Net Sales By Segment (Detail) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Net sales	$ 378,924	$ 383,588	$ 316,113
Eliminations and Other	(4,321)	(2,824)	(2,632)
Performance Materials Segment [Member]
Net sales	118,035	134,059	123,135
Performance Materials Segment [Member] | Industrial Filtration
Net sales	68,379	72,888	71,480
Performance Materials Segment [Member] | Industrial Thermal Insulation
Net sales	38,449	47,299	38,951
Performance Materials Segment [Member] | Life Sciences Filtration
Net sales	11,207	13,872	12,704
Other Products and Services Segment [Member]
Net sales	16,853	14,670	15,562
Other Products and Services Segment [Member] | Life Sciences Vital Fluids
Net sales	16,853	14,670	15,562
Thermal Acoustical Fibers Segments [Member]
Net sales	94,436	81,747	51,767
Thermal Acoustical Fibers Segments [Member] | Fiber Parts
Net sales	93,519	79,631	49,326
Thermal Acoustical Fibers Segments [Member] | Tooling
Net sales	917	2,116	2,441
Thermal Acoustical Metals Segments [Member]
Net sales	153,921	155,936	128,281
Thermal Acoustical Metals Segments [Member] | Metal Parts
Net sales	136,276	142,646	110,085
Thermal Acoustical Metals Segments [Member] | Tooling
Net sales	$ 17,645	$ 13,290	$ 18,196