Derivative Financial Instruments (Credit Risk) (Details) $ in Millions	Dec. 31, 2023 USD ($)
Credit Derivatives [Line Items]
Derivative, Net Liability Position, Aggregate Fair Value	$ 98
Current collateral assets	6
Additional Collateral, Aggregate Fair Value	85
Ameren Missouri
Credit Derivatives [Line Items]
Derivative, Net Liability Position, Aggregate Fair Value	24
Current collateral assets	0
Additional Collateral, Aggregate Fair Value	19
Ameren Illinois
Credit Derivatives [Line Items]
Derivative, Net Liability Position, Aggregate Fair Value	74
Current collateral assets	6
Additional Collateral, Aggregate Fair Value	$ 66

Cash Collateral Posted, Aggregate Fair Value

No definition available.

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- Definition

The aggregate fair value of additional assets that would be required to be posted as collateral for derivative instruments with credit-risk-related contingent features if the credit-risk-related contingent features were triggered at the end of the reporting period.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Name Accounting Standards Codification
-Topic 815
-SubTopic 10
-Section 50
-Paragraph 4H
-Subparagraph (e)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480434/815-10-50-4H

+ Details

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- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References

No definition available.

+ Details

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- Definition

The aggregate fair value amounts of derivative instruments that contain credit-risk-related contingent features that are in a net liability position at the end of the reporting period. For nonderivative instruments that are designated and qualify as hedging instruments, the fair value amounts are the carrying value of the nonderivative hedging instrument, including the adjustment for the foreign currency transaction gain (loss) on that instrument.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Name Accounting Standards Codification
-Topic 815
-SubTopic 10
-Section 50
-Paragraph 4H
-Subparagraph (c)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480434/815-10-50-4H

+ Details

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