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Income Taxes (Narrative) (Details) - USD ($) $ in Millions | 12 Months Ended
--- | ---
Dec. 31, 2021 | Dec. 31, 2020 | Dec. 31, 2019 | Dec. 31, 2018
Income Tax [Line Items] |  |  |  |
Valuation allowance, reversal |  | $ 4 |  |
Income tax expense (benefits) Federal Tax Reform |  |  |  | $ (6)
Overall income tax rate |  | (10.00%) | 11.00% | 8.00%
IPL [Member] |  |  |  |
Income Tax [Line Items] |  |  |  |
Income tax expense (benefits) Federal Tax Reform |  |  |  | $ (1)
Overall income tax rate |  | (16.00%) | 8.00% | (1.00%)
WPL [Member] |  |  |  |
Income Tax [Line Items] |  |  |  |
Income tax expense (benefits) Federal Tax Reform |  |  |  | $ (5)
Overall income tax rate |  | (8.00%) | 17.00% | 15.00%
State [Member] |  |  |  |
Income Tax [Line Items] |  |  |  |
Overall income tax rate |  | 12.00% |  |
State [Member] | Forecast [Member] |  |  |  |
Income Tax [Line Items] |  |  |  |
Overall income tax rate | 9.80% |  |  |
State [Member] | IPL [Member] |  |  |  |
Income Tax [Line Items] |  |  |  |
Overall income tax rate |  | 12.00% |  |
State [Member] | IPL [Member] | Forecast [Member] |  |  |  |
Income Tax [Line Items] |  |  |  |
Overall income tax rate | 9.80% |  |  |
State [Member] | WPL [Member] |  |  |  |
Income Tax [Line Items] |  |  |  |
Overall income tax rate |  | 12.00% |  |
State [Member] | WPL [Member] | Forecast [Member] |  |  |  |
Income Tax [Line Items] |  |  |  |
Overall income tax rate | 9.80% |  |  |

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- Definition Percentage of current income tax expense (benefit) and deferred income tax expense (benefit) pertaining to continuing operations. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 740 -SubTopic 10 -Section 50 -Paragraph 12 -URI http://asc.fasb.org/extlink&oid=84230637&loc=d3e32687-109319 + Details
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