Segment Information (Classification of Segments) (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Segment Reporting Information [Line Items]
Operating Income	$ 54,792	$ 52,477	$ 34,048
Total Assets	527,029	358,260	361,770
Capital Expenditures	28,159	21,555	19,001
Depreciation and Amortization	19,559	17,275	17,646
Operating Segments | Performance Materials Segment
Segment Reporting Information [Line Items]
Operating Income	12,339	6,790	9,706
Total Assets	66,965	66,706	71,325
Capital Expenditures	4,098	3,519	4,124
Depreciation and Amortization	4,023	4,499	4,654
Operating Segments | Technical Nonwovens Segment
Segment Reporting Information [Line Items]
Operating Income	15,584	13,431	6,412
Total Assets	268,104	89,566	100,201
Capital Expenditures	1,248	968	1,804
Depreciation and Amortization	6,778	4,996	4,536
Operating Segments | Thermal/Acoustical Metals Segment
Segment Reporting Information [Line Items]
Operating Income	11,562	15,517	13,823
Total Assets	119,494	111,195	106,210
Capital Expenditures	15,425	11,494	8,544
Depreciation and Amortization	5,094	4,233	4,578
Operating Segments | Thermal/Acoustical Fibers Segment
Segment Reporting Information [Line Items]
Operating Income	41,452	37,086	29,167
Total Assets	47,097	38,881	33,109
Capital Expenditures	6,899	4,807	3,296
Depreciation and Amortization	2,570	2,400	2,166
Operating Segments | Other Products and Services
Segment Reporting Information [Line Items]
Operating Income	0	118	1,582
Total Assets	0	0	11,580
Capital Expenditures	0	22	574
Depreciation and Amortization	0	45	804
Corporate
Segment Reporting Information [Line Items]
Operating Income	(26,145)	(20,465)	(26,642)
Total Assets	25,369	51,912	39,345
Capital Expenditures	489	745	659
Depreciation and Amortization	$ 1,094	$ 1,102	$ 908