Business Segment Information (Schedule Of Net Sales And Earnings Before Income Tax) (Details) (USD $)	3 Months Ended								12 Months Ended
	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2012	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2012
Segment Reporting Information [Line Items]
Net sales	$ 151,413,000	$ 130,495,000	$ 124,762,000	$ 124,450,000	$ 144,600,000	$ 116,922,000	$ 118,039,000	$ 110,518,000	$ 531,120,000	$ 490,079,000	$ 478,699,000
Consolidated EBIT									63,800,000	52,300,000	54,700,000
Less: Interest expense									(1,567,000)	(2,693,000)	(2,469,000)
Earnings before income tax									62,207,000	49,595,000	52,182,000
Filtration [Member]
Segment Reporting Information [Line Items]
Net sales									233,700,000	214,100,000	194,800,000
Consolidated EBIT									41,400,000	42,400,000	38,000,000
Test [Member]
Segment Reporting Information [Line Items]
Net sales									181,800,000	166,700,000	175,900,000
Consolidated EBIT									21,100,000	16,300,000	14,000,000
Utility Solutions [Member]
Segment Reporting Information [Line Items]
Net sales									115,600,000	109,300,000	108,000,000
Consolidated EBIT									26,600,000	21,600,000	25,900,000
Corporate [Member]
Segment Reporting Information [Line Items]
Consolidated EBIT									$ (25,300,000)	$ (28,000,000)	$ (23,200,000)