REVENUES - Disaggregation of Revenues (Details) - USD ($) $ in Thousands	3 Months Ended
	Dec. 31, 2021	Dec. 31, 2020
Disaggregation of revenues
Revenue from contract with customer excluding assessed tax	$ 177,010	$ 162,674
Point in time
Disaggregation of revenues
Revenue from contract with customer excluding assessed tax	92,214	78,181
Over time
Disaggregation of revenues
Revenue from contract with customer excluding assessed tax	84,796	84,493
United States [Member]
Disaggregation of revenues
Revenue from contract with customer excluding assessed tax	122,403	117,849
International
Disaggregation of revenues
Revenue from contract with customer excluding assessed tax	54,607	44,825
Commercial
Disaggregation of revenues
Revenue from contract with customer excluding assessed tax	131,954	118,190
Government [Member]
Disaggregation of revenues
Revenue from contract with customer excluding assessed tax	45,056	44,484
A&D
Disaggregation of revenues
Revenue from contract with customer excluding assessed tax	70,244	66,616
A&D | Point in time
Disaggregation of revenues
Revenue from contract with customer excluding assessed tax	28,558	26,946
A&D | Over time
Disaggregation of revenues
Revenue from contract with customer excluding assessed tax	41,686	39,670
A&D | United States [Member]
Disaggregation of revenues
Revenue from contract with customer excluding assessed tax	60,687	57,538
A&D | International
Disaggregation of revenues
Revenue from contract with customer excluding assessed tax	9,557	9,078
A&D | Commercial
Disaggregation of revenues
Revenue from contract with customer excluding assessed tax	28,075	27,604
A&D | Government [Member]
Disaggregation of revenues
Revenue from contract with customer excluding assessed tax	42,169	39,012
USG
Disaggregation of revenues
Revenue from contract with customer excluding assessed tax	63,485	54,540
USG | Point in time
Disaggregation of revenues
Revenue from contract with customer excluding assessed tax	50,835	42,367
USG | Over time
Disaggregation of revenues
Revenue from contract with customer excluding assessed tax	12,650	12,173
USG | United States [Member]
Disaggregation of revenues
Revenue from contract with customer excluding assessed tax	38,741	37,045
USG | International
Disaggregation of revenues
Revenue from contract with customer excluding assessed tax	24,744	17,495
USG | Commercial
Disaggregation of revenues
Revenue from contract with customer excluding assessed tax	62,842	53,864
USG | Government [Member]
Disaggregation of revenues
Revenue from contract with customer excluding assessed tax	643	676
Test
Disaggregation of revenues
Revenue from contract with customer excluding assessed tax	43,281	41,518
Test | Point in time
Disaggregation of revenues
Revenue from contract with customer excluding assessed tax	12,821	8,868
Test | Over time
Disaggregation of revenues
Revenue from contract with customer excluding assessed tax	30,460	32,650
Test | United States [Member]
Disaggregation of revenues
Revenue from contract with customer excluding assessed tax	22,975	23,266
Test | International
Disaggregation of revenues
Revenue from contract with customer excluding assessed tax	20,306	18,252
Test | Commercial
Disaggregation of revenues
Revenue from contract with customer excluding assessed tax	41,037	36,722
Test | Government [Member]
Disaggregation of revenues
Revenue from contract with customer excluding assessed tax	$ 2,244	$ 4,796