Revenues - Disaggregation of Revenues (Details) - USD ($) $ in Thousands	12 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2021
Disaggregation of revenues
Revenue from contract with customer excluding assessed tax	$ 956,033	$ 857,502	$ 715,440
Point in time
Disaggregation of revenues
Revenue from contract with customer excluding assessed tax	504,241	428,979
Over time
Disaggregation of revenues
Revenue from contract with customer excluding assessed tax	451,792	428,523
United States
Disaggregation of revenues
Revenue from contract with customer excluding assessed tax	665,391	603,172	517,000
International
Disaggregation of revenues
Revenue from contract with customer excluding assessed tax	290,642	254,330
Commercial
Disaggregation of revenues
Revenue from contract with customer excluding assessed tax	704,027	625,753
Government
Disaggregation of revenues
Revenue from contract with customer excluding assessed tax	252,006	231,749
A&D
Disaggregation of revenues
Revenue from contract with customer excluding assessed tax	392,443	351,413	314,800
A&D | Point in time
Disaggregation of revenues
Revenue from contract with customer excluding assessed tax	178,222	144,039
A&D | Over time
Disaggregation of revenues
Revenue from contract with customer excluding assessed tax	214,221	207,374
A&D | United States
Disaggregation of revenues
Revenue from contract with customer excluding assessed tax	326,566	299,158
A&D | International
Disaggregation of revenues
Revenue from contract with customer excluding assessed tax	65,877	52,255
A&D | Commercial
Disaggregation of revenues
Revenue from contract with customer excluding assessed tax	178,447	144,305
A&D | Government
Disaggregation of revenues
Revenue from contract with customer excluding assessed tax	213,996	207,108
USG
Disaggregation of revenues
Revenue from contract with customer excluding assessed tax	342,320	278,367	202,900
USG | Point in time
Disaggregation of revenues
Revenue from contract with customer excluding assessed tax	281,977	226,418
USG | Over time
Disaggregation of revenues
Revenue from contract with customer excluding assessed tax	60,343	51,949
USG | United States
Disaggregation of revenues
Revenue from contract with customer excluding assessed tax	220,536	180,586
USG | International
Disaggregation of revenues
Revenue from contract with customer excluding assessed tax	121,784	97,781
USG | Commercial
Disaggregation of revenues
Revenue from contract with customer excluding assessed tax	331,836	272,432
USG | Government
Disaggregation of revenues
Revenue from contract with customer excluding assessed tax	10,484	5,935
Test
Disaggregation of revenues
Revenue from contract with customer excluding assessed tax	221,270	227,722	$ 197,700
Test | Point in time
Disaggregation of revenues
Revenue from contract with customer excluding assessed tax	44,042	58,522
Test | Over time
Disaggregation of revenues
Revenue from contract with customer excluding assessed tax	177,228	169,200
Test | United States
Disaggregation of revenues
Revenue from contract with customer excluding assessed tax	118,289	123,428
Test | International
Disaggregation of revenues
Revenue from contract with customer excluding assessed tax	102,981	104,294
Test | Commercial
Disaggregation of revenues
Revenue from contract with customer excluding assessed tax	193,744	209,016
Test | Government
Disaggregation of revenues
Revenue from contract with customer excluding assessed tax	$ 27,526	$ 18,706