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Regulatory Matters - Narrative (Details) - USD ($)
$ in Millions
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%
Requested return on equity, percent (as a percent)   10.80%
Requested equity ratio, percent (as a percent)   53.54%
Requested rate increase rates on interim, term   180 days
Minnesota Rate Case | MPUC | Subsequent Event    
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  
Requested interim rate , increase amount $ 31.8  
Requested interim rate increase percentage (as a percent) 12.60%