[Line Items] for Accounting Policies [Table]

No definition available.

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

- Definition

The resettlement of MISO-related purchase and sale transactions.

+ References

No definition available.

+ Details

Name:	aee_MISOResettlements
Namespace Prefix:	aee_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

Number of Months Between Callaway Maintenance Outages

+ References

No definition available.

+ Details

Name:	aee_NumberofMonthsBetweenCallawayMaintenanceOutages
Namespace Prefix:	aee_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

- Definition

Provision For Depreciation Percent Of Average Depreciable Cost

+ References

No definition available.

+ Details

Name:	aee_ProvisionForDepreciationPercentOfAverageDepreciableCost
Namespace Prefix:	aee_
Data Type:	dtr-types:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

Public Utilities, Area Serviced

+ References

No definition available.

+ Details

Name:	aee_PublicUtilitiesAreaServiced
Namespace Prefix:	aee_
Data Type:	dtr-types:areaItemType
Balance Type:	na
Period Type:	duration

- Definition

Public Utilities, Number of Customers

+ References

No definition available.

+ Details

Name:	aee_PublicUtilitiesNumberOfCustomers
Namespace Prefix:	aee_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	instant

- Definition

Carrying amount as of the balance sheet date of amounts which could be received based on the terms of the insurance contract upon surrendering life policies owned by the entity.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section 45
-Paragraph 4
-Subparagraph (d)
-URI http://asc.fasb.org/extlink&oid=124098289&loc=d3e6812-107765

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.17)
-URI http://asc.fasb.org/extlink&oid=120391452&loc=d3e13212-122682

+ Details

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

- Definition

Amount after accumulated impairment loss of an asset representing future economic benefits arising from other assets acquired in a business combination that are not individually identified and separately recognized.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 210
-Section S99
-Paragraph 1
-Subparagraph (SX 210.9-03(10)(1))
-URI http://asc.fasb.org/extlink&oid=120398452&loc=d3e534808-122878

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 350
-SubTopic 20
-Section 45
-Paragraph 5
-URI http://asc.fasb.org/extlink&oid=120320667&loc=SL49117168-202975

Reference 3: http://www.xbrl.org/2003/role/exampleRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 852
-SubTopic 10
-Section 55
-Paragraph 10
-URI http://asc.fasb.org/extlink&oid=84165509&loc=d3e56426-112766

Reference 4: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 350
-SubTopic 20
-Section 45
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=99380562&loc=d3e13770-109266

+ Details

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

- Definition

Amount of accumulated impairment loss for an asset representing future economic benefits arising from other assets acquired in a business combination that are not individually identified and separately recognized.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 350
-SubTopic 20
-Section 50
-Paragraph 1
-Subparagraph (h)
-URI http://asc.fasb.org/extlink&oid=121556970&loc=d3e13816-109267

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 350
-SubTopic 20
-Section 50
-Paragraph 1
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=121556970&loc=d3e13816-109267

+ Details

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

- Definition

Amount before allowance of loans made to policy and contract holders using their life insurance contracts' cash value or separate accounts as collateral. Includes deferred interest and fees, undisbursed portion of loan balance, unamortized costs and premiums over and discounts from face amounts. Excludes loans and leases covered under loss sharing agreements.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 944
-SubTopic 210
-Section S99
-Paragraph 1
-Subparagraph (SX 210.7-03.1(e))
-URI http://asc.fasb.org/extlink&oid=120400017&loc=d3e572229-122910

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 210
-Section S99
-Paragraph 1
-Subparagraph (SX 210.9-03.7(a)(7))
-URI http://asc.fasb.org/extlink&oid=120398452&loc=d3e534808-122878

+ Details

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

- Definition

Portion of equity (net assets) in a variable interest entity (VIE) not attributable, directly or indirectly, to the parent entity. That is, this is the portion of equity in a VIE that is attributable to the noncontrolling interest (previously referred to as minority interest).

+ References

No definition available.

+ Details

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

- Definition

Number of segments reported by the entity. A reportable segment is a component of an entity for which there is an accounting requirement to report separate financial information on that component in the entity's financial statements.

