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Regulatory Matters - Narrative (Details) - Minnesota Rate Case - MPUC - USD ($)
$ in Millions
 3 Months Ended
Feb. 01, 2022
Dec. 03, 2020
Sep. 30, 2022
Jun. 30, 2022
Schedule of Regulatory Assets and Liabilities [Line Items]        
Revenue, approved rate increase, amount   $ 6.9 $ 15.3 $ 4.1
Revenue, approved rate increase, percent   3.20%    
Revenue requirement amount $ 209.0      
Approved return on base rate, percent 7.18%      
Approved return on equity, percent 9.48%      
Approved equity ratio, percent 52.50%      
Recovery period 5 years      
Approved cap of annual base revenues, percent 4.00%