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Property, Plant and Equipment (Tables) | 12 Months Ended
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Dec. 31, 2021
Property, Plant and Equipment [Line Items] |
Property, Plant and Equipment | At December 31, details of property, plant and equipment on the balance sheets were as follows (in millions):
| Alliant Energy |  | IPL |  | WPL
| 2021 |  | 2020 |  | 2021 |  | 2020 |  | 2021 |  | 2020
Utility: |  |  |  |  |  |  |  |  |  |  |
Electric plant: |  |  |  |  |  |  |  |  |  |  |
Generation in service | $7,539 |  |  | $8,222 |  |  | $4,922 |  |  | $4,884 |  |  | $2,617 |  |  | $3,338 |
Distribution in service | 6,537 |  |  | 6,216 |  |  | 3,652 |  |  | 3,470 |  |  | 2,885 |  |  | 2,746 |
Other in service | 540 |  |  | 536 |  |  | 363 |  |  | 358 |  |  | 177 |  |  | 178 |
Anticipated to be retired early (a) | 2,094 |  |  | 1,269 |  |  | 487 |  |  | 459 |  |  | 1,607 |  |  | 810 |
Total electric plant | 16,710 |  |  | 16,243 |  |  | 9,424 |  |  | 9,171 |  |  | 7,286 |  |  | 7,072 |
Gas plant in service | 1,636 |  |  | 1,563 |  |  | 878 |  |  | 844 |  |  | 758 |  |  | 719 |
Other plant in service | 621 |  |  | 534 |  |  | 398 |  |  | 354 |  |  | 223 |  |  | 180 |
Accumulated depreciation | (5,263) |  |  | (4,868) |  |  | (2,897) |  |  | (2,671) |  |  | (2,366) |  |  | (2,197) |
Net plant | 13,704 |  |  | 13,472 |  |  | 7,803 |  |  | 7,698 |  |  | 5,901 |  |  | 5,774 |
Leased Sheboygan Falls Energy Facility, net (b) | — |  |  | — |  |  | — |  |  | — |  |  | 21 |  |  | 27 |
Leased land for solar generation, net | 11 |  |  | — |  |  | — |  |  | — |  |  | 11 |  |  | — |
Construction work in progress | 778 |  |  | 405 |  |  | 174 |  |  | 185 |  |  | 604 |  |  | 220 |
Other, net | 7 |  |  | 7 |  |  | 6 |  |  | 6 |  |  | 1 |  |  | 1 |
Total utility | 14,500 |  |  | 13,884 |  |  | 7,983 |  |  | 7,889 |  |  | 6,538 |  |  | 6,022 |
Non-utility and other: |  |  |  |  |  |  |  |  |  |  |
Non-utility Generation, net (c) | 75 |  |  | 79 |  |  | — |  |  | — |  |  | — |  |  | — |
Corporate Services and other, net (d) | 412 |  |  | 373 |  |  | — |  |  | — |  |  | — |  |  | — |
Total non-utility and other | 487 |  |  | 452 |  |  | — |  |  | — |  |  | — |  |  | — |
Total property, plant and equipment | $14,987 |  |  | $14,336 |  |  | $7,983 |  |  | $7,889 |  |  | $6,538 |  |  | $6,022 |
(a)In 2020, IPL and WPL received approval from MISO to retire Lansing and Edgewater Unit 5, respectively, and currently anticipate retiring Lansing by the end of 2022 and Edgewater Unit 5 by early 2023. In 2021, WPL received approval from MISO to retire Columbia Units 1 and 2, and currently anticipates retiring Columbia Unit 1 by the end of 2023 and Columbia Unit 2 by the end of 2024. Alliant Energy and IPL concluded that Lansing, and Alliant Energy and WPL concluded that Edgewater Unit 5 and Columbia Units 1 and 2, met the criteria to be considered probable of abandonment as of December 31, 2021. IPL and WPL are currently allowed a full recovery of and a full return on its respective EGUs from both its retail and wholesale customers, and as a result, Alliant Energy, IPL and WPL concluded that no disallowance was required as of December 31, 2021. As of December 31, 2021, net book values were $245 million for Lansing, $527 million for Edgewater Unit 5, and $460 million for Columbia Units 1 and 2 in aggregate. (b)Less accumulated amortization of $100 million and $95 million for WPL as of December 31, 2021 and 2020, respectively. For Alliant Energy, the leased Sheboygan Falls Energy Facility is eliminated upon consolidation and is included in the “Non-utility Generation, net” line within Alliant Energy’s consolidated property, plant and equipment. (c)Less accumulated depreciation of $67 million and $63 million for Alliant Energy as of December 31, 2021 and 2020, respectively. (d)Less accumulated depreciation of $245 million and $210 million for Alliant Energy as of December 31, 2021 and 2020, respectively.
