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Income Taxes (Narrative) (Details) - USD ($) $ in Millions | 3 Months Ended | 9 Months Ended
--- | --- | ---
Sep. 30, 2025 | Sep. 30, 2024 | Sep. 30, 2025 | Sep. 30, 2024
Income Taxes [Line Items] |  |  |  |
Asset valuation charge for IPL's Lansing Generating Station | $ 0 | $ 0 | $ 0 | $ 60
Income tax expense attributable to state income tax apportionment remeasurement | 8 |  |  |
Steam Plant [Member] |  |  |  |
Income Taxes [Line Items] |  |  |  |
Asset retirement obligation charge for IPL's steam assets |  |  |  | 20
IPL [Member] |  |  |  |
Income Taxes [Line Items] |  |  |  |
Asset valuation charge for IPL's Lansing Generating Station | 0 | 0 | 0 | 60
Asset retirement obligation charge for IPL's steam assets | $ 108 | $ 96 | $ 275 | 281
IPL [Member] | Steam Plant [Member] |  |  |  |
Income Taxes [Line Items] |  |  |  |
Asset retirement obligation charge for IPL's steam assets |  |  |  | $ 20

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- Definition Amount of write-down of assets recognized in the income statement. Includes, but is not limited to, losses from tangible assets, intangible assets and goodwill. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Name Accounting Standards Codification -Section 45 -Paragraph 28 -Subparagraph (b) -SubTopic 10 -Topic 230 -Publisher FASB -URI https://asc.fasb.org/1943274/2147482740/230-10-45-28 Reference 2: http://www.xbrl.org/2003/role/exampleRef -Topic 942 -SubTopic 10 -Name Accounting Standards Codification -Section S50 -Paragraph 1 -Publisher FASB -URI https://asc.fasb.org/1943274/2147480095/942-10-S50-1 Reference 3: http://www.xbrl.org/2003/role/exampleRef -Topic 942 -SubTopic 10 -Name Accounting Standards Codification -Section S99 -Paragraph 6 -Publisher FASB -URI https://asc.fasb.org/1943274/2147480035/942-10-S99-6 Reference 4: http://fasb.org/us-gaap/role/ref/legacyRef -Name Accounting Standards Codification -Topic 360 -SubTopic 10 -Section 45 -Paragraph 4 -Publisher FASB -URI https://asc.fasb.org/1943274/2147482130/360-10-45-4 + Details
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- Definition Amount of deferred state and local tax expense (benefit) attributable to income (loss) from continuing operations. Includes, but is not limited to, deferred regional, territorial, and provincial tax expense (benefit) for non-US (United States of America) jurisdiction. + References Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef -Topic 235 -SubTopic 10 -Name Accounting Standards Codification -Section S50 -Paragraph 1 -Publisher FASB -URI https://asc.fasb.org/1943274/2147480738/235-10-S50-1 Reference 2: http://www.xbrl.org/2009/role/commonPracticeRef -Topic 740 -SubTopic 10 -Name Accounting Standards Codification -Section S99 -Paragraph 1 -Subparagraph (SAB Topic 6.I.7) -Publisher FASB -URI https://asc.fasb.org/1943274/2147479360/740-10-S99-1 Reference 3: http://www.xbrl.org/2009/role/commonPracticeRef -Topic 235 -SubTopic 10 -Name Accounting Standards Codification -Section S99 -Paragraph 1 -Subparagraph (SX 210.4-08(h)(1)(Note 1)) -Publisher FASB -URI https://asc.fasb.org/1943274/2147480678/235-10-S99-1 Reference 4: http://www.xbrl.org/2009/role/commonPracticeRef -Topic 740 -SubTopic 10 -Name Accounting Standards Codification -Section 50 -Paragraph 9 -Subparagraph (b) -Publisher FASB -URI https://asc.fasb.org/1943274/2147482685/740-10-50-9 + Details
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