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Related Parties (Service Agreements) (Details) - Corporate Services [Member] - Subsidiary of Common Parent [Member] - USD ($) $ in Millions | 3 Months Ended | 9 Months Ended
--- | --- | ---
Sep. 30, 2020 | Sep. 30, 2019 | Sep. 30, 2020 | Sep. 30, 2019
Corporate Services Billings [Member] | IPL [Member] |  |  |  |
Related Party Transactions [Line Items] |  |  |  |
Amounts billed between related parties | $ 53 | $ 47 | $ 134 | $ 137
Corporate Services Billings [Member] | WPL [Member] |  |  |  |
Related Party Transactions [Line Items] |  |  |  |
Amounts billed between related parties | 41 | 36 | 108 | 104
Sales Credited [Member] | IPL [Member] |  |  |  |
Related Party Transactions [Line Items] |  |  |  |
Amounts billed between related parties | 10 | 23 | 35 | 50
Sales Credited [Member] | WPL [Member] |  |  |  |
Related Party Transactions [Line Items] |  |  |  |
Amounts billed between related parties | 0 | 2 | 4 | 6
Purchases Billed [Member] | IPL [Member] |  |  |  |
Related Party Transactions [Line Items] |  |  |  |
Amounts billed between related parties | 110 | 93 | 248 | 251
Purchases Billed [Member] | WPL [Member] |  |  |  |
Related Party Transactions [Line Items] |  |  |  |
Amounts billed between related parties | $ 39 | $ 32 | $ 79 | $ 91

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- Definition Amount of transactions with related party during the financial reporting period. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -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 4 -URI http://asc.fasb.org/extlink&oid=6457730&loc=d3e39622-107864 Reference 3: 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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