Debt (Credit Facilities) (Details) - USD ($) $ in Millions	Dec. 31, 2022	Dec. 31, 2021
Commercial paper and borrowings under the single credit facility:
Amount outstanding	$ 642	$ 515
Weighted average interest rates	4.60%	0.20%
Available credit facility capacity	$ 358	$ 485
IPL [Member]
Commercial paper and borrowings under the single credit facility:
Amount outstanding	0	0
Available credit facility capacity	100	250
WPL [Member]
Commercial paper and borrowings under the single credit facility:
Amount outstanding	$ 290	$ 236
Weighted average interest rates	4.50%	0.20%
Available credit facility capacity	$ 110	$ 64