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Segments Of Business (Tables) | 9 Months Ended
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Sep. 30, 2017
Segment Reporting Information [Line Items] |
Schedule Of Segments Of Business | Certain financial information relating to Alliant Energy’s business segments is as follows. Intersegment revenues were not material to Alliant Energy’s operations. Refer to Note 5(a) for discussion of Alliant Energy’s acquisition of an interest in a non-regulated wind farm in Oklahoma in July 2017, which increased the assets for “Non-Regulated, Parent and Other.” Refer to Note 3 for discussion of asset valuation charges recorded in the third quarter of 2016 related to the Franklin County wind farm.
| Utility (a) |  | Non-Regulated, |  | Alliant Energy
| Electric |  | Gas |  | Other |  | Total |  | Parent and Other |  | Consolidated
| (in millions)
Three Months Ended September 30, 2017 |  |  |  |  |  |  |  |  |  |  |
Operating revenues |  | $840.6 |  |  |  | $45.8 |  |  |  | $11.2 |  |  |  | $897.6 |  |  |  | $9.3 |  |  |  | $906.9 |
Operating income (loss) | 232.6 |  |  | (2.4 | ) |  | (7.7 | ) |  | 222.5 |  |  | 9.0 |  |  | 231.5 |
Net income (loss) attributable to Alliant Energy common shareowners |  |  |  |  |  |  | 176.3 |  |  | (7.5 | ) |  | 168.8 |
Three Months Ended September 30, 2016 |  |  |  |  |  |  |  |  |  |  |
Operating revenues |  | $864.3 |  |  |  | $39.5 |  |  |  | $9.4 |  |  |  | $913.2 |  |  |  | $11.4 |  |  |  | $924.6 |
Operating income (loss) | 244.2 |  |  | (3.7 | ) |  | 0.4 |  |  | 240.9 |  |  | (78.3 | ) |  | 162.6 |
Amounts attributable to Alliant Energy common shareowners: |  |  |  |  |  |  |  |  |  |  |
Income (loss) from continuing operations, net of tax |  |  |  |  |  |  | 183.1 |  |  | (54.3 | ) |  | 128.8 |
Loss from discontinued operations, net of tax |  |  |  |  |  |  | — |  |  | (0.4 | ) |  | (0.4 | )
Net income (loss) |  |  |  |  |  |  | 183.1 |  |  | (54.7 | ) |  | 128.4 |
| Utility (a) |  | Non-Regulated, |  | Alliant Energy
| Electric |  | Gas |  | Other |  | Total |  | Parent and Other |  | Consolidated
| (in millions)
Nine Months Ended September 30, 2017 |  |  |  |  |  |  |  |  |  |  |
Operating revenues |  | $2,199.1 |  |  |  | $262.7 |  |  |  | $34.4 |  |  |  | $2,496.2 |  |  |  | $29.9 |  |  |  | $2,526.1 |
Operating income (loss) | 475.4 |  |  | 29.5 |  |  | (6.8 | ) |  | 498.1 |  |  | 25.6 |  |  | 523.7 |
Amounts attributable to Alliant Energy common shareowners: |  |  |  |  |  |  |  |  |  |  |
Income from continuing operations, net of tax |  |  |  |  |  |  | 353.5 |  |  | 8.6 |  |  | 362.1 |
Income from discontinued operations, net of tax |  |  |  |  |  |  | — |  |  | 1.4 |  |  | 1.4 |
Net income |  |  |  |  |  |  | 353.5 |  |  | 10.0 |  |  | 363.5 |
Nine Months Ended September 30, 2016 |  |  |  |  |  |  |  |  |  |  |
Operating revenues |  | $2,209.1 |  |  |  | $248.7 |  |  |  | $35.0 |  |  |  | $2,492.8 |  |  |  | $30.2 |  |  |  | $2,523.0 |
Operating income (loss) | 473.3 |  |  | 27.0 |  |  | 4.4 |  |  | 504.7 |  |  | (67.6 | ) |  | 437.1 |
Amounts attributable to Alliant Energy common shareowners: |  |  |  |  |  |  |  |  |  |  |
Income (loss) from continuing operations, net of tax |  |  |  |  |  |  | 350.3 |  |  | (39.5 | ) |  | 310.8 |
Loss from discontinued operations, net of tax |  |  |  |  |  |  | — |  |  | (2.0 | ) |  | (2.0 | )
Net income (loss) |  |  |  |  |  |  | 350.3 |  |  | (41.5 | ) |  | 308.8 |
(a) | Alliant Energy’s utility business segments include: a) utility electric operations, which include Alliant Energy’s entire investment in ATC; b) utility gas operations; and c) utility other, which includes steam operations and the unallocated portions of the utility business.
