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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, 2024 | Dec. 31, 2023 | Dec. 31, 2022
Capitalized software costs |  |  |
Finite-Lived Intangible Assets [Line Items] |  |  |
Capitalized Computer Software, Amortization | $ 224 | $ 212 | $ 159
Capitalized Computer Software, Gross | 1,996 | 1,823 |
Capitalized Computer Software, Accumulated Amortization | (1,348) | (1,126) |
Hosting Arrangement, Service Contract, Implementation Cost, Expense, Amortization | 20 | 17 | 15
Hosting Arrangement, Service Contract, Implementation Cost, Capitalized, before Accumulated Amortization | 157 | 142 |
Hosting Arrangement, Service Contract, Implementation Cost, Capitalized, Accumulated Amortization | (71) | (51) |
Ameren Missouri | Capitalized software costs |  |  |
Finite-Lived Intangible Assets [Line Items] |  |  |
Capitalized Computer Software, Amortization | 118 | 114 | 85
Capitalized Computer Software, Gross | 881 | 795 |
Capitalized Computer Software, Accumulated Amortization | (567) | (453) |
Hosting Arrangement, Service Contract, Implementation Cost, Expense, Amortization | 9 | 8 | 7
Hosting Arrangement, Service Contract, Implementation Cost, Capitalized, before Accumulated Amortization | 71 | 63 |
Hosting Arrangement, Service Contract, Implementation Cost, Capitalized, Accumulated Amortization | (32) | (23) |
Ameren Illinois | Capitalized software costs |  |  |
Finite-Lived Intangible Assets [Line Items] |  |  |
Capitalized Computer Software, Amortization | 100 | 92 | 69
Capitalized Computer Software, Gross | 867 | 786 |
Capitalized Computer Software, Accumulated Amortization | (552) | (452) |
Hosting Arrangement, Service Contract, Implementation Cost, Expense, Amortization | 10 | 9 | $ 8
Hosting Arrangement, Service Contract, Implementation Cost, Capitalized, before Accumulated Amortization | 82 | 76 |
Hosting Arrangement, Service Contract, Implementation Cost, Capitalized, Accumulated Amortization | $ (36) | $ (26) |
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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