REVENUE RECOGNITION - Disaggregation of Revenue (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2022	Sep. 30, 2022	Jun. 30, 2022	Mar. 31, 2022	Dec. 31, 2021	Sep. 30, 2021	Jun. 30, 2021	Mar. 31, 2021	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Disaggregation of Revenue [Line Items]
Total revenue	$ 47,343	$ 63,593	$ 55,791	$ 50,160	$ 64,051	$ 68,981	$ 53,644	$ 55,757	$ 216,887	$ 242,433	$ 179,917
Revenue from Contract with Customer, Product and Service Benchmark | Customer Concentration Risk
Disaggregation of Revenue [Line Items]
Total revenue									216,887	242,433	179,917
Revenue from Contract with Customer, Product and Service Benchmark | Customer Concentration Risk | Firm fixed-price
Disaggregation of Revenue [Line Items]
Total revenue									$ 179,803	$ 212,304	$ 151,703
Concentration risk, percentage									83.00%	88.00%	84.00%
Revenue from Contract with Customer, Product and Service Benchmark | Customer Concentration Risk | Time-and-materials
Disaggregation of Revenue [Line Items]
Total revenue									$ 12,963	$ 12,461	$ 13,455
Concentration risk, percentage									6.00%	5.00%	8.00%
Revenue from Contract with Customer, Product and Service Benchmark | Customer Concentration Risk | Cost plus fixed-fee
Disaggregation of Revenue [Line Items]
Total revenue									$ 24,121	$ 17,668	$ 14,759
Concentration risk, percentage									11.00%	7.00%	8.00%
Federal government | Revenue from Contract with Customer, Product and Service Benchmark
Disaggregation of Revenue [Line Items]
Total revenue										$ 232,876
Federal government | Revenue from Contract with Customer, Product and Service Benchmark | Customer Concentration Risk
Disaggregation of Revenue [Line Items]
Total revenue									$ 205,538		$ 171,677
Concentration risk, percentage									95.00%	96.00%	95.00%
State & local government, and commercial | Revenue from Contract with Customer, Product and Service Benchmark | Customer Concentration Risk
Disaggregation of Revenue [Line Items]
Total revenue									$ 11,349	$ 9,557	$ 8,240
Concentration risk, percentage									5.00%	4.00%	5.00%
U.S. Department of Defense ("DoD") | Revenue from Contract with Customer, Product and Service Benchmark | Customer Concentration Risk
Disaggregation of Revenue [Line Items]
Concentration risk, percentage									74.00%	74.00%	65.00%
Civilian federal agencies | Revenue from Contract with Customer, Product and Service Benchmark | Customer Concentration Risk
Disaggregation of Revenue [Line Items]
Concentration risk, percentage									21.00%	22.00%	30.00%