IPL [Member] |
Segment Reporting Information [Line Items] |
Schedule Of Segments Of Business | Certain financial information relating to IPL’s business segments is as follows. Intersegment revenues were not material to IPL’s operations.
| Electric |  | Gas |  | Other |  | Total
| (in millions)
Three Months Ended September 30, 2017 |  |  |  |  |  |  |
Operating revenues |  | $489.0 |  |  |  | $27.4 |  |  |  | $11.0 |  |  |  | $527.4 |
Operating income (loss) | 138.3 |  |  | (2.1 | ) |  | (4.4 | ) |  | 131.8 |
Earnings available for common stock |  |  |  |  |  |  | 120.4 |
Three Months Ended September 30, 2016 |  |  |  |  |  |  |
Operating revenues |  | $483.2 |  |  |  | $23.9 |  |  |  | $9.1 |  |  |  | $516.2 |
Operating income (loss) | 125.9 |  |  | (1.4 | ) |  | 1.4 |  |  | 125.9 |
Earnings available for common stock |  |  |  |  |  |  | 114.1 |
Nine Months Ended September 30, 2017 |  |  |  |  |  |  |
Operating revenues |  | $1,217.6 |  |  |  | $147.2 |  |  |  | $33.3 |  |  |  | $1,398.1 |
Operating income (loss) | 234.5 |  |  | 14.7 |  |  | (1.5 | ) |  | 247.7 |
Earnings available for common stock |  |  |  |  |  |  | 200.4 |
Nine Months Ended September 30, 2016 |  |  |  |  |  |  |
Operating revenues |  | $1,209.2 |  |  |  | $142.6 |  |  |  | $34.1 |  |  |  | $1,385.9 |
Operating income | 213.8 |  |  | 15.3 |  |  | 6.8 |  |  | 235.9 |
Earnings available for common stock |  |  |  |  |  |  | 191.6 |
WPL [Member] |
Segment Reporting Information [Line Items] |
Schedule Of Segments Of Business | Certain financial information relating to WPL’s business segments is as follows. Intersegment revenues were not material to WPL’s operations.
| Electric |  | Gas |  | Other |  | Total
| (in millions)
Three Months Ended September 30, 2017 |  |  |  |  |  |  |
Operating revenues |  | $351.6 |  |  |  | $18.4 |  |  |  | $0.2 |  |  |  | $370.2 |
Operating income (loss) | 94.3 |  |  | (0.3 | ) |  | (3.3 | ) |  | 90.7 |
Earnings available for common stock |  |  |  |  |  |  | 49.8 |
Three Months Ended September 30, 2016 |  |  |  |  |  |  |
Operating revenues |  | $381.1 |  |  |  | $15.6 |  |  |  | $0.3 |  |  |  | $397.0 |
Operating income (loss) | 118.3 |  |  | (2.3 | ) |  | (1.0 | ) |  | 115.0 |
Earnings available for common stock |  |  |  |  |  |  | 69.0 |
Nine Months Ended September 30, 2017 |  |  |  |  |  |  |
Operating revenues |  | $981.5 |  |  |  | $115.5 |  |  |  | $1.1 |  |  |  | $1,098.1 |
Operating income (loss) | 240.9 |  |  | 14.8 |  |  | (5.3 | ) |  | 250.4 |
Earnings available for common stock |  |  |  |  |  |  | 133.4 |
Nine Months Ended September 30, 2016 |  |  |  |  |  |  |
Operating revenues |  | $999.9 |  |  |  | $106.1 |  |  |  | $0.9 |  |  |  | $1,106.9 |
Operating income (loss) | 259.5 |  |  | 11.7 |  |  | (2.4 | ) |  | 268.8 |
Earnings available for common stock |  |  |  |  |  |  | 158.7 |

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