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Property And Plant, Net (Tables) | 12 Months Ended
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Dec. 31, 2023
Property, Plant and Equipment [Abstract] |
Schedule Of Property And Plant, Net | The following table presents components of “Property, plant, and equipment, net” at December 31, 2023 and 2022:
|  | Ameren Missouri |  | Ameren Illinois |  | Other |  | Ameren
2023 |  |  |  |  |  |  |  |
Property, plant, and equipment at original cost(a): |  |  |  |  |  |  |  |
Electric generation: |  |  |  |  |  |  |  |
Coal(b) |  | $ | 3,452 |  |  | $ | — |  |  | $ | — |  |  | $ | 3,452 |
Natural gas |  | 921 |  |  | — |  |  | — |  |  | 921 |
Nuclear |  | 5,879 |  |  | — |  |  | — |  |  | 5,879 |
Renewable(c) |  | 1,973 |  |  | 11 |  |  | — |  |  | 1,984 |
Electric distribution |  | 8,638 |  |  | 7,820 |  |  | — |  |  | 16,458 |
Electric transmission |  | 2,134 |  |  | 5,381 |  |  | 1,993 |  |  | 9,508 |
Natural gas |  | 688 |  |  | 4,186 |  |  | — |  |  | 4,874 |
Other(d) |  | 2,191 |  |  | 1,657 |  |  | 255 |  |  | 4,103 |
|  | 25,876 |  |  | 19,055 |  |  | 2,248 |  |  | 47,179 |
Less: Accumulated depreciation and amortization |  | 10,243 |  |  | 4,783 |  |  | 400 |  |  | 15,426 |
|  | 15,633 |  |  | 14,272 |  |  | 1,848 |  |  | 31,753 |
Construction work in progress: |  |  |  |  |  |  |  |
Nuclear fuel in progress |  | 173 |  |  | — |  |  | — |  |  | 173 |
Other |  | 914 |  |  | 360 |  |  | 46 |  |  | 1,320 |
Plant to be abandoned, net(e) |  | 530 |  |  | — |  |  | — |  |  | 530 |
Property, plant, and equipment, net |  | $ | 17,250 |  |  | $ | 14,632 |  |  | $ | 1,894 |  |  | $ | 33,776 |
2022 |  |  |  |  |  |  |  |
Property, plant, and equipment at original cost(a): |  |  |  |  |  |  |  |
Electric generation: |  |  |  |  |  |  |  |
Coal(b)(f) |  | $ | 3,454 |  |  | $ | — |  |  | $ | — |  |  | $ | 3,454 |
Natural gas |  | 961 |  |  | — |  |  | — |  |  | 961 |
Nuclear |  | 5,725 |  |  | — |  |  | — |  |  | 5,725 |
Renewable(c) |  | 1,957 |  |  | 11 |  |  | — |  |  | 1,968 |
Electric distribution |  | 7,993 |  |  | 7,351 |  |  | — |  |  | 15,344 |
Electric transmission |  | 1,884 |  |  | 4,617 |  |  | 1,815 |  |  | 8,316 |
Natural gas |  | 640 |  |  | 3,883 |  |  | — |  |  | 4,523 |
Other(d) |  | 1,904 |  |  | 1,395 |  |  | 249 |  |  | 3,548 |
|  | 24,518 |  |  | 17,257 |  |  | 2,064 |  |  | 43,839 |
Less: Accumulated depreciation and amortization(f) |  | 9,682 |  |  | 4,418 |  |  | 365 |  |  | 14,465 |
|  | 14,836 |  |  | 12,839 |  |  | 1,699 |  |  | 29,374 |
Construction work in progress: |  |  |  |  |  |  |  |
Nuclear fuel in progress |  | 108 |  |  | — |  |  | — |  |  | 108 |
Other |  | 598 |  |  | 514 |  |  | 86 |  |  | 1,198 |
Plant to be abandoned, net(e) |  | 582 |  |  | — |  |  | — |  |  | 582 |
Property, plant, and equipment, net |  | $ | 16,124 |  |  | $ | 13,353 |  |  | $ | 1,785 |  |  | $ | 31,262 |
(a)The estimated lives for each asset group are as follows: 5 to 72 years for electric generation, excluding Ameren Missouri’s hydroelectric generating assets, which have useful lives of up to 150 years; 20 to 80 years for electric distribution; 50 to 75 years for electric transmission; 20 to 80 years for natural gas; and 2 to 55 years for other. (b)Includes $29 million of oil-fired generation at December 31, 2023 and 2022. (c)Renewable includes hydroelectric, wind, solar, and methane gas generation facilities. (d)Other