Property and Equipment

12 Months Ended

Dec. 31, 2020

Property Plant And Equipment [Abstract]

Property and Equipment

6. PROPERTY AND EQUIPMENT, NET

Property and equipment are stated at cost or estimated fair value for assets acquired through business combinations. Depreciation and amortization are provided using the straight-line method over the estimated useful lives of the assets. Leasehold improvements are amortized using the straight-line method over the shorter of the remaining lease term, including options that are deemed to be reasonably assured, or the estimated useful life of the improvement.

Property and equipment, net, as of December 31, consisted of the following:

	Estimated Useful Life	2020			2019
Lab and test equipment	7 years	$	18,631		$	14,810
Vehicles	5 years		13,320			11,073
Equipment	3-7 years		32,177			29,922
Furniture and fixtures	7 years		2,938			1,119
Leasehold improvements	7 years		6,767			5,954
Aircraft	10 years		834			—
Building	39 years		2,975			—
			77,642			62,878
Land			725			—
Construction in progress			219			796
Less accumulated depreciation and amortization			(44,187	)		(36,638	)
Total property and equipment—net		$	34,399		$	27,036

Total depreciation expense included on the consolidated statements of operations was $8.4 million, $7.7 million and $7.6 million for the years ended December 31, 2020, 2019, and 2018, respectively.