Revenue Recognition - Disaggregation of Revenue (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Jun. 30, 2023	Jun. 30, 2022	Jun. 30, 2023	Jun. 30, 2022
Disaggregation of Revenue [Line Items]
Total	$ 102,241	$ 66,440	$ 274,385	$ 327,940
Prime Contractor
Disaggregation of Revenue [Line Items]
Total	97,885	58,743	259,692	304,862
Subcontractor
Disaggregation of Revenue [Line Items]
Total	4,356	7,697	14,693	23,078
Time and Materials
Disaggregation of Revenue [Line Items]
Total	51,572	44,672	154,366	263,072
Cost Reimbursable
Disaggregation of Revenue [Line Items]
Total	29,110	11,979	58,951	34,364
Firm Fixed Price
Disaggregation of Revenue [Line Items]
Total	21,559	9,789	61,068	30,504
Department of Veterans Affairs
Disaggregation of Revenue [Line Items]
Total	35,898	33,344	104,489	92,270
Department of Health and Human Services
Disaggregation of Revenue [Line Items]
Total	44,536	27,741	115,528	78,452
Department of Defense
Disaggregation of Revenue [Line Items]
Total	21,003	8,272	50,802	25,227
Department of Homeland Security
Disaggregation of Revenue [Line Items]
Total	256	(4,908)	639	126,397
Other
Disaggregation of Revenue [Line Items]
Total	$ 548	$ 1,991	$ 2,927	$ 5,594