Balance Sheet Detail - Narrative (Details) - USD ($)	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020
Valuation adjustment for excess and obsolete inventory	$ 4,900,000	$ 3,900,000
Finance lease	392,000	467,000
Goodwill	1,339,000	1,339,000
Goodwill impairment	0	0
Goodwill additions during the year	0	0
Vehicles
Finance lease	2,600,000	1,800,000
Leased vehicles, accumulated depreciation	1,500,000	1,400,000
Construction in Progress
Construction in progress to be depreciated	$ 800,000	$ 400,000