Business Segment Information - Identifiable Assets (Details) - USD ($) $ in Thousands	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2018
Identifiable Assets	$ 1,373,523	$ 1,466,720
Goodwill	408,063	390,256	$ 361,900
Assets from discontinued operations		67,377
Corporate
Goodwill	408,100	390,300
Other assets	388,100	422,900
Segment reconciling items
Assets from discontinued operations		92,700
Aerospace & Defense
Identifiable Assets	279,500	260,300
USG
Identifiable Assets	144,800	146,300
Goodwill	271,900	254,000	254,100
Test
Identifiable Assets	153,000	154,200
Goodwill	$ 34,100	$ 34,100	$ 34,100