Balance Sheet Components - Summary of Property and Equipment, Net (Detail) - USD ($) $ in Thousands	Jun. 30, 2021	Dec. 31, 2020
Property, Plant and Equipment [Line Items]
Property and equipment, gross	$ 401	$ 361
Less: accumulated depreciation	(330)	(309)
Total property and equipment, net	71	52
Software [Member]
Property, Plant and Equipment [Line Items]
Property and equipment, gross	361	$ 361
Leasehold Improvements [Member]
Property, Plant and Equipment [Line Items]
Property and equipment, gross	35
Computer Equipment [Member]
Property, Plant and Equipment [Line Items]
Property and equipment, gross	$ 5

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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Amount after accumulated depreciation, depletion and amortization of physical assets used in the normal conduct of business to produce goods and services 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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