REVENUES - Disaggregation of Revenues (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Mar. 31, 2023	Mar. 31, 2022	Mar. 31, 2023	Mar. 31, 2022
Disaggregation of revenues
Revenue from contract with customer excluding assessed tax	$ 229,136	$ 204,928	$ 434,637	$ 381,938
Point in time
Disaggregation of revenues
Revenue from contract with customer excluding assessed tax	123,303	101,706	222,039	193,920
Over time
Disaggregation of revenues
Revenue from contract with customer excluding assessed tax	105,833	103,222	212,598	188,018
United States
Disaggregation of revenues
Revenue from contract with customer excluding assessed tax	163,040	145,150	305,856	267,559
International
Disaggregation of revenues
Revenue from contract with customer excluding assessed tax	66,096	59,778	128,781	114,379
Commercial
Disaggregation of revenues
Revenue from contract with customer excluding assessed tax	169,526	148,844	322,421	280,651
Government
Disaggregation of revenues
Revenue from contract with customer excluding assessed tax	59,610	56,084	112,216	101,287
Aerospace & Defense
Disaggregation of revenues
Revenue from contract with customer excluding assessed tax	98,982	84,821	181,965	155,065
Aerospace & Defense | Point in time
Disaggregation of revenues
Revenue from contract with customer excluding assessed tax	47,255	35,666	80,859	64,223
Aerospace & Defense | Over time
Disaggregation of revenues
Revenue from contract with customer excluding assessed tax	51,727	49,155	101,106	90,842
Aerospace & Defense | United States
Disaggregation of revenues
Revenue from contract with customer excluding assessed tax	82,516	72,621	151,450	133,313
Aerospace & Defense | International
Disaggregation of revenues
Revenue from contract with customer excluding assessed tax	16,466	12,200	30,515	21,752
Aerospace & Defense | Commercial
Disaggregation of revenues
Revenue from contract with customer excluding assessed tax	48,228	33,562	84,968	61,489
Aerospace & Defense | Government
Disaggregation of revenues
Revenue from contract with customer excluding assessed tax	50,754	51,259	96,997	93,576
USG
Disaggregation of revenues
Revenue from contract with customer excluding assessed tax	79,161	64,191	150,206	127,676
USG | Point in time
Disaggregation of revenues
Revenue from contract with customer excluding assessed tax	64,080	51,202	120,111	102,037
USG | Over time
Disaggregation of revenues
Revenue from contract with customer excluding assessed tax	15,081	12,989	30,095	25,639
USG | United States
Disaggregation of revenues
Revenue from contract with customer excluding assessed tax	53,020	41,458	99,399	80,199
USG | International
Disaggregation of revenues
Revenue from contract with customer excluding assessed tax	26,141	22,733	50,807	47,477
USG | Commercial
Disaggregation of revenues
Revenue from contract with customer excluding assessed tax	78,110	63,379	148,273	126,221
USG | Government
Disaggregation of revenues
Revenue from contract with customer excluding assessed tax	1,051	812	1,933	1,455
Test
Disaggregation of revenues
Revenue from contract with customer excluding assessed tax	50,993	55,916	102,466	99,197
Test | Point in time
Disaggregation of revenues
Revenue from contract with customer excluding assessed tax	11,968	14,838	21,069	27,660
Test | Over time
Disaggregation of revenues
Revenue from contract with customer excluding assessed tax	39,025	41,078	81,397	71,537
Test | United States
Disaggregation of revenues
Revenue from contract with customer excluding assessed tax	27,504	31,071	55,007	54,047
Test | International
Disaggregation of revenues
Revenue from contract with customer excluding assessed tax	23,489	24,845	47,459	45,150
Test | Commercial
Disaggregation of revenues
Revenue from contract with customer excluding assessed tax	43,188	51,903	89,180	92,941
Test | Government
Disaggregation of revenues
Revenue from contract with customer excluding assessed tax	$ 7,805	$ 4,013	$ 13,286	$ 6,256