Supplemental Information (Schedule Of Excise Taxes) (Details) - USD ($) $ in Millions |
3 Months Ended | 6 Months Ended | ||
|---|---|---|---|---|
Jun. 30, 2025 |
Jun. 30, 2024 |
Jun. 30, 2025 |
Jun. 30, 2024 |
|
| Accounting Policies [Line Items] | ||||
| Excise tax expense | $ 74 | $ 69 | $ 155 | $ 141 |
| Union Electric Company | ||||
| Accounting Policies [Line Items] | ||||
| Excise tax expense | 43 | 41 | 81 | 76 |
| Ameren Illinois Company | ||||
| Accounting Policies [Line Items] | ||||
| Excise tax expense | $ 31 | $ 28 | $ 74 | $ 65 |