Segment Information - Operating Income by Segment (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015
Segment Reporting Information [Line Items]
Consolidated Operating Income	$ 15,522	$ 17,029	$ 29,201	$ 27,107
Operating Segments | Performance Materials
Segment Reporting Information [Line Items]
Consolidated Operating Income	4,681	2,265	6,819	3,571
Operating Segments | Industrial Filtration
Segment Reporting Information [Line Items]
Consolidated Operating Income	3,219	4,552	7,145	7,706
Operating Segments | Thermal/Acoustical Metals
Segment Reporting Information [Line Items]
Consolidated Operating Income	4,082	4,853	7,639	8,434
Operating Segments | Thermal/Acoustical Fibers
Segment Reporting Information [Line Items]
Consolidated Operating Income	10,630	10,544	20,954	17,637
Operating Segments | Other Products and Services
Segment Reporting Information [Line Items]
Consolidated Operating Income	0	0	0	118
Corporate Office Expenses
Segment Reporting Information [Line Items]
Consolidated Operating Income	$ (7,090)	$ (5,185)	$ (13,356)	$ (10,359)