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Derivative Instruments (Tables) | 12 Months Ended
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Dec. 31, 2023
Derivative [Line Items] |
Notional Amounts of Derivative Instruments | As of December 31, 2023, gross notional amounts and settlement/delivery years related to outstanding swap contracts, option contracts, physical forward contracts and FTRs that were accounted for as commodity derivative instruments were as follows (units in thousands):
| Electricity |  | FTRs |  | Natural Gas |  |  |  |
| MWhs |  | Years |  | MWhs |  | Years |  | Dths |  | Years |  |  |  |  |  |  |  |
Alliant Energy | 1,640 |  |  | 2024-2026 |  | 11,927 |  |  | 2024 |  | 176,349 |  |  | 2024-2032 |  |  |  |  |  |  |  |
IPL | 673 |  |  | 2024-2026 |  | 5,336 |  |  | 2024 |  | 74,360 |  |  | 2024-2030 |  |  |  |  |  |  |  |
WPL | 967 |  |  | 2024-2026 |  | 6,591 |  |  | 2024 |  | 101,989 |  |  | 2024-2032 |  |  |  |  |  |  |  |
Fair Value of Financial Instruments | At December 31, the fair values of current derivative assets are included in “Other current assets,” non-current derivative assets are included in “Deferred charges and other,” current derivative liabilities are included in “Other current liabilities” and non-current derivative liabilities are included in “Other liabilities” on the balance sheets as follows (in millions):
| Alliant Energy |  | IPL |  | WPL
| 2023 |  | 2022 |  | 2023 |  | 2022 |  | 2023 |  | 2022
Current derivative assets | $44 |  | $111 |  | $30 |  | $69 |  | $14 |  | $42
Non-current derivative assets | 44 |  | 126 |  | 24 |  | 69 |  | 20 |  | 57
Current derivative liabilities | 51 |  | 59 |  | 22 |  | 40 |  | 29 |  | 19
Non-current derivative liabilities | 47 |  | 20 |  | 8 |  | 6 |  | 39 |  | 14
Balance Sheet Offsetting | However, if the fair value amounts of derivative instruments by counterparty were netted, derivative assets and derivative liabilities related to commodity contracts would have been presented on the balance sheets at December 31 as follows:
| Alliant Energy |  | IPL |  | WPL
| Gross |  |  |  | Gross |  |  |  | Gross |  |
| (as reported) |  | Net |  | (as reported) |  | Net |  | (as reported) |  | Net
2023 |  |  |  |  |  |  |  |  |  |  |
Derivative assets | $88 |  | $47 |  | $54 |  | $32 |  | $34 |  | $15
Derivative liabilities | 98 |  | 57 |  | 30 |  | 8 |  | 68 |  | 49
2022 |  |  |  |  |  |  |  |  |  |  |
Derivative assets | 237 |  | 193 |  | 138 |  | 108 |  | 99 |  | 85
Derivative liabilities | 79 |  | 35 |  | 46 |  | 16 |  | 33 |  | 19
IPL [Member] |
Derivative [Line Items] |
Notional Amounts of Derivative Instruments | As of December 31, 2023, gross notional amounts and settlement/delivery years related to outstanding swap contracts, option contracts, physical forward contracts and FTRs that were accounted for as commodity derivative instruments were as follows (units in thousands):
| Electricity |  | FTRs |  | Natural Gas |  |  |  |
| MWhs |  | Years |  | MWhs |  | Years |  | Dths |  | Years |  |  |  |  |  |  |  |
Alliant Energy | 1,640 |  |  | 2024-2026 |  | 11,927 |  |  | 2024 |  | 176,349 |  |  | 2024-2032 |  |  |  |  |  |  |  |
IPL | 673 |  |  | 2024-2026 |  | 5,336 |  |  | 2024 |  | 74,360 |  |  | 2024-2030 |  |  |  |  |  |  |  |
WPL | 967 |  |  | 2024-2026 |  | 6,591 |  |  | 2024 |  | 101,989 |  |  | 2024-2032 |  |  |  |  |  |  |  |
Fair Value of Financial Instruments | At December 31, the fair values of current derivative assets are included in “Other current assets,” non-current derivative assets are included in “Deferred charges and other,” current derivative liabilities are included in “Other current liabilities” and non-current derivative liabilities are included in “Other liabilities” on the balance sheets as follows (in millions):
