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Fair Value Measurements (Tables) | 6 Months Ended
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Jun. 30, 2024
Statement [Line Items] |
Fair Value Measurements | Carrying amounts and related estimated fair values of other financial instruments were as follows (in millions):
Alliant Energy | June 30, 2024 |  | December 31, 2023
|  |  | Fair Value |  |  |  | Fair Value
| Carrying |  | Level |  | Level |  | Level |  |  |  | Carrying |  | Level |  | Level |  | Level |  |
| Amount |  | 1 |  | 2 |  | 3 |  | Total |  | Amount |  | 1 |  | 2 |  | 3 |  | Total
Assets: |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Money market fund investments | $73 |  |  | $73 |  |  | $— |  |  | $— |  |  | $73 |  |  | $45 |  |  | $45 |  |  | $— |  |  | $— |  |  | $45 |
Commodity derivatives | 103 |  |  | — |  |  | 46 |  |  | 57 |  |  | 103 |  |  | 88 |  |  | — |  |  | 59 |  |  | 29 |  |  | 88 |
Interest rate derivatives | 3 |  |  | — |  |  | 3 |  |  | — |  |  | 3 |  |  | 1 |  |  | — |  |  | 1 |  |  | — |  |  | 1 |
Deferred proceeds | 171 |  |  | — |  |  | — |  |  | 171 |  |  | 171 |  |  | 216 |  |  | — |  |  | — |  |  | 216 |  |  | 216 |
Liabilities: |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Commodity derivatives | 91 |  |  | — |  |  | 85 |  |  | 6 |  |  | 91 |  |  | 98 |  |  | — |  |  | 93 |  |  | 5 |  |  | 98 |
Long-term debt (incl. current maturities) | 9,704 |  |  | — |  |  | 9,352 |  |  | — |  |  | 9,352 |  |  | 9,034 |  |  | — |  |  | 8,677 |  |  | — |  |  | 8,677 |
IPL | June 30, 2024 |  | December 31, 2023
|  |  | Fair Value |  |  |  | Fair Value
| Carrying |  | Level |  | Level |  | Level |  |  |  | Carrying |  | Level |  | Level |  | Level |  |
| Amount |  | 1 |  | 2 |  | 3 |  | Total |  | Amount |  | 1 |  | 2 |  | 3 |  | Total
Assets: |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Money market fund investments | $1 |  |  | $1 |  |  | $— |  |  | $— |  |  | $1 |  |  | $45 |  |  | $45 |  |  | $— |  |  | $— |  |  | $45 |
Commodity derivatives | 72 |  |  | — |  |  | 26 |  |  | 46 |  |  | 72 |  |  | 54 |  |  | — |  |  | 30 |  |  | 24 |  |  | 54 |
Deferred proceeds | 171 |  |  | — |  |  | — |  |  | 171 |  |  | 171 |  |  | 216 |  |  | — |  |  | — |  |  | 216 |  |  | 216 |
Liabilities: |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Commodity derivatives | 31 |  |  | — |  |  | 25 |  |  | 6 |  |  | 31 |  |  | 30 |  |  | — |  |  | 25 |  |  | 5 |  |  | 30 |
Long-term debt (incl. current maturities) | 3,946 |  |  | — |  |  | 3,577 |  |  | — |  |  | 3,577 |  |  | 3,945 |  |  | — |  |  | 3,664 |  |  | — |  |  | 3,664 |
WPL | June 30, 2024 |  | December 31, 2023
|  |  | Fair Value |  |  |  | Fair Value
| Carrying |  | Level |  | Level |  | Level |  |  |  | Carrying |  | Level |  | Level |  | Level |  |
| Amount |  | 1 |  | 2 |  | 3 |  | Total |  | Amount |  | 1 |  | 2 |  | 3 |  | Total
Assets: |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Money market fund investments | $72 |  |  | $72 |  |  | $— |  |  | $— |  |  | $72 |  |  | $— |  |  | $— |  |  | $— |  |  | $— |  |  | $— |
Commodity derivatives | 31 |  |  | — |  |  | 20 |  |  | 11 |  |  | 31 |  |  | 34 |  |  | — |  |  | 29 |  |  | 5 |  |  | 34 |
Liabilities: |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Commodity derivatives | 60 |  |  | — |  |  | 60 |  |  | — |  |  | 60 |  |  | 68 |  |  | — |  |  | 68 |  |  | — |  |  | 68 |
Long-term debt | 3,368 |  |  | — |  |  | 3,141 |  |  | — |  |  | 3,141 |  |  | 3,070 |  |  | — |  |  | 2,933 |  |  | — |  |  | 2,933 |
Fair Value Measurements Using Significant Unobservable Inputs | Information for fair value measurements using significant unobservable inputs (Level 3 inputs) was as follows (in millions):
Alliant Energy | Commodity Contract Derivative |  |
| Assets and (Liabilities), net |  | Deferred Proceeds
Three Months Ended June 30 | 2024 |  | 2023 |  | 2024 |  | 2023
Beginning balance, April 1 | $7 |  | ($5) |  | $184 |  | $153
