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Property, Plant and Equipment (Tables) | 12 Months Ended
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Dec. 31, 2022
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
| 2022 |  | 2021 |  | 2022 |  | 2021 |  | 2022 |  | 2021
Utility: |  |  |  |  |  |  |  |  |  |  |
Electric plant: |  |  |  |  |  |  |  |  |  |  |
Generation in service | $8,060 |  |  | $7,539 |  |  | $4,962 |  |  | $4,922 |  |  | $3,098 |  |  | $2,617 |
Distribution in service | 6,912 |  |  | 6,537 |  |  | 3,876 |  |  | 3,652 |  |  | 3,036 |  |  | 2,885 |
Other in service | 543 |  |  | 540 |  |  | 354 |  |  | 363 |  |  | 189 |  |  | 177 |
Anticipated to be retired early (a) | 2,103 |  |  | 2,094 |  |  | 491 |  |  | 487 |  |  | 1,612 |  |  | 1,607 |
Total electric plant | 17,618 |  |  | 16,710 |  |  | 9,683 |  |  | 9,424 |  |  | 7,935 |  |  | 7,286 |
Gas plant in service | 1,705 |  |  | 1,636 |  |  | 910 |  | 878 |  |  | 795 |  |  | 758 |
Other plant in service | 624 |  |  | 621 |  |  | 402 |  | 398 |  |  | 222 |  |  | 223 |
Accumulated depreciation | (5,690) |  |  | (5,263) |  |  | (3,149) |  |  | (2,897) |  |  | (2,541) |  |  | (2,366) |
Net plant | 14,257 |  |  | 13,704 |  |  | 7,846 |  |  | 7,803 |  |  | 6,411 |  |  | 5,901 |
Leased Sheboygan Falls Energy Facility, net (b) | — |  |  | — |  |  | — |  |  | — |  |  | 15 |  |  | 21 |
Leased land for solar generation, net | 133 |  |  | 11 |  |  | — |  |  | — |  |  | 133 |  |  | 11 |
Construction work in progress | 1,357 |  |  | 778 |  |  | 194 |  | 174 |  |  | 1,163 |  |  | 604 |
Other, net | 6 |  |  | 7 |  |  | 6 |  |  | 6 |  |  | — |  |  | 1 |
Total utility | 15,753 |  |  | 14,500 |  |  | 8,046 |  |  | 7,983 |  |  | 7,722 |  |  | 6,538 |
Non-utility and other: |  |  |  |  |  |  |  |  |  |  |
Non-utility Generation, net (c) | 71 |  |  | 75 |  |  | — |  |  | — |  |  | — |  |  | — |
Corporate Services and other, net (d) | 423 |  | 412 |  |  | — |  |  | — |  |  | — |  |  | — |
Total non-utility and other | 494 |  |  | 487 |  |  | — |  |  | — |  |  | — |  |  | — |
Total property, plant and equipment | $16,247 |  |  | $14,987 |  |  | $8,046 |  |  | $7,983 |  |  | $7,722 |  |  | $6,538 |
(a)In 2020, IPL and WPL received approval from MISO to retire Lansing and Edgewater Unit 5, respectively, and currently anticipate retiring Lansing in the first half of 2023 and Edgewater Unit 5 by June 1, 2025. In 2021, WPL received approval from MISO to retire Columbia Units 1 and 2, and currently anticipates retiring Columbia Units 1 and 2 by June 1, 2026. 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, 2022. 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, 2022. As of December 31, 2022, net book values were $233 million for Lansing, $511 million for Edgewater Unit 5, and $440 million for Columbia Units 1 and 2 in aggregate. (b)Less accumulated amortization of $106 million and $100 million for WPL as of December 31, 2022 and 2021, 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 $71 million and $67 million for Alliant Energy as of December 31, 2022 and 2021, respectively. (d)Less accumulated depreciation of $269 million and $245 million for Alliant Energy as of December 31, 2022 and 2021, 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
| 2022 |  | 2021 |  | 2020 |  | 2022 |  | 2021 |  | 2020 |  | 2022 |  | 2021 |  | 2020
Equity | $44 |  | $18 |  | $39 |  | $8 |  | $7 |  | $17 |  | $36 |  | $11 |  | $22
Debt | 16 |  | 7 |  | 16 |  | 3 |  | 2 |  | 7 |  | 13 |  | 5 |  | 9
| $60 |  | $25 |  | $55 |  | $11 |  | $9 |  | $24 |  | $49 |  | $16 |  | $31
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
