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Leases (Tables) | 12 Months Ended
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Dec. 31, 2021
Leases [Line Items] |
Schedule of Operating Lease Details | Operating lease details are as follows (dollars in millions):
| December 31, 2021 |  | December 31, 2020
| Alliant Energy |  | IPL |  | WPL |  | Alliant Energy |  | IPL |  | WPL
Property, plant and equipment, net | $14 |  | $9 |  | $5 |  | $15 |  | $9 |  | $6
Other current liabilities | $2 |  | $1 |  | $1 |  | $2 |  | $1 |  | $1
Other liabilities | 12 |  | 8 |  | 4 |  | 13 |  | 8 |  | 5
Total operating lease liabilities | $14 |  | $9 |  | $5 |  | $15 |  | $9 |  | $6
Weighted average remaining lease term | 9 years |  | 11 years |  | 8 years |  | 10 years |  | 11 years |  | 9 years
Weighted average discount rate | 4% |  | 4% |  | 4% |  | 4% |  | 4% |  | 4%
Schedule of Finance Lease Details | Finance lease details are as follows (dollars in millions):
| Alliant Energy |  | WPL
| December 31, 2021 |  | December 31, 2021 |  | December 31, 2020 |  |
Property, plant and equipment, net: |  |  |  |  |  |  |
Sheboygan Falls Energy Facility | n/a |  | $21 |  | $27 |  |
Leased land for solar generation | $11 |  | 11 |  | — |  |
| $11 |  | $32 |  | $27 |  |
Other current liabilities: |  |  |  |  |  |  |
Sheboygan Falls Energy Facility | n/a |  | $10 |  | $9 |  |
Leased land for solar generation | $1 |  | 1 |  | — |  |
| 1 |  | 11 |  | 9 |  |
Other liabilities: |  |  |  |  |  |  |
Sheboygan Falls Energy Facility | n/a |  | 31 |  | 42 |  |
Leased land for solar generation | 11 |  | 11 |  | — |  |
| 11 |  | 42 |  | 42 |  |
Total finance lease liabilities | $12 |  | $53 |  | $51 |  |
Weighted average remaining lease term | 34 years |  | 10 years |  | 4 years |  |
Weighted average discount rate | 3% |  | 9% |  | 11% |  |
| 2021 |  | 2021 |  | 2020 |  | 2019
Depreciation and amortization expenses | $— |  | $6 |  | $6 |  | $6
Interest expense | — |  | 5 |  | 6 |  | 7
Total finance lease expense | $— |  | $11 |  | $12 |  | $13
Schedule of Operating Lease Liability Maturities | As of December 31, 2021, expected maturities of lease liabilities were as follows (in millions):
| 2022 |  | 2023 |  | 2024 |  | 2025 |  | 2026 |  | Thereafter |  | Total |  | Less: amount representing interest |  | Present value of minimum lease payments
Operating Leases: |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Alliant Energy | $2 |  |  | $2 |  |  | $2 |  |  | $2 |  |  | $2 |  |  | $7 |  | $17 |  | $3 |  | $14
IPL | 1 |  |  | 1 |  |  | 1 |  |  | 1 |  |  | 1 |  |  | 6 |  | 11 |  | 2 |  | 9
WPL | 1 |  |  | 1 |  |  | 1 |  |  | 1 |  |  | 1 |  |  | 1 |  | 6 |  | 1 |  | 5
Finance Leases: |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Alliant Energy | — |  |  | — |  |  | — |  |  | — |  |  | 1 |  |  | 19 |  | 20 |  | 8 |  | 12
WPL | 15 |  |  | 15 |  |  | 15 |  |  | 6 |  |  | 1 |  |  | 19 |  | 71 |  | 18 |  | 53
Schedule of Finance Lease Liability Maturities | As of December 31, 2021, expected maturities of lease liabilities were as follows (in millions):
