Revenue Recognition - Disaggregation of Revenue (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Mar. 31, 2021	Mar. 31, 2020	Mar. 31, 2021	Mar. 31, 2020
Disaggregation of Revenue [Line Items]
Total revenue	$ 61,506	$ 54,798	$ 119,358	$ 107,036
Prime contractor
Disaggregation of Revenue [Line Items]
Total revenue	53,888	50,920	105,652	99,815
Subcontractor
Disaggregation of Revenue [Line Items]
Total revenue	7,618	3,878	13,706	7,221
Time and materials
Disaggregation of Revenue [Line Items]
Total revenue	46,508	38,162	90,702	74,603
Cost reimbursable
Disaggregation of Revenue [Line Items]
Total revenue	12,005	15,430	23,726	30,046
Firm fixed price
Disaggregation of Revenue [Line Items]
Total revenue	2,993	1,206	4,930	2,387
Department of Veterans Affairs
Disaggregation of Revenue [Line Items]
Total revenue	27,871	25,556	55,513	49,619
Department of Health and Human Services
Disaggregation of Revenue [Line Items]
Total revenue	23,341	25,861	43,503	49,951
Department of Defense
Disaggregation of Revenue [Line Items]
Total revenue	7,522	342	14,502	673
Other
Disaggregation of Revenue [Line Items]
Total revenue	$ 2,772	$ 3,039	$ 5,840	$ 6,793