v3.26.1
Regulatory Matters - Narrative (Details) - USD ($)
$ in Millions
Apr. 01, 2026
Mar. 10, 2026
Dec. 23, 2025
Oct. 31, 2025
Jun. 04, 2025
South Dakota Rate Case | SDPUC          
Schedule of Regulatory Assets and Liabilities [Line Items]          
Requested rate increase, amount         $ 5.7
Requested rate increase, percent (as a percent)         12.50%
Requested return on base rate, percent (as a percent)         8.29%
Approved rate increase, amount   $ 3.3      
Approved rate increase, percent (as a percent)   7.70%      
Approved return on base rate, percent (as a percent)   7.09%      
South Dakota Rate Case | SDPUC | Subsequent Event          
Schedule of Regulatory Assets and Liabilities [Line Items]          
Amounts to be refunded to customers $ 1.3        
Minnesota Rate Case | MPUC          
Schedule of Regulatory Assets and Liabilities [Line Items]          
Requested rate increase, amount       $ 44.8  
Requested rate increase, percent (as a percent)       17.70%  
Requested return on base rate, percent (as a percent)       7.92%  
Requested return on equity, percent (as a percent)       10.65%  
Requested equity ratio, percent (as a percent)       53.50%  
Requested accelerated recovery of remaining investments       $ 4.3  
Revenue, interim rate increase, amount     $ 28.6 $ 31.8  
Revenue, interim rate increase, percentage (as a percent)     11.30% 12.60%