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Leases (Tables) | 12 Months Ended
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Dec. 31, 2023
Leases [Line Items] |
Schedule of Lease Details | Operating lease details are as follows (dollars in millions):
| December 31, 2023 |  | December 31, 2022
| Alliant Energy |  | IPL |  | WPL |  | Alliant Energy |  | IPL |  | WPL
Property, plant and equipment, net | $23 |  | $13 |  | $9 |  | $16 |  | $9 |  | $6
Other current liabilities | $2 |  | $1 |  | $1 |  | $3 |  | $1 |  | $1
Other liabilities | 21 |  | 12 |  | 8 |  | 13 |  | 8 |  | 5
Total operating lease liabilities | $23 |  | $13 |  | $9 |  | $16 |  | $9 |  | $6
Weighted average remaining lease term | 12 years |  | 12 years |  | 12 years |  | 10 years |  | 11 years |  | 9 years
Weighted average discount rate | 4% |  | 4% |  | 4% |  | 4% |  | 4% |  | 4%
Finance lease details are as follows (dollars in millions):
| December 31, 2023 |  | December 31, 2022
| Alliant Energy |  | IPL |  | WPL |  | Alliant Energy |  | IPL |  | WPL
Property, plant and equipment, net: |  |  |  |  |  |  |  |  |  |  |
Sheboygan Falls Energy Facility | N/A |  | N/A |  | $79 |  | N/A |  | N/A |  | $15
Leased land for solar generation | $172 |  | $33 |  | 139 |  | $133 |  | $— |  | 133
| $172 |  | $33 |  | $218 |  | $133 |  | $— |  | $148
Other current liabilities: |  |  |  |  |  |  |  |  |  |  |
Sheboygan Falls Energy Facility | N/A |  | N/A |  | $11 |  | N/A |  | N/A |  | $12
Leased land for solar generation | $— |  | $— |  | — |  | $5 |  | $— |  | 5
| — |  | — |  | 11 |  | 5 |  | — |  | 17
Other liabilities: |  |  |  |  |  |  |  |  |  |  |
Sheboygan Falls Energy Facility | N/A |  | N/A |  | 78 |  | N/A |  | N/A |  | 19
Leased land for solar generation | 172 |  | 33 |  | 139 |  | 131 |  | — |  | 131
| 172 |  | 33 |  | 217 |  | 131 |  | — |  | 150
Total finance lease liabilities | $172 |  | $33 |  | $228 |  | $136 |  | $— |  | $167
Weighted average remaining lease term | 33 years |  | 29 years |  | 27 years |  | 34 years |  | N/A |  | 28 years
Weighted average discount rate | 5% |  | 5% |  | 5% |  | 5% |  | N/A |  | 5%
| Alliant Energy |  | IPL |  | WPL
| 2023 |  | 2022 |  | 2021 |  | 2023 |  | 2022 |  | 2021 |  | 2023 |  | 2022 |  | 2021
Depreciation and amortization expenses | $1 |  |  | $— |  |  | $— |  |  | $— |  |  | $— |  |  | $— |  |  | $6 |  |  | $6 |  |  | $6 |
Interest expense | 6 |  |  | 3 |  |  | — |  |  | 1 |  |  | — |  |  | — |  |  | 8 |  |  | 7 |  |  | 5 |
Total finance lease expense | $7 |  |  | $3 |  |  | $— |  |  | $1 |  |  | $— |  |  | $— |  |  | $14 |  |  | $13 |  |  | $11 |
Finance lease liabilities arising from obtaining leased assets, which represent non-cash financing activities, were as follows (in millions):
| Alliant Energy |  | IPL |  | WPL
| 2023 |  | 2022 |  |  |  | 2023 |  | 2022 |  |  |  | 2023 |  | 2022 |  |
Finance lease liabilities arising from obtaining leased assets | $34 |  |  | $125 |  |  |  |  | $33 |  |  | $— |  |  |  |  | $71 |  |  | $125 |  |  |
