v3.25.2
Supplemental Information (Schedule of Asset Retirement Obligations) (Details) - USD ($)
$ in Millions
6 Months Ended
Jun. 30, 2025
Dec. 31, 2024
Asset Retirement Obligation, Roll Forward Analysis [Roll Forward]    
Asset Retirement Obligation, Beginning Balance $ 827  
Liabilities settled (2)  
Accretion 18  
Asset Retirement Obligation, Ending Balance 843  
Other current liabilities 410 $ 415
Union Electric Company    
Asset Retirement Obligation, Roll Forward Analysis [Roll Forward]    
Asset Retirement Obligation, Beginning Balance 823  
Liabilities settled (2)  
Accretion 18  
Asset Retirement Obligation, Ending Balance 839  
Other current liabilities 204 206
Ameren Illinois Company    
Asset Retirement Obligation, Roll Forward Analysis [Roll Forward]    
Asset Retirement Obligation, Beginning Balance 4  
Liabilities settled 0  
Accretion 0  
Asset Retirement Obligation, Ending Balance 4  
Other current liabilities 152 172
Asset Retirement Obligation Balance    
Asset Retirement Obligation, Roll Forward Analysis [Roll Forward]    
Other current liabilities $ 5 $ 5