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Commitments And Contingencies (Narrative) (Details) $ in Millions | 9 Months Ended
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Sep. 30, 2017 USD ($)
Commitments and Contingencies [Line Items] |  |
Minimum future commitments | $ 2,303 |
Present value abandonment obligation | 33 |
IPL [Member] |  |
Commitments and Contingencies [Line Items] |  |
Minimum future commitments | 1,707 |
Indemnification obligations, maximum | 17 |
WPL [Member] |  |
Commitments and Contingencies [Line Items] |  |
Minimum future commitments | 588 |
Capital Purchase Obligation [Member] |  |
Commitments and Contingencies [Line Items] |  |
Minimum future commitments | 105 |
Capital Purchase Obligation [Member] | IPL [Member] |  |
Commitments and Contingencies [Line Items] |  |
Minimum future commitments | 8 |
Capital Purchase Obligation [Member] | WPL [Member] |  |
Commitments and Contingencies [Line Items] |  |
Minimum future commitments | 97 |
Purchased Power [Member] |  |
Commitments and Contingencies [Line Items] |  |
Minimum future commitments | 1,278 | [1]
Purchased Power [Member] | IPL [Member] |  |
Commitments and Contingencies [Line Items] |  |
Minimum future commitments | 1,194 | [1]
Purchased Power [Member] | WPL [Member] |  |
Commitments and Contingencies [Line Items] |  |
Minimum future commitments | 84 | [1]
Environmental Issue [Member] | IPL [Member] |  |
Commitments and Contingencies [Line Items] |  |
Environmental mitigation projects to be completed, value | 6 |
Environmental Issue [Member] | WPL [Member] |  |
Commitments and Contingencies [Line Items] |  |
Environmental mitigation projects to be completed, value | 7 |
Indemnification Agreement [Member] |  |
Commitments and Contingencies [Line Items] |  |
Indemnification obligations, maximum | 98 |
Indemnification Agreement [Member] | Purchased Power [Member] |  |
Commitments and Contingencies [Line Items] |  |
Indemnification obligations, maximum | $ 17 |
[1] | Includes payments required by purchased power agreements for capacity rights and minimum quantities of MWhs required to be purchased.

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Balance Type: | credit
Period Type: | instant

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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/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 460 -SubTopic 10 -Section 50 -Paragraph 4 -Subparagraph (b)(1) -URI http://asc.fasb.org/extlink&oid=6851643&loc=d3e12069-110248 + 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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- Definition Amount of damages awarded to the plaintiff in the legal matter. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 450 -SubTopic 20 -Section 50 -Paragraph 1 -URI http://asc.fasb.org/extlink&oid=25496072&loc=d3e14326-108349 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 450 -SubTopic 20 -Section 50 -Paragraph 4 -Subparagraph (a) -URI http://asc.fasb.org/extlink&oid=25496072&loc=d3e14435-108349 Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 450 -SubTopic 20 -Section 50 -Paragraph 9 -Subparagraph (a) -URI http://asc.fasb.org/extlink&oid=25496072&loc=d3e14557-108349 + 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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