Balance Sheet Components - Property and Equipment (Details) - USD ($) $ in Thousands	Jun. 30, 2024	Dec. 31, 2023
Property Plant And Equipment [Line Items]
Property and equipment, gross	$ 7,250	$ 7,228
Less: accumulated depreciation and amortization	(7,144)	(7,091)
Property and equipment, net	106	136
Leasehold Improvements
Property Plant And Equipment [Line Items]
Property and equipment, gross	3,277	3,277
Research Equipment
Property Plant And Equipment [Line Items]
Property and equipment, gross	3,373	3,351
Furniture and Fixtures
Property Plant And Equipment [Line Items]
Property and equipment, gross	350	350
Computer Equipment
Property Plant And Equipment [Line Items]
Property and equipment, gross	$ 250	$ 250

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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