v3.25.4
Loss per Share - Schedule of Loss Per Share, Basic, and Diluted, For Common Stock (Details) - USD ($)
$ / shares in Units, shares in Thousands, $ in Thousands
 12 Months Ended
Dec. 31, 2025
Dec. 31, 2024
Numerator    
Net loss after income tax $ (1,673,427) $ (164,644)
Net loss attributable to NET Power Inc. $ (578,628) $ (49,191)
Denominator    
Weighted-average number shares outstanding, basic (in shares) 78,822 73,397
Weighted-average number shares outstanding, diluted (in shares) 78,822 73,397
Loss per share attributable to shareholders, basic (in dollars per share) $ (7.34) $ (0.67)
Loss per share attributable to shareholders, diluted (in dollars per share) $ (7.34) $ (0.67)