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Supplemental Information (Schedule of Asset Retirement Obligations) (Details) - USD ($) $ in Millions | 9 Months Ended |
--- | --- | ---
Sep. 30, 2023 | Dec. 31, 2022
Asset Retirement Obligation, Roll Forward Analysis [Roll Forward] |  |
Asset Retirement Obligation, Beginning Balance | $ 786 |
Liabilities settled | (9) |
Accretion | 25 |
Change in estimates | (18) |
Asset Retirement Obligation, Ending Balance | 784 |
Other current liabilities | 664 | $ 738
Union Electric Company |  |
Asset Retirement Obligation, Roll Forward Analysis [Roll Forward] |  |
Asset Retirement Obligation, Beginning Balance | 782 |
Liabilities settled | (9) |
Accretion | 25 |
Change in estimates | (18) |
Asset Retirement Obligation, Ending Balance | 780 |
Other current liabilities | 213 | 323
Ameren Illinois Company |  |
Asset Retirement Obligation, Roll Forward Analysis [Roll Forward] |  |
Asset Retirement Obligation, Beginning Balance | 4 |
Liabilities settled | 0 |
Accretion | 0 |
Change in estimates | 0 |
Asset Retirement Obligation, Ending Balance | 4 |
Other current liabilities | 242 | 232
Asset Retirement Obligation Balance |  |
Asset Retirement Obligation, Roll Forward Analysis [Roll Forward] |  |
Other current liabilities | 23 | 23
Asset Retirement Obligation Balance | Union Electric Company |  |
Asset Retirement Obligation, Roll Forward Analysis [Roll Forward] |  |
Other current liabilities | $ 23 | $ 23

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- Definition The carrying amount of a liability for an asset retirement obligation. An asset retirement obligation is a legal obligation associated with the disposal or retirement of a tangible long-lived asset that results from the acquisition, construction or development, or the normal operations of a long-lived asset, except for certain obligations of lessees. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Topic 410 -SubTopic 20 -Name Accounting Standards Codification -Section 25 -Paragraph 4 -Publisher FASB -URI https://asc.fasb.org//1943274/2147481999/410-20-25-4 Reference 2: http://www.xbrl.org/2003/role/disclosureRef -Topic 410 -SubTopic 20 -Name Accounting Standards Codification -Section 50 -Paragraph 1 -Subparagraph (c) -Publisher FASB -URI https://asc.fasb.org//1943274/2147481850/410-20-50-1 + Details
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- Definition Amount of accretion expense recognized during the period that is associated with an asset retirement obligation. Accretion expense measures and incorporates changes due to the passage of time into the carrying amount of the liability. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Topic 410 -SubTopic 20 -Name Accounting Standards Codification -Section 45 -Paragraph 1 -Publisher FASB -URI https://asc.fasb.org//1943274/2147481879/410-20-45-1 Reference 2: http://www.xbrl.org/2003/role/disclosureRef -Topic 410 -SubTopic 20 -Name Accounting Standards Codification -Section 50 -Paragraph 1 -Subparagraph (c)(3) -Publisher FASB -URI https://asc.fasb.org//1943274/2147481850/410-20-50-1 + Details
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- Definition Amount of asset retirement obligations settled, or otherwise disposed of, during the period. This may include asset retirement obligations transferred to third parties associated with the sale of a long-lived asset. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Topic 410 -SubTopic 20 -Name Accounting Standards Codification -Section 50 -Paragraph 1 -Subparagraph (c)(2) -Publisher FASB -URI https://asc.fasb.org//1943274/2147481850/410-20-50-1 + Details
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- Definition Amount of increase (decrease) in the asset retirement obligation from changes in the amount or timing of the estimated cash flows associated with the settlement of the obligation. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Topic 410 -SubTopic 20 -Name Accounting Standards Codification -Section 50 -Paragraph 1 -Subparagraph (c)(4) -Publisher FASB -URI https://asc.fasb.org//1943274/2147481850/410-20-50-1 + Details
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- Definition Amount of liabilities classified as other, due within one year or the normal operating cycle, if longer. + References Reference 1: http://www.xbrl.org/2003/role/exampleRef -Topic 852 -SubTopic 10 -Name Accounting Standards Codification -Section 55 -Paragraph 10 -Publisher FASB -URI https://asc.fasb.org//1943274/2147481372/852-10-55-10 Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef -Name Accounting Standards Codification -Topic 210 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.5-02.20) -Publisher FASB -URI https://asc.fasb.org//1943274/2147480566/210-10-S99-1 + Details
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