| 2022 |  | 2021 |  | 2022 |  | 2021 |  | 2022 |  | 2021
Utility: |  |  |  |  |  |  |  |  |  |  |
Electric plant: |  |  |  |  |  |  |  |  |  |  |
Generation in service | $8,060 |  |  | $7,539 |  |  | $4,962 |  |  | $4,922 |  |  | $3,098 |  |  | $2,617 |
Distribution in service | 6,912 |  |  | 6,537 |  |  | 3,876 |  |  | 3,652 |  |  | 3,036 |  |  | 2,885 |
Other in service | 543 |  |  | 540 |  |  | 354 |  |  | 363 |  |  | 189 |  |  | 177 |
Anticipated to be retired early (a) | 2,103 |  |  | 2,094 |  |  | 491 |  |  | 487 |  |  | 1,612 |  |  | 1,607 |
Total electric plant | 17,618 |  |  | 16,710 |  |  | 9,683 |  |  | 9,424 |  |  | 7,935 |  |  | 7,286 |
Gas plant in service | 1,705 |  |  | 1,636 |  |  | 910 |  | 878 |  |  | 795 |  |  | 758 |
Other plant in service | 624 |  |  | 621 |  |  | 402 |  | 398 |  |  | 222 |  |  | 223 |
Accumulated depreciation | (5,690) |  |  | (5,263) |  |  | (3,149) |  |  | (2,897) |  |  | (2,541) |  |  | (2,366) |
Net plant | 14,257 |  |  | 13,704 |  |  | 7,846 |  |  | 7,803 |  |  | 6,411 |  |  | 5,901 |
Leased Sheboygan Falls Energy Facility, net (b) | — |  |  | — |  |  | — |  |  | — |  |  | 15 |  |  | 21 |
Leased land for solar generation, net | 133 |  |  | 11 |  |  | — |  |  | — |  |  | 133 |  |  | 11 |
Construction work in progress | 1,357 |  |  | 778 |  |  | 194 |  | 174 |  |  | 1,163 |  |  | 604 |
Other, net | 6 |  |  | 7 |  |  | 6 |  |  | 6 |  |  | — |  |  | 1 |
Total utility | 15,753 |  |  | 14,500 |  |  | 8,046 |  |  | 7,983 |  |  | 7,722 |  |  | 6,538 |
Non-utility and other: |  |  |  |  |  |  |  |  |  |  |
Non-utility Generation, net (c) | 71 |  |  | 75 |  |  | — |  |  | — |  |  | — |  |  | — |
Corporate Services and other, net (d) | 423 |  | 412 |  |  | — |  |  | — |  |  | — |  |  | — |
Total non-utility and other | 494 |  |  | 487 |  |  | — |  |  | — |  |  | — |  |  | — |
Total property, plant and equipment | $16,247 |  |  | $14,987 |  |  | $8,046 |  |  | $7,983 |  |  | $7,722 |  |  | $6,538 |
(a)In 2020, IPL and WPL received approval from MISO to retire Lansing and Edgewater Unit 5, respectively, and currently anticipate retiring Lansing in the first half of 2023 and Edgewater Unit 5 by June 1, 2025. In 2021, WPL received approval from MISO to retire Columbia Units 1 and 2, and currently anticipates retiring Columbia Units 1 and 2 by June 1, 2026. 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, 2022. 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, 2022. As of December 31, 2022, net book values were $233 million for Lansing, $511 million for Edgewater Unit 5, and $440 million for Columbia Units 1 and 2 in aggregate. (b)Less accumulated amortization of $106 million and $100 million for WPL as of December 31, 2022 and 2021, 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 $71 million and $67 million for Alliant Energy as of December 31, 2022 and 2021, respectively. (d)Less accumulated depreciation of $269 million and $245 million for Alliant Energy as of December 31, 2022 and 2021, 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
| 2022 |  | 2021 |  | 2020 |  | 2022 |  | 2021 |  | 2020 |  | 2022 |  | 2021 |  | 2020
Equity | $44 |  | $18 |  | $39 |  | $8 |  | $7 |  | $17 |  | $36 |  | $11 |  | $22
Debt | 16 |  | 7 |  | 16 |  | 3 |  | 2 |  | 7 |  | 13 |  | 5 |  | 9
| $60 |  | $25 |  | $55 |  | $11 |  | $9 |  | $24 |  | $49 |  | $16 |  | $31
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
| 2022 |  | 2021 |  | 2022 |  | 2021 |  | 2022 |  | 2021
Utility: |  |  |  |  |  |  |  |  |  |  |
Electric plant: |  |  |  |  |  |  |  |  |  |  |
Generation in service | $8,060 |  |  | $7,539 |  |  | $4,962 |  |  | $4,922 |  |  | $3,098 |  |  | $2,617 |
