Property, Plant and Equipment (Details) - USD ($) $ in Thousands	Mar. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Property, Plant and Equipment, Net, by Type [Abstract]
Gross property, plant and equipment	$ 25,270	$ 24,074	$ 21,896
Less: Accumulated deprecation	(21,209)	(20,632)	(18,614)
Net property, plant and equipment	5,569	4,960	5,025
Furniture and fixtures
Property, Plant and Equipment, Net, by Type [Abstract]
Gross property, plant and equipment	173	173	173
Office and computer equipment
Property, Plant and Equipment, Net, by Type [Abstract]
Gross property, plant and equipment	5,638	5,638	5,436
Software
Property, Plant and Equipment, Net, by Type [Abstract]
Gross property, plant and equipment	16,423	15,227	13,251
Test Equipment
Property, Plant and Equipment, Net, by Type [Abstract]
Gross property, plant and equipment	347	347	347
Leasehold improvements
Property, Plant and Equipment, Net, by Type [Abstract]
Gross property, plant and equipment	2,689	2,689	2,689
Assets under development
Property, Plant and Equipment, Net, by Type [Abstract]
Net property, plant and equipment	$ 1,508	$ 1,518	$ 1,743

Amount of accumulated depreciation, depletion and amortization for physical assets used in the normal conduct of business to produce goods and services.

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Amount before accumulated depreciation, depletion and amortization of physical assets used in the normal conduct of business and not intended for resale. Examples include, but are not limited to, land, buildings, machinery and equipment, office equipment, and furniture and fixtures.

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