|
Selected Consolidated Quarterly Financial Data (Unaudited) (Details) (USD $)
In Millions, except Per Share data, unless otherwise specified |
3 Months Ended | 12 Months Ended | |||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|
|
Dec. 31, 2012
|
Sep. 30, 2012
|
Jun. 30, 2012
|
Mar. 31, 2012
|
Dec. 31, 2011
|
Sep. 30, 2011
|
Jun. 30, 2011
|
Mar. 31, 2011
|
Dec. 31, 2012
|
Dec. 31, 2011
|
Dec. 31, 2010
|
|
| Operating revenues | $ 750.9 | $ 887.6 | $ 690.3 | $ 765.7 | $ 760.8 | $ 870.9 | $ 712.5 | $ 877.2 | $ 3,094.5 | $ 3,221.4 | $ 3,262.1 |
| Operating income | 101.6 | 213.7 | 108.8 | 95.6 | 106.0 | 209.4 | 70.6 | 127.3 | 519.7 | 513.3 | 560.0 |
| Income from continuing operations, net of tax | 71.1 | 149.0 | 65.5 | 39.3 | 63.9 | 136.9 | 50.3 | 72.0 | 324.9 | 323.1 | 291.5 |
| Income (loss) from discontinued operations, net of tax | (2.8) | 1.7 | 0.4 | (4.4) | (6.9) | (14.9) | 0.8 | 1.5 | (5.1) | (19.5) | (3.9) |
| Net income (loss) | 335.7 | 321.9 | 306.3 | ||||||||
| Net income (loss) attributable to common shareowners | 68.3 | 150.7 | 65.9 | 34.9 | 57.0 | 122.0 | 51.1 | 73.5 | 319.8 | 303.6 | 287.6 |
| Income from continuing operations, net of tax (in dollars per share) | $ 0.64 | $ 1.34 | $ 0.60 | $ 0.36 | $ 0.58 | $ 1.23 | $ 0.45 | $ 0.65 | |||
| Income (loss) from discontinued operations, net of tax (in dollars per share) | $ (0.02) | $ 0.02 | $ 0.00 | $ (0.04) | $ (0.07) | $ (0.13) | $ 0.01 | $ 0.01 | |||
| Net income (in dollars per share) | $ 0.62 | $ 1.36 | $ 0.60 | $ 0.32 | $ 0.51 | $ 1.10 | $ 0.46 | $ 0.66 | |||
|
IPL [Member]
|
|||||||||||
| Operating revenues | 393.2 | 497.7 | 360.7 | 398.7 | 404.0 | 484.5 | 374.1 | 477.5 | 1,650.3 | 1,740.1 | 1,795.8 |
| Operating income | 29.0 | 112.0 | 35.4 | 23.9 | 26.3 | 116.5 | 18.5 | 47.1 | 200.3 | 208.4 | 261.9 |
| Net income (loss) | 25.6 | 106.5 | 19.6 | (1.5) | 9.8 | 101.4 | 1.0 | 27.1 | 150.2 | 139.3 | 143.4 |
| Net income (loss) attributable to common shareowners | 22.4 | 103.3 | 16.6 | (4.7) | 6.6 | 98.3 | (2.3) | 21.7 | 137.6 | 124.3 | 128.0 |
|
WPL [Member]
|
|||||||||||
| Operating revenues | 345.2 | 376.6 | 315.7 | 354.5 | 344.5 | 374.6 | 326.8 | 388.5 | 1,392.0 | 1,434.4 | 1,423.6 |
| Operating income | 65.3 | 93.4 | 61.5 | 64.6 | 73.2 | 86.9 | 45.5 | 74.8 | 284.8 | 280.4 | 278.8 |
| Net income (loss) | 41.0 | 56.7 | 36.1 | 31.9 | 42.7 | 51.4 | 25.0 | 44.4 | 165.7 | 163.5 | 152.3 |
| Net income (loss) attributable to common shareowners | $ 40.2 | $ 55.9 | $ 35.2 | $ 31.1 | $ 41.9 | $ 50.6 | $ 24.1 | $ 43.6 | $ 162.4 | $ 160.2 | $ 149.0 |