Commitments And Contingencies (Environmental Matters) (Details) $ in Millions	12 Months Ended
	Dec. 31, 2024 USD ($) energyCenter scrubber site	Dec. 31, 2023 USD ($)	Dec. 31, 2022 USD ($)
Estimated capital costs to comply with existing and known federal CO2 emissions regulations	$ 580
Estimated capital costs to comply with existing and known federal MATS regulations	320
Other current liabilities	475	$ 501
Other deferred credits and liabilities	487	426
Other operations and maintenance	1,969	1,866	$ 1,937
Asset Retirement Obligation	$ 827	791	786
Environmental Loss Contingency Statement Of Financial Position Extensible Enumeration Not Disclosed Flag	false
Rush Island Energy Center Additional Mitigation Relief Ordered
Other current liabilities	$ 40
Other deferred credits and liabilities	24
Other operations and maintenance	$ 59
Ameren Missouri
Number of Energy Center Scrubbers | scrubber	2
Number of days of the EPA's requested appellate court suspension	60 days
Estimated capital costs to comply with existing and known federal CO2 emissions regulations	$ 580
Estimated capital costs to comply with existing and known federal MATS regulations	320
Cost of additional mitigation ordered for the Rush Island Energy Center	64
Other current liabilities	235	181
Other deferred credits and liabilities	150	56
Other operations and maintenance	1,050	1,003	1,028
Asset Retirement Obligation	$ 823	787	782
Number of Ameren Missouri Natural Gas Energy Centers Subject To IETL | energyCenter	4
Ameren Missouri | Rush Island Energy Center Additional Mitigation Relief Ordered
Other current liabilities	$ 40
Other deferred credits and liabilities	24
Other operations and maintenance	59
Ameren Illinois
Other current liabilities	231	298
Other deferred credits and liabilities	273	308
Other operations and maintenance	906	818	882
Asset Retirement Obligation	$ 4	$ 4	$ 4
Number of remediation sites | site	3
Manufactured Gas Plant
Accrual for environmental loss contingencies	$ 44
Manufactured Gas Plant | Ameren Illinois
Number of remediation sites | site	44
Accrual for environmental loss contingencies	$ 44
Minimum
Estimated capital costs to comply with existing and known federal and state air emissions regulations	900
Minimum | Ameren Missouri
Estimated capital costs to comply with existing and known federal and state air emissions regulations	900
Minimum | Manufactured Gas Plant | Ameren Illinois
Estimate of possible loss	44
Maximum
Estimated capital costs to comply with existing and known federal and state air emissions regulations	1,000
Maximum | Ameren Missouri
Estimated capital costs to comply with existing and known federal and state air emissions regulations	1,000
Maximum | Manufactured Gas Plant | Ameren Illinois
Estimate of possible loss	91
New CCR Rules Estimate
Asset Retirement Obligation	46
New CCR Rules Estimate | Ameren Missouri
Asset Retirement Obligation	$ 46