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