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Property, Plant and Equipment (Tables) | 12 Months Ended
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Dec. 31, 2020
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
| 2020 |  | 2019 |  | 2020 |  | 2019 |  | 2020 |  | 2019
Utility: |  |  |  |  |  |  |  |  |  |  |
Electric plant: |  |  |  |  |  |  |  |  |  |  |
Generation in service | $8,222 |  |  | $7,625 |  |  | $4,884 |  |  | $4,432 |  |  | $3,338 |  |  | $3,193 |
Distribution in service | 6,216 |  |  | 5,783 |  |  | 3,470 |  |  | 3,190 |  |  | 2,746 |  |  | 2,593 |
Other in service | 536 |  |  | 457 |  |  | 358 |  |  | 299 |  |  | 178 |  |  | 158 |
Anticipated to be retired early (a) | 1,269 |  |  | — |  |  | 459 |  |  | — |  |  | 810 |  |  | — |
Total electric plant | 16,243 |  |  | 13,865 |  |  | 9,171 |  |  | 7,921 |  |  | 7,072 |  |  | 5,944 |
Gas plant in service | 1,563 |  |  | 1,463 |  |  | 844 |  |  | 802 |  |  | 719 |  |  | 661 |
Other plant in service | 534 |  |  | 520 |  |  | 354 |  |  | 345 |  |  | 180 |  |  | 175 |
Accumulated depreciation | (4,868) |  |  | (4,602) |  |  | (2,671) |  |  | (2,499) |  |  | (2,197) |  |  | (2,103) |
Net plant | 13,472 |  |  | 11,246 |  |  | 7,698 |  |  | 6,569 |  |  | 5,774 |  |  | 4,677 |
Leased Sheboygan Falls Energy Facility, net (b) | — |  |  | — |  |  | — |  |  | — |  |  | 27 |  |  | 32 |
Construction work in progress | 405 |  |  | 1,835 |  |  | 185 |  |  | 907 |  |  | 220 |  |  | 928 |
Other, net | 7 |  |  | 6 |  |  | 6 |  |  | 5 |  |  | 1 |  |  | 1 |
Total utility | 13,884 |  |  | 13,087 |  |  | 7,889 |  |  | 7,481 |  |  | 6,022 |  |  | 5,638 |
Non-utility and other: |  |  |  |  |  |  |  |  |  |  |
Non-utility Generation, net (c) | 79 |  |  | 83 |  |  | — |  |  | — |  |  | — |  |  | — |
Corporate Services and other, net (d) | 373 |  |  | 357 |  |  | — |  |  | — |  |  | — |  |  | — |
Total non-utility and other | 452 |  |  | 440 |  |  | — |  |  | — |  |  | — |  |  | — |
Total property, plant and equipment | $14,336 |  |  | $13,527 |  |  | $7,889 |  |  | $7,481 |  |  | $6,022 |  |  | $5,638 |
(a)In 2020, IPL and WPL received approval from MISO to retire Lansing and Edgewater Unit 5, respectively, and currently anticipate retiring these EGUs by the end of 2022. Alliant Energy and IPL concluded that Lansing, and Alliant Energy and WPL concluded that Edgewater Unit 5, met the criteria to be considered probable of abandonment as of December 31, 2020. IPL and WPL are currently allowed a full recovery of and a full return on its respective EGU from both its retail and wholesale customers. (b)Less accumulated amortization of $95 million and $89 million for WPL as of December 31, 2020 and 2019, respectively. The leased Sheboygan Falls Energy Facility is eliminated from WPL 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 $63 million and $59 million for Alliant Energy as of December 31, 2020 and 2019, respectively. (d)Less accumulated depreciation of $210 million and $172 million for Alliant Energy as of December 31, 2020 and 2019, 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
| 2020 |  | 2019 |  | 2018 |  | 2020 |  | 2019 |  | 2018 |  | 2020 |  | 2019 |  | 2018
Equity | $39 |  | $66 |  | $51 |  | $17 |  | $35 |  | $29 |  | $22 |  | $31 |  | $22
Debt | 16 |  | 27 |  | 25 |  | 7 |  | 15 |  | 13 |  | 9 |  | 12 |  | 12
| $55 |  | $93 |  | $76 |  | $24 |  | $50 |  | $42 |  | $31 |  | $43 |  | $34
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
