Net Sales by Segment (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2012	Jun. 30, 2011	Jun. 30, 2012	Jun. 30, 2011
Segment Reporting, Revenue Reconciling Item [Line Items]
Eliminations and Other	$ (1,332)	$ (656)	$ (2,182)	$ (1,356)
Net sales	97,535	98,831	194,289	200,504
Performance Materials Segment
Segment Reporting, Revenue Reconciling Item [Line Items]
Net sales	32,523	35,892	61,611	72,361
Performance Materials Segment | Industrial Filtration
Segment Reporting, Revenue Reconciling Item [Line Items]
Net sales	18,109	18,449	36,285	38,920
Performance Materials Segment | Industrial Thermal Insulation
Segment Reporting, Revenue Reconciling Item [Line Items]
Net sales	11,119	13,624	19,850	25,576
Performance Materials Segment | Life Sciences Filtration
Segment Reporting, Revenue Reconciling Item [Line Items]
Net sales	3,295	3,819	5,476	7,865
Thermal/Acoustical Metals Segment
Segment Reporting, Revenue Reconciling Item [Line Items]
Net sales	37,685	39,861	79,798	81,313
Thermal/Acoustical Metals Segment | Metal Parts
Segment Reporting, Revenue Reconciling Item [Line Items]
Net sales	35,738	37,455	73,546	72,969
Thermal/Acoustical Metals Segment | Tooling
Segment Reporting, Revenue Reconciling Item [Line Items]
Net sales	1,947	2,406	6,252	8,344
Thermal/Acoustical Fibers Segment
Segment Reporting, Revenue Reconciling Item [Line Items]
Net sales	24,910	20,331	47,082	41,015
Thermal/Acoustical Fibers Segment | Fiber Parts
Segment Reporting, Revenue Reconciling Item [Line Items]
Net sales	24,191	20,283	46,337	39,712
Thermal/Acoustical Fibers Segment | Tooling
Segment Reporting, Revenue Reconciling Item [Line Items]
Net sales	719	48	745	1,303
Other Products and Services
Segment Reporting, Revenue Reconciling Item [Line Items]
Net sales	3,749	3,403	7,980	7,171
Other Products and Services | Life Sciences Vital Fluids
Segment Reporting, Revenue Reconciling Item [Line Items]
Net sales	$ 3,749	$ 3,403	$ 7,980	$ 7,171