Receivables (Details of Accounts Receivable) (Details) - USD ($) $ in Millions	Dec. 31, 2024	Dec. 31, 2023
Receivables [Line Items]
Customer	$ 113	$ 121
Unbilled utility revenues	101	93
Deferred proceeds	163	216
Other	58	53
Allowance for expected credit losses	(8)	(8)
Accounts receivable, less allowance for expected credit losses	427	475
IPL [Member]
Receivables [Line Items]
Customer	0	0
Unbilled utility revenues	0	0
Deferred proceeds	163	216
Other	29	26
Allowance for expected credit losses	0	0
Accounts receivable, less allowance for expected credit losses	192	242
WPL [Member]
Receivables [Line Items]
Customer	98	110
Unbilled utility revenues	101	93
Other	29	24
Allowance for expected credit losses	(8)	(8)
Accounts receivable, less allowance for expected credit losses	$ 220	$ 219