Total net losses included in changes in net assets (realized/unrealized) | (5) |  | (7) |  | — |  | —
Purchases | 59 |  | 62 |  | — |  | —
Sales | (1) |  | (1) |  | — |  | —
Settlements (a) | (9) |  | 5 |  | (13) |  | 22
Ending balance, June 30 | $51 |  | $54 |  | $171 |  | $175
The amount of total net losses for the period included in changes in net assets attributable to the change in unrealized losses relating to assets and liabilities held at June 30 | ($5) |  | ($7) |  | $— |  | $—
Alliant Energy | Commodity Contract Derivative |  |
| Assets and (Liabilities), net |  | Deferred Proceeds
Six Months Ended June 30 | 2024 |  | 2023 |  | 2024 |  | 2023
Beginning balance, January 1 | $24 |  | $19 |  | $216 |  | $185
Total net losses included in changes in net assets (realized/unrealized) | (8) |  | (11) |  | — |  | —
Purchases | 59 |  | 62 |  | — |  | —
Sales | (1) |  | (1) |  | — |  | —
Settlements (a) | (23) |  | (15) |  | (45) |  | (10)
Ending balance, June 30 | $51 |  | $54 |  | $171 |  | $175
The amount of total net losses for the period included in changes in net assets attributable to the change in unrealized losses relating to assets and liabilities held at June 30 | ($8) |  | ($11) |  | $— |  | $—
IPL | Commodity Contract Derivative |  |
| Assets and (Liabilities), net |  | Deferred Proceeds
Three Months Ended June 30 | 2024 |  | 2023 |  | 2024 |  | 2023
Beginning balance, April 1 | $5 |  | $— |  | $184 |  | $153
Total net losses included in changes in net assets (realized/unrealized) | (2) |  | (13) |  | — |  | —
Purchases | 45 |  | 51 |  | — |  | —
Sales | (1) |  | (1) |  | — |  | —
Settlements (a) | (7) |  | 4 |  | (13) |  | 22
Ending balance, June 30 | $40 |  | $41 |  | $171 |  | $175
The amount of total net losses for the period included in changes in net assets attributable to the change in unrealized losses relating to assets and liabilities held at June 30 | ($2) |  | ($13) |  | $— |  | $—
IPL | Commodity Contract Derivative |  |
| Assets and (Liabilities), net |  | Deferred Proceeds
Six Months Ended June 30 | 2024 |  | 2023 |  | 2024 |  | 2023
Beginning balance, January 1 | $19 |  | $16 |  | $216 |  | $185
Total net losses included in changes in net assets (realized/unrealized) | (6) |  | (12) |  | — |  | —
Purchases | 45 |  | 51 |  | — |  | —
Sales | (1) |  | (1) |  | — |  | —
Settlements (a) | (17) |  | (13) |  | (45) |  | (10)
Ending balance, June 30 | $40 |  | $41 |  | $171 |  | $175
The amount of total net losses for the period included in changes in net assets attributable to the change in unrealized losses relating to assets and liabilities held at June 30 | ($6) |  | ($12) |  | $— |  | $—
WPL | Commodity Contract Derivative
| Assets and (Liabilities), net
Three Months Ended June 30 | 2024 |  | 2023
Beginning balance, April 1 | $2 |  | ($5)
Total net gains (losses) included in changes in net assets (realized/unrealized) | (3) |  | 6
Purchases | 14 |  | 11
Settlements | (2) |  | 1
Ending balance, June 30 | $11 |  | $13
The amount of total net gains (losses) for the period included in changes in net assets attributable to the change in unrealized gains (losses) relating to assets and liabilities held at June 30 | ($3) |  | $6
WPL | Commodity Contract Derivative
| Assets and (Liabilities), net
Six Months Ended June 30 | 2024 |  | 2023
Beginning balance, January 1 | $5 |  | $3
Total net gains (losses) included in changes in net assets (realized/unrealized) | (2) |  | 1
Purchases | 14 |  | 11
Settlements | (6) |  | (2)
Ending balance, June 30 | $11 |  | $13
The amount of total net gains (losses) for the period included in changes in net assets attributable to the change in unrealized gains (losses) relating to assets and liabilities held at June 30 | ($2) |  | $1
(a)Settlements related to deferred proceeds are due to the change in the carrying amount of receivables sold less the allowance for expected credit losses associated with the receivables sold and cash amounts received from the receivables sold.
