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Rate And Regulatory Matters (Schedule Of Regulatory Assets And Liabilities) (Details) - USD ($) $ in Millions | 12 Months Ended |
--- | --- | ---
Dec. 31, 2024 | Dec. 31, 2023
Regulatory assets: |  |
Less: current regulatory assets | $ (366) | $ (365)
Noncurrent regulatory assets | 2,397 | 1,810
Regulatory liabilities: |  |
Noncurrent regulatory liabilities | 5,897 | 5,512
Ameren Missouri |  |
Regulatory assets: |  |
Total regulatory assets | 1,432 | 856
Less: current regulatory assets | (66) | (101)
Noncurrent regulatory assets | 1,366 | 755
Regulatory liabilities: |  |
Total regulatory liabilities | 3,213 | 2,974
Less: current regulatory liabilities | (37) | (15)
Noncurrent regulatory liabilities | $ 3,176 | 2,959
PISA deferral percentage | 85.00% |
Ameren Illinois |  |
Regulatory assets: |  |
Total regulatory assets | $ 1,292 | 1,287
Less: current regulatory assets | (281) | (252)
Noncurrent regulatory assets | 1,011 | 1,035
Regulatory liabilities: |  |
Total regulatory liabilities | 2,652 | 2,489
Less: current regulatory liabilities | (79) | (71)
Noncurrent regulatory liabilities | 2,573 | 2,418
Ameren (parent) |  |
Regulatory assets: |  |
Total regulatory assets | 2,763 | 2,175
Less: current regulatory assets | (366) | (365)
Noncurrent regulatory assets | 2,397 | 1,810
Regulatory liabilities: |  |
Total regulatory liabilities | 6,017 | 5,599
Less: current regulatory liabilities | (120) | (87)
Noncurrent regulatory liabilities | 5,897 | 5,512
Under-recovered FAC |  |
Regulatory assets: |  |
Total regulatory assets | 41 | 72
Under-recovered FAC | Ameren Missouri |  |
Regulatory assets: |  |
Total regulatory assets | 41 | 72
Under-recovered FAC | Ameren Illinois |  |
Regulatory assets: |  |
Total regulatory assets | 0 | 0
MTM derivative losses |  |
Regulatory assets: |  |
Total regulatory assets | 103 | 168
MTM derivative losses | Ameren Missouri |  |
Regulatory assets: |  |
Total regulatory assets | 15 | 25
MTM derivative losses | Ameren Illinois |  |
Regulatory assets: |  |
Total regulatory assets | 88 | 143
IEIMA revenue requirement reconciliation adjustment |  |
Regulatory assets: |  |
Total regulatory assets | 139 | 239
IEIMA revenue requirement reconciliation adjustment | Ameren Missouri |  |
Regulatory assets: |  |
Total regulatory assets | 0 | 0
IEIMA revenue requirement reconciliation adjustment | Ameren Illinois |  |
Regulatory assets: |  |
Total regulatory assets | $ 139 | 239
Regulatory liabilities: |  |
Regulatory asset, amortization period | 2 years |
MYRP revenue requirement reconciliation adjustment |  |
Regulatory assets: |  |
Total regulatory assets | $ 24 | 0
MYRP revenue requirement reconciliation adjustment | Ameren Missouri |  |
Regulatory assets: |  |
Total regulatory assets | 0 | 0
MYRP revenue requirement reconciliation adjustment | Ameren Illinois |  |
Regulatory assets: |  |
Total regulatory assets | 24 | 0
Under-recovered RBA |  |
Regulatory assets: |  |
Total regulatory assets | 22 | 0
Under-recovered RBA | Ameren Missouri |  |
Regulatory assets: |  |
Total regulatory assets | 0 | 0
Under-recovered RBA | Ameren Illinois |  |
Regulatory assets: |  |
Total regulatory assets | 22 | 0
FERC revenue requirement reconciliation adjustment |  |
Regulatory assets: |  |
