Regulatory Matters (Narrative) (Details) - USD ($) $ in Millions	Sep. 30, 2022	Dec. 31, 2021
Regulatory Matters [Line Items]
Regulatory assets	$ 2,041	$ 1,940
IPL [Member]
Regulatory Matters [Line Items]
Regulatory assets	1,423	1,443
WPL [Member]
Regulatory Matters [Line Items]
Regulatory assets	618	$ 497
Deferred Fuel Costs | WPL [Member]
Regulatory Matters [Line Items]
Regulatory assets	$ 83