Schedule of Operating Lease Liability Maturities | As of December 31, 2023, expected maturities of lease liabilities were as follows (in millions):
| 2024 |  | 2025 |  | 2026 |  | 2027 |  | 2028 |  | Thereafter |  | Total |  | Less: amount representing interest |  | Present value of minimum lease payments
Operating Leases: |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Alliant Energy | $3 |  |  | $3 |  |  | $3 |  |  | $3 |  |  | $2 |  |  | $16 |  | $30 |  | $7 |  | $23
IPL | 1 |  |  | 2 |  |  | 2 |  |  | 1 |  |  | 1 |  |  | 10 |  | 17 |  | 4 |  | 13
WPL | 2 |  |  | 1 |  |  | 1 |  |  | 1 |  |  | 1 |  |  | 6 |  | 12 |  | 3 |  | 9
Finance Leases: |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Alliant Energy | 8 |  |  | 8 |  |  | 8 |  |  | 8 |  |  | 8 |  |  | 320 |  | 360 |  | 188 |  | 172
IPL | 2 |  |  | 2 |  |  | 2 |  |  | 2 |  |  | 2 |  |  | 59 |  | 69 |  | 36 |  | 33
WPL | 21 |  |  | 17 |  |  | 13 |  |  | 13 |  |  | 13 |  |  | 334 |  | 411 |  | 183 |  | 228
Schedule of Finance Lease Liability Maturities | As of December 31, 2023, expected maturities of lease liabilities were as follows (in millions):
| 2024 |  | 2025 |  | 2026 |  | 2027 |  | 2028 |  | Thereafter |  | Total |  | Less: amount representing interest |  | Present value of minimum lease payments
Operating Leases: |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Alliant Energy | $3 |  |  | $3 |  |  | $3 |  |  | $3 |  |  | $2 |  |  | $16 |  | $30 |  | $7 |  | $23
IPL | 1 |  |  | 2 |  |  | 2 |  |  | 1 |  |  | 1 |  |  | 10 |  | 17 |  | 4 |  | 13
WPL | 2 |  |  | 1 |  |  | 1 |  |  | 1 |  |  | 1 |  |  | 6 |  | 12 |  | 3 |  | 9
Finance Leases: |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Alliant Energy | 8 |  |  | 8 |  |  | 8 |  |  | 8 |  |  | 8 |  |  | 320 |  | 360 |  | 188 |  | 172
IPL | 2 |  |  | 2 |  |  | 2 |  |  | 2 |  |  | 2 |  |  | 59 |  | 69 |  | 36 |  | 33
WPL | 21 |  |  | 17 |  |  | 13 |  |  | 13 |  |  | 13 |  |  | 334 |  | 411 |  | 183 |  | 228
IPL [Member] |
Leases [Line Items] |
Schedule of Lease Details | Operating lease details are as follows (dollars in millions):
| December 31, 2023 |  | December 31, 2022
| Alliant Energy |  | IPL |  | WPL |  | Alliant Energy |  | IPL |  | WPL
Property, plant and equipment, net | $23 |  | $13 |  | $9 |  | $16 |  | $9 |  | $6
Other current liabilities | $2 |  | $1 |  | $1 |  | $3 |  | $1 |  | $1
Other liabilities | 21 |  | 12 |  | 8 |  | 13 |  | 8 |  | 5
Total operating lease liabilities | $23 |  | $13 |  | $9 |  | $16 |  | $9 |  | $6
Weighted average remaining lease term | 12 years |  | 12 years |  | 12 years |  | 10 years |  | 11 years |  | 9 years
Weighted average discount rate | 4% |  | 4% |  | 4% |  | 4% |  | 4% |  | 4%
Finance lease details are as follows (dollars in millions):
| December 31, 2023 |  | December 31, 2022
| Alliant Energy |  | IPL |  | WPL |  | Alliant Energy |  | IPL |  | WPL
Property, plant and equipment, net: |  |  |  |  |  |  |  |  |  |  |
Sheboygan Falls Energy Facility | N/A |  | N/A |  | $79 |  | N/A |  | N/A |  | $15
Leased land for solar generation | $172 |  | $33 |  | 139 |  | $133 |  | $— |  | 133
