Business Segment Information (Schedule Of Net Sales) (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended		6 Months Ended
	Mar. 31, 2012	Mar. 31, 2011	Mar. 31, 2012	Mar. 31, 2011
Segment Reporting Information [Line Items]
Net sales	$ 173,863	$ 166,748	$ 326,788	$ 326,684
USG [Member]
Segment Reporting Information [Line Items]
Net sales	74,475	84,992	144,824	177,182
Test [Member]
Segment Reporting Information [Line Items]
Net sales	50,483	42,103	89,837	74,106
Filtration [Member]
Segment Reporting Information [Line Items]
Net sales	$ 48,905	$ 39,653	$ 92,127	$ 75,396