REVENUE RECOGNITION - Revenue by Customer Type and Revenue Concentration Greater than 10% of Total Revenue (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2023	Jun. 30, 2022	Jun. 30, 2023	Jun. 30, 2022
Disaggregation of Revenue [Line Items]
Total revenue	$ 32,911	$ 55,791	$ 68,133	$ 105,951
Revenue from Contract with Customer, Product and Service Benchmark | Customer Concentration Risk
Disaggregation of Revenue [Line Items]
Total revenue	$ 32,911	$ 55,791	$ 68,133	$ 105,951
Concentration risk, percentage	100.00%	100.00%	100.00%	100.00%
Revenue from Contract with Customer, Product and Service Benchmark | Customer Concentration Risk | Firm fixed-price
Disaggregation of Revenue [Line Items]
Total revenue	$ 25,293	$ 45,305	$ 52,306	$ 86,581
Concentration risk, percentage	77.00%	81.00%	77.00%	82.00%
Revenue from Contract with Customer, Product and Service Benchmark | Customer Concentration Risk | Time-and-materials
Disaggregation of Revenue [Line Items]
Total revenue	$ 3,548	$ 2,731	$ 7,104	$ 5,646
Concentration risk, percentage	11.00%	5.00%	10.00%	5.00%
Revenue from Contract with Customer, Product and Service Benchmark | Customer Concentration Risk | Cost plus fixed fee
Disaggregation of Revenue [Line Items]
Total revenue	$ 4,070	$ 7,755	$ 8,723	$ 13,724
Concentration risk, percentage	12.00%	14.00%	13.00%	13.00%
Federal | Revenue from Contract with Customer, Product and Service Benchmark | Customer Concentration Risk
Disaggregation of Revenue [Line Items]
Total revenue	$ 27,512	$ 52,213	$ 60,501	$ 100,056
Concentration risk, percentage	84.00%	94.00%	89.00%	94.00%
State & local, and commercial | Revenue from Contract with Customer, Product and Service Benchmark | Customer Concentration Risk
Disaggregation of Revenue [Line Items]
Total revenue	$ 5,399	$ 3,578	$ 7,632	$ 5,895
Concentration risk, percentage	16.00%	6.00%	11.00%	6.00%
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	66.00%	72.00%	67.00%	71.00%