Allowance For Funds Used During Construction | The amount of AFUDC generated by equity and debt components was as follows (in millions):
| Alliant Energy |  | IPL |  | WPL
| 2021 |  | 2020 |  | 2019 |  | 2021 |  | 2020 |  | 2019 |  | 2021 |  | 2020 |  | 2019
Equity | $18 |  | $39 |  | $66 |  | $7 |  | $17 |  | $35 |  | $11 |  | $22 |  | $31
Debt | 7 |  | 16 |  | 27 |  | 2 |  | 7 |  | 15 |  | 5 |  | 9 |  | 12
| $25 |  | $55 |  | $93 |  | $9 |  | $24 |  | $50 |  | $16 |  | $31 |  | $43
IPL [Member] |
Property, Plant and Equipment [Line Items] |
Property, Plant and Equipment | At December 31, details of property, plant and equipment on the balance sheets were as follows (in millions):
| Alliant Energy |  | IPL |  | WPL
| 2021 |  | 2020 |  | 2021 |  | 2020 |  | 2021 |  | 2020
Utility: |  |  |  |  |  |  |  |  |  |  |
Electric plant: |  |  |  |  |  |  |  |  |  |  |
Generation in service | $7,539 |  |  | $8,222 |  |  | $4,922 |  |  | $4,884 |  |  | $2,617 |  |  | $3,338 |
Distribution in service | 6,537 |  |  | 6,216 |  |  | 3,652 |  |  | 3,470 |  |  | 2,885 |  |  | 2,746 |
Other in service | 540 |  |  | 536 |  |  | 363 |  |  | 358 |  |  | 177 |  |  | 178 |
Anticipated to be retired early (a) | 2,094 |  |  | 1,269 |  |  | 487 |  |  | 459 |  |  | 1,607 |  |  | 810 |
Total electric plant | 16,710 |  |  | 16,243 |  |  | 9,424 |  |  | 9,171 |  |  | 7,286 |  |  | 7,072 |
Gas plant in service | 1,636 |  |  | 1,563 |  |  | 878 |  |  | 844 |  |  | 758 |  |  | 719 |
Other plant in service | 621 |  |  | 534 |  |  | 398 |  |  | 354 |  |  | 223 |  |  | 180 |
Accumulated depreciation | (5,263) |  |  | (4,868) |  |  | (2,897) |  |  | (2,671) |  |  | (2,366) |  |  | (2,197) |
Net plant | 13,704 |  |  | 13,472 |  |  | 7,803 |  |  | 7,698 |  |  | 5,901 |  |  | 5,774 |
Leased Sheboygan Falls Energy Facility, net (b) | — |  |  | — |  |  | — |  |  | — |  |  | 21 |  |  | 27 |
Leased land for solar generation, net | 11 |  |  | — |  |  | — |  |  | — |  |  | 11 |  |  | — |
Construction work in progress | 778 |  |  | 405 |  |  | 174 |  |  | 185 |  |  | 604 |  |  | 220 |
Other, net | 7 |  |  | 7 |  |  | 6 |  |  | 6 |  |  | 1 |  |  | 1 |
Total utility | 14,500 |  |  | 13,884 |  |  | 7,983 |  |  | 7,889 |  |  | 6,538 |  |  | 6,022 |
Non-utility and other: |  |  |  |  |  |  |  |  |  |  |
Non-utility Generation, net (c) | 75 |  |  | 79 |  |  | — |  |  | — |  |  | — |  |  | — |
Corporate Services and other, net (d) | 412 |  |  | 373 |  |  | — |  |  | — |  |  | — |  |  | — |
Total non-utility and other | 487 |  |  | 452 |  |  | — |  |  | — |  |  | — |  |  | — |
Total property, plant and equipment | $14,987 |  |  | $14,336 |  |  | $7,983 |  |  | $7,889 |  |  | $6,538 |  |  | $6,022 |
