v3.26.1
Short-Term Debt And Liquidity (Narrative) (Details)
$ in Millions
3 Months Ended 6 Months Ended
Jun. 30, 2026
USD ($)
Jun. 30, 2025
Jun. 30, 2026
USD ($)
Jun. 30, 2025
Dec. 31, 2025
USD ($)
Short-term Debt [Line Items]          
Short-term debt $ 1,220   $ 1,220   $ 643
Credit Agreements          
Short-term Debt [Line Items]          
Net Liquidity Available $ 1,900   $ 1,900    
Actual debt-to-capital ratio 0.61   0.61    
Letter of Credit          
Short-term Debt [Line Items]          
Line of Credit Facility, Maximum Borrowing Capacity $ 100   $ 100    
Utilities          
Short-term Debt [Line Items]          
Short-term Debt, Weighted Average Interest Rate, over Time 3.92% 4.64% 3.88% 4.58%  
Union Electric Company          
Short-term Debt [Line Items]          
Short-term debt $ 0   $ 0   471
Union Electric Company | Missouri Credit Agreement          
Short-term Debt [Line Items]          
Actual debt-to-capital ratio 0.50   0.50    
Union Electric Company | Letter of Credit          
Short-term Debt [Line Items]          
Line of Credit Facility, Maximum Borrowing Capacity $ 75   $ 75    
Short-term debt 68   68    
Ameren Illinois Company          
Short-term Debt [Line Items]          
Short-term debt $ 312   $ 312   $ 17
Ameren Illinois Company | Illinois Credit Agreement          
Short-term Debt [Line Items]          
Actual debt-to-capital ratio 0.46   0.46