XML 194 R176.htm IDEA: XBRL DOCUMENT v3.25.0.1
Regulatory Environment - MERC 2023 Rate Order (Details) - USD ($)
$ in Millions
1 Months Ended 3 Months Ended
Nov. 30, 2023
Dec. 31, 2022
Jun. 30, 2024
Dec. 31, 2024
Dec. 31, 2023
Public Utilities, General Disclosures          
Regulatory liability       $ 4,003.3 $ 3,745.2
Minnesota Public Utilities Commission (MPUC) | MERC          
Public Utilities, General Disclosures          
Interim rate increase   $ 37.0      
Approved rate increase $ 28.8        
Approved rate increase (as a percent) 7.10%        
Approved return on equity (as a percent) 9.65%        
Approved common equity component average (as a percent) 53.00%        
Minnesota Public Utilities Commission (MPUC) | MERC | Interim rate refunds          
Public Utilities, General Disclosures          
Amortization of regulatory liabilities     $ 8.9