Segment Information - Consolidated Net Sales by Segment (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015
Segment Reporting, Revenue Reconciling Item [Line Items]
Net sales	$ 137,235	$ 134,561	$ 266,935	$ 261,867
Operating Segments | Performance Materials Segment
Segment Reporting, Revenue Reconciling Item [Line Items]
Net sales	29,966	26,032	56,349	51,090
Operating Segments | Performance Materials Segment | Filtration
Segment Reporting, Revenue Reconciling Item [Line Items]
Net sales	18,657	16,476	35,816	31,543
Operating Segments | Performance Materials Segment | Thermal Insulation
Segment Reporting, Revenue Reconciling Item [Line Items]
Net sales	7,214	7,039	13,489	14,524
Operating Segments | Performance Materials Segment | Life Sciences Filtration
Segment Reporting, Revenue Reconciling Item [Line Items]
Net sales	4,095	2,517	7,044	5,023
Operating Segments | Industrial Filtration Segment
Segment Reporting, Revenue Reconciling Item [Line Items]
Net sales	27,840	35,902	59,047	70,102
Operating Segments | Industrial Filtration Segment | Industrial Filtration
Segment Reporting, Revenue Reconciling Item [Line Items]
Net sales	27,840	35,902	59,047	70,102
Operating Segments | Thermal/Acoustical Metals
Segment Reporting, Revenue Reconciling Item [Line Items]
Net sales	45,245	41,432	87,242	79,547
Operating Segments | Thermal/Acoustical Metals | Metal parts
Segment Reporting, Revenue Reconciling Item [Line Items]
Net sales	41,053	36,359	77,836	71,381
Operating Segments | Thermal/Acoustical Metals | Tooling
Segment Reporting, Revenue Reconciling Item [Line Items]
Net sales	4,192	5,073	9,406	8,166
Operating Segments | Thermal/Acoustical Fibers
Segment Reporting, Revenue Reconciling Item [Line Items]
Net sales	40,168	35,470	76,029	66,587
Operating Segments | Thermal/Acoustical Fibers | Tooling
Segment Reporting, Revenue Reconciling Item [Line Items]
Net sales	3,234	183	3,418	889
Operating Segments | Thermal/Acoustical Fibers | Fiber parts
Segment Reporting, Revenue Reconciling Item [Line Items]
Net sales	36,934	35,287	72,611	65,698
Operating Segments | Other Products and Services
Segment Reporting, Revenue Reconciling Item [Line Items]
Net sales	0	0	0	1,671
Operating Segments | Other Products and Services | Life Sciences Vital Fluids
Segment Reporting, Revenue Reconciling Item [Line Items]
Net sales	0	0	0	1,671
Intersegment Eliminations
Segment Reporting, Revenue Reconciling Item [Line Items]
Net sales	$ (5,984)	$ (4,275)	$ (11,732)	$ (7,130)