Balance Sheet Components - Property and Equipment, net (Details) - USD ($)	12 Months Ended
Dec. 31, 2018	Dec. 31, 2017
Property and Equipment, net
Property and Equipment, gross	$ 1,762,000	$ 965,000
Less: Accumulated depreciation	(491,000)	(215,000)
Property and equipment, net	1,271,000	750,000
Depreciation expense	276,000	57,000
Lab equipment
Property and Equipment, net
Property and Equipment, gross	1,737,000	940,000
Computer equipment and software
Property and Equipment, net
Property and Equipment, gross	$ 25,000	$ 25,000

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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The amount of expense recognized in the current period that reflects the allocation of the cost of tangible assets over the assets' useful lives. Includes production and non-production related depreciation.

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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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Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

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