Receivables (Details of Accounts Receivable) (Details) - USD ($) $ in Millions	Dec. 31, 2023	Dec. 31, 2022
Receivables [Line Items]
Customer	$ 121	$ 114
Unbilled utility revenues	93	115
Deferred proceeds	216	185
Other	53	109
Allowance for expected credit losses	(8)	(7)
Accounts receivable, less allowance for expected credit losses	475	516
IPL [Member]
Receivables [Line Items]
Customer	0	0
Unbilled utility revenues	0	0
Deferred proceeds	216	185
Other	26	74
Allowance for expected credit losses	0	0
Accounts receivable, less allowance for expected credit losses	242	259
WPL [Member]
Receivables [Line Items]
Customer	110	102
Unbilled utility revenues	93	115
Other	24	34
Allowance for expected credit losses	(8)	(7)
Accounts receivable, less allowance for expected credit losses	$ 219	$ 244