Fair Value Of Net Derivative Assets (Liabilities) | The fair value of FTR and natural gas commodity contracts categorized as Level 3 was recognized as net derivative asset s (liabilities) as follows (in millions):
| Alliant Energy |  | IPL |  | WPL
| Excluding FTRs |  | FTRs |  | Excluding FTRs |  | FTRs |  | Excluding FTRs |  | FTRs
June 30, 2024 | ($4) |  | $55 |  | ($4) |  | $44 |  | $— |  | $11
December 31, 2023 | 3 |  | 21 |  | 3 |  | 16 |  | — |  | 5
IPL [Member] |
Statement [Line Items] |
Fair Value Measurements | Carrying amounts and related estimated fair values of other financial instruments were as follows (in millions):
Alliant Energy | June 30, 2024 |  | December 31, 2023
|  |  | Fair Value |  |  |  | Fair Value
| Carrying |  | Level |  | Level |  | Level |  |  |  | Carrying |  | Level |  | Level |  | Level |  |
| Amount |  | 1 |  | 2 |  | 3 |  | Total |  | Amount |  | 1 |  | 2 |  | 3 |  | Total
Assets: |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Money market fund investments | $73 |  |  | $73 |  |  | $— |  |  | $— |  |  | $73 |  |  | $45 |  |  | $45 |  |  | $— |  |  | $— |  |  | $45 |
Commodity derivatives | 103 |  |  | — |  |  | 46 |  |  | 57 |  |  | 103 |  |  | 88 |  |  | — |  |  | 59 |  |  | 29 |  |  | 88 |
Interest rate derivatives | 3 |  |  | — |  |  | 3 |  |  | — |  |  | 3 |  |  | 1 |  |  | — |  |  | 1 |  |  | — |  |  | 1 |
Deferred proceeds | 171 |  |  | — |  |  | — |  |  | 171 |  |  | 171 |  |  | 216 |  |  | — |  |  | — |  |  | 216 |  |  | 216 |
Liabilities: |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Commodity derivatives | 91 |  |  | — |  |  | 85 |  |  | 6 |  |  | 91 |  |  | 98 |  |  | — |  |  | 93 |  |  | 5 |  |  | 98 |
Long-term debt (incl. current maturities) | 9,704 |  |  | — |  |  | 9,352 |  |  | — |  |  | 9,352 |  |  | 9,034 |  |  | — |  |  | 8,677 |  |  | — |  |  | 8,677 |
IPL | June 30, 2024 |  | December 31, 2023
|  |  | Fair Value |  |  |  | Fair Value
| Carrying |  | Level |  | Level |  | Level |  |  |  | Carrying |  | Level |  | Level |  | Level |  |
| Amount |  | 1 |  | 2 |  | 3 |  | Total |  | Amount |  | 1 |  | 2 |  | 3 |  | Total
Assets: |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Money market fund investments | $1 |  |  | $1 |  |  | $— |  |  | $— |  |  | $1 |  |  | $45 |  |  | $45 |  |  | $— |  |  | $— |  |  | $45 |
Commodity derivatives | 72 |  |  | — |  |  | 26 |  |  | 46 |  |  | 72 |  |  | 54 |  |  | — |  |  | 30 |  |  | 24 |  |  | 54 |
Deferred proceeds | 171 |  |  | — |  |  | — |  |  | 171 |  |  | 171 |  |  | 216 |  |  | — |  |  | — |  |  | 216 |  |  | 216 |
Liabilities: |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Commodity derivatives | 31 |  |  | — |  |  | 25 |  |  | 6 |  |  | 31 |  |  | 30 |  |  | — |  |  | 25 |  |  | 5 |  |  | 30 |
Long-term debt (incl. current maturities) | 3,946 |  |  | — |  |  | 3,577 |  |  | — |  |  | 3,577 |  |  | 3,945 |  |  | — |  |  | 3,664 |  |  | — |  |  | 3,664 |
WPL | June 30, 2024 |  | December 31, 2023
|  |  | Fair Value |  |  |  | Fair Value
| Carrying |  | Level |  | Level |  | Level |  |  |  | Carrying |  | Level |  | Level |  | Level |  |
| Amount |  | 1 |  | 2 |  | 3 |  | Total |  | Amount |  | 1 |  | 2 |  | 3 |  | Total
Assets: |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Money market fund investments | $72 |  |  | $72 |  |  | $— |  |  | $— |  |  | $72 |  |  | $— |  |  | $— |  |  | $— |  |  | $— |  |  | $— |
