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v3.25.4

Supplemental Information (Narrative) (Details) - USD ($) $ in Millions | Dec. 31, 2025 | Dec. 31, 2024
--- | --- | ---
Supplemental Information [Line Items] |  |
Deferred Compensation Liability, Classified, Noncurrent | $ 79 | $ 79
Ameren Illinois |  |
Supplemental Information [Line Items] |  |
Payables for purchased receivables | $ 47 | $ 43

X
- Definition Amount of liabilities for purchased receivables + References No definition available. + Details
Name: | aee_PayablesForPurchasedReceivables
Namespace Prefix: | aee_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

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- Definition Supplemental Information [Line Items] + References No definition available. + Details
Name: | aee_SupplementalInformationLineItems
Namespace Prefix: | aee_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition Aggregate carrying value as of the balance sheet date of the liabilities for all deferred compensation arrangements payable beyond one year (or the operating cycle, if longer). + References No definition available. + Details
Name: | us-gaap_DeferredCompensationLiabilityClassifiedNoncurrent
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Details
Name: | dei_LegalEntityAxis=aee_AmerenIllinoisCompanyMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |