Property and Equipment - Components of Property and Equipment (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Property, Plant and Equipment [Line Items]
Property and equipment	$ 3,817	$ 3,398
Less: accumulated depreciation and amortization	(3,090)	(2,835)
Property and equipment, net	727	563
Lab equipment
Property, Plant and Equipment [Line Items]
Property and equipment	2,489	2,229
Leasehold improvements
Property, Plant and Equipment [Line Items]
Property and equipment	741	737
Computer hardware and software
Property, Plant and Equipment [Line Items]
Property and equipment	428	355
Furniture and fixtures
Property, Plant and Equipment [Line Items]
Property and equipment	$ 159	$ 77

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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