Income Taxes (Narrative) (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2024	Jun. 30, 2023	Jun. 30, 2024	Jun. 30, 2023
Income Taxes [Line Items]
Asset valuation charge for IPL's Lansing Generating Station	$ 60	$ 0	$ 60	$ 0
Steam Plant
Income Taxes [Line Items]
Asset retirement obligation charge for IPL's steam assets	20		20
IPL [Member]
Income Taxes [Line Items]
Asset valuation charge for IPL's Lansing Generating Station	60	0	60	0
Asset retirement obligation charge for IPL's steam assets	102	85	187	181
IPL [Member] | Steam Plant
Income Taxes [Line Items]
Asset retirement obligation charge for IPL's steam assets	20		20
WPL [Member]
Income Taxes [Line Items]
Asset retirement obligation charge for IPL's steam assets	$ 67	$ 67	$ 128	$ 133