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Leases (Finance Lease) (Details) - USD ($) $ in Millions | 12 Months Ended
--- | ---
Dec. 31, 2023 | Dec. 31, 2022 | Dec. 31, 2021
Leases [Line Items] |  |  |
Finance lease assets, Property, plant and equipment, net | $ 172 | $ 133 |
Finance lease liabilities, Other current liabilities | 0 | 5 |
Finance lease liabilities, Other liabilities | 172 | 131 |
Finance lease liabilities, Total | $ 172 | $ 136 |
Finance lease, Remaining lease term | 33 years | 34 years |
Finance lease, Discount rate, percent | 5.00% | 5.00% |
Finance lease, Depreciation expense | $ 1 | $ 0 | $ 0
Finance lease, Interest expense | 6 | 3 | 0
Finance lease, Total expense | $ 7 | $ 3 | 0
Finance Lease, Right-of-Use Asset, Statement of Financial Position [Extensible Enumeration] | Property, plant and equipment, net | Property, plant and equipment, net |
Finance Lease, Liability, Current, Statement of Financial Position [Extensible Enumeration] | Other | Other |
Finance Lease, Liability, Noncurrent, Statement of Financial Position [Extensible Enumeration] | Other | Other |
Sheboygan Falls Energy Facility [Member] |  |  |
Leases [Line Items] |  |  |
Finance Lease, Right-of-Use Asset, Statement of Financial Position [Extensible Enumeration] | Property, plant and equipment, net | Property, plant and equipment, net |
Finance Lease, Liability, Current, Statement of Financial Position [Extensible Enumeration] | Other | Other |
Finance Lease, Liability, Noncurrent, Statement of Financial Position [Extensible Enumeration] | Other | Other |
Leased land for solar generation [Member] |  |  |
Leases [Line Items] |  |  |
Finance lease assets, Property, plant and equipment, net | $ 172 | $ 133 |
Finance lease liabilities, Other current liabilities | 0 | 5 |
Finance lease liabilities, Other liabilities | $ 172 | $ 131 |
Finance Lease, Right-of-Use Asset, Statement of Financial Position [Extensible Enumeration] | Property, plant and equipment, net | Property, plant and equipment, net |
Finance Lease, Liability, Current, Statement of Financial Position [Extensible Enumeration] | Other | Other |
Finance Lease, Liability, Noncurrent, Statement of Financial Position [Extensible Enumeration] | Other | Other |
IPL [Member] |  |  |
Leases [Line Items] |  |  |
Finance lease assets, Property, plant and equipment, net | $ 33 | $ 0 |
Finance lease liabilities, Other current liabilities | 0 |  |
Finance lease liabilities, Other liabilities | 33 | 0 |
Finance lease liabilities, Total | $ 33 | 0 |
Finance lease, Remaining lease term | 29 years |  |
Finance lease, Discount rate, percent | 5.00% |  |
Finance lease, Depreciation expense | $ 0 | 0 | 0
Finance lease, Interest expense | 1 | 0 | 0
Finance lease, Total expense | 1 | 0 | 0
IPL [Member] | Leased land for solar generation [Member] |  |  |
Leases [Line Items] |  |  |
Finance lease assets, Property, plant and equipment, net | 33 | 0 |
Finance lease liabilities, Other current liabilities | 0 | 0 |
Finance lease liabilities, Other liabilities | 33 | 0 |
WPL [Member] |  |  |
Leases [Line Items] |  |  |
Finance lease assets, Property, plant and equipment, net | 218 | 148 |
Finance lease liabilities, Other current liabilities | 11 | 17 |
Finance lease liabilities, Other liabilities | 217 | 150 |
Finance lease liabilities, Total | $ 228 | $ 167 |
Finance lease, Remaining lease term | 27 years | 28 years |
Finance lease, Discount rate, percent | 5.00% | 5.00% |
Finance lease, Depreciation expense | $ 6 | $ 6 | 6
Finance lease, Interest expense | 8 | 7 | 5
Finance lease, Total expense | 14 | 13 | $ 11
WPL [Member] | Sheboygan Falls Energy Facility [Member] |  |  |
Leases [Line Items] |  |  |
Finance lease assets, Property, plant and equipment, net | 79 | 15 |
Finance lease liabilities, Other current liabilities | 11 | 12 |
Finance lease liabilities, Other liabilities | 78 | 19 |
WPL [Member] | Leased land for solar generation [Member] |  |  |
Leases [Line Items] |  |  |
Finance lease assets, Property, plant and equipment, net | 139 | 133 |
Finance lease liabilities, Other current liabilities | 0 | 5 |
Finance lease liabilities, Other liabilities | $ 139 | $ 131 |

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