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Income Taxes (Schedule Of Net Operating Loss Carryforwards And Tax Credit Carryforwards) (Details) - USD ($) $ in Millions | Dec. 31, 2025 | Dec. 31, 2024
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Net operating loss carryforwards: |  |
Net operating loss carryforwards: | $ 165 | $ 93
Tax credit carryforwards: | 178 | 410
Federal |  |
Net operating loss carryforwards: |  |
Net operating loss carryforwards: | 77 | 30
Tax credit carryforwards: | 176 | 408
State |  |
Net operating loss carryforwards: |  |
Net operating loss carryforwards: | 88 | 63
Tax credit carryforwards: | 2 | 2
Ameren Missouri |  |
Net operating loss carryforwards: |  |
Net operating loss carryforwards: | 62 | 0
Tax credit carryforwards: | 128 | 355
Ameren Missouri | Federal |  |
Net operating loss carryforwards: |  |
Net operating loss carryforwards: | 53 | 0
Tax credit carryforwards: | 128 | 355
Ameren Missouri | State |  |
Net operating loss carryforwards: |  |
Net operating loss carryforwards: | 9 | 0
Tax credit carryforwards: | 0 | 0
Ameren Illinois |  |
Net operating loss carryforwards: |  |
Net operating loss carryforwards: | 34 | 34
Tax credit carryforwards: | 11 | 11
Ameren Illinois | Federal |  |
Net operating loss carryforwards: |  |
Net operating loss carryforwards: | 0 | 0
Tax credit carryforwards: | 9 | 9
Ameren Illinois | State |  |
Net operating loss carryforwards: |  |
Net operating loss carryforwards: | 34 | 34
Tax credit carryforwards: | 2 | 2
Other |  |
Net operating loss carryforwards: |  |
Net operating loss carryforwards: | 69 | 59
Tax credit carryforwards: | 39 | 44
Other | Federal |  |
Net operating loss carryforwards: |  |
Net operating loss carryforwards: | 24 | 30
Tax credit carryforwards: | 39 | 44
Other | State |  |
Net operating loss carryforwards: |  |
Net operating loss carryforwards: | 45 | 29
Tax credit carryforwards: | $ 0 | $ 0

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- Definition Amount of operating loss carryforward, before tax effects, available to reduce future taxable income under enacted tax laws. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Topic 740 -SubTopic 10 -Name Accounting Standards Codification -Section 50 -Paragraph 3 -Subparagraph (a) -Publisher FASB -URI https://asc.fasb.org/1943274/2147482685/740-10-50-3 + Details
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