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Minimum Tax on Book Income, Inflation Reduction Act, Percent

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The percentage of retail sales from renewable sources required by the Missouri renewable energy standard.

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The percentage of retail sales from solar sources required by the Missouri renewable energy standard.

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The MoPSC Staff's recommended rate increase (decrease).

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The MoPSC Staff's recommended capital structure

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The MoPSC Staff's recommended return on equity.

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The MoPSC Staff's recommended rate base.

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The MoPSC Staff's recommended revenue requirement true-up adjustments.

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Number of months to complete a rate proceeding.

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The number of countries being investigated by the Department of Commerce related to solar panel imports.

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The PISA rate increase limitation to take effect beginning in 2024.

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The maximum percentage of energy allowed to be sourced from renewable resources under the Renewable Solutions Program.

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The percentage of High Prairie costs included in Ameren Missouri's requested revenue requirement challenged by the MoOPC.

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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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Percentage of public utility's approved equity to capital, including debt and equity.

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Amount of public utility's approved rate increase (decrease) by regulatory agency.

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Percentage of public utility's requested equity to capital, including debt and equity.

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Amount of public utility's requested rate increase (decrease) with regulatory agency.

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Percentage of public utility's requested return on equity.

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Amount of revenue recognized from goods sold, services rendered, insurance premiums, or other activities that constitute an earning process. Includes, but is not limited to, investment and interest income before deduction of interest expense when recognized as a component of revenue, and sales and trading gain (loss).

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Rate and Regulatory Matters (Narrative-Missouri) (Details) $ in Millions	3 Months Ended			12 Months Ended
	Mar. 31, 2023 USD ($)	Jun. 30, 2022 MWh	Mar. 31, 2022 MWh	Dec. 31, 2022 USD ($) MWh numberOfCountriesInvestigatedByTheDOC	Dec. 31, 2021 USD ($)	Dec. 31, 2020 USD ($)	Aug. 16, 2022
Public Utilities, General Disclosures [Line Items]
Minimum Tax on Book Income, Inflation Reduction Act, Percent							15.00%
Revenues				$ 7,957	$ 6,394	$ 5,794
Depreciation and amortization				1,289	1,146	1,075
Other operations and maintenance				$ 1,937	1,774	1,661
Union Electric Company
Public Utilities, General Disclosures [Line Items]
Amount of Megawatts \| MWh				102
Missouri Renewable Energy Standard Percentage				15.00%
Missouri Renewable Energy Standard Percentage - Solar				2.00%
Number of Countries Investigated by the DOC \| numberOfCountriesInvestigatedByTheDOC				4
Depreciation and amortization				$ 732	632	604
Other operations and maintenance				$ 1,028	948	886
Union Electric Company \| Wind Generation Facility
Public Utilities, General Disclosures [Line Items]
Amount of Megawatts \| MWh		200	150
Union Electric Company \| Maximum
Public Utilities, General Disclosures [Line Items]
PISA Rate Increase Limit Beginning 2024				2.50%
Percentage of energy sourced from renewable resources				100.00%
Union Electric Company \| Electric \| Pending Rate Case
Public Utilities, General Disclosures [Line Items]
Public Utilities, Requested Rate Increase (Decrease), Amount				$ 316
Public Utilities, Requested Return on Equity, Percentage				10.20%
Public Utilities, Requested Equity Capital Structure, Percentage				51.93%
Rate Base				$ 11,600
Months to complete a rate proceeding				11 months
Union Electric Company \| Electric \| Final Rate Order
Public Utilities, General Disclosures [Line Items]
Rate Base					10,200
Public Utilities, Approved Rate Increase (Decrease), Amount					$ 220
Public Utilities, Approved Equity Capital Structure, Percentage					51.97%
Depreciation and amortization					$ 140
Other operations and maintenance					40
Union Electric Company \| Electric \| Subsequent Event \| Pending Rate Case
Public Utilities, General Disclosures [Line Items]
MoPSC Staff recommended rate increase (decrease)	$ 199
MoPSC Staff's recommended ROE	9.59%
MoPSC Staff's recommended capital structure	51.84%
MoPSC Staff's recommended rate base	$ 10,500
MoPSC Staff's recommended true-up adjustments	$ 128
Percentage of High Prairie costs challenged by the MoOPC	29.00%
Union Electric Company \| Natural gas \| Final Rate Order
Public Utilities, General Disclosures [Line Items]
Rate Base				$ 313
Public Utilities, Approved Rate Increase (Decrease), Amount					5
Union Electric Company \| MEEIA 2019 [Domain] \| Electric
Public Utilities, General Disclosures [Line Items]
Revenues				$ 22
Union Electric Company \| MEEIA 2019 [Domain] \| Electric \| Final Rate Order
Public Utilities, General Disclosures [Line Items]
Revenues					$ 9	$ 6