Property and Equipment - Net Property and Equipment at Cost (Details) - USD ($) $ in Thousands	Mar. 31, 2022	Dec. 31, 2021
Property, Plant and Equipment
Total property and equipment, at cost	$ 819	$ 819
Less: Accumulated depreciation and amortization	801	797
Property and equipment, net	18	22
Leasehold improvements
Property, Plant and Equipment
Total property and equipment, at cost	107	107
Equipment and other
Property, Plant and Equipment
Total property and equipment, at cost	$ 712	$ 712