property, plant, and equipment includes assets used to support electric and natural gas services. (e)Represents the net book value of the Rush Island Energy Center as Ameren Missouri expects to retire the energy center significantly in advance of its previously expected useful life and in the near term. See Plant to be Abandoned, Net under Note 1 – Summary of Significant Accounting Policies, NSR and Clean Air Act Litigation under Note 14 – Commitments and Contingencies, and Securitization of the Rush Island Energy Center under Note 2 – Rate and Regulatory Matters for additional information on the planned accelerated retirement of the Rush Island Energy Center. (f)Original cost amounts include two CTs that had related financing obligations. The financing obligation for the Peno Creek CT Energy Center was settled in December 2022, while the financing obligation for the Audrain CT Energy Center was settled in January 2023. The gross cumulative plant asset values related to outstanding financing obligations as of December 31, 2022 was $125 million and the related accumulated depreciation was $54 million. See Note 5 – Long-term Debt and Equity Financings for additional information on these agreements.
Schedule of Capitalized Software and Deferred Cloud Implementation Costs | Capitalized software costs are classified within “Property, Plant, and Equipment, Net” on the balance sheet and are amortized on a straight-line basis over the expected period of benefit, ranging from 2 to 15 years, with the amortization expense included in “Depreciation and amortization” on the statement of income. Deferred cloud implementation costs are classified within “Other Assets” on the balance sheet and are amortized on a straight-line basis over the term of the associated hosting arrangement, ranging from 5 to 15 years, with the amortization expense included in “Other operations and maintenance” on the statement of income. The following table presents the amortization expense, gross carrying value, and related accumulated amortization of capitalized software and deferred cloud implementation costs by year:
|  | Amortization Expense |  | Gross Carrying Value |  | Accumulated Amortization
|  | 2023 | 2022 | 2021 |  | 2023 | 2022 |  | 2023 | 2022
Capitalized software costs: |  |  |  |  |  |  |  |  |  |
Ameren |  | $ | 212 |  | $ | 159 |  | $ | 125 |  |  | $ | 1,823 |  | $ | 1,443 |  |  | $ | (1,126) |  | $ | (914) |
Ameren Missouri |  | 114 |  | 85 |  | 66 |  |  | 795 |  | 613 |  |  | (453) |  | (339) |
Ameren Illinois |  | 92 |  | 69 |  | 53 |  |  | 786 |  | 601 |  |  | (452) |  | (360) |
Deferred cloud implementation costs: |  |  |  |  |  |  |  |  |  |
Ameren |  | $ | 17 |  | $ | 15 |  | $ | 13 |  |  | $ | 142 |  | $ | 106 |  |  | $ | (51) |  | $ | (34) |
Ameren Missouri |  | 8 |  | 7 |  | 6 |  |  | 63 |  | 48 |  |  | (23) |  | (15) |
Ameren Illinois |  | 9 |  | 8 |  | 6 |  |  | 76 |  | 54 |  |  | (26) |  | (17) |
Schedule of Capitalized Software, Future Amortization Expense | Annual amortization expense for capitalized software placed in service as of December 31, 2023, is estimated to be as follows:
|  | 2024 |  | 2025 |  | 2026 |  | 2027 |  | 2028
Ameren |  | $ | 202 |  |  | $ | 147 |  |  | $ | 106 |  |  | $ | 79 |  |  | $ | 45 |
Ameren Missouri |  | 106 |  |  | 76 |  |  | 52 |  |  | 38 |  |  | 22 |
Ameren Illinois |  | 90 |  |  | 65 |  |  | 51 |  |  | 38 |  |  | 23 |

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