Financial Statement Components - Property and Equipment (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020	Dec. 31, 2020
Property, Plant and Equipment [Line Items]
Total property and equipment	$ 20,720		$ 20,720
Accumulated depreciation and amortization	(9,592)		(9,592)
Total property and equipment, net	11,128		11,128		$ 7,689
Total property and equipment					13,540
Accumulated depreciation and amortization					(5,851)
Total property and equipment, net					7,689
Depreciation and amortization	700	$ 700	2,100	$ 1,900
Machinery and equipment
Property, Plant and Equipment [Line Items]
Total property and equipment	10,265		10,265
Total property and equipment					5,940
Computer hardware and software
Property, Plant and Equipment [Line Items]
Total property and equipment	3,263		3,263
Total property and equipment					2,450
Demonstration fleet and demonstration units
Property, Plant and Equipment [Line Items]
Total property and equipment	1,709		1,709
Total property and equipment					1,821
Leasehold improvements
Property, Plant and Equipment [Line Items]
Total property and equipment	990		990
Total property and equipment					791
Vehicles
Property, Plant and Equipment [Line Items]
Total property and equipment	795		795
Total property and equipment					835
Furniture and fixtures
Property, Plant and Equipment [Line Items]
Total property and equipment	571		571
Total property and equipment					293
Construction in progress
Property, Plant and Equipment [Line Items]
Total property and equipment	$ 3,127		$ 3,127
Total property and equipment					$ 1,410