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v3.20.4

Related Parties (Service Agreements) (Details) - Corporate Services [Member] - Subsidiary of Common Parent [Member] - USD ($) $ in Millions | 12 Months Ended
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Dec. 31, 2020 | Dec. 31, 2019 | Dec. 31, 2018
Administrative and General Services Billings [Member] | IPL [Member] |  |  |
Related Party Transaction [Line Items] |  |  |
Amounts billed between related parties | $ 176 | $ 185 | $ 170
Administrative and General Services Billings [Member] | WPL [Member] |  |  |
Related Party Transaction [Line Items] |  |  |
Amounts billed between related parties | 142 | 142 | 132
Transmission Sales Credited [Member] | IPL [Member] |  |  |
Related Party Transaction [Line Items] |  |  |
Amounts billed between related parties | 35 | 68 | 48
Transmission Sales Credited [Member] | WPL [Member] |  |  |
Related Party Transaction [Line Items] |  |  |
Amounts billed between related parties | 3 | 7 | 28
Transmission Purchases Billed [Member] | IPL [Member] |  |  |
Related Party Transaction [Line Items] |  |  |
Amounts billed between related parties | 329 | 331 | 358
Transmission Purchases Billed [Member] | WPL [Member] |  |  |
Related Party Transaction [Line Items] |  |  |
Amounts billed between related parties | $ 108 | $ 120 | $ 81

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- Definition Amount of transactions with related party during the financial reporting period. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 850 -SubTopic 10 -Section 50 -Paragraph 1 -Subparagraph (c) -URI http://asc.fasb.org/extlink&oid=6457730&loc=d3e39549-107864 Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 850 -SubTopic 10 -Section 50 -Paragraph 3 -URI http://asc.fasb.org/extlink&oid=6457730&loc=d3e39603-107864 + 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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- Details
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- Details
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- Details
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- Details
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- Details
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- Details
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- Details
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