Segment Information (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012
Segment Reporting, Revenue Reconciling Item [Line Items]
Net sales	$ 97,995	$ 94,167	$ 298,075	$ 288,456
Performance Materials
Segment Reporting, Revenue Reconciling Item [Line Items]
Net sales	27,860	30,810	84,311	92,421
Performance Materials | Industrial Filtration
Segment Reporting, Revenue Reconciling Item [Line Items]
Net sales	15,536	17,035	50,089	53,320
Performance Materials | Industrial Thermal Insulation
Segment Reporting, Revenue Reconciling Item [Line Items]
Net sales	9,877	10,647	26,612	30,497
Performance Materials | Life Sciences Filtration
Segment Reporting, Revenue Reconciling Item [Line Items]
Net sales	2,447	3,128	7,610	8,604
Thermal/Acoustical Metals Segment
Segment Reporting, Revenue Reconciling Item [Line Items]
Net sales	35,849	36,596	116,971	116,394
Thermal/Acoustical Metals Segment | Metal Parts
Segment Reporting, Revenue Reconciling Item [Line Items]
Net sales	32,910	31,347	101,976	104,893
Thermal/Acoustical Metals Segment | Tooling
Segment Reporting, Revenue Reconciling Item [Line Items]
Net sales	2,939	5,249	14,995	11,501
Thermal/Acoustical Fibers Segment
Segment Reporting, Revenue Reconciling Item [Line Items]
Net sales	31,175	23,630	87,061	70,712
Thermal/Acoustical Fibers Segment | Fiber Parts
Segment Reporting, Revenue Reconciling Item [Line Items]
Net sales	26,642	23,484	80,884	69,821
Thermal/Acoustical Fibers Segment | Tooling
Segment Reporting, Revenue Reconciling Item [Line Items]
Net sales	4,533	146	6,177	891
Other Products and Services
Segment Reporting, Revenue Reconciling Item [Line Items]
Eliminations and Other	(1,003)	(1,195)	(2,952)	(3,377)
Net sales	4,114	4,326	12,684	12,306
Other Products and Services | Life Sciences Vital Fluids
Segment Reporting, Revenue Reconciling Item [Line Items]
Net sales	$ 4,114	$ 4,326	$ 12,684	$ 12,306