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Leases (Finance Lease) (Details) - USD ($) $ in Millions | 12 Months Ended
--- | ---
Dec. 31, 2021 | Dec. 31, 2020 | Dec. 31, 2019
Leases [Line Items] |  |  |
Finance lease assets, Property, plant and equipment, net | $ 11 |  |
Finance Lease, Liability, Current, Statement of Financial Position [Extensible Enumeration] | Other | Other |
Finance lease liabilities, Other current liabilities | $ 1 |  |
Finance Lease, Liability, Noncurrent, Statement of Financial Position [Extensible Enumeration] | Other | Other |
Finance lease liabilities, Other liabilities | $ 11 |  |
Finance lease liabilities, Total | $ 12 |  |
Finance lease, Weighted average remaining lease term | 34 years |  |
Finance lease, Weighted average discount rate, percent | 3.00% |  |
Finance lease, Depreciation and amortization expense | $ 0 |  |
Finance lease, Interest expense | 0 |  |
Finance lease, Total expense | $ 0 |  |
Finance Lease, Right-of-Use Asset, Statement of Financial Position [Extensible Enumeration] | Other Assets | Other Assets |
Leased land for solar generation [Member] |  |  |
Leases [Line Items] |  |  |
Finance lease assets, Property, plant and equipment, net | $ 11 |  |
Finance lease liabilities, Other current liabilities | 1 |  |
Finance lease liabilities, Other liabilities | 11 |  |
WPL [Member] |  |  |
Leases [Line Items] |  |  |
Finance lease assets, Property, plant and equipment, net | 32 | $ 27 |
Finance lease liabilities, Other current liabilities | 11 | 9 |
Finance lease liabilities, Other liabilities | 42 | 42 |
Finance lease liabilities, Total | $ 53 | $ 51 |
Finance lease, Weighted average remaining lease term | 10 years | 4 years |
Finance lease, Weighted average discount rate, percent | 9.00% | 11.00% |
Finance lease, Depreciation and amortization expense | $ 6 | $ 6 | $ 6
Finance lease, Interest expense | 5 | 6 | 7
Finance lease, Total expense | 11 | 12 | $ 13
WPL [Member] | Sheboygan Falls Energy Facility [Member] |  |  |
Leases [Line Items] |  |  |
Finance lease assets, Property, plant and equipment, net | 21 | 27 |
Finance lease liabilities, Other current liabilities | 10 | 9 |
Finance lease liabilities, Other liabilities | 31 | 42 |
WPL [Member] | Leased land for solar generation [Member] |  |  |
Leases [Line Items] |  |  |
Finance lease assets, Property, plant and equipment, net | 11 | 0 |
Finance lease liabilities, Other current liabilities | 1 | 0 |
Finance lease liabilities, Other liabilities | $ 11 | $ 0 |

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- Definition Amount, after accumulated amortization, of right-of-use asset from finance lease. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 842 -SubTopic 20 -Section 45 -Paragraph 1 -Subparagraph (a) -URI http://asc.fasb.org/extlink&oid=123391704&loc=SL77918627-209977 + Details
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- Definition Weighted average remaining lease term for finance lease, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents reported fact of one year, five months, and thirteen days. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 842 -SubTopic 20 -Section 50 -Paragraph 4 -Subparagraph (g)(3) -URI http://asc.fasb.org/extlink&oid=123408670&loc=SL77918686-209980 Reference 2: http://www.xbrl.org/2003/role/exampleRef -Publisher FASB -Name Accounting Standards Codification -Topic 842 -SubTopic 20 -Section 55 -Paragraph 53 -URI http://asc.fasb.org/extlink&oid=123414884&loc=SL77918982-209971 + Details
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