Financial Statement Components - Property and Equipment (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020	Dec. 31, 2020
Property, Plant and Equipment [Line Items]
Total property and equipment	$ 16,326		$ 16,326
Accumulated depreciation and amortization	(7,068)		(7,068)
Total property and equipment, net	9,258		9,258
Total property and equipment					$ 13,540
Accumulated depreciation and amortization					(5,851)
Total property and equipment, net					7,689
Depreciation and amortization	675	$ 613	1,332	$ 1,241
Computer hardware and software
Property, Plant and Equipment [Line Items]
Total property and equipment	2,978		2,978
Total property and equipment					2,450
Demonstration fleet and demonstration units
Property, Plant and Equipment [Line Items]
Total property and equipment	1,973		1,973
Total property and equipment					1,821
Machinery and equipment
Property, Plant and Equipment [Line Items]
Total property and equipment	6,803		6,803
Total property and equipment					5,940
Furniture and fixtures
Property, Plant and Equipment [Line Items]
Total property and equipment	293		293
Total property and equipment					293
Vehicles
Property, Plant and Equipment [Line Items]
Total property and equipment	856		856
Total property and equipment					835
Leasehold improvements
Property, Plant and Equipment [Line Items]
Total property and equipment	960		960
Total property and equipment					791
Construction in progress
Property, Plant and Equipment [Line Items]
Total property and equipment	$ 2,463		$ 2,463
Total property and equipment					$ 1,410