Total regulatory assets | $ 90 | 54
Regulatory liabilities: |  |
Regulatory asset, amortization period | 2 years |
FERC revenue requirement reconciliation adjustment | Ameren Missouri |  |
Regulatory assets: |  |
Total regulatory assets | $ 0 | 0
FERC revenue requirement reconciliation adjustment | Ameren Illinois |  |
Regulatory assets: |  |
Total regulatory assets | 55 | 25
Under-recovered VBA |  |
Regulatory assets: |  |
Total regulatory assets | 49 | 49
Under-recovered VBA | Ameren Missouri |  |
Regulatory assets: |  |
Total regulatory assets | 0 | 0
Under-recovered VBA | Ameren Illinois |  |
Regulatory assets: |  |
Total regulatory assets | 49 | 49
Income taxes |  |
Regulatory assets: |  |
Total regulatory assets | 322 | 207
Regulatory liabilities: |  |
Total regulatory liabilities | $ 1,804 | 1,809
Weighted-average amortization period | 39 years |
Income taxes | Ameren Missouri |  |
Regulatory assets: |  |
Total regulatory assets | $ 237 | 126
Regulatory liabilities: |  |
Total regulatory liabilities | $ 1,040 | 999
Weighted-average amortization period | 30 years |
Income taxes | Ameren Illinois |  |
Regulatory assets: |  |
Total regulatory assets | $ 81 | 78
Regulatory liabilities: |  |
Total regulatory liabilities | $ 679 | 724
Weighted-average amortization period | 46 years |
Bad debt rider |  |
Regulatory assets: |  |
Total regulatory assets | $ 25 | 43
Bad debt rider | Ameren Missouri |  |
Regulatory assets: |  |
Total regulatory assets | 0 | 0
Bad debt rider | Ameren Illinois |  |
Regulatory assets: |  |
Total regulatory assets | 25 | 43
Callaway refueling and maintenance outage costs |  |
Regulatory assets: |  |
Total regulatory assets | 13 | 37
Callaway refueling and maintenance outage costs | Ameren Missouri |  |
Regulatory assets: |  |
Total regulatory assets | $ 13 | 37
Regulatory liabilities: |  |
Regulatory asset, amortization period | 18 months |
Callaway refueling and maintenance outage costs | Ameren Illinois |  |
Regulatory assets: |  |
Total regulatory assets | $ 0 | 0
Unamortized loss on reacquired debt |  |
Regulatory assets: |  |
Total regulatory assets | 47 | 50
Unamortized loss on reacquired debt | Ameren Missouri |  |
Regulatory assets: |  |
Total regulatory assets | 42 | 45
Unamortized loss on reacquired debt | Ameren Illinois |  |
Regulatory assets: |  |
Total regulatory assets | 5 | 5
Environmental cost riders |  |
Regulatory assets: |  |
Total regulatory assets | 43 | 50
Environmental cost riders | Ameren Missouri |  |
Regulatory assets: |  |
Total regulatory assets | 0 | 0
Environmental cost riders | Ameren Illinois |  |
Regulatory assets: |  |
Total regulatory assets | 43 | 50
Storm costs |  |
Regulatory assets: |  |
Total regulatory assets | 18 | 27
Storm costs | Ameren Missouri |  |
Regulatory assets: |  |
Total regulatory assets | 0 | 0
Storm costs | Ameren Illinois |  |
Regulatory assets: |  |
Total regulatory assets | 18 | 27
Customer generation rebate program |  |
Regulatory assets: |  |
Total regulatory assets | 89 | 54
Customer generation rebate program | Ameren Missouri |  |
Regulatory assets: |  |
Total regulatory assets | 0 | 0
Customer generation rebate program | Ameren Illinois |  |
Regulatory assets: |  |
Total regulatory assets | 89 | 54
PISA |  |
Regulatory assets: |  |
Total regulatory assets | 464 | 386
PISA | Ameren Missouri |  |
