Segment Information (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013
Segment Reporting, Revenue Reconciling Item [Line Items]
Net sales	$ 134,227	$ 97,995	$ 408,246	$ 298,075
Performance Materials [Member]
Segment Reporting, Revenue Reconciling Item [Line Items]
Net sales	28,626	27,860	88,731	84,311
Performance Materials [Member] | Industrial Filtration [Member]
Segment Reporting, Revenue Reconciling Item [Line Items]
Net sales	17,911	15,536	55,330	50,089
Performance Materials [Member] | Thermal Insulation [Member]
Segment Reporting, Revenue Reconciling Item [Line Items]
Net sales	7,525	9,877	24,046	26,612
Performance Materials [Member] | Life Sciences Filtration [Member]
Segment Reporting, Revenue Reconciling Item [Line Items]
Net sales	3,190	2,447	9,355	7,610
Industrial Filtration Segment [Member]
Segment Reporting, Revenue Reconciling Item [Line Items]
Net sales	30,553	0	82,344	0
Industrial Filtration Segment [Member] | Industrial Filtration [Member]
Segment Reporting, Revenue Reconciling Item [Line Items]
Net sales	30,553	0	82,344	0
Thermal/Acoustical Metals Segment [Member]
Segment Reporting, Revenue Reconciling Item [Line Items]
Net sales	40,000	35,849	125,795	116,971
Thermal/Acoustical Metals Segment [Member] | Metal Parts [Member]
Segment Reporting, Revenue Reconciling Item [Line Items]
Net sales	35,165	32,910	110,891	101,976
Thermal/Acoustical Metals Segment [Member] | Tooling [Member]
Segment Reporting, Revenue Reconciling Item [Line Items]
Net sales	4,835	2,939	14,904	14,995
Thermal/Acoustical Fibers Segment [Member]
Segment Reporting, Revenue Reconciling Item [Line Items]
Net sales	31,013	31,175	99,834	87,061
Thermal/Acoustical Fibers Segment [Member] | Tooling [Member]
Segment Reporting, Revenue Reconciling Item [Line Items]
Net sales	206	4,533	4,043	6,177
Thermal/Acoustical Fibers Segment [Member] | Fiber Parts [Member]
Segment Reporting, Revenue Reconciling Item [Line Items]
Net sales	30,807	26,642	95,791	80,884
Other Products and Services [Member]
Segment Reporting, Revenue Reconciling Item [Line Items]
Net sales	5,164	4,114	14,752	12,684
Other Products and Services [Member] | Life Sciences Vital Fluids [Member]
Segment Reporting, Revenue Reconciling Item [Line Items]
Net sales	5,164	4,114	14,752	12,684
Intersegment Eliminations [Member]
Segment Reporting, Revenue Reconciling Item [Line Items]
Net sales	$ (1,129)	$ (1,003)	$ (3,210)	$ (2,952)