| 2022 |  | 2023 |  | 2024 |  | 2025 |  | 2026 |  | Thereafter |  | Total |  | Less: amount representing interest |  | Present value of minimum lease payments
Operating Leases: |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Alliant Energy | $2 |  |  | $2 |  |  | $2 |  |  | $2 |  |  | $2 |  |  | $7 |  | $17 |  | $3 |  | $14
IPL | 1 |  |  | 1 |  |  | 1 |  |  | 1 |  |  | 1 |  |  | 6 |  | 11 |  | 2 |  | 9
WPL | 1 |  |  | 1 |  |  | 1 |  |  | 1 |  |  | 1 |  |  | 1 |  | 6 |  | 1 |  | 5
Finance Leases: |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Alliant Energy | — |  |  | — |  |  | — |  |  | — |  |  | 1 |  |  | 19 |  | 20 |  | 8 |  | 12
WPL | 15 |  |  | 15 |  |  | 15 |  |  | 6 |  |  | 1 |  |  | 19 |  | 71 |  | 18 |  | 53
IPL [Member] |
Leases [Line Items] |
Schedule of Operating Lease Details | Operating lease details are as follows (dollars in millions):
| December 31, 2021 |  | December 31, 2020
| Alliant Energy |  | IPL |  | WPL |  | Alliant Energy |  | IPL |  | WPL
Property, plant and equipment, net | $14 |  | $9 |  | $5 |  | $15 |  | $9 |  | $6
Other current liabilities | $2 |  | $1 |  | $1 |  | $2 |  | $1 |  | $1
Other liabilities | 12 |  | 8 |  | 4 |  | 13 |  | 8 |  | 5
Total operating lease liabilities | $14 |  | $9 |  | $5 |  | $15 |  | $9 |  | $6
Weighted average remaining lease term | 9 years |  | 11 years |  | 8 years |  | 10 years |  | 11 years |  | 9 years
Weighted average discount rate | 4% |  | 4% |  | 4% |  | 4% |  | 4% |  | 4%
Schedule of Operating Lease Liability Maturities | As of December 31, 2021, expected maturities of lease liabilities were as follows (in millions):
| 2022 |  | 2023 |  | 2024 |  | 2025 |  | 2026 |  | Thereafter |  | Total |  | Less: amount representing interest |  | Present value of minimum lease payments
Operating Leases: |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Alliant Energy | $2 |  |  | $2 |  |  | $2 |  |  | $2 |  |  | $2 |  |  | $7 |  | $17 |  | $3 |  | $14
IPL | 1 |  |  | 1 |  |  | 1 |  |  | 1 |  |  | 1 |  |  | 6 |  | 11 |  | 2 |  | 9
WPL | 1 |  |  | 1 |  |  | 1 |  |  | 1 |  |  | 1 |  |  | 1 |  | 6 |  | 1 |  | 5
Finance Leases: |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Alliant Energy | — |  |  | — |  |  | — |  |  | — |  |  | 1 |  |  | 19 |  | 20 |  | 8 |  | 12
WPL | 15 |  |  | 15 |  |  | 15 |  |  | 6 |  |  | 1 |  |  | 19 |  | 71 |  | 18 |  | 53
WPL [Member] |
Leases [Line Items] |
Schedule of Operating Lease Details | Operating lease details are as follows (dollars in millions):
| December 31, 2021 |  | December 31, 2020
| Alliant Energy |  | IPL |  | WPL |  | Alliant Energy |  | IPL |  | WPL
Property, plant and equipment, net | $14 |  | $9 |  | $5 |  | $15 |  | $9 |  | $6
Other current liabilities | $2 |  | $1 |  | $1 |  | $2 |  | $1 |  | $1
Other liabilities | 12 |  | 8 |  | 4 |  | 13 |  | 8 |  | 5
Total operating lease liabilities | $14 |  | $9 |  | $5 |  | $15 |  | $9 |  | $6
Weighted average remaining lease term | 9 years |  | 11 years |  | 8 years |  | 10 years |  | 11 years |  | 9 years
