Goodwill and Other Intangible Assets - Changes in carrying amount of goodwill (Details) - USD ($) $ in Thousands	12 Months Ended
	Sep. 30, 2023	Sep. 30, 2022
Goodwill and Other Intangible Assets
Beginning Balance	$ 492,709	$ 504,900
Acquisition activity	5,600	1,000
Foreign currency translation and other	4,900	(13,200)
Ending Balance	503,177	492,709
A&D
Goodwill and Other Intangible Assets
Beginning Balance	110,000	104,300
Acquisition activity	5,600	5,700
Ending Balance	115,600	110,000
Test
Goodwill and Other Intangible Assets
Beginning Balance	34,000	34,100
Foreign currency translation and other		(100)
Ending Balance	34,000	34,000
USG
Goodwill and Other Intangible Assets
Beginning Balance	348,700	366,500
Acquisition activity		(4,700)
Foreign currency translation and other	4,900	(13,100)
Ending Balance	$ 353,600	$ 348,700