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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

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