REVENUES - Disaggregation of Revenues (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Jun. 30, 2022	Jun. 30, 2021	Jun. 30, 2022	Jun. 30, 2021
Disaggregation of revenues
Revenue from contract with customer excluding assessed tax	$ 219,066	$ 181,394	$ 601,004	$ 509,962
Point in time
Disaggregation of revenues
Revenue from contract with customer excluding assessed tax	104,721	82,428	298,645	236,454
Over time
Disaggregation of revenues
Revenue from contract with customer excluding assessed tax	114,345	98,966	302,359	273,508
United States [Member]
Disaggregation of revenues
Revenue from contract with customer excluding assessed tax	156,020	135,531	423,578	376,078
International
Disaggregation of revenues
Revenue from contract with customer excluding assessed tax	63,046	45,863	177,426	133,884
Commercial
Disaggregation of revenues
Revenue from contract with customer excluding assessed tax	158,977	123,506	439,629	352,950
Government [Member]
Disaggregation of revenues
Revenue from contract with customer excluding assessed tax	60,089	57,888	161,375	157,012
Aerospace & Defense
Disaggregation of revenues
Revenue from contract with customer excluding assessed tax	92,606	85,576	247,671	234,720
Aerospace & Defense | Point in time
Disaggregation of revenues
Revenue from contract with customer excluding assessed tax	35,238	37,513	99,464	103,492
Aerospace & Defense | Over time
Disaggregation of revenues
Revenue from contract with customer excluding assessed tax	57,368	48,063	148,207	131,228
Aerospace & Defense | United States [Member]
Disaggregation of revenues
Revenue from contract with customer excluding assessed tax	79,536	75,701	212,849	205,527
Aerospace & Defense | International
Disaggregation of revenues
Revenue from contract with customer excluding assessed tax	13,070	9,875	34,822	29,193
Aerospace & Defense | Commercial
Disaggregation of revenues
Revenue from contract with customer excluding assessed tax	38,918	34,708	100,407	95,712
Aerospace & Defense | Government [Member]
Disaggregation of revenues
Revenue from contract with customer excluding assessed tax	53,688	50,868	147,264	139,008
USG
Disaggregation of revenues
Revenue from contract with customer excluding assessed tax	67,201	47,704	194,877	141,799
USG | Point in time
Disaggregation of revenues
Revenue from contract with customer excluding assessed tax	53,656	35,242	155,693	105,173
USG | Over time
Disaggregation of revenues
Revenue from contract with customer excluding assessed tax	13,545	12,462	39,184	36,626
USG | United States [Member]
Disaggregation of revenues
Revenue from contract with customer excluding assessed tax	41,822	32,111	122,021	96,601
USG | International
Disaggregation of revenues
Revenue from contract with customer excluding assessed tax	25,379	15,593	72,856	45,198
USG | Commercial
Disaggregation of revenues
Revenue from contract with customer excluding assessed tax	65,610	46,735	191,832	139,149
USG | Government [Member]
Disaggregation of revenues
Revenue from contract with customer excluding assessed tax	1,591	969	3,045	2,650
Test
Disaggregation of revenues
Revenue from contract with customer excluding assessed tax	59,259	48,114	158,456	133,443
Test | Point in time
Disaggregation of revenues
Revenue from contract with customer excluding assessed tax	15,827	9,673	43,488	27,789
Test | Over time
Disaggregation of revenues
Revenue from contract with customer excluding assessed tax	43,432	38,441	114,968	105,654
Test | United States [Member]
Disaggregation of revenues
Revenue from contract with customer excluding assessed tax	34,662	27,719	88,708	73,950
Test | International
Disaggregation of revenues
Revenue from contract with customer excluding assessed tax	24,597	20,395	69,748	59,493
Test | Commercial
Disaggregation of revenues
Revenue from contract with customer excluding assessed tax	54,449	42,063	147,390	118,089
Test | Government [Member]
Disaggregation of revenues
Revenue from contract with customer excluding assessed tax	$ 4,810	$ 6,051	$ 11,066	$ 15,354