Segment Information (Net Sales By Segment) (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Segment Reporting Information [Line Items]
Net sales	$ 524,505	$ 535,829	$ 397,969
Operating Segments | Performance Materials Segment
Segment Reporting Information [Line Items]
Net sales	101,478	115,866	112,001
Operating Segments | Performance Materials Segment | Industrial Filtration
Segment Reporting Information [Line Items]
Net sales	62,716	71,648	64,752
Operating Segments | Performance Materials Segment | Thermal Insulation
Segment Reporting Information [Line Items]
Net sales	28,311	31,404	36,929
Operating Segments | Performance Materials Segment | Life Sciences Filtration
Segment Reporting Information [Line Items]
Net sales	10,451	12,814	10,320
Operating Segments | Industrial Filtration Segment
Segment Reporting Information [Line Items]
Net sales	139,133	112,220	0
Operating Segments | Industrial Filtration Segment | Industrial Filtration
Segment Reporting Information [Line Items]
Net sales	139,133	112,220	0
Operating Segments | Thermal/Acoustical Metals Segment
Segment Reporting Information [Line Items]
Net sales	160,932	164,265	158,406
Operating Segments | Thermal/Acoustical Metals Segment | Metal parts
Segment Reporting Information [Line Items]
Net sales	141,117	145,135	135,833
Operating Segments | Thermal/Acoustical Metals Segment | Tooling
Segment Reporting Information [Line Items]
Net sales	19,815	19,130	22,573
Operating Segments | Thermal/Acoustical Fibers Segment
Segment Reporting Information [Line Items]
Net sales	138,747	128,591	114,320
Operating Segments | Thermal/Acoustical Fibers Segment | Tooling
Segment Reporting Information [Line Items]
Net sales	3,152	4,133	8,444
Operating Segments | Thermal/Acoustical Fibers Segment | Fiber parts
Segment Reporting Information [Line Items]
Net sales	135,595	124,458	105,876
Operating Segments | Other Products and Services
Segment Reporting Information [Line Items]
Net sales	1,671	19,682	17,175
Operating Segments | Other Products and Services | Life Sciences Vital Fluids
Segment Reporting Information [Line Items]
Net sales	1,671	19,682	17,175
Intersegment Eliminations
Segment Reporting Information [Line Items]
Net sales	$ (17,456)	$ (4,795)	$ (3,933)