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Forward Contract Indexed to Issuer's Equity, Basis Spread

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Forward Sale Agreement Gross Sales Price

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Long-Term Debt And Equity Financings [Line Items]

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Maximum Value Of Shares To Be Issued Under ATM Program

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Period End Net Cash Settlement Price

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Period End Net Share Settlement Price

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- Definition

Face (par) amount of debt instrument at time of issuance.

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Contractual interest rate for funds borrowed, under the debt agreement.

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The per share price of the Company's stock at which the contract holder of the freestanding contract has the right to purchase or sell the Company's stock at a future date.

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Amount that would be paid upon settlement of forward contract indexed to equity.

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Number of shares as a settlement alternative for each freestanding forward contract.

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The cash inflow from parent as a source of financing that is recorded as additional paid in capital.

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The cash inflow from the additional capital contribution to the entity.

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Number of shares issued during the period from a dividend reinvestment plan (DRIP). A dividend reinvestment plan allows the shareholders to reinvest dividends paid to them by the entity on new issues of stock by the entity.

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Number of shares of stock issued attributable to transactions classified as other.

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Value of shares of stock issued attributable to transactions classified as other.

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Long-Term debt and Equity Financings (Details) $ / shares in Units, shares in Millions, $ in Millions	3 Months Ended			6 Months Ended
	Jun. 30, 2024 USD ($) shares	Mar. 31, 2024 USD ($) shares	Jun. 30, 2023 USD ($) shares	Jun. 30, 2024 USD ($) $ / shares shares	Jun. 30, 2023 USD ($) shares	Apr. 30, 2024 USD ($)	Jan. 31, 2024 USD ($)
Long-Term Debt And Equity Financings [Line Items]
Shares issued under the DRPlus and 401(k) plan \| shares	0.2		0.1	0.3	0.2
Issuances of common stock				$ 21.0	$ 16.0
Stock Issued During Period, Shares, Other \| shares	0.0	0.2	0.0	0.2	0.5
Stock Issued During Period, Value, Other		$ 16.0
Maximum Value Of Shares To Be Issued Under ATM Program	$ 770.0			$ 770.0
Forward Contract Indexed to Issuer's Equity, Basis Spread	75			75
Minimum
Long-Term Debt And Equity Financings [Line Items]
Forward Contract Indexed to Issuer's Equity, Forward Rate Per Share \| $ / shares				$ 76.69
Maximum
Long-Term Debt And Equity Financings [Line Items]
Forward Contract Indexed to Issuer's Equity, Forward Rate Per Share \| $ / shares				89.31
Weighted Average
Long-Term Debt And Equity Financings [Line Items]
Forward Contract Indexed to Issuer's Equity, Forward Rate Per Share \| $ / shares				$ 80.45
Dividend reinvestment and 401 (k) plans
Long-Term Debt And Equity Financings [Line Items]
Issuances of common stock	$ 4.0			$ 14.0
Accrued Proceeds from Issuance of Common Stock				$ 7.0
Forward Sale Agreements Outstanding
Long-Term Debt And Equity Financings [Line Items]
Forward Contract Indexed to Issuer's Equity, Settlement Alternatives, Shares, at Fair Value \| shares	2.9			2.9
Forward Contract Indexed to Issuer's Equity, Settlement Alternatives, Cash, at Fair Value	$ 232.0			$ 232.0
Period End Net Cash Settlement Price	29.0			29.0
Period End Net Share Settlement Price	$ 0.4			$ 0.4
Forward Sale Agreement Equity Offering Shares \| shares	2.9			2.9
Forward Sale Agreement Gross Sales Price	$ 232.0			$ 232.0
Union Electric Company
Long-Term Debt And Equity Financings [Line Items]
Capital contributions from parent				350.0	$ 0.0
Union Electric Company \| Other Paid-in Capital:
Long-Term Debt And Equity Financings [Line Items]
Capital contributions from parent	350.0		$ 0.0	350.0	$ 0.0
Union Electric Company \| Secured Debt \| First Mortgage Bonds, 5.25%, Due 2054 - $350 Issuance
Long-Term Debt And Equity Financings [Line Items]
Debt Instrument, Face Amount							$ 350.0
Debt Instrument, Interest Rate, Stated Percentage							5.25%
Union Electric Company \| Secured Debt \| Senior Secured Notes 5.20% Due 2034
Long-Term Debt And Equity Financings [Line Items]
Debt Instrument, Face Amount						$ 500.0
Debt Instrument, Interest Rate, Stated Percentage						5.20%
Union Electric Company \| Secured Debt \| Senior Secured Notes350 Due2024
Long-Term Debt And Equity Financings [Line Items]
Debt Instrument, Face Amount						$ 350.0
Debt Instrument, Interest Rate, Stated Percentage						3.50%
Ameren Illinois Company \| Secured Debt \| First Mortgage Bonds, 5.55%, Due 2054 - $625 Issuance
Long-Term Debt And Equity Financings [Line Items]
Debt Instrument, Face Amount	$ 625.0			$ 625.0
Debt Instrument, Interest Rate, Stated Percentage	5.55%			5.55%