v3.26.1
Note 3 - Revenue - Revenues Disaggregated by Product Technology (Details) - USD ($)
$ in Thousands
3 Months Ended
Mar. 31, 2026
Mar. 31, 2025
Revenues $ 6,080 $ 6,382
Air Pollution Control [Member]    
Revenues 1,604 1,303
Air Pollution Control [Member] | Technology Solutions [Member]    
Revenues 755 571
Air Pollution Control [Member] | Spare Parts [Member]    
Revenues 394 251
Air Pollution Control [Member] | Ancillary Revenue [Member]    
Revenues 455 481
FUEL CHEM [Member]    
Revenues 4,476 5,079
FUEL CHEM [Member] | Technology Solutions [Member]    
Revenues $ 4,476 $ 5,079