Selected Balance Sheet Information - Schedule of property and equipment, net (Details) - USD ($) $ in Thousands	Sep. 30, 2021	Dec. 31, 2020
Property and equipment, net
Property, Plant and Equipment, Gross, Total	$ 932	$ 1,263
Less: accumulated depreciation and amortization	(817)	(1,089)
Total	115	174
Computers and office equipment [Member]
Property and equipment, net
Property, Plant and Equipment, Gross, Total	827	813
Leasehold improvements [Member]
Property and equipment, net
Property, Plant and Equipment, Gross, Total	94	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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