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Property and Plant, Net (Schedule of Capitalized Software and Deferred Cloud Implementation Costs) (Details) - USD ($) $ in Millions | 12 Months Ended
--- | ---
Dec. 31, 2023 | Dec. 31, 2022 | Dec. 31, 2021
Capitalized software costs |  |  |
Finite-Lived Intangible Assets [Line Items] |  |  |
Capitalized Computer Software, Amortization | $ 212 | $ 159 | $ 125
Capitalized Computer Software, Gross | 1,823 | 1,443 |
Capitalized Computer Software, Accumulated Amortization | (1,126) | (914) |
Hosting Arrangement, Service Contract, Implementation Cost, Expense, Amortization | 17 | 15 | 13
Hosting Arrangement, Service Contract, Implementation Cost, Capitalized, before Accumulated Amortization | 142 | 106 |
Hosting Arrangement, Service Contract, Implementation Cost, Capitalized, Accumulated Amortization | (51) | (34) |
Ameren Missouri | Capitalized software costs |  |  |
Finite-Lived Intangible Assets [Line Items] |  |  |
Capitalized Computer Software, Amortization | 114 | 85 | 66
Capitalized Computer Software, Gross | 795 | 613 |
Capitalized Computer Software, Accumulated Amortization | (453) | (339) |
Hosting Arrangement, Service Contract, Implementation Cost, Expense, Amortization | 8 | 7 | 6
Hosting Arrangement, Service Contract, Implementation Cost, Capitalized, before Accumulated Amortization | 63 | 48 |
Hosting Arrangement, Service Contract, Implementation Cost, Capitalized, Accumulated Amortization | (23) | (15) |
Ameren Illinois | Capitalized software costs |  |  |
Finite-Lived Intangible Assets [Line Items] |  |  |
Capitalized Computer Software, Amortization | 92 | 69 | 53
Capitalized Computer Software, Gross | 786 | 601 |
Capitalized Computer Software, Accumulated Amortization | (452) | (360) |
Hosting Arrangement, Service Contract, Implementation Cost, Expense, Amortization | 9 | 8 | $ 6
Hosting Arrangement, Service Contract, Implementation Cost, Capitalized, before Accumulated Amortization | 76 | 54 |
Hosting Arrangement, Service Contract, Implementation Cost, Capitalized, Accumulated Amortization | $ (26) | $ (17) |
Minimum | Software and Software Development Costs |  |  |
Finite-Lived Intangible Assets [Line Items] |  |  |
Property, Plant and Equipment, Useful Life | 2 years |  |
Minimum | Capitalized software costs |  |  |
Finite-Lived Intangible Assets [Line Items] |  |  |
Finite-Lived Intangible Asset, Useful Life | 5 years |  |
Maximum | Software and Software Development Costs |  |  |
Finite-Lived Intangible Assets [Line Items] |  |  |
Property, Plant and Equipment, Useful Life | 15 years |  |
Maximum | Capitalized software costs |  |  |
Finite-Lived Intangible Assets [Line Items] |  |  |
Finite-Lived Intangible Asset, Useful Life | 15 years |  |

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