Property and Equipment (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Gross	$ 1,029	$ 1,029
Less accumulated depreciation	(798)	(726)
Net property and equipment	231	303
Leasehold Improvements [Member]
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Gross	$ 463	463
Leasehold Improvements [Member] | Minimum [Member]
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Useful Life	2 years
Leasehold Improvements [Member] | Maximum [Member]
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Useful Life	5 years
Computer And Office Equipment [Member]
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Useful Life	3 years
Property, Plant and Equipment, Gross	$ 60	60
Furniture and fixtures
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Useful Life	7 years
Property, Plant and Equipment, Gross	$ 46	46
Scientific equipment
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Useful Life	7 years
Property, Plant and Equipment, Gross	$ 460	$ 460