Weighted average discount rate | 4% |  | 4% |  | 4% |  | 4% |  | 4% |  | 4%
Schedule of Finance Lease Details | Finance lease details are as follows (dollars in millions):
| Alliant Energy |  | WPL
| December 31, 2021 |  | December 31, 2021 |  | December 31, 2020 |  |
Property, plant and equipment, net: |  |  |  |  |  |  |
Sheboygan Falls Energy Facility | n/a |  | $21 |  | $27 |  |
Leased land for solar generation | $11 |  | 11 |  | — |  |
| $11 |  | $32 |  | $27 |  |
Other current liabilities: |  |  |  |  |  |  |
Sheboygan Falls Energy Facility | n/a |  | $10 |  | $9 |  |
Leased land for solar generation | $1 |  | 1 |  | — |  |
| 1 |  | 11 |  | 9 |  |
Other liabilities: |  |  |  |  |  |  |
Sheboygan Falls Energy Facility | n/a |  | 31 |  | 42 |  |
Leased land for solar generation | 11 |  | 11 |  | — |  |
| 11 |  | 42 |  | 42 |  |
Total finance lease liabilities | $12 |  | $53 |  | $51 |  |
Weighted average remaining lease term | 34 years |  | 10 years |  | 4 years |  |
Weighted average discount rate | 3% |  | 9% |  | 11% |  |
| 2021 |  | 2021 |  | 2020 |  | 2019
Depreciation and amortization expenses | $— |  | $6 |  | $6 |  | $6
Interest expense | — |  | 5 |  | 6 |  | 7
Total finance lease expense | $— |  | $11 |  | $12 |  | $13
Schedule of Operating Lease Liability Maturities | As of December 31, 2021, expected maturities of lease liabilities were as follows (in millions):
| 2022 |  | 2023 |  | 2024 |  | 2025 |  | 2026 |  | Thereafter |  | Total |  | Less: amount representing interest |  | Present value of minimum lease payments
Operating Leases: |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Alliant Energy | $2 |  |  | $2 |  |  | $2 |  |  | $2 |  |  | $2 |  |  | $7 |  | $17 |  | $3 |  | $14
IPL | 1 |  |  | 1 |  |  | 1 |  |  | 1 |  |  | 1 |  |  | 6 |  | 11 |  | 2 |  | 9
WPL | 1 |  |  | 1 |  |  | 1 |  |  | 1 |  |  | 1 |  |  | 1 |  | 6 |  | 1 |  | 5
Finance Leases: |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Alliant Energy | — |  |  | — |  |  | — |  |  | — |  |  | 1 |  |  | 19 |  | 20 |  | 8 |  | 12
WPL | 15 |  |  | 15 |  |  | 15 |  |  | 6 |  |  | 1 |  |  | 19 |  | 71 |  | 18 |  | 53
Schedule of Finance Lease Liability Maturities | As of December 31, 2021, expected maturities of lease liabilities were as follows (in millions):
| 2022 |  | 2023 |  | 2024 |  | 2025 |  | 2026 |  | Thereafter |  | Total |  | Less: amount representing interest |  | Present value of minimum lease payments
Operating Leases: |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Alliant Energy | $2 |  |  | $2 |  |  | $2 |  |  | $2 |  |  | $2 |  |  | $7 |  | $17 |  | $3 |  | $14
IPL | 1 |  |  | 1 |  |  | 1 |  |  | 1 |  |  | 1 |  |  | 6 |  | 11 |  | 2 |  | 9
WPL | 1 |  |  | 1 |  |  | 1 |  |  | 1 |  |  | 1 |  |  | 1 |  | 6 |  | 1 |  | 5
Finance Leases: |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Alliant Energy | — |  |  | — |  |  | — |  |  | — |  |  | 1 |  |  | 19 |  | 20 |  | 8 |  | 12
WPL | 15 |  |  | 15 |  |  | 15 |  |  | 6 |  |  | 1 |  |  | 19 |  | 71 |  | 18 |  | 53

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