| Alliant Energy |  | IPL |  | WPL
| 2023 |  | 2022 |  | 2023 |  | 2022 |  | 2023 |  | 2022
Current derivative assets | $44 |  | $111 |  | $30 |  | $69 |  | $14 |  | $42
Non-current derivative assets | 44 |  | 126 |  | 24 |  | 69 |  | 20 |  | 57
Current derivative liabilities | 51 |  | 59 |  | 22 |  | 40 |  | 29 |  | 19
Non-current derivative liabilities | 47 |  | 20 |  | 8 |  | 6 |  | 39 |  | 14
Balance Sheet Offsetting | However, if the fair value amounts of derivative instruments by counterparty were netted, derivative assets and derivative liabilities related to commodity contracts would have been presented on the balance sheets at December 31 as follows:
| Alliant Energy |  | IPL |  | WPL
| Gross |  |  |  | Gross |  |  |  | Gross |  |
| (as reported) |  | Net |  | (as reported) |  | Net |  | (as reported) |  | Net
2023 |  |  |  |  |  |  |  |  |  |  |
Derivative assets | $88 |  | $47 |  | $54 |  | $32 |  | $34 |  | $15
Derivative liabilities | 98 |  | 57 |  | 30 |  | 8 |  | 68 |  | 49
2022 |  |  |  |  |  |  |  |  |  |  |
Derivative assets | 237 |  | 193 |  | 138 |  | 108 |  | 99 |  | 85
Derivative liabilities | 79 |  | 35 |  | 46 |  | 16 |  | 33 |  | 19
WPL [Member] |
Derivative [Line Items] |
Notional Amounts of Derivative Instruments | As of December 31, 2023, gross notional amounts and settlement/delivery years related to outstanding swap contracts, option contracts, physical forward contracts and FTRs that were accounted for as commodity derivative instruments were as follows (units in thousands):
| Electricity |  | FTRs |  | Natural Gas |  |  |  |
| MWhs |  | Years |  | MWhs |  | Years |  | Dths |  | Years |  |  |  |  |  |  |  |
Alliant Energy | 1,640 |  |  | 2024-2026 |  | 11,927 |  |  | 2024 |  | 176,349 |  |  | 2024-2032 |  |  |  |  |  |  |  |
IPL | 673 |  |  | 2024-2026 |  | 5,336 |  |  | 2024 |  | 74,360 |  |  | 2024-2030 |  |  |  |  |  |  |  |
WPL | 967 |  |  | 2024-2026 |  | 6,591 |  |  | 2024 |  | 101,989 |  |  | 2024-2032 |  |  |  |  |  |  |  |
Fair Value of Financial Instruments | At December 31, the fair values of current derivative assets are included in “Other current assets,” non-current derivative assets are included in “Deferred charges and other,” current derivative liabilities are included in “Other current liabilities” and non-current derivative liabilities are included in “Other liabilities” on the balance sheets as follows (in millions):
| Alliant Energy |  | IPL |  | WPL
| 2023 |  | 2022 |  | 2023 |  | 2022 |  | 2023 |  | 2022
Current derivative assets | $44 |  | $111 |  | $30 |  | $69 |  | $14 |  | $42
Non-current derivative assets | 44 |  | 126 |  | 24 |  | 69 |  | 20 |  | 57
Current derivative liabilities | 51 |  | 59 |  | 22 |  | 40 |  | 29 |  | 19
Non-current derivative liabilities | 47 |  | 20 |  | 8 |  | 6 |  | 39 |  | 14
Balance Sheet Offsetting | However, if the fair value amounts of derivative instruments by counterparty were netted, derivative assets and derivative liabilities related to commodity contracts would have been presented on the balance sheets at December 31 as follows:
| Alliant Energy |  | IPL |  | WPL
| Gross |  |  |  | Gross |  |  |  | Gross |  |
| (as reported) |  | Net |  | (as reported) |  | Net |  | (as reported) |  | Net
2023 |  |  |  |  |  |  |  |  |  |  |
Derivative assets | $88 |  | $47 |  | $54 |  | $32 |  | $34 |  | $15
Derivative liabilities | 98 |  | 57 |  | 30 |  | 8 |  | 68 |  | 49
2022 |  |  |  |  |  |  |  |  |  |  |
Derivative assets | 237 |  | 193 |  | 138 |  | 108 |  | 99 |  | 85
Derivative liabilities | 79 |  | 35 |  | 46 |  | 16 |  | 33 |  | 19

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