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Commitments And Contingencies (Environmental Matters) (Details) $ in Millions | 12 Months Ended
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Dec. 31, 2024 USD ($) energyCenter scrubber site | Dec. 31, 2023 USD ($) | Dec. 31, 2022 USD ($)
Estimated capital costs to comply with existing and known federal CO2 emissions regulations | $ 580 |  |
Estimated capital costs to comply with existing and known federal MATS regulations | 320 |  |
Other current liabilities | 475 | $ 501 |
Other deferred credits and liabilities | 487 | 426 |
Other operations and maintenance | 1,969 | 1,866 | $ 1,937
Asset Retirement Obligation | $ 827 | 791 | 786
Environmental Loss Contingency Statement Of Financial Position Extensible Enumeration Not Disclosed Flag | false |  |
Rush Island Energy Center Additional Mitigation Relief Ordered |  |  |
Other current liabilities | $ 40 |  |
Other deferred credits and liabilities | 24 |  |
Other operations and maintenance | $ 59 |  |
Ameren Missouri |  |  |
Number of Energy Center Scrubbers | scrubber | 2 |  |
Number of days of the EPA's requested appellate court suspension | 60 days |  |
Estimated capital costs to comply with existing and known federal CO2 emissions regulations | $ 580 |  |
Estimated capital costs to comply with existing and known federal MATS regulations | 320 |  |
Cost of additional mitigation ordered for the Rush Island Energy Center | 64 |  |
Other current liabilities | 235 | 181 |
Other deferred credits and liabilities | 150 | 56 |
Other operations and maintenance | 1,050 | 1,003 | 1,028
Asset Retirement Obligation | $ 823 | 787 | 782
Number of Ameren Missouri Natural Gas Energy Centers Subject To IETL | energyCenter | 4 |  |
Ameren Missouri | Rush Island Energy Center Additional Mitigation Relief Ordered |  |  |
Other current liabilities | $ 40 |  |
Other deferred credits and liabilities | 24 |  |
Other operations and maintenance | 59 |  |
Ameren Illinois |  |  |
Other current liabilities | 231 | 298 |
Other deferred credits and liabilities | 273 | 308 |
Other operations and maintenance | 906 | 818 | 882
Asset Retirement Obligation | $ 4 | $ 4 | $ 4
Number of remediation sites | site | 3 |  |
Manufactured Gas Plant |  |  |
Accrual for environmental loss contingencies | $ 44 |  |
Manufactured Gas Plant | Ameren Illinois |  |  |
Number of remediation sites | site | 44 |  |
Accrual for environmental loss contingencies | $ 44 |  |
Minimum |  |  |
Estimated capital costs to comply with existing and known federal and state air emissions regulations | 900 |  |
Minimum | Ameren Missouri |  |  |
Estimated capital costs to comply with existing and known federal and state air emissions regulations | 900 |  |
Minimum | Manufactured Gas Plant | Ameren Illinois |  |  |
Estimate of possible loss | 44 |  |
Maximum |  |  |
Estimated capital costs to comply with existing and known federal and state air emissions regulations | 1,000 |  |
Maximum | Ameren Missouri |  |  |
Estimated capital costs to comply with existing and known federal and state air emissions regulations | 1,000 |  |
Maximum | Manufactured Gas Plant | Ameren Illinois |  |  |
Estimate of possible loss | 91 |  |
New CCR Rules Estimate |  |  |
Asset Retirement Obligation | 46 |  |
New CCR Rules Estimate | Ameren Missouri |  |  |
Asset Retirement Obligation | $ 46 |  |

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