Business Segment Information - Depreciation And Amortization (Details) - USD ($) $ in Thousands	12 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2017
Depreciation and Amortization	$ 40,050	$ 37,755	$ 32,229
Filtration
Depreciation and Amortization	8,300	7,600	6,600
USG
Depreciation and Amortization	11,300	11,000	9,800
Test
Depreciation and Amortization	5,100	4,500	3,600
Technical Packaging
Depreciation and Amortization	4,100	4,100	3,500
Corporate
Depreciation and Amortization	$ 11,300	$ 10,600	$ 8,700