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Summary Of Significant Accounting Policies (Schedule Of Allowance For Funds Used During Construction Recovery Rate) (Details) | 12 Months Ended
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Dec. 31, 2019 | Dec. 31, 2018 | Dec. 31, 2017
IPL [Member] | IPL (Marshalltown CWIP) [Member] |  |  |
Public Utility, Property, Plant and Equipment [Line Items] |  |  |
Recovery rates |  |  | 7.80%
IPL [Member] | IPL (Wind generation CWIP) [Member] |  |  |
Public Utility, Property, Plant and Equipment [Line Items] |  |  |
Recovery rates | 7.40% | 7.50% | 7.60%
IPL [Member] | IPL (other CWIP) [Member] |  |  |
Public Utility, Property, Plant and Equipment [Line Items] |  |  |
Recovery rates | 7.50% | 7.50% | 7.60%
WPL [Member] | WPL (retail jurisdiction) [Member] |  |  |
Public Utility, Property, Plant and Equipment [Line Items] |  |  |
Recovery rates | 6.80% | 7.70% | 7.60%
WPL [Member] | WPL (wholesale jurisdiction) [Member] |  |  |
Public Utility, Property, Plant and Equipment [Line Items] |  |  |
Recovery rates | 6.90% | 7.20% | 6.00%

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- Definition Effective rate, including composite rate, of cost of financing additions to qualifying regulated assets, commonly called allowance for funds used during construction. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 980 -SubTopic 835 -Section 45 -Paragraph 1 -URI http://asc.fasb.org/extlink&oid=6501662&loc=d3e56162-110433 Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 980 -SubTopic 835 -Section 25 -Paragraph 1 -URI http://asc.fasb.org/extlink&oid=6501569&loc=d3e55921-110430 + Details
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- Definition Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table. + References No definition available. + Details
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