Property and Equipment, Net - Components of Property and Equipment (Detail) - USD ($) $ in Thousands	Mar. 31, 2019	Dec. 31, 2018
Property, Plant and Equipment [Line Items]
Property and equipment gross	$ 16,601	$ 16,402
Less: Accumulated depreciation	(6,272)	(5,692)
Total property and equipment, net	10,329	10,710
Computer and Office Equipment [Member]
Property, Plant and Equipment [Line Items]
Property and equipment gross	1,133	1,133
Manufacturing Equipment [Member]
Property, Plant and Equipment [Line Items]
Property and equipment gross	12,147	12,000
Furniture and Fixtures [Member]
Property, Plant and Equipment [Line Items]
Property and equipment gross	609	604
Leasehold Improvements [Member]
Property, Plant and Equipment [Line Items]
Property and equipment gross	815	815
Construction in Progress [Member]
Property, Plant and Equipment [Line Items]
Property and equipment gross	1,450	1,416
Software [Member]
Property, Plant and Equipment [Line Items]
Property and equipment gross	$ 447	$ 434

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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