Property and Equipment, net - Major Classes of Property and Equipment (Details) - USD ($) $ in Thousands	Dec. 31, 2021	Dec. 31, 2020
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	$ 4,595	$ 5,331
Less accumulated depreciation and amortization	(4,314)	(4,859)
Property and equipment, net	281	472
Laboratory equipment
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	4,215	4,967
Computer equipment and software
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	265	281
Furniture and fixtures
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	0	0
Leasehold improvements
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	$ 115	$ 83

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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