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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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Income tax

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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.

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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.

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Amount of operating expense for routine plant maintenance, repairs and operations of regulated operation.

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