax	49.7	46.3
Europe and the former Commonwealth of Independent States [Member]
Revenue from External Customer [Line Items]
Revenue from Contract with Customer, Including Assessed Tax	73.4	60.4
Europe and the former Commonwealth of Independent States [Member] | Advanced Materials & Structures Segment [Member]
Revenue from External Customer [Line Items]
Revenue from Contract with Customer, Including Assessed Tax	15.8	11.2
Europe and the former Commonwealth of Independent States [Member] | Engineered Papers Segment [Member]
Revenue from External Customer [Line Items]
Revenue from Contract with Customer, Including Assessed Tax	57.6	49.2
Segment, Geographical, Groups of Countries, Group Four [Member]
Revenue from External Customer [Line Items]
Revenue from Contract with Customer, Including Assessed Tax	35.9	35.8
Segment, Geographical, Groups of Countries, Group Four [Member] | Advanced Materials & Structures Segment [Member]
Revenue from External Customer [Line Items]
Revenue from Contract with Customer, Including Assessed Tax	14.6	14.7
Segment, Geographical, Groups of Countries, Group Four [Member] | Engineered Papers Segment [Member]
Revenue from External Customer [Line Items]
Revenue from Contract with Customer, Including Assessed Tax	21.3	21.1
Segment, Geographical, Groups of Countries, Group Three [Member]
Revenue from External Customer [Line Items]
Revenue from Contract with Customer, Including Assessed Tax	14.7	12.8
Segment, Geographical, Groups of Countries, Group Three [Member] | Advanced Materials & Structures Segment [Member]
Revenue from External Customer [Line Items]
Revenue from Contract with Customer, Including Assessed Tax	3.2	2.3
Segment, Geographical, Groups of Countries, Group Three [Member] | Engineered Papers Segment [Member]
Revenue from External Customer [Line Items]
Revenue from Contract with Customer, Including Assessed Tax	11.5	10.5
Other Foreign Countries [Member]
Revenue from External Customer [Line Items]
Revenue from Contract with Customer, Including Assessed Tax	10.1	9.3
Other Foreign Countries [Member] | Advanced Materials & Structures Segment [Member]
Revenue from External Customer [Line Items]
Revenue from Contract with Customer, Including Assessed Tax	3.6	3.1
Other Foreign Countries [Member] | Engineered Papers Segment [Member]
Revenue from External Customer [Line Items]
Revenue from Contract with Customer, Including Assessed Tax	$ 6.5	$ 6.2