Debt (Other Short-Term Borrowings) (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2024	Sep. 30, 2023	Sep. 30, 2024	Sep. 30, 2023
Debt [Line Items]
Maximum amount outstanding (based on daily outstanding balances)	$ 330	$ 474	$ 632	$ 793
Average amount outstanding (based on daily outstanding balances)	$ 197	$ 440	$ 320	$ 367
Weighted average interest rates	5.40%	5.50%	5.50%	5.10%
IPL [Member]
Debt [Line Items]
Maximum amount outstanding (based on daily outstanding balances)	$ 0	$ 7	$ 19	$ 70
Average amount outstanding (based on daily outstanding balances)	$ 0	$ 0	$ 1	$ 2
Weighted average interest rates	0.00%	5.50%	5.50%	5.30%
WPL [Member]
Debt [Line Items]
Maximum amount outstanding (based on daily outstanding balances)	$ 0	$ 125	$ 390	$ 349
Average amount outstanding (based on daily outstanding balances)	$ 0	$ 86	$ 87	$ 135
Weighted average interest rates	0.00%	5.40%	5.50%	4.90%