v3.26.1
Loss per Share - Schedule of Loss Per Share, Basic, and Diluted, For Common Stock (Details) - USD ($)
$ / shares in Units, shares in Thousands, $ in Thousands
 3 Months Ended
Mar. 31, 2026
Mar. 31, 2025
Numerator    
Net loss after income tax $ (25,810) $ (373,586)
Net loss attributable to NET Power Inc. $ (9,857) $ (119,350)
Denominator    
Weighted-average number shares outstanding, basic (in shares) 85,382 76,997
Weighted-average number shares outstanding, diluted (in shares) 85,382 76,997
Loss per share attributable to shareholders, basic (in dollars per share) $ (0.12) $ (1.55)
Loss per share attributable to shareholders, diluted (in dollars per share) $ (0.12) $ (1.55)