Derivative Instruments (Balance Sheet Offsetting) (Details) - Commodity Contracts [Member] - USD ($) $ in Millions	Sep. 30, 2024	Dec. 31, 2023
Derivative Instruments [Line Items]
Derivative assets, Gross (as reported)	$ 82	$ 88
Derivative assets, Net	63	47
Derivative liabilities, Gross (as reported)	76	98
Derivative liabilities, Net	57	57
IPL [Member]
Derivative Instruments [Line Items]
Derivative assets, Gross (as reported)	55	54
Derivative assets, Net	45	32
Derivative liabilities, Gross (as reported)	20	30
Derivative liabilities, Net	10	8
WPL [Member]
Derivative Instruments [Line Items]
Derivative assets, Gross (as reported)	27	34
Derivative assets, Net	18	15
Derivative liabilities, Gross (as reported)	56	68
Derivative liabilities, Net	$ 47	$ 49

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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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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