v3.25.2
Related Party Transactions (Schedule of Affiliate Receivables and Payables) (Details) - USD ($)
$ in Millions
Jun. 30, 2025
Dec. 31, 2024
Related Party Transaction [Line Items]    
Accounts Payable, Related Parties, Current $ 882 $ 1,059
Accounts Receivable, Related Parties, Current 567 525
Union Electric Company | Related Party    
Related Party Transaction [Line Items]    
Accounts Payable, Related Parties, Current 44 50
Accounts Receivable, Related Parties, Current 39 40
Union Electric Company | Income taxes payable to parent | Related Party    
Related Party Transaction [Line Items]    
Accounts Payable, Related Parties, Current 1 0
Union Electric Company | Income taxes receivable from parent | Related Party    
Related Party Transaction [Line Items]    
Accounts Receivable, Related Parties, Current 25 28
Ameren Illinois Company | Related Party    
Related Party Transaction [Line Items]    
Accounts Payable, Related Parties, Current 62 74
Accounts Receivable, Related Parties, Current 14 15
Ameren Illinois Company | Income taxes payable to parent | Related Party    
Related Party Transaction [Line Items]    
Accounts Payable, Related Parties, Current 24 32
Ameren Illinois Company | Income taxes receivable from parent | Related Party    
Related Party Transaction [Line Items]    
Accounts Receivable, Related Parties, Current $ 0 $ 0