| 2020 |  | 2019 |  | 2020 |  | 2019 |  | 2020 |  | 2019
Utility: |  |  |  |  |  |  |  |  |  |  |
Electric plant: |  |  |  |  |  |  |  |  |  |  |
Generation in service | $8,222 |  |  | $7,625 |  |  | $4,884 |  |  | $4,432 |  |  | $3,338 |  |  | $3,193 |
Distribution in service | 6,216 |  |  | 5,783 |  |  | 3,470 |  |  | 3,190 |  |  | 2,746 |  |  | 2,593 |
Other in service | 536 |  |  | 457 |  |  | 358 |  |  | 299 |  |  | 178 |  |  | 158 |
Anticipated to be retired early (a) | 1,269 |  |  | — |  |  | 459 |  |  | — |  |  | 810 |  |  | — |
Total electric plant | 16,243 |  |  | 13,865 |  |  | 9,171 |  |  | 7,921 |  |  | 7,072 |  |  | 5,944 |
Gas plant in service | 1,563 |  |  | 1,463 |  |  | 844 |  |  | 802 |  |  | 719 |  |  | 661 |
Other plant in service | 534 |  |  | 520 |  |  | 354 |  |  | 345 |  |  | 180 |  |  | 175 |
Accumulated depreciation | (4,868) |  |  | (4,602) |  |  | (2,671) |  |  | (2,499) |  |  | (2,197) |  |  | (2,103) |
Net plant | 13,472 |  |  | 11,246 |  |  | 7,698 |  |  | 6,569 |  |  | 5,774 |  |  | 4,677 |
Leased Sheboygan Falls Energy Facility, net (b) | — |  |  | — |  |  | — |  |  | — |  |  | 27 |  |  | 32 |
Construction work in progress | 405 |  |  | 1,835 |  |  | 185 |  |  | 907 |  |  | 220 |  |  | 928 |
Other, net | 7 |  |  | 6 |  |  | 6 |  |  | 5 |  |  | 1 |  |  | 1 |
Total utility | 13,884 |  |  | 13,087 |  |  | 7,889 |  |  | 7,481 |  |  | 6,022 |  |  | 5,638 |
Non-utility and other: |  |  |  |  |  |  |  |  |  |  |
Non-utility Generation, net (c) | 79 |  |  | 83 |  |  | — |  |  | — |  |  | — |  |  | — |
Corporate Services and other, net (d) | 373 |  |  | 357 |  |  | — |  |  | — |  |  | — |  |  | — |
Total non-utility and other | 452 |  |  | 440 |  |  | — |  |  | — |  |  | — |  |  | — |
Total property, plant and equipment | $14,336 |  |  | $13,527 |  |  | $7,889 |  |  | $7,481 |  |  | $6,022 |  |  | $5,638 |
(a)In 2020, IPL and WPL received approval from MISO to retire Lansing and Edgewater Unit 5, respectively, and currently anticipate retiring these EGUs by the end of 2022. Alliant Energy and IPL concluded that Lansing, and Alliant Energy and WPL concluded that Edgewater Unit 5, met the criteria to be considered probable of abandonment as of December 31, 2020. IPL and WPL are currently allowed a full recovery of and a full return on its respective EGU from both its retail and wholesale customers. (b)Less accumulated amortization of $95 million and $89 million for WPL as of December 31, 2020 and 2019, respectively. The leased Sheboygan Falls Energy Facility is eliminated from WPL 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 $63 million and $59 million for Alliant Energy as of December 31, 2020 and 2019, respectively. (d)Less accumulated depreciation of $210 million and $172 million for Alliant Energy as of December 31, 2020 and 2019, 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
| 2020 |  | 2019 |  | 2018 |  | 2020 |  | 2019 |  | 2018 |  | 2020 |  | 2019 |  | 2018
Equity | $39 |  | $66 |  | $51 |  | $17 |  | $35 |  | $29 |  | $22 |  | $31 |  | $22
Debt | 16 |  | 27 |  | 25 |  | 7 |  | 15 |  | 13 |  | 9 |  | 12 |  | 12
| $55 |  | $93 |  | $76 |  | $24 |  | $50 |  | $42 |  | $31 |  | $43 |  | $34
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
| 2020 |  | 2019 |  | 2020 |  | 2019 |  | 2020 |  | 2019
Utility: |  |  |  |  |  |  |  |  |  |  |
Electric plant: |  |  |  |  |  |  |  |  |  |  |
