v3.26.1
Summary of Significant Accounting Principles (Details-1) - USD ($)
$ in Thousands
 3 Months Ended
Mar. 31, 2026
Mar. 31, 2025
Dec. 31, 2025
Dec. 31, 2024
Supplemental Cash Flow Information [Abstract]        
Income tax receipts, net - US Federal [1] $ (364) $ (19)    
Accrued capital expenditures 12,961 9,802    
Short-Term Debt [Abstract]        
Short-Term Debt 40,250   $ 94,527  
Cash, Cash Equivalents, And Restricted Cash [Abstract]        
Cash and cash equivalents 9,468   5,666  
Restricted cash 665   952  
Receivable - margin account 2,352   2,118  
Cash, cash equivalents, and restricted cash 12,485 36,659 8,736 $ 24,496
Indemnification Agreement [Member] | Renewable Tax Credits Transferred [Member]        
Effects of The Inflation Reduction Act [Abstract]        
Guarantor Obligations, Liquidation Proceeds, Monetary Amount 400      
MGE [Member]        
Supplemental Cash Flow Information [Abstract]        
Income tax receipts, net - US Federal [1] (364) (19)    
Accrued capital expenditures [2] 12,961 9,802    
Short-Term Debt [Abstract]        
Short-Term Debt 40,250   94,527  
Cash, Cash Equivalents, And Restricted Cash [Abstract]        
Cash and cash equivalents 5,418   2,248  
Restricted cash 665   952  
Receivable - margin account 2,352   2,118  
Cash, cash equivalents, and restricted cash $ 8,435 $ 26,506 $ 5,318 $ 20,059
[1] For the three months ended March 31, 2026, federal tax receipts include $0.4 million of proceeds from the transfer of federal tax credits under Internal Revenue Code Section 6418.
[2] MGE Energy files a consolidated federal income tax return with its subsidiaries. While taxes are filed on a consolidated basis, MGE calculates its respective share of tax liability and makes intercompany tax payments to or from its parent company.