Debt (Other Short-Term Borrowings) (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2023	Jun. 30, 2022	Jun. 30, 2023	Jun. 30, 2022
Debt [Line Items]
Maximum amount outstanding (based on daily outstanding balances)	$ 391	$ 441	$ 793	$ 577
Average amount outstanding (based on daily outstanding balances)	$ 88	$ 337	$ 330	$ 390
Weighted average interest rates	5.30%	1.00%	4.80%	0.60%
IPL [Member]
Debt [Line Items]
Maximum amount outstanding (based on daily outstanding balances)	$ 70	$ 0	$ 70	$ 0
Average amount outstanding (based on daily outstanding balances)	$ 6	$ 0	$ 3	$ 0
Weighted average interest rates	5.30%	0.00%	5.30%	0.00%
WPL [Member]
Debt [Line Items]
Maximum amount outstanding (based on daily outstanding balances)	$ 91	$ 222	$ 349	$ 252
Average amount outstanding (based on daily outstanding balances)	$ 18	$ 166	$ 160	$ 185
Weighted average interest rates	5.20%	0.90%	4.80%	0.50%