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Segments Of Business (Schedule Of Segments Of Business) (Details) - USD ($) $ in Millions | 3 Months Ended | 9 Months Ended
--- | --- | ---
Sep. 30, 2015 | Sep. 30, 2014 | Sep. 30, 2015 | Sep. 30, 2014
Segment Reporting Information [Line Items] |  |  |  |
Operating revenues | $ 898.9 | $ 843.1 | $ 2,513.5 | $ 2,546.2
Operating income (loss) | 235.9 | 194.8 | 497.8 | 452.3
Income (loss) from continuing operations, net of tax | 180.0 | 155.2 | 345.5 | 325.3
Loss from discontinued operations, net of tax | (0.1) | (1.9) | (1.4) | (2.2)
Net income (loss) attributable to common shareowners | 179.9 | 153.3 | 344.1 | 323.1
IPL [Member] |  |  |  |
Segment Reporting Information [Line Items] |  |  |  |
Operating revenues | 504.6 | 476.2 | 1,375.8 | 1,417.0
Operating income (loss) | 117.0 | 93.9 | 216.3 | 185.4
Net income (loss) attributable to common shareowners | 117.4 | 102.5 | 181.9 | 164.3
WPL [Member] |  |  |  |
Segment Reporting Information [Line Items] |  |  |  |
Operating revenues | 382.6 | 354.4 | 1,104.4 | 1,089.3
Operating income (loss) | 110.3 | 93.9 | 259.4 | 241.6
Net income (loss) attributable to common shareowners | 67.5 | 61.6 | 151.1 | 151.0
Electric [Member] |  |  |  |
Segment Reporting Information [Line Items] |  |  |  |
Operating revenues | 835.8 | 771.2 | 2,147.5 | 2,090.9
Operating income (loss) | 232.8 | 190.8 | 438.4 | 374.2
Electric [Member] | IPL [Member] |  |  |  |
Segment Reporting Information [Line Items] |  |  |  |
Operating revenues | 468.6 | 435.9 | 1,170.6 | 1,164.7
Operating income (loss) | 119.4 | 94.7 | 193.6 | 150.2
Electric [Member] | WPL [Member] |  |  |  |
Segment Reporting Information [Line Items] |  |  |  |
Operating revenues | 367.2 | 335.3 | 976.9 | 926.2
Operating income (loss) | 113.4 | 96.1 | 244.8 | 224.0
Gas [Member] |  |  |  |
Segment Reporting Information [Line Items] |  |  |  |
Operating revenues | 38.0 | 47.2 | 288.1 | 364.8
Operating income (loss) | (5.7) | (4.4) | 28.6 | 41.3
Gas [Member] | IPL [Member] |  |  |  |
Segment Reporting Information [Line Items] |  |  |  |
Operating revenues | 23.1 | 28.7 | 164.1 | 208.1
Operating income (loss) | (2.9) | (2.8) | 15.3 | 22.1
Gas [Member] | WPL [Member] |  |  |  |
Segment Reporting Information [Line Items] |  |  |  |
Operating revenues | 14.9 | 18.5 | 124.0 | 156.7
Operating income (loss) | (2.8) | (1.6) | 13.3 | 19.2
Other Utilities [Member] |  |  |  |
Segment Reporting Information [Line Items] |  |  |  |
Operating revenues | 13.4 | 12.2 | 44.6 | 50.6
Operating income (loss) | 0.2 | 1.4 | 8.7 | 11.5
Other Utilities [Member] | IPL [Member] |  |  |  |
Segment Reporting Information [Line Items] |  |  |  |
Operating revenues | 12.9 | 11.6 | 41.1 | 44.2
Operating income (loss) | 0.5 | 2.0 | 7.4 | 13.1
Other Utilities [Member] | WPL [Member] |  |  |  |
Segment Reporting Information [Line Items] |  |  |  |
Operating revenues | 0.5 | 0.6 | 3.5 | 6.4
Operating income (loss) | (0.3) | (0.6) | 1.3 | (1.6)
Utilities Business [Member] |  |  |  |
Segment Reporting Information [Line Items] |  |  |  |
Operating revenues | 887.2 | 830.6 | 2,480.2 | 2,506.3
Operating income (loss) | 227.3 | 187.8 | 475.7 | 427.0
Income (loss) from continuing operations, net of tax | 184.9 | 164.1 | 333.0 | 315.3
Loss from discontinued operations, net of tax | 0.0 | 0.0 | 0.0 | 0.0
Net income (loss) attributable to common shareowners | 184.9 | 164.1 | 333.0 | 315.3
Non-Regulated [Member] | Other Segments [Member] |  |  |  |
Segment Reporting Information [Line Items] |  |  |  |
Operating revenues | 11.7 | 12.5 | 33.3 | 39.9
Operating income (loss) | 8.6 | 7.0 | 22.1 | 25.3
Income (loss) from continuing operations, net of tax | (4.9) | (8.9) | 12.5 | 10.0
Loss from discontinued operations, net of tax | (0.1) | (1.9) | (1.4) | (2.2)
Net income (loss) attributable to common shareowners | $ (5.0) | $ (10.8) | $ 11.1 | $ 7.8

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