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 of lessee's right to use underlying asset under finance lease.

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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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Amount after accumulated depreciation, depletion and amortization of physical assets used in the normal conduct of business to produce goods and services 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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Property and Equipment, Net (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018	Dec. 31, 2018
Property and Equipment, Net
Finance lease right-of-use assets	$ 2,557
Property and equipment, gross	6,099		$ 5,951
Accumulated depreciation	(2,073)		(1,671)
Operating lease right-of-use assets	4,026		4,280
Depreciation	402	$ 203
Computer equipment
Property and Equipment, Net
Property and equipment, gross	1,323		1,292
Fleet vehicles
Property and Equipment, Net
Property and equipment, gross			2,131
Manufacturing equipment
Property and Equipment, Net
Property and equipment, gross	607		604
Lab equipment
Property and Equipment, Net
Property and equipment, gross	649		1,068
Furniture and fixtures
Property and Equipment, Net
Property and equipment, gross	628		524
Leasehold improvements
Property and Equipment, Net
Property and equipment, gross	$ 335		$ 332