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Receivables (Tables) | 12 Months Ended
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Dec. 31, 2024
Receivables [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
| 2024 |  | 2023 |  | 2024 |  | 2023 |  | 2024 |  | 2023
Customer | $113 |  |  | $121 |  |  | $— |  |  | $— |  |  | $98 |  |  | $110 |
Unbilled utility revenues | 101 |  |  | 93 |  |  | — |  |  | — |  |  | 101 |  |  | 93 |
Deferred proceeds | 163 |  |  | 216 |  |  | 163 |  |  | 216 |  |  | — |  |  | — |
Other | 58 |  |  | 53 |  |  | 29 |  |  | 26 |  |  | 29 |  |  | 24 |
Allowance for expected credit losses | (8) |  |  | (8) |  |  | — |  |  | — |  |  | (8) |  |  | (8) |
| $427 |  |  | $475 |  |  | $192 |  |  | $242 |  |  | $220 |  |  | $219 |
Gross Write-offs for Accounts Receivable | In 2024, gross write-offs for accounts receivable were as follows (in millions):
| Originated in 2023 |  | Originated in 2024
Alliant Energy | $12 |  | $14
IPL | 8 |  | 9
WPL | 4 |  | 5
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
| 2024 |  | 2023 |  | 2022 |  | 2024 |  | 2023 |  | 2022
Outstanding aggregate cash proceeds | $110 |  | $110 |  | $80 |  | $31 |  | $51 |  | $14
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):
| 2024 |  | 2023
Customer accounts receivable | $137 |  | $130
Unbilled utility revenues | 108 |  | 98
Other receivables | — |  | 1
Receivables sold to third party | 245 |  | 229
Less: cash proceeds | 70 |  | 1
Deferred proceeds | 175 |  | 228
Less: allowance for expected credit losses | 12 |  | 12
Fair value of deferred proceeds | $163 |  | $216
Outstanding receivables past due | $21 |  | $22
Additional Attributes Of Receivables Sold Under The Agreement | Additional attributes of IPL’s receivables sold under the Receivables Agreement were as follows (in millions):
| 2024 |  | 2023 |  | 2022
Collections | $2,090 |  | $2,233 |  | $2,302 |
Write-offs, net of recoveries | 12 |  | 12 |  | 9 |
IPL [Member] |
Receivables [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
| 2024 |  | 2023 |  | 2024 |  | 2023 |  | 2024 |  | 2023
Customer | $113 |  |  | $121 |  |  | $— |  |  | $— |  |  | $98 |  |  | $110 |
Unbilled utility revenues | 101 |  |  | 93 |  |  | — |  |  | — |  |  | 101 |  |  | 93 |
Deferred proceeds | 163 |  |  | 216 |  |  | 163 |  |  | 216 |  |  | — |  |  | — |
Other | 58 |  |  | 53 |  |  | 29 |  |  | 26 |  |  | 29 |  |  | 24 |
Allowance for expected credit losses | (8) |  |  | (8) |  |  | — |  |  | — |  |  | (8) |  |  | (8) |
| $427 |  |  | $475 |  |  | $192 |  |  | $242 |  |  | $220 |  |  | $219 |
Gross Write-offs for Accounts Receivable | In 2024, gross write-offs for accounts receivable were as follows (in millions):
| Originated in 2023 |  | Originated in 2024
Alliant Energy | $12 |  | $14
IPL | 8 |  | 9
WPL | 4 |  | 5
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
| 2024 |  | 2023 |  | 2022 |  | 2024 |  | 2023 |  | 2022
Outstanding aggregate cash proceeds | $110 |  | $110 |  | $80 |  | $31 |  | $51 |  | $14
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):
| 2024 |  | 2023
Customer accounts receivable | $137 |  | $130
Unbilled utility revenues | 108 |  | 98
Other receivables | — |  | 1
Receivables sold to third party | 245 |  | 229
Less: cash proceeds | 70 |  | 1
Deferred proceeds | 175 |  | 228
Less: allowance for expected credit losses | 12 |  | 12
Fair value of deferred proceeds | $163 |  | $216
Outstanding receivables past due | $21 |  | $22
Additional Attributes Of Receivables Sold Under The Agreement | Additional attributes of IPL’s receivables sold under the Receivables Agreement were as follows (in millions):
| 2024 |  | 2023 |  | 2022
Collections | $2,090 |  | $2,233 |  | $2,302 |
Write-offs, net of recoveries | 12 |  | 12 |  | 9 |
WPL [Member] |
Receivables [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
| 2024 |  | 2023 |  | 2024 |  | 2023 |  | 2024 |  | 2023
Customer | $113 |  |  | $121 |  |  | $— |  |  | $— |  |  | $98 |  |  | $110 |
Unbilled utility revenues | 101 |  |  | 93 |  |  | — |  |  | — |  |  | 101 |  |  | 93 |
Deferred proceeds | 163 |  |  | 216 |  |  | 163 |  |  | 216 |  |  | — |  |  | — |
Other | 58 |  |  | 53 |  |  | 29 |  |  | 26 |  |  | 29 |  |  | 24 |
Allowance for expected credit losses | (8) |  |  | (8) |  |  | — |  |  | — |  |  | (8) |  |  | (8) |
| $427 |  |  | $475 |  |  | $192 |  |  | $242 |  |  | $220 |  |  | $219 |
Gross Write-offs for Accounts Receivable | In 2024, gross write-offs for accounts receivable were as follows (in millions):
| Originated in 2023 |  | Originated in 2024
Alliant Energy | $12 |  | $14
IPL | 8 |  | 9
WPL | 4 |  | 5

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- Definition Tabular disclosure of financing receivables by credit quality indicator. The credit quality indicator is a statistic about the credit quality of financing receivables. Examples include, but not limited to, consumer credit risk scores, credit-rating-agency ratings, an entity's internal credit risk grades, loan-to-value ratios, collateral, collection experience and other internal metrics. + References Reference 1: http://fasb.org/us-gaap/role/ref/otherTransitionRef -Topic 310 -SubTopic 10 -Name Accounting Standards Codification -Section 50 -Paragraph 29 -Publisher FASB -URI https://asc.fasb.org/1943274/2147481962/310-10-50-29 Reference 2: http://www.xbrl.org/2009/role/commonPracticeRef -Topic 326 -SubTopic 20 -Name Accounting Standards Codification -Section 50 -Paragraph 5 -Publisher FASB -URI https://asc.fasb.org/1943274/2147479319/326-20-50-5 + Details
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- Definition Tabular disclosure of the various types of trade accounts and notes receivable and for each the gross carrying value, allowance, and net carrying value as of the balance sheet date. Presentation is categorized by current, noncurrent and unclassified receivables. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Topic 210 -SubTopic 10 -Name Accounting Standards Codification -Section S99 -Paragraph 1 -Subparagraph (SX 210.5-02(4)) -Publisher FASB -URI https://asc.fasb.org/1943274/2147480566/210-10-S99-1 Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef -Topic 210 -SubTopic 10 -Name Accounting Standards Codification -Section S99 -Paragraph 1 -Subparagraph (SX 210.5-02(3)) -Publisher FASB -URI https://asc.fasb.org/1943274/2147480566/210-10-S99-1 + Details
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