Derivative Instruments (Balance Sheet Offsetting) (Details) - Commodity Contracts [Member] - USD ($) $ in Millions	Sep. 30, 2023	Dec. 31, 2022
Derivative Instruments [Line Items]
Derivative assets, Gross (as reported)	$ 129	$ 237
Derivative assets, Net	108	193
Derivative liabilities, Gross (as reported)	66	79
Derivative liabilities, Net	45	35
IPL [Member]
Derivative Instruments [Line Items]
Derivative assets, Gross (as reported)	85	138
Derivative assets, Net	73	108
Derivative liabilities, Gross (as reported)	21	46
Derivative liabilities, Net	9	16
WPL [Member]
Derivative Instruments [Line Items]
Derivative assets, Gross (as reported)	44	99
Derivative assets, Net	35	85
Derivative liabilities, Gross (as reported)	45	33
Derivative liabilities, Net	$ 36	$ 19

Fair value, before effects of master netting arrangements, of a financial asset or other contract with one or more underlyings, notional amount or payment provision or both, and the contract can be net settled by means outside the contract or delivery of an asset. Includes assets elected not to be offset. Excludes assets not subject to a master netting arrangement.

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Fair value, after effect of master netting arrangement and deduction of obligation to return financial collateral not offset and financial instrument subject to master netting arrangement not offset, of financial asset or other contract with one or more underlyings, notional amount or payment provision or both, and contract can be net settled by means outside contract or delivery of asset. Includes derivative not subject to master netting arrangement or similar agreement.

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Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

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