Business Segment Information - Identifiable Assets (Details) - USD ($) $ in Thousands	Sep. 30, 2019	Sep. 30, 2018
Identifiable Assets	$ 1,466,720	$ 1,265,122
Filtration
Identifiable Assets	260,300	204,700
USG
Identifiable Assets	190,000	176,900
Test
Identifiable Assets	154,200	138,300
Technical Packaging
Identifiable Assets	59,100	50,900
Corporate - Goodwill
Identifiable Assets	409,200	381,700
Corporate - Other assets
Identifiable Assets	$ 393,900	$ 312,600