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Summary Of Significant Accounting Policies - Schedule of Other Assets and Other Liabilities (Details) - USD ($) $ in Millions | Mar. 31, 2025 | Dec. 31, 2024
--- | --- | ---
Accounting Policies [Line Items] |  |
Unbilled revenue | $ 253 | $ 346
Other current assets | 176 | 162
Regulatory Asset | 2,569 | 2,397
Current maturities of long-term debt | 17 | 317
Interest accrued | 159 | 196
Long-term debt, net | 18,354 | 17,262
Ameren Missouri Securitization Funding I, LLC |  |
Accounting Policies [Line Items] |  |
Unbilled revenue | 2 | 0
Other current assets | 15 | 2
Regulatory Asset | 459 | 465
Current maturities of long-term debt | 17 | 17
Interest accrued | 6 | 1
Current regulatory liabilities | 5 | 0
Long-term debt, net | $ 449 | $ 448

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