| $172 |  | $33 |  | $218 |  | $133 |  | $— |  | $148
Other current liabilities: |  |  |  |  |  |  |  |  |  |  |
Sheboygan Falls Energy Facility | N/A |  | N/A |  | $11 |  | N/A |  | N/A |  | $12
Leased land for solar generation | $— |  | $— |  | — |  | $5 |  | $— |  | 5
| — |  | — |  | 11 |  | 5 |  | — |  | 17
Other liabilities: |  |  |  |  |  |  |  |  |  |  |
Sheboygan Falls Energy Facility | N/A |  | N/A |  | 78 |  | N/A |  | N/A |  | 19
Leased land for solar generation | 172 |  | 33 |  | 139 |  | 131 |  | — |  | 131
| 172 |  | 33 |  | 217 |  | 131 |  | — |  | 150
Total finance lease liabilities | $172 |  | $33 |  | $228 |  | $136 |  | $— |  | $167
Weighted average remaining lease term | 33 years |  | 29 years |  | 27 years |  | 34 years |  | N/A |  | 28 years
Weighted average discount rate | 5% |  | 5% |  | 5% |  | 5% |  | N/A |  | 5%
| Alliant Energy |  | IPL |  | WPL
| 2023 |  | 2022 |  | 2021 |  | 2023 |  | 2022 |  | 2021 |  | 2023 |  | 2022 |  | 2021
Depreciation and amortization expenses | $1 |  |  | $— |  |  | $— |  |  | $— |  |  | $— |  |  | $— |  |  | $6 |  |  | $6 |  |  | $6 |
Interest expense | 6 |  |  | 3 |  |  | — |  |  | 1 |  |  | — |  |  | — |  |  | 8 |  |  | 7 |  |  | 5 |
Total finance lease expense | $7 |  |  | $3 |  |  | $— |  |  | $1 |  |  | $— |  |  | $— |  |  | $14 |  |  | $13 |  |  | $11 |
Finance lease liabilities arising from obtaining leased assets, which represent non-cash financing activities, were as follows (in millions):
| Alliant Energy |  | IPL |  | WPL
| 2023 |  | 2022 |  |  |  | 2023 |  | 2022 |  |  |  | 2023 |  | 2022 |  |
Finance lease liabilities arising from obtaining leased assets | $34 |  |  | $125 |  |  |  |  | $33 |  |  | $— |  |  |  |  | $71 |  |  | $125 |  |  |
Schedule of Operating Lease Liability Maturities | As of December 31, 2023, expected maturities of lease liabilities were as follows (in millions):
| 2024 |  | 2025 |  | 2026 |  | 2027 |  | 2028 |  | Thereafter |  | Total |  | Less: amount representing interest |  | Present value of minimum lease payments
Operating Leases: |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Alliant Energy | $3 |  |  | $3 |  |  | $3 |  |  | $3 |  |  | $2 |  |  | $16 |  | $30 |  | $7 |  | $23
IPL | 1 |  |  | 2 |  |  | 2 |  |  | 1 |  |  | 1 |  |  | 10 |  | 17 |  | 4 |  | 13
WPL | 2 |  |  | 1 |  |  | 1 |  |  | 1 |  |  | 1 |  |  | 6 |  | 12 |  | 3 |  | 9
Finance Leases: |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Alliant Energy | 8 |  |  | 8 |  |  | 8 |  |  | 8 |  |  | 8 |  |  | 320 |  | 360 |  | 188 |  | 172
IPL | 2 |  |  | 2 |  |  | 2 |  |  | 2 |  |  | 2 |  |  | 59 |  | 69 |  | 36 |  | 33
WPL | 21 |  |  | 17 |  |  | 13 |  |  | 13 |  |  | 13 |  |  | 334 |  | 411 |  | 183 |  | 228
Schedule of Finance Lease Liability Maturities | As of December 31, 2023, expected maturities of lease liabilities were as follows (in millions):
| 2024 |  | 2025 |  | 2026 |  | 2027 |  | 2028 |  | Thereafter |  | Total |  | Less: amount representing interest |  | Present value of minimum lease payments
