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Property and Plant, Net (Schedule of Capitalized Software) (Details) - USD ($) $ in Millions | 12 Months Ended
--- | ---
Dec. 31, 2022 | Dec. 31, 2021 | Dec. 31, 2020
Capitalized software costs |  |  |
Finite-Lived Intangible Assets [Line Items] |  |  |
Amortization Expense | $ 159 | $ 125 | $ 93
Gross Carrying Value | 1,443 | 1,199 |
Accumulated Amortization | (914) | (757) |
Union Electric Company | Capitalized software costs |  |  |
Finite-Lived Intangible Assets [Line Items] |  |  |
Amortization Expense | 85 | 66 | 44
Gross Carrying Value | 613 | 523 |
Accumulated Amortization | (339) | (255) |
Ameren Illinois Company | Capitalized software costs |  |  |
Finite-Lived Intangible Assets [Line Items] |  |  |
Amortization Expense | 69 | 53 | $ 45
Gross Carrying Value | 601 | 452 |
Accumulated Amortization | $ (360) | $ (291) |
Minimum |  |  |
Finite-Lived Intangible Assets [Line Items] |  |  |
Finite-Lived Intangible Asset, Useful Life | 2 years |  |
Maximum |  |  |
Finite-Lived Intangible Assets [Line Items] |  |  |
Finite-Lived Intangible Asset, Useful Life | 15 years |  |

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