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Receivables (Details of Accounts Receivable) (Details) - USD ($) $ in Millions | Dec. 31, 2021 | Dec. 31, 2020
--- | --- | ---
Accounts Receivable [Line Items] |  |
Customer | $ 93 | $ 101
Unbilled utility revenues | 91 | 82
Deferred proceeds | 214 | 188
Other | 53 | 59
Allowance for expected credit losses | (11) | (18)
Accounts receivable, less allowance for expected credit losses | 440 | 412
IPL [Member] |  |
Accounts Receivable [Line Items] |  |
Customer | 0 | 0
Unbilled utility revenues | 0 | 0
Deferred proceeds | 214 | 188
Other | 28 | 23
Allowance for expected credit losses | (1) | (1)
Accounts receivable, less allowance for expected credit losses | 241 | 210
WPL [Member] |  |
Accounts Receivable [Line Items] |  |
Customer | 82 | 92
Unbilled utility revenues | 91 | 82
Other | 25 | 35
Allowance for expected credit losses | (10) | (17)
Accounts receivable, less allowance for expected credit losses | $ 188 | $ 192

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