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Benefit Plans (Estimated Future Funding) (Details) - Forecast [Member] $ in Millions | Dec. 31, 2021 USD ($)
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Defined Benefit Pension Plans [Member] |
Defined Benefit Plan Disclosure [Line Items] |
Estimated funding for calendar year 2021 | $ 39
Defined Benefit Pension Plans [Member] | IPL [Member] |
Defined Benefit Plan Disclosure [Line Items] |
Estimated funding for calendar year 2021 | 17
Defined Benefit Pension Plans [Member] | WPL [Member] |
Defined Benefit Plan Disclosure [Line Items] |
Estimated funding for calendar year 2021 | 18
Other Postretirement Benefits Plans [Member] |
Defined Benefit Plan Disclosure [Line Items] |
Estimated funding for calendar year 2021 | 8
Other Postretirement Benefits Plans [Member] | IPL [Member] |
Defined Benefit Plan Disclosure [Line Items] |
Estimated funding for calendar year 2021 | 2
Other Postretirement Benefits Plans [Member] | WPL [Member] |
Defined Benefit Plan Disclosure [Line Items] |
Estimated funding for calendar year 2021 | $ 6

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- Definition Amount of contribution expected to be received by defined benefit plan from employer in next fiscal year following current fiscal year. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 20 -Section 50 -Paragraph 1 -Subparagraph (g) -URI http://asc.fasb.org/extlink&oid=118255775&loc=d3e1928-114920 Reference 2: http://www.xbrl.org/2003/role/exampleRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 20 -Section 55 -Paragraph 18 -URI http://asc.fasb.org/extlink&oid=118257860&loc=d3e4587-114921 + Details
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