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Commitments And Contingencies (Narrative) (Details) - USD ($) $ in Millions | 6 Months Ended | 9 Months Ended
--- | --- | ---
Jun. 30, 2021 | Jun. 30, 2020 | Sep. 30, 2024
Commitments and Contingencies [Line Items] |  |  |
Minimum future commitments |  |  | $ 995
IPL [Member] |  |  |
Commitments and Contingencies [Line Items] |  |  |
Minimum future commitments |  |  | $ 448
MISO base return on equity, percentage |  |  | 10.25%
WPL [Member] |  |  |
Commitments and Contingencies [Line Items] |  |  |
Minimum future commitments |  |  | $ 505
Federal Energy Regulatory Commission [Member] |  |  |
Commitments and Contingencies [Line Items] |  |  |
MISO base return on equity, percentage | 10.02% | 9.88% | 9.98%
Indemnification Agreement [Member] |  |  |
Commitments and Contingencies [Line Items] |  |  |
Obligations, maximum |  |  | $ 43
Whiting Petroleum Affiliate [Member] |  |  |
Commitments and Contingencies [Line Items] |  |  |
Partnership share, percent |  |  | 6.00%
Obligations, maximum |  |  | $ 49
Capital Purchase Commitment [Member] |  |  |
Commitments and Contingencies [Line Items] |  |  |
Minimum future commitments |  |  | 99
Capital Purchase Commitment [Member] | IPL [Member] |  |  |
Commitments and Contingencies [Line Items] |  |  |
Minimum future commitments |  |  | 24
Capital Purchase Commitment [Member] | WPL [Member] |  |  |
Commitments and Contingencies [Line Items] |  |  |
Minimum future commitments |  |  | 72
Purchased Power [Member] | Indemnification Agreement [Member] |  |  |
Commitments and Contingencies [Line Items] |  |  |
Obligations, maximum |  |  | 17
Renewable Tax Credits Transferred [Member] | Indemnification Agreement [Member] | IPL [Member] |  |  |
Commitments and Contingencies [Line Items] |  |  |
Obligations, maximum |  |  | 165
Renewable Tax Credits Transferred [Member] | Indemnification Agreement [Member] | WPL [Member] |  |  |
Commitments and Contingencies [Line Items] |  |  |
Obligations, maximum |  |  | $ 105

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- Definition Maximum potential amount of future payments (undiscounted) the guarantor could be required to make under the guarantee or each group of similar guarantees before reduction for potential recoveries under recourse or collateralization provisions. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Topic 460 -SubTopic 10 -Name Accounting Standards Codification -Section 50 -Paragraph 4 -Subparagraph (b)(1) -Publisher FASB -URI https://asc.fasb.org/1943274/2147482425/460-10-50-4 + Details
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- Definition Percentage investment held by members or limited partners of limited liability company (LLC) or limited partnership (LP). + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Name Accounting Standards Codification -Topic 272 -SubTopic 10 -Section 50 -Paragraph 3 -Subparagraph (b) -Publisher FASB -URI https://asc.fasb.org/1943274/2147482987/272-10-50-3 + Details
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- Definition The minimum amount the entity agreed to spend under the long-term purchase commitment. + References No definition available. + 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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