Segment Information (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014	Jun. 30, 2013
Segment Reporting, Revenue Reconciling Item [Line Items]
Net sales	$ 148,793	$ 101,051	$ 274,019	$ 200,080
Performance Materials [Member]
Segment Reporting, Revenue Reconciling Item [Line Items]
Net sales	31,252	28,968	60,105	56,451
Performance Materials [Member] | Industrial Filtration [Member]
Segment Reporting, Revenue Reconciling Item [Line Items]
Net sales	19,546	17,903	37,419	34,553
Performance Materials [Member] | Thermal Insulation [Member]
Segment Reporting, Revenue Reconciling Item [Line Items]
Net sales	7,993	8,579	16,521	16,735
Performance Materials [Member] | Life Sciences Filtration [Member]
Segment Reporting, Revenue Reconciling Item [Line Items]
Net sales	3,713	2,486	6,165	5,163
Industrial Filtration Segment [Member]
Segment Reporting, Revenue Reconciling Item [Line Items]
Net sales	34,135	0	51,791	0
Industrial Filtration Segment [Member] | Industrial Filtration [Member]
Segment Reporting, Revenue Reconciling Item [Line Items]
Net sales	34,135	0	51,791	0
Thermal/Acoustical Metals Segment [Member]
Segment Reporting, Revenue Reconciling Item [Line Items]
Net sales	43,339	40,920	85,795	81,122
Thermal/Acoustical Metals Segment [Member] | Metal Parts [Member]
Segment Reporting, Revenue Reconciling Item [Line Items]
Net sales	38,701	35,957	75,726	69,066
Thermal/Acoustical Metals Segment [Member] | Tooling [Member]
Segment Reporting, Revenue Reconciling Item [Line Items]
Net sales	4,638	4,963	10,069	12,056
Thermal/Acoustical Fibers Segment [Member]
Segment Reporting, Revenue Reconciling Item [Line Items]
Net sales	36,308	27,959	68,821	55,886
Thermal/Acoustical Fibers Segment [Member] | Tooling [Member]
Segment Reporting, Revenue Reconciling Item [Line Items]
Net sales	1,646	1,501	3,837	1,644
Thermal/Acoustical Fibers Segment [Member] | Fiber Parts [Member]
Segment Reporting, Revenue Reconciling Item [Line Items]
Net sales	34,662	26,458	64,984	54,242
Other Products and Services [Member]
Segment Reporting, Revenue Reconciling Item [Line Items]
Net sales	4,864	4,263	9,588	8,570
Other Products and Services [Member] | Life Sciences Vital Fluids [Member]
Segment Reporting, Revenue Reconciling Item [Line Items]
Net sales	4,864	4,263	9,588	8,570
Intersegment Eliminations [Member]
Segment Reporting, Revenue Reconciling Item [Line Items]
Net sales	$ (1,105)	$ (1,059)	$ (2,081)	$ (1,949)