Commodity derivatives | 31 |  |  | — |  |  | 20 |  |  | 11 |  |  | 31 |  |  | 34 |  |  | — |  |  | 29 |  |  | 5 |  |  | 34 |
Liabilities: |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Commodity derivatives | 60 |  |  | — |  |  | 60 |  |  | — |  |  | 60 |  |  | 68 |  |  | — |  |  | 68 |  |  | — |  |  | 68 |
Long-term debt | 3,368 |  |  | — |  |  | 3,141 |  |  | — |  |  | 3,141 |  |  | 3,070 |  |  | — |  |  | 2,933 |  |  | — |  |  | 2,933 |
Fair Value Measurements Using Significant Unobservable Inputs | Information for fair value measurements using significant unobservable inputs (Level 3 inputs) was as follows (in millions):
Alliant Energy | Commodity Contract Derivative |  |
| Assets and (Liabilities), net |  | Deferred Proceeds
Three Months Ended June 30 | 2024 |  | 2023 |  | 2024 |  | 2023
Beginning balance, April 1 | $7 |  | ($5) |  | $184 |  | $153
Total net losses included in changes in net assets (realized/unrealized) | (5) |  | (7) |  | — |  | —
Purchases | 59 |  | 62 |  | — |  | —
Sales | (1) |  | (1) |  | — |  | —
Settlements (a) | (9) |  | 5 |  | (13) |  | 22
Ending balance, June 30 | $51 |  | $54 |  | $171 |  | $175
The amount of total net losses for the period included in changes in net assets attributable to the change in unrealized losses relating to assets and liabilities held at June 30 | ($5) |  | ($7) |  | $— |  | $—
Alliant Energy | Commodity Contract Derivative |  |
| Assets and (Liabilities), net |  | Deferred Proceeds
Six Months Ended June 30 | 2024 |  | 2023 |  | 2024 |  | 2023
Beginning balance, January 1 | $24 |  | $19 |  | $216 |  | $185
Total net losses included in changes in net assets (realized/unrealized) | (8) |  | (11) |  | — |  | —
Purchases | 59 |  | 62 |  | — |  | —
Sales | (1) |  | (1) |  | — |  | —
Settlements (a) | (23) |  | (15) |  | (45) |  | (10)
Ending balance, June 30 | $51 |  | $54 |  | $171 |  | $175
The amount of total net losses for the period included in changes in net assets attributable to the change in unrealized losses relating to assets and liabilities held at June 30 | ($8) |  | ($11) |  | $— |  | $—
IPL | Commodity Contract Derivative |  |
| Assets and (Liabilities), net |  | Deferred Proceeds
Three Months Ended June 30 | 2024 |  | 2023 |  | 2024 |  | 2023
Beginning balance, April 1 | $5 |  | $— |  | $184 |  | $153
Total net losses included in changes in net assets (realized/unrealized) | (2) |  | (13) |  | — |  | —
Purchases | 45 |  | 51 |  | — |  | —
Sales | (1) |  | (1) |  | — |  | —
Settlements (a) | (7) |  | 4 |  | (13) |  | 22
Ending balance, June 30 | $40 |  | $41 |  | $171 |  | $175
The amount of total net losses for the period included in changes in net assets attributable to the change in unrealized losses relating to assets and liabilities held at June 30 | ($2) |  | ($13) |  | $— |  | $—
IPL | Commodity Contract Derivative |  |
| Assets and (Liabilities), net |  | Deferred Proceeds
Six Months Ended June 30 | 2024 |  | 2023 |  | 2024 |  | 2023
Beginning balance, January 1 | $19 |  | $16 |  | $216 |  | $185
Total net losses included in changes in net assets (realized/unrealized) | (6) |  | (12) |  | — |  | —
Purchases | 45 |  | 51 |  | — |  | —
Sales | (1) |  | (1) |  | — |  | —
Settlements (a) | (17) |  | (13) |  | (45) |  | (10)
Ending balance, June 30 | $40 |  | $41 |  | $171 |  | $175