Distribution in service | 6,912 |  |  | 6,537 |  |  | 3,876 |  |  | 3,652 |  |  | 3,036 |  |  | 2,885 |
Other in service | 543 |  |  | 540 |  |  | 354 |  |  | 363 |  |  | 189 |  |  | 177 |
Anticipated to be retired early (a) | 2,103 |  |  | 2,094 |  |  | 491 |  |  | 487 |  |  | 1,612 |  |  | 1,607 |
Total electric plant | 17,618 |  |  | 16,710 |  |  | 9,683 |  |  | 9,424 |  |  | 7,935 |  |  | 7,286 |
Gas plant in service | 1,705 |  |  | 1,636 |  |  | 910 |  | 878 |  |  | 795 |  |  | 758 |
Other plant in service | 624 |  |  | 621 |  |  | 402 |  | 398 |  |  | 222 |  |  | 223 |
Accumulated depreciation | (5,690) |  |  | (5,263) |  |  | (3,149) |  |  | (2,897) |  |  | (2,541) |  |  | (2,366) |
Net plant | 14,257 |  |  | 13,704 |  |  | 7,846 |  |  | 7,803 |  |  | 6,411 |  |  | 5,901 |
Leased Sheboygan Falls Energy Facility, net (b) | — |  |  | — |  |  | — |  |  | — |  |  | 15 |  |  | 21 |
Leased land for solar generation, net | 133 |  |  | 11 |  |  | — |  |  | — |  |  | 133 |  |  | 11 |
Construction work in progress | 1,357 |  |  | 778 |  |  | 194 |  | 174 |  |  | 1,163 |  |  | 604 |
Other, net | 6 |  |  | 7 |  |  | 6 |  |  | 6 |  |  | — |  |  | 1 |
Total utility | 15,753 |  |  | 14,500 |  |  | 8,046 |  |  | 7,983 |  |  | 7,722 |  |  | 6,538 |
Non-utility and other: |  |  |  |  |  |  |  |  |  |  |
Non-utility Generation, net (c) | 71 |  |  | 75 |  |  | — |  |  | — |  |  | — |  |  | — |
Corporate Services and other, net (d) | 423 |  | 412 |  |  | — |  |  | — |  |  | — |  |  | — |
Total non-utility and other | 494 |  |  | 487 |  |  | — |  |  | — |  |  | — |  |  | — |
Total property, plant and equipment | $16,247 |  |  | $14,987 |  |  | $8,046 |  |  | $7,983 |  |  | $7,722 |  |  | $6,538 |
(a)In 2020, IPL and WPL received approval from MISO to retire Lansing and Edgewater Unit 5, respectively, and currently anticipate retiring Lansing in the first half of 2023 and Edgewater Unit 5 by June 1, 2025. In 2021, WPL received approval from MISO to retire Columbia Units 1 and 2, and currently anticipates retiring Columbia Units 1 and 2 by June 1, 2026. 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, 2022. 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, 2022. As of December 31, 2022, net book values were $233 million for Lansing, $511 million for Edgewater Unit 5, and $440 million for Columbia Units 1 and 2 in aggregate. (b)Less accumulated amortization of $106 million and $100 million for WPL as of December 31, 2022 and 2021, 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 $71 million and $67 million for Alliant Energy as of December 31, 2022 and 2021, respectively. (d)Less accumulated depreciation of $269 million and $245 million for Alliant Energy as of December 31, 2022 and 2021, 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
| 2022 |  | 2021 |  | 2020 |  | 2022 |  | 2021 |  | 2020 |  | 2022 |  | 2021 |  | 2020
Equity | $44 |  | $18 |  | $39 |  | $8 |  | $7 |  | $17 |  | $36 |  | $11 |  | $22
Debt | 16 |  | 7 |  | 16 |  | 3 |  | 2 |  | 7 |  | 13 |  | 5 |  | 9
| $60 |  | $25 |  | $55 |  | $11 |  | $9 |  | $24 |  | $49 |  | $16 |  | $31

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- Definition Tabular disclosure of physical assets used in the normal conduct of business and not intended for resale. Includes, but is not limited to, balances by class of assets, depreciation and depletion expense and method used, including composite depreciation, and accumulated deprecation. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 360 -SubTopic 10 -Section 50 -Paragraph 1 -URI https://asc.fasb.org/extlink&oid=6391035&loc=d3e2868-110229 + Details
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