Revenue Recognition - Disaggregation of Revenue (Details) - USD ($) $ in Thousands	3 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Disaggregation of Revenue [Line Items]
Total revenue	$ 57,852	$ 52,238
Prime contractor
Disaggregation of Revenue [Line Items]
Total revenue	51,764	48,896
Subcontractor
Disaggregation of Revenue [Line Items]
Total revenue	6,088	3,342
Time and materials
Disaggregation of Revenue [Line Items]
Total revenue	44,194	36,441
Cost reimbursable
Disaggregation of Revenue [Line Items]
Total revenue	11,721	14,617
Firm fixed price
Disaggregation of Revenue [Line Items]
Total revenue	1,937	1,180
Department of Veterans Affairs
Disaggregation of Revenue [Line Items]
Total revenue	27,642	24,063
Department of Health and Human Services
Disaggregation of Revenue [Line Items]
Total revenue	20,163	24,089
Department of Defense
Disaggregation of Revenue [Line Items]
Total revenue	6,980	331
Other
Disaggregation of Revenue [Line Items]
Total revenue	$ 3,067	$ 3,755