Supplementary Balance Sheet Information - Property and Equipment (Details) - USD ($) $ in Thousands	Mar. 31, 2021	Dec. 31, 2020
Property Plant And Equipment [Line Items]
Property and equipment, gross	$ 10,369	$ 9,902
Less accumulated depreciation	(6,982)	(6,724)
Total property and equipment, net	3,387	3,178
Lab Equipment
Property Plant And Equipment [Line Items]
Property and equipment, gross	6,292	5,730
Leasehold Improvements
Property Plant And Equipment [Line Items]
Property and equipment, gross	2,012	1,845
Computer Equipment
Property Plant And Equipment [Line Items]
Property and equipment, gross	871	871
Furniture and Fixtures
Property Plant And Equipment [Line Items]
Property and equipment, gross	424	424
Software
Property Plant And Equipment [Line Items]
Property and equipment, gross	655	651
Construction in Process
Property Plant And Equipment [Line Items]
Property and equipment, gross	$ 115	$ 381

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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