Derivative Instruments (Balance Sheet Offsetting) (Details) - Commodity Contracts [Member] - USD ($) $ in Millions	Dec. 31, 2023	Dec. 31, 2022
Derivative [Line Items]
Derivative assets, Gross (as reported)	$ 88	$ 237
Derivative assets, net	47	193
Derivative liabilities, gross (as reported)	98	79
Derivative liabilities, net	57	35
IPL [Member]
Derivative [Line Items]
Derivative assets, Gross (as reported)	54	138
Derivative assets, net	32	108
Derivative liabilities, gross (as reported)	30	46
Derivative liabilities, net	8	16
WPL [Member]
Derivative [Line Items]
Derivative assets, Gross (as reported)	34	99
Derivative assets, net	15	85
Derivative liabilities, gross (as reported)	68	33
Derivative liabilities, net	$ 49	$ 19