Summary Of Significant Accounting Policies - Schedule of Other Assets and Other Liabilities (Details) - USD ($) $ in Millions	Jun. 30, 2026	Dec. 31, 2025
Accounting Policies [Line Items]
Unbilled revenue	$ 478	$ 415
Other current assets	218	210
Regulatory Asset	2,888	2,524
Current maturities of long-term debt	1,524	973
Interest accrued	246	229
Long-term debt, net	19,064	18,214
Variable Interest Entity, Primary Beneficiary
Accounting Policies [Line Items]
Regulatory Asset	432	443
Current maturities of long-term debt	24	23
Long-term debt, net	414	426
Ameren Missouri Securitization Funding I, LLC \| Variable Interest Entity, Primary Beneficiary
Accounting Policies [Line Items]
Unbilled revenue	2	2
Other current assets	15	21
Regulatory Asset	432	443
Current maturities of long-term debt	24	23
Interest accrued	6	6
Current regulatory liabilities	5	11
Long-term debt, net	$ 414	$ 426

[Line Items] for Accounting Policies [Table]

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Carrying value as of the balance sheet date of [accrued] interest payable on all forms of debt, including trade payables, that has been incurred and is unpaid. 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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Amount, after deduction of unamortized premium (discount) and debt issuance cost, of long-term debt classified as noncurrent. Excludes lease obligation.

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Carrying amount as of the balance sheet date of capitalized costs of regulated entities that are not expected to be recovered through revenue sources within one year or the normal operating cycle if longer.

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The amount for the individual regulatory current liability as itemized in a table of regulatory current liabilities as of the end of the period.

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