Accrued Proceeds from Issuance of Common Stock

No definition available.

Name:	aee_AccruedProceedsFromIssuanceOfCommonStock
Namespace Prefix:	aee_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Forward Contract Indexed to Issuer's Equity, Basis Spread

+ References

No definition available.

+ Details

Name:	aee_ForwardContractIndexedToIssuersEquityBasisSpread
Namespace Prefix:	aee_
Data Type:	xbrli:pureItemType
Balance Type:	na
Period Type:	instant

- Definition

Forward Sale Agreement Equity Offering Shares

+ References

No definition available.

+ Details

Name:	aee_ForwardSaleAgreementEquityOfferingShares
Namespace Prefix:	aee_
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	instant

- Definition

Forward Sale Agreement Gross Sales Price

+ References

No definition available.

+ Details

Name:	aee_ForwardSaleAgreementGrossSalesPrice
Namespace Prefix:	aee_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Long-Term Debt And Equity Financings [Line Items]

+ References

No definition available.

+ Details

Name:	aee_LongTermDebtAndEquityFinancingsLineItems
Namespace Prefix:	aee_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

Maximum Value Of Shares To Be Issued Under ATM Program

+ References

No definition available.

+ Details

Name:	aee_MaximumValueOfSharesToBeIssuedUnderATMProgram
Namespace Prefix:	aee_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Period End Net Cash Settlement Price

+ References

No definition available.

+ Details

Name:	aee_PeriodEndNetCashSettlementPrice
Namespace Prefix:	aee_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Period End Net Share Settlement Price

+ References

No definition available.

+ Details

Name:	aee_PeriodEndNetShareSettlementPrice
Namespace Prefix:	aee_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

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

+ References

Reference 1: http://www.xbrl.org/2003/role/exampleRef
-Topic 835
-SubTopic 30
-Name Accounting Standards Codification
-Section 55
-Paragraph 8
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482949/835-30-55-8

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Topic 470
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 1B
-Subparagraph (a)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147481139/470-20-50-1B

Reference 3: http://www.xbrl.org/2003/role/exampleRef
-Topic 470
-SubTopic 20
-Name Accounting Standards Codification
-Section 55
-Paragraph 69B
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147481568/470-20-55-69B

Reference 4: http://www.xbrl.org/2003/role/exampleRef
-Topic 470
-SubTopic 20
-Name Accounting Standards Codification
-Section 55
-Paragraph 69C
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147481568/470-20-55-69C

Reference 5: http://www.xbrl.org/2003/role/disclosureRef
-Topic 835
-SubTopic 30
-Name Accounting Standards Codification
-Section 50
-Paragraph 1
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482900/835-30-50-1

Reference 6: http://www.xbrl.org/2003/role/disclosureRef
-Topic 835
-SubTopic 30
-Name Accounting Standards Codification
-Section 45
-Paragraph 2
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482925/835-30-45-2

+ Details

Name:	us-gaap_DebtInstrumentFaceAmount
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

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

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Topic 210
-SubTopic 10
-Name Accounting Standards Codification
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02(22)(a)(1))
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147480566/210-10-S99-1

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Topic 470
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 1B
-Subparagraph (b)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147481139/470-20-50-1B

+ Details

Name:	us-gaap_DebtInstrumentInterestRateStatedPercentage
Namespace Prefix:	us-gaap_
Data Type:	dtr-types:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

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.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Name Accounting Standards Codification
-Topic 815
-SubTopic 40
-Section 50
-Paragraph 5
-Subparagraph (a)(1)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147480237/815-40-50-5

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Subparagraph (f)(1)
-SubTopic 10
-Topic 480
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147481648/480-10-50-2

+ Details

Name:	us-gaap_ForwardContractIndexedToIssuersEquityForwardRate
Namespace Prefix:	us-gaap_
Data Type:	dtr-types:perShareItemType
Balance Type:	na
Period Type:	duration

- Definition

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

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Name Accounting Standards Codification
-Section 50
-Paragraph 5
-Subparagraph (d)
-SubTopic 40
-Topic 815
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147480237/815-40-50-5

+ Details

Name:	us-gaap_ForwardContractIndexedToIssuersEquitySettlementAlternativesCashAtFairValue
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

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

+ References

+ Details

Name:	us-gaap_ForwardContractIndexedToIssuersEquitySettlementAlternativesSharesAtFairValue
Namespace Prefix:	us-gaap_
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	instant

- Definition

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

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Name Accounting Standards Codification
-Section 45
-Paragraph 14
-Subparagraph (a)
-SubTopic 10
-Topic 230
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482740/230-10-45-14

+ Details

Name:	us-gaap_ProceedsFromIssuanceOfCommonStock
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

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.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-SubTopic 10
-Topic 505
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147481112/505-10-50-2

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Topic 946
-SubTopic 505
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Subparagraph (b)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147478448/946-505-50-2

Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Topic 946
-SubTopic 220
-Name Accounting Standards Codification
-Section S99
-Paragraph 3
-Subparagraph (SX 210.6-09(4)(b))
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479134/946-220-S99-3

+ Details

Name:	us-gaap_StockIssuedDuringPeriodSharesDividendReinvestmentPlan
Namespace Prefix:	us-gaap_
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	duration

- Definition

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

+ References

No definition available.

