v3.26.1
Pending Merger with NorthWestern - Additional Information (Details)
Jun. 30, 2026
$ / shares
Dec. 31, 2025
$ / shares
Aug. 18, 2025
$ / shares
Business Combination [Line Items]      
Common stock, par value (usd per share) $ 1 $ 1  
NorthWestern      
Business Combination [Line Items]      
Common stock, par value (usd per share)     $ 0.01
Business acquisition exchange ratio on common stock     0.98
Business acquisition exchange of common stock par value per share     $ 1