(a)In 2020, IPL and WPL received approval from MISO to retire Lansing and Edgewater Unit 5, respectively, and currently anticipate retiring Lansing by the end of 2022 and Edgewater Unit 5 by early 2023. In 2021, WPL received approval from MISO to retire Columbia Units 1 and 2, and currently anticipates retiring Columbia Unit 1 by the end of 2023 and Columbia Unit 2 by the end of 2024. Alliant Energy and IPL concluded that Lansing, and Alliant Energy and WPL concluded that Edgewater Unit 5 and Columbia Units 1 and 2, met the criteria to be considered probable of abandonment as of December 31, 2021. IPL and WPL are currently allowed a full recovery of and a full return on its respective EGUs from both its retail and wholesale customers, and as a result, Alliant Energy, IPL and WPL concluded that no disallowance was required as of December 31, 2021. As of December 31, 2021, net book values were $245 million for Lansing, $527 million for Edgewater Unit 5, and $460 million for Columbia Units 1 and 2 in aggregate. (b)Less accumulated amortization of $100 million and $95 million for WPL as of December 31, 2021 and 2020, respectively. For Alliant Energy, the leased Sheboygan Falls Energy Facility is eliminated upon consolidation and is included in the “Non-utility Generation, net” line within Alliant Energy’s consolidated property, plant and equipment. (c)Less accumulated depreciation of $67 million and $63 million for Alliant Energy as of December 31, 2021 and 2020, respectively. (d)Less accumulated depreciation of $245 million and $210 million for Alliant Energy as of December 31, 2021 and 2020, respectively.
Allowance For Funds Used During Construction | The amount of AFUDC generated by equity and debt components was as follows (in millions):
| Alliant Energy |  | IPL |  | WPL
| 2021 |  | 2020 |  | 2019 |  | 2021 |  | 2020 |  | 2019 |  | 2021 |  | 2020 |  | 2019
Equity | $18 |  | $39 |  | $66 |  | $7 |  | $17 |  | $35 |  | $11 |  | $22 |  | $31
Debt | 7 |  | 16 |  | 27 |  | 2 |  | 7 |  | 15 |  | 5 |  | 9 |  | 12
| $25 |  | $55 |  | $93 |  | $9 |  | $24 |  | $50 |  | $16 |  | $31 |  | $43
WPL [Member] |
Property, Plant and Equipment [Line Items] |
Property, Plant and Equipment | At December 31, details of property, plant and equipment on the balance sheets were as follows (in millions):
| Alliant Energy |  | IPL |  | WPL
| 2021 |  | 2020 |  | 2021 |  | 2020 |  | 2021 |  | 2020
Utility: |  |  |  |  |  |  |  |  |  |  |
Electric plant: |  |  |  |  |  |  |  |  |  |  |
Generation in service | $7,539 |  |  | $8,222 |  |  | $4,922 |  |  | $4,884 |  |  | $2,617 |  |  | $3,338 |
Distribution in service | 6,537 |  |  | 6,216 |  |  | 3,652 |  |  | 3,470 |  |  | 2,885 |  |  | 2,746 |
Other in service | 540 |  |  | 536 |  |  | 363 |  |  | 358 |  |  | 177 |  |  | 178 |
Anticipated to be retired early (a) | 2,094 |  |  | 1,269 |  |  | 487 |  |  | 459 |  |  | 1,607 |  |  | 810 |
Total electric plant | 16,710 |  |  | 16,243 |  |  | 9,424 |  |  | 9,171 |  |  | 7,286 |  |  | 7,072 |
Gas plant in service | 1,636 |  |  | 1,563 |  |  | 878 |  |  | 844 |  |  | 758 |  |  | 719 |
Other plant in service | 621 |  |  | 534 |  |  | 398 |  |  | 354 |  |  | 223 |  |  | 180 |
Accumulated depreciation | (5,263) |  |  | (4,868) |  |  | (2,897) |  |  | (2,671) |  |  | (2,366) |  |  | (2,197) |
Net plant | 13,704 |  |  | 13,472 |  |  | 7,803 |  |  | 7,698 |  |  | 5,901 |  |  | 5,774 |
