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Summary of Significant Accounting Policies (Narrative) (Details) - USD ($) $ in Millions | Mar. 31, 2024 | Dec. 31, 2023
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Basis Of Presentation And Significant Accounting Policies [Line Items] |  |
Unconsolidated variable interest | $ 74 | $ 73
Cash Surrender Value of Life Insurance | 255 | 248
Corporate owned life insurance, borrowings | 104 | 104
Ameren Illinois Company |  |
Basis Of Presentation And Significant Accounting Policies [Line Items] |  |
Cash Surrender Value of Life Insurance | 112 | 111
Corporate owned life insurance, borrowings | 104 | $ 104
Partnership Funding Commitment |  |
Basis Of Presentation And Significant Accounting Policies [Line Items] |  |
Outstanding funding commitments | $ 14 |

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- 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://www.xbrl.org/2009/role/commonPracticeRef -Topic 210 -SubTopic 10 -Name Accounting Standards Codification -Section S99 -Paragraph 1 -Subparagraph (SX 210.5-02(17)) -Publisher FASB -URI https://asc.fasb.org//1943274/2147480566/210-10-S99-1 + Details
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- 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
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