Operating Leases: |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Alliant Energy | $3 |  |  | $3 |  |  | $3 |  |  | $3 |  |  | $2 |  |  | $16 |  | $30 |  | $7 |  | $23
IPL | 1 |  |  | 2 |  |  | 2 |  |  | 1 |  |  | 1 |  |  | 10 |  | 17 |  | 4 |  | 13
WPL | 2 |  |  | 1 |  |  | 1 |  |  | 1 |  |  | 1 |  |  | 6 |  | 12 |  | 3 |  | 9
Finance Leases: |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Alliant Energy | 8 |  |  | 8 |  |  | 8 |  |  | 8 |  |  | 8 |  |  | 320 |  | 360 |  | 188 |  | 172
IPL | 2 |  |  | 2 |  |  | 2 |  |  | 2 |  |  | 2 |  |  | 59 |  | 69 |  | 36 |  | 33
WPL | 21 |  |  | 17 |  |  | 13 |  |  | 13 |  |  | 13 |  |  | 334 |  | 411 |  | 183 |  | 228
WPL [Member] |
Leases [Line Items] |
Schedule of Lease Details | Operating lease details are as follows (dollars in millions):
| December 31, 2023 |  | December 31, 2022
| Alliant Energy |  | IPL |  | WPL |  | Alliant Energy |  | IPL |  | WPL
Property, plant and equipment, net | $23 |  | $13 |  | $9 |  | $16 |  | $9 |  | $6
Other current liabilities | $2 |  | $1 |  | $1 |  | $3 |  | $1 |  | $1
Other liabilities | 21 |  | 12 |  | 8 |  | 13 |  | 8 |  | 5
Total operating lease liabilities | $23 |  | $13 |  | $9 |  | $16 |  | $9 |  | $6
Weighted average remaining lease term | 12 years |  | 12 years |  | 12 years |  | 10 years |  | 11 years |  | 9 years
Weighted average discount rate | 4% |  | 4% |  | 4% |  | 4% |  | 4% |  | 4%
Finance lease details are as follows (dollars in millions):
| December 31, 2023 |  | December 31, 2022
| Alliant Energy |  | IPL |  | WPL |  | Alliant Energy |  | IPL |  | WPL
Property, plant and equipment, net: |  |  |  |  |  |  |  |  |  |  |
Sheboygan Falls Energy Facility | N/A |  | N/A |  | $79 |  | N/A |  | N/A |  | $15
Leased land for solar generation | $172 |  | $33 |  | 139 |  | $133 |  | $— |  | 133
| $172 |  | $33 |  | $218 |  | $133 |  | $— |  | $148
Other current liabilities: |  |  |  |  |  |  |  |  |  |  |
Sheboygan Falls Energy Facility | N/A |  | N/A |  | $11 |  | N/A |  | N/A |  | $12
Leased land for solar generation | $— |  | $— |  | — |  | $5 |  | $— |  | 5
| — |  | — |  | 11 |  | 5 |  | — |  | 17
Other liabilities: |  |  |  |  |  |  |  |  |  |  |
Sheboygan Falls Energy Facility | N/A |  | N/A |  | 78 |  | N/A |  | N/A |  | 19
Leased land for solar generation | 172 |  | 33 |  | 139 |  | 131 |  | — |  | 131
| 172 |  | 33 |  | 217 |  | 131 |  | — |  | 150
Total finance lease liabilities | $172 |  | $33 |  | $228 |  | $136 |  | $— |  | $167
Weighted average remaining lease term | 33 years |  | 29 years |  | 27 years |  | 34 years |  | N/A |  | 28 years
Weighted average discount rate | 5% |  | 5% |  | 5% |  | 5% |  | N/A |  | 5%
| Alliant Energy |  | IPL |  | WPL
| 2023 |  | 2022 |  | 2021 |  | 2023 |  | 2022 |  | 2021 |  | 2023 |  | 2022 |  | 2021
Depreciation and amortization expenses | $1 |  |  | $— |  |  | $— |  |  | $— |  |  | $— |  |  | $— |  |  | $6 |  |  | $6 |  |  | $6 |
Interest expense | 6 |  |  | 3 |  |  | — |  |  | 1 |  |  | — |  |  | — |  |  | 8 |  |  | 7 |  |  | 5 |
