Note 2 - Summary of Significant Accounting Policies (Details Textual) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2022	Jun. 30, 2022	Dec. 31, 2021
Investment Plan, Maximum Amount. Approved		$ 10,000
Inventory, Net, Total	$ 391		$ 348
Equipment Contstructed for Resale [Member]
Inventory, Net, Total	208		227
Spare Parts [Member]
Inventory, Net, Total	$ 183		$ 121
Minimum [Member]
Debt Securities, Held-to-maturity, Maturity Term (Month)	3 months
Maximum [Member]
Debt Securities, Held-to-maturity, Maturity Term (Month)	36 months
Asset Pledged as Collateral [Member] | Letter of Credit [Member]
Restricted Cash and Investments, Total	$ 1,090