The amount of total net losses for the period included in changes in net assets attributable to the change in unrealized losses relating to assets and liabilities held at June 30 | ($6) |  | ($12) |  | $— |  | $—
WPL | Commodity Contract Derivative
| Assets and (Liabilities), net
Three Months Ended June 30 | 2024 |  | 2023
Beginning balance, April 1 | $2 |  | ($5)
Total net gains (losses) included in changes in net assets (realized/unrealized) | (3) |  | 6
Purchases | 14 |  | 11
Settlements | (2) |  | 1
Ending balance, June 30 | $11 |  | $13
The amount of total net gains (losses) for the period included in changes in net assets attributable to the change in unrealized gains (losses) relating to assets and liabilities held at June 30 | ($3) |  | $6
WPL | Commodity Contract Derivative
| Assets and (Liabilities), net
Six Months Ended June 30 | 2024 |  | 2023
Beginning balance, January 1 | $5 |  | $3
Total net gains (losses) included in changes in net assets (realized/unrealized) | (2) |  | 1
Purchases | 14 |  | 11
Settlements | (6) |  | (2)
Ending balance, June 30 | $11 |  | $13
The amount of total net gains (losses) for the period included in changes in net assets attributable to the change in unrealized gains (losses) relating to assets and liabilities held at June 30 | ($2) |  | $1
(a)Settlements related to deferred proceeds are due to the change in the carrying amount of receivables sold less the allowance for expected credit losses associated with the receivables sold and cash amounts received from the receivables sold.
Fair Value Of Net Derivative Assets (Liabilities) | The fair value of FTR and natural gas commodity contracts categorized as Level 3 was recognized as net derivative asset s (liabilities) as follows (in millions):
| Alliant Energy |  | IPL |  | WPL
| Excluding FTRs |  | FTRs |  | Excluding FTRs |  | FTRs |  | Excluding FTRs |  | FTRs
June 30, 2024 | ($4) |  | $55 |  | ($4) |  | $44 |  | $— |  | $11
December 31, 2023 | 3 |  | 21 |  | 3 |  | 16 |  | — |  | 5
WPL [Member] |
Statement [Line Items] |
Fair Value Measurements | Carrying amounts and related estimated fair values of other financial instruments were as follows (in millions):
Alliant Energy | June 30, 2024 |  | December 31, 2023
|  |  | Fair Value |  |  |  | Fair Value
| Carrying |  | Level |  | Level |  | Level |  |  |  | Carrying |  | Level |  | Level |  | Level |  |
| Amount |  | 1 |  | 2 |  | 3 |  | Total |  | Amount |  | 1 |  | 2 |  | 3 |  | Total
Assets: |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Money market fund investments | $73 |  |  | $73 |  |  | $— |  |  | $— |  |  | $73 |  |  | $45 |  |  | $45 |  |  | $— |  |  | $— |  |  | $45 |
Commodity derivatives | 103 |  |  | — |  |  | 46 |  |  | 57 |  |  | 103 |  |  | 88 |  |  | — |  |  | 59 |  |  | 29 |  |  | 88 |
Interest rate derivatives | 3 |  |  | — |  |  | 3 |  |  | — |  |  | 3 |  |  | 1 |  |  | — |  |  | 1 |  |  | — |  |  | 1 |
Deferred proceeds | 171 |  |  | — |  |  | — |  |  | 171 |  |  | 171 |  |  | 216 |  |  | — |  |  | — |  |  | 216 |  |  | 216 |
Liabilities: |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Commodity derivatives | 91 |  |  | — |  |  | 85 |  |  | 6 |  |  | 91 |  |  | 98 |  |  | — |  |  | 93 |  |  | 5 |  |  | 98 |
Long-term debt (incl. current maturities) | 9,704 |  |  | — |  |  | 9,352 |  |  | — |  |  | 9,352 |  |  | 9,034 |  |  | — |  |  | 8,677 |  |  | — |  |  | 8,677 |
IPL | June 30, 2024 |  | December 31, 2023
|  |  | Fair Value |  |  |  | Fair Value