Total finance lease expense | $7 |  |  | $3 |  |  | $— |  |  | $1 |  |  | $— |  |  | $— |  |  | $14 |  |  | $13 |  |  | $11 |
Finance lease liabilities arising from obtaining leased assets, which represent non-cash financing activities, were as follows (in millions):
| Alliant Energy |  | IPL |  | WPL
| 2023 |  | 2022 |  |  |  | 2023 |  | 2022 |  |  |  | 2023 |  | 2022 |  |
Finance lease liabilities arising from obtaining leased assets | $34 |  |  | $125 |  |  |  |  | $33 |  |  | $— |  |  |  |  | $71 |  |  | $125 |  |  |
Schedule of Operating Lease Liability Maturities | As of December 31, 2023, expected maturities of lease liabilities were as follows (in millions):
| 2024 |  | 2025 |  | 2026 |  | 2027 |  | 2028 |  | Thereafter |  | Total |  | Less: amount representing interest |  | Present value of minimum lease payments
Operating Leases: |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Alliant Energy | $3 |  |  | $3 |  |  | $3 |  |  | $3 |  |  | $2 |  |  | $16 |  | $30 |  | $7 |  | $23
IPL | 1 |  |  | 2 |  |  | 2 |  |  | 1 |  |  | 1 |  |  | 10 |  | 17 |  | 4 |  | 13
WPL | 2 |  |  | 1 |  |  | 1 |  |  | 1 |  |  | 1 |  |  | 6 |  | 12 |  | 3 |  | 9
Finance Leases: |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Alliant Energy | 8 |  |  | 8 |  |  | 8 |  |  | 8 |  |  | 8 |  |  | 320 |  | 360 |  | 188 |  | 172
IPL | 2 |  |  | 2 |  |  | 2 |  |  | 2 |  |  | 2 |  |  | 59 |  | 69 |  | 36 |  | 33
WPL | 21 |  |  | 17 |  |  | 13 |  |  | 13 |  |  | 13 |  |  | 334 |  | 411 |  | 183 |  | 228
Schedule of Finance Lease Liability Maturities | As of December 31, 2023, expected maturities of lease liabilities were as follows (in millions):
| 2024 |  | 2025 |  | 2026 |  | 2027 |  | 2028 |  | Thereafter |  | Total |  | Less: amount representing interest |  | Present value of minimum lease payments
Operating Leases: |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Alliant Energy | $3 |  |  | $3 |  |  | $3 |  |  | $3 |  |  | $2 |  |  | $16 |  | $30 |  | $7 |  | $23
IPL | 1 |  |  | 2 |  |  | 2 |  |  | 1 |  |  | 1 |  |  | 10 |  | 17 |  | 4 |  | 13
WPL | 2 |  |  | 1 |  |  | 1 |  |  | 1 |  |  | 1 |  |  | 6 |  | 12 |  | 3 |  | 9
Finance Leases: |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Alliant Energy | 8 |  |  | 8 |  |  | 8 |  |  | 8 |  |  | 8 |  |  | 320 |  | 360 |  | 188 |  | 172
IPL | 2 |  |  | 2 |  |  | 2 |  |  | 2 |  |  | 2 |  |  | 59 |  | 69 |  | 36 |  | 33
WPL | 21 |  |  | 17 |  |  | 13 |  |  | 13 |  |  | 13 |  |  | 334 |  | 411 |  | 183 |  | 228

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- Definition Tabular disclosure of undiscounted cash flows of lessee's operating lease liability. Includes, but is not limited to, reconciliation of undiscounted cash flows to operating lease liability recognized in statement of financial position. + References Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef -Topic 842 -SubTopic 20 -Name Accounting Standards Codification -Section 50 -Paragraph 6 -Publisher FASB -URI https://asc.fasb.org//1943274/2147478964/842-20-50-6 + Details
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