Regulatory assets: |  |
Total regulatory assets | $ 464 | 386
Regulatory liabilities: |  |
Regulatory asset, amortization period | 20 years |
PISA | Ameren Illinois |  |
Regulatory assets: |  |
Total regulatory assets | $ 0 | 0
Rush Island Energy Center securitization |  |
Regulatory assets: |  |
Total regulatory assets | 465 | 0
Rush Island Energy Center securitization | Ameren Missouri |  |
Regulatory assets: |  |
Total regulatory assets | 465 | 0
Rush Island Energy Center securitization | Ameren Illinois |  |
Regulatory assets: |  |
Total regulatory assets | 0 | 0
RESRAM |  |
Regulatory assets: |  |
Total regulatory assets | 51 | 48
RESRAM | Ameren Missouri |  |
Regulatory assets: |  |
Total regulatory assets | 51 | 48
RESRAM | Ameren Illinois |  |
Regulatory assets: |  |
Total regulatory assets | 0 | 0
Certain Meramec Energy Center costs |  |
Regulatory assets: |  |
Total regulatory assets | 26 | 39
Certain Meramec Energy Center costs | Ameren Missouri |  |
Regulatory assets: |  |
Total regulatory assets | $ 26 | 39
Regulatory liabilities: |  |
Regulatory asset, amortization period | 5 years |
Certain Meramec Energy Center costs | Ameren Illinois |  |
Regulatory assets: |  |
Total regulatory assets | $ 0 | 0
FEJA energy-efficiency rider |  |
Regulatory assets: |  |
Total regulatory assets | 576 | 500
FEJA energy-efficiency rider | Ameren Missouri |  |
Regulatory assets: |  |
Total regulatory assets | 0 | 0
FEJA energy-efficiency rider | Ameren Illinois |  |
Regulatory assets: |  |
Total regulatory assets | 576 | 500
Property Tax Tracker |  |
Regulatory assets: |  |
Total regulatory assets | $ 22 | 13
Regulatory liabilities: |  |
Regulatory asset, amortization period | 2 years |
Property Tax Tracker | Ameren Missouri |  |
Regulatory assets: |  |
Total regulatory assets | $ 22 | 13
Property Tax Tracker | Ameren Illinois |  |
Regulatory assets: |  |
Total regulatory assets | 0 | 0
Other regulatory assets |  |
Regulatory assets: |  |
Total regulatory assets | 134 | 139
Other regulatory assets | Ameren Missouri |  |
Regulatory assets: |  |
Total regulatory assets | 56 | 65
Other regulatory assets | Ameren Illinois |  |
Regulatory assets: |  |
Total regulatory assets | 78 | 74
Over-recovered Illinois electric power costs |  |
Regulatory liabilities: |  |
Total regulatory liabilities | 34 | 36
Over-recovered Illinois electric power costs | Ameren Missouri |  |
Regulatory liabilities: |  |
Total regulatory liabilities | 0 | 0
Over-recovered Illinois electric power costs | Ameren Illinois |  |
Regulatory liabilities: |  |
Total regulatory liabilities | $ 34 | 36
Amortization period | 1 year |
Over-recovered PGA |  |
Regulatory liabilities: |  |
Total regulatory liabilities | $ 35 | 40
Over-recovered PGA | Ameren Missouri |  |
Regulatory liabilities: |  |
Total regulatory liabilities | 2 | 7
Over-recovered PGA | Ameren Illinois |  |
Regulatory liabilities: |  |
Total regulatory liabilities | 33 | 33
MTM derivative gains |  |
Regulatory liabilities: |  |
Total regulatory liabilities | 16 | 22
MTM derivative gains | Ameren Missouri |  |
Regulatory liabilities: |  |
Total regulatory liabilities | 10 | 19
MTM derivative gains | Ameren Illinois |  |
Regulatory liabilities: |  |
Total regulatory liabilities | 6 | 3
Cost of removal |  |
Regulatory liabilities: |  |
