GOODWILL AND OTHER INTANGIBLE ASSETS - Changes in carrying amount of goodwill (Details) $ in Thousands	9 Months Ended
	Jun. 30, 2022 USD ($)
Changes in goodwill
Balance as of September 30, 2021	$ 504,853
Acquisition activity and adjustments	5,700
Foreign currency translation	(7,200)
Balance as of March 31, 2022	503,439
USG
Changes in goodwill
Balance as of September 30, 2021	366,500
Foreign currency translation	(7,200)
Balance as of March 31, 2022	359,300
Test
Changes in goodwill
Balance as of September 30, 2021	34,100
Balance as of March 31, 2022	34,100
Aerospace & Defense
Changes in goodwill
Balance as of September 30, 2021	104,300
Acquisition activity and adjustments	5,700
Balance as of March 31, 2022	$ 110,000