| Carrying |  | Level |  | Level |  | Level |  |  |  | Carrying |  | Level |  | Level |  | Level |  |
| Amount |  | 1 |  | 2 |  | 3 |  | Total |  | Amount |  | 1 |  | 2 |  | 3 |  | Total
Assets: |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Money market fund investments | $1 |  |  | $1 |  |  | $— |  |  | $— |  |  | $1 |  |  | $45 |  |  | $45 |  |  | $— |  |  | $— |  |  | $45 |
Commodity derivatives | 72 |  |  | — |  |  | 26 |  |  | 46 |  |  | 72 |  |  | 54 |  |  | — |  |  | 30 |  |  | 24 |  |  | 54 |
Deferred proceeds | 171 |  |  | — |  |  | — |  |  | 171 |  |  | 171 |  |  | 216 |  |  | — |  |  | — |  |  | 216 |  |  | 216 |
Liabilities: |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Commodity derivatives | 31 |  |  | — |  |  | 25 |  |  | 6 |  |  | 31 |  |  | 30 |  |  | — |  |  | 25 |  |  | 5 |  |  | 30 |
Long-term debt (incl. current maturities) | 3,946 |  |  | — |  |  | 3,577 |  |  | — |  |  | 3,577 |  |  | 3,945 |  |  | — |  |  | 3,664 |  |  | — |  |  | 3,664 |
WPL | June 30, 2024 |  | December 31, 2023
|  |  | Fair Value |  |  |  | Fair Value
| Carrying |  | Level |  | Level |  | Level |  |  |  | Carrying |  | Level |  | Level |  | Level |  |
| Amount |  | 1 |  | 2 |  | 3 |  | Total |  | Amount |  | 1 |  | 2 |  | 3 |  | Total
Assets: |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Money market fund investments | $72 |  |  | $72 |  |  | $— |  |  | $— |  |  | $72 |  |  | $— |  |  | $— |  |  | $— |  |  | $— |  |  | $— |
Commodity derivatives | 31 |  |  | — |  |  | 20 |  |  | 11 |  |  | 31 |  |  | 34 |  |  | — |  |  | 29 |  |  | 5 |  |  | 34 |
Liabilities: |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Commodity derivatives | 60 |  |  | — |  |  | 60 |  |  | — |  |  | 60 |  |  | 68 |  |  | — |  |  | 68 |  |  | — |  |  | 68 |
Long-term debt | 3,368 |  |  | — |  |  | 3,141 |  |  | — |  |  | 3,141 |  |  | 3,070 |  |  | — |  |  | 2,933 |  |  | — |  |  | 2,933 |
Fair Value Measurements Using Significant Unobservable Inputs | Information for fair value measurements using significant unobservable inputs (Level 3 inputs) was as follows (in millions):
Alliant Energy | Commodity Contract Derivative |  |
| Assets and (Liabilities), net |  | Deferred Proceeds
Three Months Ended June 30 | 2024 |  | 2023 |  | 2024 |  | 2023
Beginning balance, April 1 | $7 |  | ($5) |  | $184 |  | $153
Total net losses included in changes in net assets (realized/unrealized) | (5) |  | (7) |  | — |  | —
Purchases | 59 |  | 62 |  | — |  | —
Sales | (1) |  | (1) |  | — |  | —
Settlements (a) | (9) |  | 5 |  | (13) |  | 22
Ending balance, June 30 | $51 |  | $54 |  | $171 |  | $175
The amount of total net losses for the period included in changes in net assets attributable to the change in unrealized losses relating to assets and liabilities held at June 30 | ($5) |  | ($7) |  | $— |  | $—
Alliant Energy | Commodity Contract Derivative |  |
| Assets and (Liabilities), net |  | Deferred Proceeds
Six Months Ended June 30 | 2024 |  | 2023 |  | 2024 |  | 2023
Beginning balance, January 1 | $24 |  | $19 |  | $216 |  | $185
Total net losses included in changes in net assets (realized/unrealized) | (8) |  | (11) |  | — |  | —
Purchases | 59 |  | 62 |  | — |  | —
Sales | (1) |  | (1) |  | — |  | —
Settlements (a) | (23) |  | (15) |  | (45) |  | (10)
Ending balance, June 30 | $51 |  | $54 |  | $171 |  | $175
