Goodwill and Intangible Assets (Changes in Carrying Amount of Goodwill by Reporting Unit) (Detail) (USD $) In Thousands, unless otherwise specified	12 Months Ended
Dec. 31, 2014	Dec. 31, 2013
Goodwill [Line Items]
Beginning Balance	$ 18,589us-gaap_Goodwill	$ 18,282us-gaap_Goodwill
Goodwill adjustment	(3,943)us-gaap_GoodwillOtherChanges	(110)us-gaap_GoodwillOtherChanges
Currency translation adjustments	(589)us-gaap_GoodwillTranslationAdjustments	197us-gaap_GoodwillTranslationAdjustments
Ending Balance	21,943us-gaap_Goodwill	18,589us-gaap_Goodwill
Performance Materials [Member]
Goodwill [Line Items]
Beginning Balance	13,929	13,622
Goodwill adjustment	0	(110)
Currency translation adjustments	(589)	197
Ending Balance	13,340	13,929
Industrial Filtration [Member]
Goodwill [Line Items]
Beginning Balance	0	0
Goodwill adjustment	(3,943)	0
Currency translation adjustments	0	0
Ending Balance	3,943	0
Other Products and Services
Goodwill [Line Items]
Beginning Balance	4,660	4,660
Goodwill adjustment	0	0
Currency translation adjustments	0	0
Ending Balance	$ 4,660	$ 4,660

Amount after accumulated impairment loss of an asset representing future economic benefits arising from other assets acquired in a business combination that are not individually identified and separately recognized.

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 350

-SubTopic 20

-Section 50

-Paragraph 1

-URI http://asc.fasb.org/extlink&oid=14024403&loc=d3e13816-109267

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 350

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-URI http://asc.fasb.org/extlink&oid=6388280&loc=d3e13770-109266

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Amount of other (increase) decrease of an asset representing the future economic benefits arising from other assets acquired in a business combination that are not individually identified and separately recognized.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 350

-SubTopic 20

-Section 50

-Paragraph 1

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Amount of increase (decrease) from foreign currency translation adjustments of an asset representing future economic benefits arising from other assets acquired in a business combination that are not individually identified and separately recognized.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

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-Section 50

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