REVENUES - Disaggregation of Revenues (Details) - USD ($) $ in Thousands	3 Months Ended
	Dec. 31, 2023	Dec. 31, 2022
Disaggregation of revenues
Revenue from contract with customer excluding assessed tax	$ 218,314	$ 205,501
Point in time
Disaggregation of revenues
Revenue from contract with customer excluding assessed tax	114,148	98,736
Over time
Disaggregation of revenues
Revenue from contract with customer excluding assessed tax	104,166	106,765
United States
Disaggregation of revenues
Revenue from contract with customer excluding assessed tax	158,114	142,816
International
Disaggregation of revenues
Revenue from contract with customer excluding assessed tax	60,200	62,685
Commercial
Disaggregation of revenues
Revenue from contract with customer excluding assessed tax	153,765	152,894
Government
Disaggregation of revenues
Revenue from contract with customer excluding assessed tax	64,549	52,607
A&D
Disaggregation of revenues
Revenue from contract with customer excluding assessed tax	94,733	82,983
A&D | Point in time
Disaggregation of revenues
Revenue from contract with customer excluding assessed tax	39,465	33,604
A&D | Over time
Disaggregation of revenues
Revenue from contract with customer excluding assessed tax	55,268	49,379
A&D | United States
Disaggregation of revenues
Revenue from contract with customer excluding assessed tax	79,901	68,934
A&D | International
Disaggregation of revenues
Revenue from contract with customer excluding assessed tax	14,832	14,049
A&D | Commercial
Disaggregation of revenues
Revenue from contract with customer excluding assessed tax	37,209	36,740
A&D | Government
Disaggregation of revenues
Revenue from contract with customer excluding assessed tax	57,524	46,243
USG
Disaggregation of revenues
Revenue from contract with customer excluding assessed tax	82,984	71,045
USG | Point in time
Disaggregation of revenues
Revenue from contract with customer excluding assessed tax	66,703	56,031
USG | Over time
Disaggregation of revenues
Revenue from contract with customer excluding assessed tax	16,281	15,014
USG | United States
Disaggregation of revenues
Revenue from contract with customer excluding assessed tax	55,961	46,379
USG | International
Disaggregation of revenues
Revenue from contract with customer excluding assessed tax	27,023	24,666
USG | Commercial
Disaggregation of revenues
Revenue from contract with customer excluding assessed tax	81,469	70,162
USG | Government
Disaggregation of revenues
Revenue from contract with customer excluding assessed tax	1,515	883
Test
Disaggregation of revenues
Revenue from contract with customer excluding assessed tax	40,597	51,473
Test | Point in time
Disaggregation of revenues
Revenue from contract with customer excluding assessed tax	7,980	9,101
Test | Over time
Disaggregation of revenues
Revenue from contract with customer excluding assessed tax	32,617	42,372
Test | United States
Disaggregation of revenues
Revenue from contract with customer excluding assessed tax	22,252	27,503
Test | International
Disaggregation of revenues
Revenue from contract with customer excluding assessed tax	18,345	23,970
Test | Commercial
Disaggregation of revenues
Revenue from contract with customer excluding assessed tax	35,087	45,992
Test | Government
Disaggregation of revenues
Revenue from contract with customer excluding assessed tax	$ 5,510	$ 5,481