Revenue - Revenues by Customers (Details) - USD ($) $ in Thousands	3 Months Ended
Mar. 31, 2022	Mar. 31, 2021
Disaggregation of Revenue [Line Items]
Total revenues	$ 32,867	$ 31,698
NASA \| Revenue from Contract with Customer Benchmark \| Customer Concentration Risk
Disaggregation of Revenue [Line Items]
Total revenues	8,439	10,937
Boeing \| Revenue from Contract with Customer Benchmark \| Customer Concentration Risk
Disaggregation of Revenue [Line Items]
Total revenues	5,463	4,031
Air Force Research Laboratory \| Revenue from Contract with Customer Benchmark \| Customer Concentration Risk
Disaggregation of Revenue [Line Items]
Total revenues	0	3,344
Major Customers \| Revenue from Contract with Customer Benchmark \| Customer Concentration Risk
Disaggregation of Revenue [Line Items]
Total revenues	$ 13,902	$ 18,312

Amount, excluding tax collected from customer, of revenue from satisfaction of performance obligation by transferring promised good or service to customer. Tax collected from customer is tax assessed by governmental authority that is both imposed on and concurrent with specific revenue-producing transaction, including, but not limited to, sales, use, value added and excise.

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+ Details