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Related Parties (Service Agreements) (Details) - Corporate Services [Member] - Subsidiary of Common Parent [Member] - USD ($) $ in Millions | 3 Months Ended | 6 Months Ended
--- | --- | ---
Jun. 30, 2020 | Jun. 30, 2019 | Jun. 30, 2020 | Jun. 30, 2019
Corporate Services Billings [Member] | IPL [Member] |  |  |  |
Related Party Transactions [Line Items] |  |  |  |
Amounts billed between related parties | $ 44 | $ 47 | $ 81 | $ 90
Corporate Services Billings [Member] | WPL [Member] |  |  |  |
Related Party Transactions [Line Items] |  |  |  |
Amounts billed between related parties | 35 | 35 | 67 | 68
Sales Credited [Member] | IPL [Member] |  |  |  |
Related Party Transactions [Line Items] |  |  |  |
Amounts billed between related parties | 10 | 12 | 25 | 27
Sales Credited [Member] | WPL [Member] |  |  |  |
Related Party Transactions [Line Items] |  |  |  |
Amounts billed between related parties | 2 | 3 | 4 | 4
Purchases Billed [Member] | IPL [Member] |  |  |  |
Related Party Transactions [Line Items] |  |  |  |
Amounts billed between related parties | 57 | 74 | 138 | 158
Purchases Billed [Member] | WPL [Member] |  |  |  |
Related Party Transactions [Line Items] |  |  |  |
Amounts billed between related parties | $ 20 | $ 29 | $ 40 | $ 59

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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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