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Income Taxes (Schedule Of Net Operating Loss Carryforwards And Tax Credit Carryforwards) (Details) - USD ($)
$ in Millions
Dec. 31, 2024
Dec. 31, 2023
Net operating loss carryforwards:    
Net operating loss carryforwards: $ 93 $ 42
Tax credit carryforwards: 410 176
Federal    
Net operating loss carryforwards:    
Net operating loss carryforwards: 30 0
Tax credit carryforwards: 408 174
State    
Net operating loss carryforwards:    
Net operating loss carryforwards: 63 42
Tax credit carryforwards: 2 2
Ameren Missouri    
Net operating loss carryforwards:    
Net operating loss carryforwards: 0 0
Tax credit carryforwards: 355 124
Ameren Missouri | Federal    
Net operating loss carryforwards:    
Net operating loss carryforwards: 0 0
Tax credit carryforwards: 355 124
Ameren Missouri | State    
Net operating loss carryforwards:    
Net operating loss carryforwards: 0 0
Tax credit carryforwards: 0 0
Ameren Illinois    
Net operating loss carryforwards:    
Net operating loss carryforwards: 34 26
Tax credit carryforwards: 11 7
Ameren Illinois | Federal    
Net operating loss carryforwards:    
Net operating loss carryforwards: 0 0
Tax credit carryforwards: 9 5
Ameren Illinois | State    
Net operating loss carryforwards:    
Net operating loss carryforwards: 34 26
Tax credit carryforwards: 2 2
Other    
Net operating loss carryforwards:    
Net operating loss carryforwards: 59 16
Tax credit carryforwards: 44 45
Other | Federal    
Net operating loss carryforwards:    
Net operating loss carryforwards: 30 0
Tax credit carryforwards: 44 45
Other | State    
Net operating loss carryforwards:    
Net operating loss carryforwards: 29 16
Tax credit carryforwards: $ 0 $ 0