Debt (Other Short-Term Borrowings) (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2022	Jun. 30, 2021	Jun. 30, 2022	Jun. 30, 2021
Debt [Line Items]
Maximum amount outstanding (based on daily outstanding balances)	$ 441	$ 571	$ 577	$ 578
Average amount outstanding (based on daily outstanding balances)	$ 337	$ 452	$ 390	$ 438
Weighted average interest rates	1.00%	0.20%	0.60%	0.20%
IPL [Member]
Debt [Line Items]
Maximum amount outstanding (based on daily outstanding balances)	$ 0	$ 19	$ 0	$ 19
Average amount outstanding (based on daily outstanding balances)	$ 0	$ 1	$ 0	$ 0
Weighted average interest rates	0.00%	0.20%	0.00%	0.20%
WPL [Member]
Debt [Line Items]
Maximum amount outstanding (based on daily outstanding balances)	$ 222	$ 232	$ 252	$ 275
Average amount outstanding (based on daily outstanding balances)	$ 166	$ 177	$ 185	$ 183
Weighted average interest rates	0.90%	0.10%	0.50%	0.10%