Related Parties (Service Agreements) (Details) - Corporate Services [Member] - Subsidiary of Common Parent [Member] - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2022	Sep. 30, 2021	Sep. 30, 2022	Sep. 30, 2021
Corporate Services Billings [Member] | IPL [Member]
Related Party Transactions [Line Items]
Amounts billed between related parties	$ 45	$ 50	$ 136	$ 138
Corporate Services Billings [Member] | WPL [Member]
Related Party Transactions [Line Items]
Amounts billed between related parties	39	37	117	113
Sales Credited [Member] | IPL [Member]
Related Party Transactions [Line Items]
Amounts billed between related parties	11	4	11	9
Sales Credited [Member] | WPL [Member]
Related Party Transactions [Line Items]
Amounts billed between related parties	31	16	62	23
Purchases Billed [Member] | IPL [Member]
Related Party Transactions [Line Items]
Amounts billed between related parties	119	105	342	347
Purchases Billed [Member] | WPL [Member]
Related Party Transactions [Line Items]
Amounts billed between related parties	$ 42	$ 24	$ 103	$ 71