Business Segment Information - Schedule Of Capital Expenditures (Details) - USD ($) $ in Thousands	12 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2021
Capital Expenditures	$ 22,400	$ 32,100	$ 26,700
Goodwill	503,177	492,709	504,900
A&D
Goodwill	115,600	110,000	104,300
USG
Goodwill	353,600	348,700	366,500
Test
Goodwill	34,000	34,000	34,100
Operating Segments [Member] | A&D
Capital Expenditures	12,900	9,400	10,400
Operating Segments [Member] | USG
Capital Expenditures	4,900	14,400	11,600
Operating Segments [Member] | Test
Capital Expenditures	4,500	8,300	4,700
Corporate
Capital Expenditures	$ 100	$ 0	$ 0