Business Segment Information (Schedule Of Basis Of Continuing Operations And Excludes Discontinued Operations) (Details) (USD $) In Thousands	3 Months Ended	9 Months Ended
Jun. 30, 2011	Jun. 30, 2010	Jun. 30, 2011	Jun. 30, 2010
NET SALES	$ 176,326	$ 157,582	$ 503,010	$ 399,568
Consolidated EBIT	20,751	24,002	58,909	36,054
Less: Interest expense	(534)	(791)	(1,846)	(3,028)
Earnings before income taxes	20,217	23,211	57,063	33,026
USG [Member]
NET SALES	86,837	91,718	264,018	224,950
Consolidated EBIT	12,428	20,424	43,597	35,615
Test [Member]
NET SALES	45,848	34,575	119,955	93,143
Consolidated EBIT	4,616	3,397	11,739	6,193
Filtration [Member]
NET SALES	43,641	31,289	119,037	81,475
Consolidated EBIT	9,595	6,072	21,604	11,419
Corporate (Loss) [Member]
Consolidated EBIT	$ (5,888)	$ (5,891)	$ (18,031)	$ (17,173)

Sum of operating profit and nonoperating income or expense before Income or Loss from equity method investments, income taxes, extraordinary items, and noncontrolling interest.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher SEC
-Name Regulation S-X (SX)
-Number 210
-Article 4
-Section 08
-Paragraph h
-Subparagraph 1(i)

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 235
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.4-08.(h)(1)(i))
-URI http://asc.fasb.org/extlink&oid=6881521&loc=d3e23780-122690

+ Details

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Balance Type:	credit
Period Type:	duration

- Definition

This element represents the income or loss from continuing operations (before interest income and interest expense) attributable to the economic entity which may also be defined as revenue less expenses from ongoing operations, after income or loss from equity method investments, but before interest income, interest expense, income taxes, extraordinary items, and noncontrolling interest.

+ Details

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Namespace Prefix:	us-gaap
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

The net amount of operating interest income (expense).

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher SEC
-Name Regulation S-X (SX)
-Number 210
-Section 04
-Paragraph 10
-Article 9

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 225
-Section S99
-Paragraph 1
-Subparagraph (SX 210.9-04.10)
-URI http://asc.fasb.org/extlink&oid=6879574&loc=d3e536633-122882

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- Definition

Total revenue from sale of goods and services rendered during the reporting period, in the normal course of business, reduced by sales returns and allowances, and sales discounts.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher SEC
-Name Regulation S-X (SX)
-Number 210
-Article 5
-Section 03
-Paragraph 1

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 225
-SubTopic 10
-Section S99
-Paragraph 2
-Subparagraph (SX 210.5-03.1)
-URI http://asc.fasb.org/extlink&oid=6880815&loc=d3e20235-122688

+ Details

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Namespace Prefix:	us-gaap
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration