Component of Property and Equipment, Net (Detail) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Property, Plant and Equipment [Line Items]
Property and equipment, Gross	$ 5,300	$ 4,842
Less: accumulated depreciation	(4,203)	(3,631)
Property and equipment, net	1,097	1,211
Office and computer equipment
Property, Plant and Equipment [Line Items]
Property and equipment, Gross	1,249	1,215
Software
Property, Plant and Equipment [Line Items]
Property and equipment, Gross	1,030	913
Leasehold improvements
Property, Plant and Equipment [Line Items]
Property and equipment, Gross	1,839	1,553
Research and development equipment
Property, Plant and Equipment [Line Items]
Property and equipment, Gross	$ 1,182	$ 1,161

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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