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 6 Months Ended
Jun. 30, 2026
Jun. 30, 2025
Jun. 30, 2026
Jun. 30, 2025
Numerator        
Net loss after income tax $ (206,932) $ (82,047) $ (232,741) $ (455,633)
Net loss attributable to NET Power Inc. $ (80,291) $ (28,142) $ (90,148) $ (147,492)
Denominator        
Weighted-average number of shares outstanding, basic (in shares) 88,405 77,699 86,895 77,350
Weighted-average number of shares outstanding, diluted (in shares) 88,405 77,699 86,895 77,350
Loss per share attributable to shareholders, basic (in dollars per share) $ (0.91) $ (0.36) $ (1.04) $ (1.91)
Loss per share attributable to shareholders, diluted (in dollars per share) $ (0.91) $ (0.36) $ (1.04) $ (1.91)