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Receivables (Tables) | 12 Months Ended
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Dec. 31, 2021
Accounts Receivable [Line Items] |
Accounts Receivable Details | Details for accounts receivable included on the balance sheets as of December 31 were as follows (in millions):
| Alliant Energy |  | IPL |  | WPL
| 2021 |  | 2020 |  | 2021 |  | 2020 |  | 2021 |  | 2020
Customer | $93 |  |  | $101 |  |  | $— |  |  | $— |  |  | $82 |  |  | $92 |
Unbilled utility revenues | 91 |  |  | 82 |  |  | — |  |  | — |  |  | 91 |  |  | 82 |
Deferred proceeds | 214 |  |  | 188 |  |  | 214 |  |  | 188 |  |  | — |  |  | — |
Other | 53 |  |  | 59 |  |  | 28 |  |  | 23 |  |  | 25 |  |  | 35 |
Allowance for expected credit losses | (11) |  |  | (18) |  |  | (1) |  |  | (1) |  |  | (10) |  |  | (17) |
| $440 |  |  | $412 |  |  | $241 |  |  | $210 |  |  | $188 |  |  | $192 |
Maximum And Average Outstanding Cash Proceeds | IPL’s maximum and average outstanding aggregate cash proceeds (based on daily outstanding balances) related to the sales of accounts receivable program were as follows (in millions):
| Maximum |  | Average
| 2021 |  | 2020 |  | 2019 |  | 2021 |  | 2020 |  | 2019
Outstanding aggregate cash proceeds | $110 |  | $96 |  | $108 |  | $46 |  | $9 |  | $36
Receivables Sold Under the Agreement | As of December 31, the attributes of IPL’s receivables sold under the Receivables Agreement were as follows (in millions):
| 2021 |  | 2020
Customer accounts receivable | $125 |  | $114
Unbilled utility revenues | 104 |  | 92
Receivables sold to third party | 229 |  | 206
Less: cash proceeds | 1 |  | 1
Deferred proceeds | 228 |  | 205
Less: allowance for expected credit losses | 14 |  | 17
Fair value of deferred proceeds | $214 |  | $188
Outstanding receivables past due | $22 |  | $27
Additional Attributes Of Receivables Sold Under The Agreement | Additional attributes of IPL’s receivables sold under the Receivables Agreement were as follows (in millions):
| 2021 |  | 2020 |  | 2019
Collections | $2,134 |  | $2,025 |  | $2,193
Write-offs, net of recoveries | 9 |  | 7 |  | 19
IPL [Member] |
Accounts Receivable [Line Items] |
Accounts Receivable Details | Details for accounts receivable included on the balance sheets as of December 31 were as follows (in millions):
| Alliant Energy |  | IPL |  | WPL
| 2021 |  | 2020 |  | 2021 |  | 2020 |  | 2021 |  | 2020
Customer | $93 |  |  | $101 |  |  | $— |  |  | $— |  |  | $82 |  |  | $92 |
Unbilled utility revenues | 91 |  |  | 82 |  |  | — |  |  | — |  |  | 91 |  |  | 82 |
Deferred proceeds | 214 |  |  | 188 |  |  | 214 |  |  | 188 |  |  | — |  |  | — |
Other | 53 |  |  | 59 |  |  | 28 |  |  | 23 |  |  | 25 |  |  | 35 |
Allowance for expected credit losses | (11) |  |  | (18) |  |  | (1) |  |  | (1) |  |  | (10) |  |  | (17) |
| $440 |  |  | $412 |  |  | $241 |  |  | $210 |  |  | $188 |  |  | $192 |
Maximum And Average Outstanding Cash Proceeds | IPL’s maximum and average outstanding aggregate cash proceeds (based on daily outstanding balances) related to the sales of accounts receivable program were as follows (in millions):
| Maximum |  | Average
| 2021 |  | 2020 |  | 2019 |  | 2021 |  | 2020 |  | 2019
Outstanding aggregate cash proceeds | $110 |  | $96 |  | $108 |  | $46 |  | $9 |  | $36
Receivables Sold Under the Agreement | As of December 31, the attributes of IPL’s receivables sold under the Receivables Agreement were as follows (in millions):
| 2021 |  | 2020
Customer accounts receivable | $125 |  | $114
Unbilled utility revenues | 104 |  | 92
Receivables sold to third party | 229 |  | 206
Less: cash proceeds | 1 |  | 1
Deferred proceeds | 228 |  | 205
Less: allowance for expected credit losses | 14 |  | 17
Fair value of deferred proceeds | $214 |  | $188
Outstanding receivables past due | $22 |  | $27
Additional Attributes Of Receivables Sold Under The Agreement | Additional attributes of IPL’s receivables sold under the Receivables Agreement were as follows (in millions):
| 2021 |  | 2020 |  | 2019
Collections | $2,134 |  | $2,025 |  | $2,193
Write-offs, net of recoveries | 9 |  | 7 |  | 19
WPL [Member] |
Accounts Receivable [Line Items] |
Accounts Receivable Details | Details for accounts receivable included on the balance sheets as of December 31 were as follows (in millions):
| Alliant Energy |  | IPL |  | WPL
| 2021 |  | 2020 |  | 2021 |  | 2020 |  | 2021 |  | 2020
Customer | $93 |  |  | $101 |  |  | $— |  |  | $— |  |  | $82 |  |  | $92 |
Unbilled utility revenues | 91 |  |  | 82 |  |  | — |  |  | — |  |  | 91 |  |  | 82 |
Deferred proceeds | 214 |  |  | 188 |  |  | 214 |  |  | 188 |  |  | — |  |  | — |
Other | 53 |  |  | 59 |  |  | 28 |  |  | 23 |  |  | 25 |  |  | 35 |
Allowance for expected credit losses | (11) |  |  | (18) |  |  | (1) |  |  | (1) |  |  | (10) |  |  | (17) |
| $440 |  |  | $412 |  |  | $241 |  |  | $210 |  |  | $188 |  |  | $192 |

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