Property and Equipment - Property and Equipment, Net (Detail) - USD ($) $ in Thousands	9 Months Ended	12 Months Ended
Sep. 30, 2020	Dec. 31, 2019	Dec. 31, 2018
Property, Plant and Equipment [Line Items]
Property and equipment, gross	$ 75,584	$ 62,878	$ 50,006
Less accumulated depreciation	(41,906)	(36,638)	(29,214)
Total property and equipment-net	$ 34,559	$ 27,036	20,792
Lab and Test Equipment
Property, Plant and Equipment [Line Items]
Estimated Useful Life	7 years	7 years
Property and equipment, gross	$ 17,755	$ 14,810	10,275
Vehicles
Property, Plant and Equipment [Line Items]
Estimated Useful Life	5 years	5 years
Property and equipment, gross	$ 12,869	$ 11,073	8,122
Equipment
Property, Plant and Equipment [Line Items]
Property and equipment, gross	$ 31,539	$ 29,922	25,468
Equipment \| Minimum
Property, Plant and Equipment [Line Items]
Estimated Useful Life	3 years	3 years
Equipment \| Maximum
Property, Plant and Equipment [Line Items]
Estimated Useful Life	7 years	7 years
Furniture and Fixtures
Property, Plant and Equipment [Line Items]
Estimated Useful Life	7 years	7 years
Property and equipment, gross	$ 2,854	$ 1,119	1,004
Leasehold Improvements
Property, Plant and Equipment [Line Items]
Estimated Useful Life	7 years	7 years
Property and equipment, gross	$ 6,758	$ 5,954	$ 5,137
Aircraft
Property, Plant and Equipment [Line Items]
Estimated Useful Life	10 years
Property and equipment, gross	$ 834
Rent
Property, Plant and Equipment [Line Items]
Estimated Useful Life	39 years
Property and equipment, gross	$ 2,975
Land
Property, Plant and Equipment [Line Items]
Property and equipment, gross	725
Construction in Progress
Property, Plant and Equipment [Line Items]
Property and equipment, gross	$ 156	$ 796

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.

+ References

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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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Useful life of long lived, physical assets used in the normal conduct of business and not intended for resale, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days. Examples include, but not limited to, land, buildings, machinery and equipment, office equipment, furniture and fixtures, and computer equipment.

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