Total regulatory liabilities | 2,294 | 2,186
Cost of removal | Ameren Missouri |  |
Regulatory liabilities: |  |
Total regulatory liabilities | 1,118 | 1,098
Cost of removal | Ameren Illinois |  |
Regulatory liabilities: |  |
Total regulatory liabilities | 1,115 | 1,038
AROs |  |
Regulatory liabilities: |  |
Total regulatory liabilities | 691 | 524
AROs | Ameren Missouri |  |
Regulatory liabilities: |  |
Total regulatory liabilities | 691 | 524
AROs | Ameren Illinois |  |
Regulatory liabilities: |  |
Total regulatory liabilities | 0 | 0
Pension and postretirement benefit costs |  |
Regulatory liabilities: |  |
Total regulatory liabilities | 358 | 346
Pension and postretirement benefit costs | Ameren Missouri |  |
Regulatory liabilities: |  |
Total regulatory liabilities | 202 | 202
Pension and postretirement benefit costs | Ameren Illinois |  |
Regulatory liabilities: |  |
Total regulatory liabilities | 156 | 144
Pension and postretirement benefit costs tracker |  |
Regulatory liabilities: |  |
Total regulatory liabilities | 70 | 111
Pension and postretirement benefit costs tracker | Ameren Missouri |  |
Regulatory liabilities: |  |
Total regulatory liabilities | $ 70 | 111
Regulatory liability, amortization period | 2 years |
Pension and postretirement benefit costs tracker | Ameren Illinois |  |
Regulatory liabilities: |  |
Total regulatory liabilities | $ 0 | 0
Renewable energy credits and zero emission credits |  |
Regulatory liabilities: |  |
Total regulatory liabilities | 586 | 489
Renewable energy credits and zero emission credits | Ameren Missouri |  |
Regulatory liabilities: |  |
Total regulatory liabilities | 0 | 0
Renewable energy credits and zero emission credits | Ameren Illinois |  |
Regulatory liabilities: |  |
Total regulatory liabilities | 586 | 489
Certain Rush Island Energy Center Costs |  |
Regulatory liabilities: |  |
Total regulatory liabilities | 66 | 0
Certain Rush Island Energy Center Costs | Ameren Missouri |  |
Regulatory liabilities: |  |
Total regulatory liabilities | 66 | 0
Certain Rush Island Energy Center Costs | Ameren Illinois |  |
Regulatory liabilities: |  |
Total regulatory liabilities | 0 | 0
Other regulatory liabilities |  |
Regulatory liabilities: |  |
Total regulatory liabilities | 63 | 36
Other regulatory liabilities | Ameren Missouri |  |
Regulatory liabilities: |  |
Total regulatory liabilities | 14 | 14
Other regulatory liabilities | Ameren Illinois |  |
Regulatory liabilities: |  |
Total regulatory liabilities | $ 43 | 22
FAC adjustments | Ameren Missouri |  |
Regulatory liabilities: |  |
Accumulation period | 4 months |
Regulatory asset, amortization period | 8 months |
Asset Retirement Obligation - Nuclear decommissioning trust fund balance | Ameren Missouri |  |
Regulatory liabilities: |  |
Total regulatory liabilities | $ 1,342 | 1,150
Asset Retirement Obligation - removal costs | Ameren Missouri |  |
Regulatory liabilities: |  |
Total regulatory liabilities | $ 651 | $ 626
Minimum | FEJA energy-efficiency rider | Ameren Illinois |  |
Regulatory liabilities: |  |
Regulatory asset, amortization period | 2 years |
Maximum | FEJA energy-efficiency rider | Ameren Illinois |  |
Regulatory liabilities: |  |
Regulatory asset, amortization period | 12 years |

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