Debt (Other Short-Term Borrowings) (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022
Debt [Line Items]
Maximum amount outstanding (based on daily outstanding balances)	$ 474	$ 449	$ 793	$ 577
Average amount outstanding (based on daily outstanding balances)	$ 440	$ 353	$ 367	$ 377
Weighted average interest rates	5.50%	2.40%	5.10%	1.20%
IPL [Member]
Debt [Line Items]
Maximum amount outstanding (based on daily outstanding balances)	$ 7	$ 0	$ 70	$ 0
Average amount outstanding (based on daily outstanding balances)	$ 0	$ 0	$ 2	$ 0
Weighted average interest rates	5.50%	0.00%	5.30%	0.00%
WPL [Member]
Debt [Line Items]
Maximum amount outstanding (based on daily outstanding balances)	$ 125	$ 251	$ 349	$ 252
Average amount outstanding (based on daily outstanding balances)	$ 86	$ 110	$ 135	$ 160
Weighted average interest rates	5.40%	2.00%	4.90%	0.90%