Estimated capital costs to comply with existing and known federal and state air emissions regulations

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Number of Ameren Missouri Natural Gas Energy Centers Subject To IETL emission standards.

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Number of Energy Centers

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Number Of Energy Centers Constructing Wastewater Treatment Facilities

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Number Of Remediation Sites

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- Definition

Number of Energy Center Scrubbers to achieve compliance with regulations

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- Definition

Plant To Be Abandoned, Net

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Value established for a utility on which the entity is allowed to earn a particular rate of return

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Total costs accrued as of the balance sheet date for environmental loss contingencies.

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The carrying amount of a liability for an asset retirement obligation. An asset retirement obligation is a legal obligation associated with the disposal or retirement of a tangible long-lived asset that results from the acquisition, construction or development, or the normal operations of a long-lived asset, except for certain obligations of lessees.

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Reflects the estimated amount of loss from the specified contingency as of the balance sheet date.

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Commitments And Contingencies (Environmental Matters) (Details) $ in Millions	12 Months Ended
	Dec. 31, 2022 USD ($) energyCenter scrubber site	Dec. 31, 2021 USD ($)	Dec. 31, 2020 USD ($)
Asset Retirement Obligation	$ 786	$ 764	$ 756
Coal Fired Electric Generation Equipment
Plant To Be Abandoned, Net	$ 582	604
Union Electric Company
Number of Energy Center Scrubbers \| scrubber	2
Number of Energy Centers Constructing Wastewater Treatment Facilities \| energyCenter	3
Number of Energy Centers \| energyCenter	4
Asset Retirement Obligation	$ 782	760	751
Number of Ameren Missouri Natural Gas Energy Centers Subject To IETL \| energyCenter	4
Union Electric Company \| Coal Fired Electric Generation Equipment
Plant To Be Abandoned, Net	$ 582	604
Ameren Illinois Company
Asset Retirement Obligation	4	4	$ 5
Ameren Illinois Company \| Coal Fired Electric Generation Equipment
Plant To Be Abandoned, Net	0	$ 0
Manufactured Gas Plant
Accrual for environmental loss contingencies	$ 63
Manufactured Gas Plant \| Ameren Illinois Company
Number of remediation sites \| site	44
Accrual for environmental loss contingencies	$ 63
Minimum
Estimated capital costs to comply with existing and known federal and state air emissions regulations	90
Minimum \| Union Electric Company
Estimated capital costs to comply with existing and known federal and state air emissions regulations	90
Minimum \| Coal Combustion Residuals Estimate \| Union Electric Company
Estimated capital costs to comply with existing and known federal and state air emissions regulations	30
Minimum \| Manufactured Gas Plant \| Ameren Illinois Company
Estimate of possible loss	63
Maximum
Estimated capital costs to comply with existing and known federal and state air emissions regulations	120
Maximum \| Union Electric Company
Estimated capital costs to comply with existing and known federal and state air emissions regulations	120
Maximum \| Coal Combustion Residuals Estimate \| Union Electric Company
Estimated capital costs to comply with existing and known federal and state air emissions regulations	50
Maximum \| Manufactured Gas Plant \| Ameren Illinois Company
Estimate of possible loss	145
Rush Island Energy Center \| Union Electric Company
Rate Base	400
New CCR Rules Estimate
Asset Retirement Obligation	49
New CCR Rules Estimate \| Union Electric Company
Asset Retirement Obligation	$ 49