+ Details

Name:	us-gaap_StockIssuedDuringPeriodSharesOther
Namespace Prefix:	us-gaap_
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	duration

- Definition

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

+ References

No definition available.

+ Details

Name:	us-gaap_StockIssuedDuringPeriodValueOther
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Details

Name:	us-gaap_SubsidiarySaleOfStockAxis=aee_DividendReinvestmentAnd401KPlansMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_DebtInstrumentAxis=aee_SeniorUnsecuredNotes5.375Due2035Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_LongtermDebtTypeAxis=us-gaap_UnsecuredDebtMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	dei_LegalEntityAxis=aee_AmerenParentMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_DebtInstrumentAxis=aee_FirstMortgageBonds5.25Due2035500IssuanceMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_LongtermDebtTypeAxis=us-gaap_SecuredDebtMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	dei_LegalEntityAxis=aee_UnionElectricCompanyMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_SubsequentEventTypeAxis=us-gaap_SubsequentEventMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_DebtInstrumentAxis=aee_FirstMortgageBonds5.625Due2055350IssuanceMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	dei_LegalEntityAxis=aee_AmerenIllinoisCompanyMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_DebtInstrumentAxis=aee_SeniorSecuredNotes3Point25Due2025Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_ForwardContractIndexedToIssuersEquityTypeAxis=aee_ForwardSaleAgreementsOutstandingMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	srt_RangeAxis=srt_MinimumMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	srt_RangeAxis=srt_MaximumMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	srt_RangeAxis=srt_WeightedAverageMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Long-Term debt and Equity Financings (Details) $ / shares in Units, shares in Millions, $ in Millions	3 Months Ended
	Mar. 31, 2025 USD ($) $ / shares shares	Mar. 31, 2024 USD ($) shares	Apr. 30, 2025 USD ($)
Long-Term Debt And Equity Financings [Line Items]
Shares issued under the DRPlus and 401(k) plan \| shares	0.1	0.1
Issuances of common stock	$ 13.0	$ 10.0
Stock Issued During Period, Shares, Other \| shares	0.3	0.2
Stock Issued During Period, Value, Other	$ 25.0
Maximum Value Of Shares To Be Issued Under ATM Program	$ 230.0
Forward Contract Indexed to Issuer's Equity, Basis Spread	75
Dividend reinvestment and 401 (k) plans
Long-Term Debt And Equity Financings [Line Items]
Issuances of common stock	$ 6.0
Accrued Proceeds from Issuance of Common Stock	9.0
Senior unsecured Notes 5.375% Due 2035 \| Unsecured Debt \| Ameren (parent)
Long-Term Debt And Equity Financings [Line Items]
Debt Instrument, Face Amount	$ 750.0
Debt Instrument, Interest Rate, Stated Percentage	5.375%
First Mortgage Bonds, 5.25%, Due 2035 - $500 Issuance \| Secured Debt \| Union Electric Company \| Subsequent Event
Long-Term Debt And Equity Financings [Line Items]
Debt Instrument, Face Amount			$ 500.0
Debt Instrument, Interest Rate, Stated Percentage			5.25%
First Mortgage Bonds, 5.625%, Due 2055 - $350 Issuance \| Secured Debt \| Ameren Illinois Company
Long-Term Debt And Equity Financings [Line Items]
Debt Instrument, Face Amount	$ 350.0
Debt Instrument, Interest Rate, Stated Percentage	5.625%
Senior Secured Notes, 3.25%, Due 2025 \| Secured Debt \| Ameren Illinois Company
Long-Term Debt And Equity Financings [Line Items]
Debt Instrument, Face Amount	$ 300.0
Debt Instrument, Interest Rate, Stated Percentage	3.25%
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	5.8
Forward Contract Indexed to Issuer's Equity, Settlement Alternatives, Cash, at Fair Value	$ 530.0
Period End Net Cash Settlement Price	55.0
Period End Net Share Settlement Price	$ 0.6
Forward Sale Agreement Equity Offering Shares \| shares	5.8
Forward Sale Agreement Gross Sales Price	$ 535.0
Minimum
Long-Term Debt And Equity Financings [Line Items]
Forward Contract Indexed to Issuer's Equity, Forward Rate Per Share \| $ / shares	$ 81.00
Maximum
Long-Term Debt And Equity Financings [Line Items]
Forward Contract Indexed to Issuer's Equity, Forward Rate Per Share \| $ / shares	98.66
Weighted Average
Long-Term Debt And Equity Financings [Line Items]
Forward Contract Indexed to Issuer's Equity, Forward Rate Per Share \| $ / shares	$ 91.02