Balance Sheet Components - Summary of Property and Equipment, Net (Detail) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Property, Plant and Equipment [Line Items]
Property and equipment, gross	$ 361	$ 556
Less: accumulated depreciation	(309)	(443)
Total property and equipment, net	52	113
Software [Member]
Property, Plant and Equipment [Line Items]
Property and equipment, gross	$ 361	352
Leasehold Improvements [Member]
Property, Plant and Equipment [Line Items]
Property and equipment, gross		112
Computer Equipment [Member]
Property, Plant and Equipment [Line Items]
Property and equipment, gross		89
Furniture and Fixtures [Member]
Property, Plant and Equipment [Line Items]
Property and equipment, gross		$ 3

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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