Note 2 - Summary of Significant Accounting Policies (Details Textual) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2025	Dec. 31, 2024	Dec. 31, 2022
Investment Plan, Maximum Amount. Approved			$ 20,000
Inventory, Net	$ 402	$ 397
Equipment Constructed for Resale [Member]
Inventory, Net	176	176
Spare Parts [Member]
Inventory, Net	226	221
In Process Equipment [Member]
Inventory, Net	$ 32	$ 44
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	$ 4,711
Asset Pledged as Collateral [Member] | Letter of Credit [Member] | Varying Maturity Dates Expiring No Later Than September 30, 2026 [Member]
Restricted Cash and Investments	2,879
Asset Pledged as Collateral [Member] | Letter of Credit [Member] | Latest Maturity Dates Expiring No Later Than October 8, 2028 [Member]
Restricted Cash and Investments	$ 1,832