Revenue Recognition - Disaggregation of Revenue (Details) - USD ($) $ in Thousands	3 Months Ended
	Dec. 31, 2021	Dec. 31, 2020
Disaggregation of Revenue [Line Items]
Total Revenue	$ 152,801	$ 57,852
Prime Contractor
Disaggregation of Revenue [Line Items]
Total Revenue	146,107	51,764
Subcontractor
Disaggregation of Revenue [Line Items]
Total Revenue	6,694	6,088
Time and Materials
Disaggregation of Revenue [Line Items]
Total Revenue	132,540	44,194
Cost Reimbursable
Disaggregation of Revenue [Line Items]
Total Revenue	10,110	11,721
Firm Fixed Price
Disaggregation of Revenue [Line Items]
Total Revenue	10,151	1,937
Department of Homeland Security
Disaggregation of Revenue [Line Items]
Total Revenue	91,328	172
Department of Veterans Affairs
Disaggregation of Revenue [Line Items]
Total Revenue	28,193	27,642
Department of Health and Human Services
Disaggregation of Revenue [Line Items]
Total Revenue	23,126	20,163
Department of Defense
Disaggregation of Revenue [Line Items]
Total Revenue	8,495	6,980
Other
Disaggregation of Revenue [Line Items]
Total Revenue	$ 1,659	$ 2,895