Business Segment Information (Schedule Of Net Sales And Earnings Before Income Tax) (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2015	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2015
Segment Reporting Information [Line Items]
NET SALES	$ 207,005	$ 171,189	$ 161,178	$ 146,368	$ 159,505	$ 140,191	$ 138,930	$ 132,833	$ 685,740	$ 571,459	$ 537,291
Consolidated EBIT									84,700	69,700	62,300
Less: interest expense									(4,578)	(1,308)	(785)
Earnings before income taxes									80,153	68,420	61,521
Filtration [Member]
Segment Reporting Information [Line Items]
NET SALES									279,500	207,800	196,700
Consolidated EBIT									52,200	45,200	41,700
Test [Member]
Segment Reporting Information [Line Items]
NET SALES									160,900	161,500	177,600
Consolidated EBIT									19,500	13,900	9,500
Utility Solutions [Member]
Segment Reporting Information [Line Items]
NET SALES									162,400	127,800	123,600
Consolidated EBIT									36,600	31,100	29,600
Technical Packaging [Member]
Segment Reporting Information [Line Items]
NET SALES									82,900	74,400	39,400
Consolidated EBIT									8,500	9,600	4,900
Corporate (loss) [Member]
Segment Reporting Information [Line Items]
Consolidated EBIT									$ (32,100)	$ (30,100)	$ (23,400)