Business Segment Information (Schedule Of Net Sales And Earnings Before Income Tax) (Details) - USD ($)	3 Months Ended								12 Months Ended
	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2013	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2013
Segment Reporting Information [Line Items]
Net sales	$ 153,612,000	$ 134,191,000	$ 128,941,000	$ 120,547,000	$ 151,413,000	$ 130,495,000	$ 124,762,000	$ 124,450,000	$ 537,291,000	$ 531,120,000	$ 490,079,000
Consolidated EBIT									62,300	63,800	52,300
Less: Interest expense									(785,000)	(1,567,000)	(2,693,000)
Earnings before income taxes									61,521,000	62,207,000	49,595,000
Filtration [Member]
Segment Reporting Information [Line Items]
Net sales									236,100	233,700	214,100
Consolidated EBIT									46,600	41,400	42,400
Test [Member]
Segment Reporting Information [Line Items]
Net sales									177,600	181,800	166,700
Consolidated EBIT									9,500	21,100	16,300
Utility Solutions [Member]
Segment Reporting Information [Line Items]
Net sales									123,600	115,600	109,300
Consolidated EBIT									29,600	26,600	21,600
Corporate (loss) [Member]
Segment Reporting Information [Line Items]
Consolidated EBIT									$ (23,400)	$ (25,300)	$ (28,000)