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Commitments And Contingencies (Narrative) (Details) $ in Millions | 3 Months Ended
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Mar. 31, 2017 USD ($)
Commitments and Contingencies [Line Items] |
Minimum future commitments | $ 2,387
Present value abandonment obligation | 31
IPL [Member] |
Commitments and Contingencies [Line Items] |
Minimum future commitments | 1,785
Maximum indemnification limit | 17
WPL [Member] |
Commitments and Contingencies [Line Items] |
Minimum future commitments | 587
Capital Purchase Obligation [Member] |
Commitments and Contingencies [Line Items] |
Minimum future commitments | 36
Capital Purchase Obligation [Member] | IPL [Member] |
Commitments and Contingencies [Line Items] |
Minimum future commitments | 5
Capital Purchase Obligation [Member] | WPL [Member] |
Commitments and Contingencies [Line Items] |
Minimum future commitments | 31
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
Workforce Subject to Collective Bargaining Arrangements [Member] |
Commitments and Contingencies [Line Items] |
Employees covered by collective bargaining agreement | 56.00%
Workforce Subject to Collective Bargaining Arrangements [Member] | IPL [Member] |
Commitments and Contingencies [Line Items] |
Employees covered by collective bargaining agreement | 64.00%
Workforce Subject to Collective Bargaining Arrangements Expiring within One Year [Member] |
Commitments and Contingencies [Line Items] |
Employees covered by collective bargaining agreement | 19.00%
Workforce Subject to Collective Bargaining Arrangements Expiring within One Year [Member] | IPL [Member] |
Commitments and Contingencies [Line Items] |
Employees covered by collective bargaining agreement | 45.00%

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- Definition For an entity that discloses a concentration risk in relation to quantitative amount, which serves as the "benchmark" (or denominator) in the equation, this concept represents the concentration percentage derived from the division. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 275 -SubTopic 10 -Section 50 -Paragraph 18 -URI http://asc.fasb.org/extlink&oid=64851502&loc=d3e6351-108592 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 825 -SubTopic 10 -Section 50 -Paragraph 20 -URI http://asc.fasb.org/extlink&oid=73719730&loc=d3e13531-108611 Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 275 -SubTopic 10 -Section 50 -Paragraph 20 -URI http://asc.fasb.org/extlink&oid=64851502&loc=d3e6404-108592 Reference 4: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 825 -SubTopic 10 -Section 50 -Paragraph 21 -Subparagraph (a) -URI http://asc.fasb.org/extlink&oid=73719730&loc=d3e13537-108611 + Details
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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 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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