v3.26.1
Related Party Transactions (Details) - USD ($)
$ in Thousands
3 Months Ended
Mar. 31, 2026
Mar. 31, 2025
Related Party Transaction [Line Items]    
Sales of goods and services $ 841,203 $ 778,612
Good and services provided 131,746 123,734
Related Party    
Related Party Transaction [Line Items]    
Good and services provided 20,187 16,802
Dakota Gas and Dakota Coal | Related Party    
Related Party Transaction [Line Items]    
Sales of goods and services 28,595 24,349
Good and services provided 64,074 50,901
Dakota Gas | Related Party | Power supply    
Related Party Transaction [Line Items]    
Sales of goods and services 19,343 15,892
Dakota Gas | Related Party | Administrative services    
Related Party Transaction [Line Items]    
Sales of goods and services 7,879 6,917
Dakota Gas | Related Party | Water supply    
Related Party Transaction [Line Items]    
Sales of goods and services 700 643
Dakota Gas | Related Party | Project and other services    
Related Party Transaction [Line Items]    
Sales of goods and services 136 267
Dakota Gas | Related Party | Screened coal    
Related Party Transaction [Line Items]    
Good and services provided 17,251 18,426
Dakota Gas | Related Party | Natural gas    
Related Party Transaction [Line Items]    
Good and services provided 9,674 2,638
Dakota Gas | Related Party | Transmission and other misc. services    
Related Party Transaction [Line Items]    
Good and services provided 264 257
Dakota Gas | Related Party | Fertilizers, urea and DEF    
Related Party Transaction [Line Items]    
Good and services provided 1,331 984
Dakota Coal | Related Party | Administrative services    
Related Party Transaction [Line Items]    
Sales of goods and services 537 630
Dakota Coal | Related Party | Coal supply    
Related Party Transaction [Line Items]    
Good and services provided 31,042 23,941
Dakota Coal | Related Party | Lime    
Related Party Transaction [Line Items]    
Good and services provided 4,074 4,214
Dakota Coal | Related Party | Limestone    
Related Party Transaction [Line Items]    
Good and services provided 429 441
Dakota Coal | Related Party | Other    
Related Party Transaction [Line Items]    
Good and services provided $ 9 $ 0