The amount of total net losses for the period included in changes in net assets attributable to the change in unrealized losses relating to assets and liabilities held at June 30 | ($8) |  | ($11) |  | $— |  | $—
IPL | Commodity Contract Derivative |  |
| Assets and (Liabilities), net |  | Deferred Proceeds
Three Months Ended June 30 | 2024 |  | 2023 |  | 2024 |  | 2023
Beginning balance, April 1 | $5 |  | $— |  | $184 |  | $153
Total net losses included in changes in net assets (realized/unrealized) | (2) |  | (13) |  | — |  | —
Purchases | 45 |  | 51 |  | — |  | —
Sales | (1) |  | (1) |  | — |  | —
Settlements (a) | (7) |  | 4 |  | (13) |  | 22
Ending balance, June 30 | $40 |  | $41 |  | $171 |  | $175
The amount of total net losses for the period included in changes in net assets attributable to the change in unrealized losses relating to assets and liabilities held at June 30 | ($2) |  | ($13) |  | $— |  | $—
IPL | Commodity Contract Derivative |  |
| Assets and (Liabilities), net |  | Deferred Proceeds
Six Months Ended June 30 | 2024 |  | 2023 |  | 2024 |  | 2023
Beginning balance, January 1 | $19 |  | $16 |  | $216 |  | $185
Total net losses included in changes in net assets (realized/unrealized) | (6) |  | (12) |  | — |  | —
Purchases | 45 |  | 51 |  | — |  | —
Sales | (1) |  | (1) |  | — |  | —
Settlements (a) | (17) |  | (13) |  | (45) |  | (10)
Ending balance, June 30 | $40 |  | $41 |  | $171 |  | $175
The amount of total net losses for the period included in changes in net assets attributable to the change in unrealized losses relating to assets and liabilities held at June 30 | ($6) |  | ($12) |  | $— |  | $—
WPL | Commodity Contract Derivative
| Assets and (Liabilities), net
Three Months Ended June 30 | 2024 |  | 2023
Beginning balance, April 1 | $2 |  | ($5)
Total net gains (losses) included in changes in net assets (realized/unrealized) | (3) |  | 6
Purchases | 14 |  | 11
Settlements | (2) |  | 1
Ending balance, June 30 | $11 |  | $13
The amount of total net gains (losses) for the period included in changes in net assets attributable to the change in unrealized gains (losses) relating to assets and liabilities held at June 30 | ($3) |  | $6
WPL | Commodity Contract Derivative
| Assets and (Liabilities), net
Six Months Ended June 30 | 2024 |  | 2023
Beginning balance, January 1 | $5 |  | $3
Total net gains (losses) included in changes in net assets (realized/unrealized) | (2) |  | 1
Purchases | 14 |  | 11
Settlements | (6) |  | (2)
Ending balance, June 30 | $11 |  | $13
The amount of total net gains (losses) for the period included in changes in net assets attributable to the change in unrealized gains (losses) relating to assets and liabilities held at June 30 | ($2) |  | $1
(a)Settlements related to deferred proceeds are due to the change in the carrying amount of receivables sold less the allowance for expected credit losses associated with the receivables sold and cash amounts received from the receivables sold.
Fair Value Of Net Derivative Assets (Liabilities) | The fair value of FTR and natural gas commodity contracts categorized as Level 3 was recognized as net derivative asset s (liabilities) as follows (in millions):
| Alliant Energy |  | IPL |  | WPL
| Excluding FTRs |  | FTRs |  | Excluding FTRs |  | FTRs |  | Excluding FTRs |  | FTRs
June 30, 2024 | ($4) |  | $55 |  | ($4) |  | $44 |  | $— |  | $11
December 31, 2023 | 3 |  | 21 |  | 3 |  | 16 |  | — |  | 5

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