Generation in service | $8,222 |  |  | $7,625 |  |  | $4,884 |  |  | $4,432 |  |  | $3,338 |  |  | $3,193 |
Distribution in service | 6,216 |  |  | 5,783 |  |  | 3,470 |  |  | 3,190 |  |  | 2,746 |  |  | 2,593 |
Other in service | 536 |  |  | 457 |  |  | 358 |  |  | 299 |  |  | 178 |  |  | 158 |
Anticipated to be retired early (a) | 1,269 |  |  | — |  |  | 459 |  |  | — |  |  | 810 |  |  | — |
Total electric plant | 16,243 |  |  | 13,865 |  |  | 9,171 |  |  | 7,921 |  |  | 7,072 |  |  | 5,944 |
Gas plant in service | 1,563 |  |  | 1,463 |  |  | 844 |  |  | 802 |  |  | 719 |  |  | 661 |
Other plant in service | 534 |  |  | 520 |  |  | 354 |  |  | 345 |  |  | 180 |  |  | 175 |
Accumulated depreciation | (4,868) |  |  | (4,602) |  |  | (2,671) |  |  | (2,499) |  |  | (2,197) |  |  | (2,103) |
Net plant | 13,472 |  |  | 11,246 |  |  | 7,698 |  |  | 6,569 |  |  | 5,774 |  |  | 4,677 |
Leased Sheboygan Falls Energy Facility, net (b) | — |  |  | — |  |  | — |  |  | — |  |  | 27 |  |  | 32 |
Construction work in progress | 405 |  |  | 1,835 |  |  | 185 |  |  | 907 |  |  | 220 |  |  | 928 |
Other, net | 7 |  |  | 6 |  |  | 6 |  |  | 5 |  |  | 1 |  |  | 1 |
Total utility | 13,884 |  |  | 13,087 |  |  | 7,889 |  |  | 7,481 |  |  | 6,022 |  |  | 5,638 |
Non-utility and other: |  |  |  |  |  |  |  |  |  |  |
Non-utility Generation, net (c) | 79 |  |  | 83 |  |  | — |  |  | — |  |  | — |  |  | — |
Corporate Services and other, net (d) | 373 |  |  | 357 |  |  | — |  |  | — |  |  | — |  |  | — |
Total non-utility and other | 452 |  |  | 440 |  |  | — |  |  | — |  |  | — |  |  | — |
Total property, plant and equipment | $14,336 |  |  | $13,527 |  |  | $7,889 |  |  | $7,481 |  |  | $6,022 |  |  | $5,638 |
(a)In 2020, IPL and WPL received approval from MISO to retire Lansing and Edgewater Unit 5, respectively, and currently anticipate retiring these EGUs by the end of 2022. Alliant Energy and IPL concluded that Lansing, and Alliant Energy and WPL concluded that Edgewater Unit 5, met the criteria to be considered probable of abandonment as of December 31, 2020. IPL and WPL are currently allowed a full recovery of and a full return on its respective EGU from both its retail and wholesale customers. (b)Less accumulated amortization of $95 million and $89 million for WPL as of December 31, 2020 and 2019, respectively. The leased Sheboygan Falls Energy Facility is eliminated from WPL 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 $63 million and $59 million for Alliant Energy as of December 31, 2020 and 2019, respectively. (d)Less accumulated depreciation of $210 million and $172 million for Alliant Energy as of December 31, 2020 and 2019, 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
| 2020 |  | 2019 |  | 2018 |  | 2020 |  | 2019 |  | 2018 |  | 2020 |  | 2019 |  | 2018
Equity | $39 |  | $66 |  | $51 |  | $17 |  | $35 |  | $29 |  | $22 |  | $31 |  | $22
Debt | 16 |  | 27 |  | 25 |  | 7 |  | 15 |  | 13 |  | 9 |  | 12 |  | 12
| $55 |  | $93 |  | $76 |  | $24 |  | $50 |  | $42 |  | $31 |  | $43 |  | $34

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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 210 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.5-02(13)) -URI http://asc.fasb.org/extlink&oid=120391452&loc=d3e13212-122682 Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 360 -SubTopic 10 -Section 50 -Paragraph 1 -URI http://asc.fasb.org/extlink&oid=6391035&loc=d3e2868-110229 + Details
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