Related Party Transactions (Schedule of Affiliate Receivables and Payables) (Details) - USD ($) $ in Millions	Dec. 31, 2024	Dec. 31, 2023
Related Party Transaction [Line Items]
Accounts receivable - affiliates	$ 525	$ 494
Ameren Missouri \| Related Party
Related Party Transaction [Line Items]
Accounts receivable - affiliates	40	72
Ameren Missouri \| Income taxes payable to parent \| Related Party
Related Party Transaction [Line Items]
Income taxes payable to parent	0	0
Ameren Missouri \| Income taxes receivable from parent \| Related Party
Related Party Transaction [Line Items]
Accounts receivable - affiliates	28	56
Ameren Illinois \| Related Party
Related Party Transaction [Line Items]
Accounts receivable - affiliates	15	35
Ameren Illinois \| Income taxes payable to parent \| Related Party
Related Party Transaction [Line Items]
Income taxes payable to parent	32	2
Ameren Illinois \| Income taxes receivable from parent \| Related Party
Related Party Transaction [Line Items]
Accounts receivable - affiliates	$ 0	$ 22

Carrying value as of the balance sheet date of liabilities incurred (and for which invoices have typically been received) and payable to vendors for goods and services received that are used in an entity's business. Used to reflect the current portion of the liabilities (due within one year or within the normal operating cycle if longer).

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Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

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