Selected Balance Sheet Information - Schedule of property, plant and equipment, net (Details) - USD ($) $ in Thousands	Mar. 31, 2021	Dec. 31, 2020
Property and equipment, net
Property, Plant and Equipment, Gross, Total	$ 1,278	$ 1,263
Less: accumulated depreciation and amortization	(1,122)	(1,089)
Total	156	174
Computers and office equipment [Member]
Property and equipment, net
Property, Plant and Equipment, Gross, Total	828	813
Leasehold Improvements [Member]
Property and equipment, net
Property, Plant and Equipment, Gross, Total	439	439
Software [Member]
Property and equipment, net
Property, Plant and Equipment, Gross, Total	$ 11	$ 11

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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