Leased Sheboygan Falls Energy Facility, net (b) | — |  |  | — |  |  | — |  |  | — |  |  | 21 |  |  | 27 |
Leased land for solar generation, net | 11 |  |  | — |  |  | — |  |  | — |  |  | 11 |  |  | — |
Construction work in progress | 778 |  |  | 405 |  |  | 174 |  |  | 185 |  |  | 604 |  |  | 220 |
Other, net | 7 |  |  | 7 |  |  | 6 |  |  | 6 |  |  | 1 |  |  | 1 |
Total utility | 14,500 |  |  | 13,884 |  |  | 7,983 |  |  | 7,889 |  |  | 6,538 |  |  | 6,022 |
Non-utility and other: |  |  |  |  |  |  |  |  |  |  |
Non-utility Generation, net (c) | 75 |  |  | 79 |  |  | — |  |  | — |  |  | — |  |  | — |
Corporate Services and other, net (d) | 412 |  |  | 373 |  |  | — |  |  | — |  |  | — |  |  | — |
Total non-utility and other | 487 |  |  | 452 |  |  | — |  |  | — |  |  | — |  |  | — |
Total property, plant and equipment | $14,987 |  |  | $14,336 |  |  | $7,983 |  |  | $7,889 |  |  | $6,538 |  |  | $6,022 |
(a)In 2020, IPL and WPL received approval from MISO to retire Lansing and Edgewater Unit 5, respectively, and currently anticipate retiring Lansing by the end of 2022 and Edgewater Unit 5 by early 2023. In 2021, WPL received approval from MISO to retire Columbia Units 1 and 2, and currently anticipates retiring Columbia Unit 1 by the end of 2023 and Columbia Unit 2 by the end of 2024. Alliant Energy and IPL concluded that Lansing, and Alliant Energy and WPL concluded that Edgewater Unit 5 and Columbia Units 1 and 2, met the criteria to be considered probable of abandonment as of December 31, 2021. IPL and WPL are currently allowed a full recovery of and a full return on its respective EGUs from both its retail and wholesale customers, and as a result, Alliant Energy, IPL and WPL concluded that no disallowance was required as of December 31, 2021. As of December 31, 2021, net book values were $245 million for Lansing, $527 million for Edgewater Unit 5, and $460 million for Columbia Units 1 and 2 in aggregate. (b)Less accumulated amortization of $100 million and $95 million for WPL as of December 31, 2021 and 2020, respectively. For Alliant Energy, the leased Sheboygan Falls Energy Facility is eliminated upon consolidation and is included in the “Non-utility Generation, net” line within Alliant Energy’s consolidated property, plant and equipment. (c)Less accumulated depreciation of $67 million and $63 million for Alliant Energy as of December 31, 2021 and 2020, respectively. (d)Less accumulated depreciation of $245 million and $210 million for Alliant Energy as of December 31, 2021 and 2020, respectively.
Allowance For Funds Used During Construction | The amount of AFUDC generated by equity and debt components was as follows (in millions):
| Alliant Energy |  | IPL |  | WPL
| 2021 |  | 2020 |  | 2019 |  | 2021 |  | 2020 |  | 2019 |  | 2021 |  | 2020 |  | 2019
Equity | $18 |  | $39 |  | $66 |  | $7 |  | $17 |  | $35 |  | $11 |  | $22 |  | $31
Debt | 7 |  | 16 |  | 27 |  | 2 |  | 7 |  | 15 |  | 5 |  | 9 |  | 12
| $25 |  | $55 |  | $93 |  | $9 |  | $24 |  | $50 |  | $16 |  | $31 |  | $43

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