Business Segment Information - Depreciation And Amortization (Details) - USD ($) $ in Thousands	12 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2018
Depreciation and Amortization	$ 41,338	$ 35,995	$ 33,690
Corporate
Depreciation and Amortization	12,500	11,300	10,600
Aerospace & Defense
Depreciation and Amortization	9,400	8,300	7,600
USG
Depreciation and Amortization	14,400	11,300	11,000
Test
Depreciation and Amortization	$ 5,000	$ 5,100	$ 4,500