Related Parties (Service Agreements) (Details) - Corporate Services [Member] - Subsidiary of Common Parent [Member] - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Administrative and General Services Billings [Member] | IPL [Member]
Related Party Transaction [Line Items]
Amounts billed between related parties	$ 181	$ 180	$ 176
Administrative and General Services Billings [Member] | WPL [Member]
Related Party Transaction [Line Items]
Amounts billed between related parties	155	154	142
Transmission Sales Credited [Member] | IPL [Member]
Related Party Transaction [Line Items]
Amounts billed between related parties	19	22	35
Transmission Sales Credited [Member] | WPL [Member]
Related Party Transaction [Line Items]
Amounts billed between related parties	74	23	3
Transmission Purchases Billed [Member] | IPL [Member]
Related Party Transaction [Line Items]
Amounts billed between related parties	435	441	329
Transmission Purchases Billed [Member] | WPL [Member]
Related Party Transaction [Line Items]
Amounts billed between related parties	$ 174	$ 116	$ 108