Business Segment Information (Schedule Of Earnings Before Income Tax) (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Dec. 31, 2011	Dec. 31, 2010
Segment Reporting Information [Line Items]
Consolidated EBIT	$ 8,833	$ 16,573
Less: Interest expense	(491)	(774)
Earnings before income taxes	8,342	15,799
Test [Member]
Segment Reporting Information [Line Items]
Consolidated EBIT	1,947	1,909
Filtration [Member]
Segment Reporting Information [Line Items]
Consolidated EBIT	8,236	5,475
Corporate (Loss) [Member]
Segment Reporting Information [Line Items]
Consolidated EBIT	(6,316)	(6,166)
USG Segment [Member]
Segment Reporting Information [Line Items]
Consolidated EBIT	$ 4,966	$ 15,355