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 280
-SubTopic 10
-Section 50
-Paragraph 18
-URI http://asc.fasb.org/extlink&oid=123359005&loc=d3e8672-108599

+ Details

Name:	us-gaap_NumberOfReportableSegments
Namespace Prefix:	us-gaap_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	duration

- Definition

Amount of increase (decrease) of physical assets used in the normal conduct of business and not intended for resale, from reclassification, impairment, donation, or changes classified as other. Examples include, but are not limited to, land, buildings, machinery and equipment, office equipment, and furniture and fixtures.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 360
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=109226691&loc=d3e2921-110230

+ Details

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

- Definition

Amount of the unrecorded obligation to transfer funds in the future for fixed or minimum amounts or quantities of goods or services at fixed or minimum prices (for example, as in take-or-pay contracts or throughput contracts).

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 440
-SubTopic 10
-Section 50
-Paragraph 4
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=123406679&loc=d3e25336-109308

+ Details

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

- Details

Name:	dei_LegalEntityAxis=aee_UnionElectricCompanyMember
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:	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_ProductOrServiceAxis=us-gaap_ElectricityMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	srt_ProductOrServiceAxis=aee_PowerMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	srt_ProductOrServiceAxis=srt_NaturalGasReservesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_StatementBusinessSegmentsAxis=aee_AmerenIllinoisElectricDistributionMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_StatementBusinessSegmentsAxis=aee_AmerenIllinoisGasMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_StatementBusinessSegmentsAxis=aee_AmerenIllinoisTransmissionMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_StatementBusinessSegmentsAxis=aee_AmerenTransmissionMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_PublicUtilitiesRegulatoryProceedingAxis=us-gaap_AssetRetirementObligationCostsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_LongTermPurchaseCommitmentByCategoryOfItemPurchasedAxis=aee_PartnershipFundingCommitmentMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Summary Of Significant Accounting Policies (Narrative) (Details) customer in Millions	12 Months Ended
	Dec. 31, 2022 USD ($) mi² customer segment	Dec. 31, 2021 USD ($)	Dec. 31, 2020 USD ($)
Accounting Policies [Line Items]
Goodwill	$ 411,000,000	$ 411,000,000
Number of reportable segments \| segment	4
Goodwill, Impairment Loss	$ 0
Noncontrolling Interest in Variable Interest Entity	68,000,000	56,000,000
Cash Surrender Value of Life Insurance	246,000,000	278,000,000
Loans, Gross, Insurance Policy	110,000,000	109,000,000
MISO Resettlements	$ 0
Union Electric Company
Accounting Policies [Line Items]
Public Utilities, Area Serviced \| mi²	24,000
Number of Months Between Callaway Maintenance Outages	18 months
Ameren Illinois Company
Accounting Policies [Line Items]
Public Utilities, Area Serviced \| mi²	43,700
Goodwill	$ 411,000,000	411,000,000
Number of reportable segments \| segment	3
Goodwill, Impairment Loss	$ 0
Cash Surrender Value of Life Insurance	118,000,000	117,000,000
Loans, Gross, Insurance Policy	$ 110,000,000	$ 109,000,000
Minimum
Accounting Policies [Line Items]
Percent of average depreciable cost	3.00%	3.00%	3.00%
Maximum
Accounting Policies [Line Items]
Percent of average depreciable cost	4.00%	4.00%	4.00%
Electric \| Union Electric Company
Accounting Policies [Line Items]
Public Utilities, Number of Customers \| customer	1.2
Power \| Ameren Illinois Company
Accounting Policies [Line Items]
Public Utilities, Number of Customers \| customer	1.2
Natural gas \| Union Electric Company
Accounting Policies [Line Items]
Public Utilities, Number of Customers \| customer	0.1
Natural gas \| Ameren Illinois Company
Accounting Policies [Line Items]
Public Utilities, Number of Customers \| customer	0.8
Ameren Illinois Electric Distribution
Accounting Policies [Line Items]
Goodwill	$ 238,000,000
Ameren Illinois Gas
Accounting Policies [Line Items]
Goodwill	80,000,000
Ameren Illinois Transmission
Accounting Policies [Line Items]
Goodwill	93,000,000
Ameren Transmission
Accounting Policies [Line Items]
Goodwill	93,000,000
AROs \| Union Electric Company
Accounting Policies [Line Items]
Noncash Depreciation related to ARO	7,000,000	$ 14,000,000	$ 28,000,000
Partnership Funding Commitment [Member]
Accounting Policies [Line Items]
Unrecorded Unconditional Purchase Obligation	$ 19,000,000