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Selected Consolidated Quarterly Financial Data (Unaudited) (Tables) | 12 Months Ended
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Dec. 31, 2018
Components Of Selected Consolidated Quarterly Financial Data | All “per share” references refer to earnings per diluted share. Summation of the individual quarters may not equal annual totals due to rounding.
| 2018 |  | 2017
| March 31 |  | June 30 |  | Sep. 30 |  | Dec. 31 |  | March 31 |  | June 30 |  | Sep. 30 |  | Dec. 31
| (in millions, except per share data)
Revenues |  | $916.3 |  |  |  | $816.1 |  |  |  | $928.6 |  |  |  | $873.5 |  |  |  | $853.9 |  |  |  | $765.3 |  |  |  | $906.9 |  |  |  | $856.1 |
Operating income | 165.7 |  |  | 151.2 |  |  | 256.1 |  |  | 121.4 |  |  | 147.2 |  |  | 153.7 |  |  | 236.3 |  |  | 134.0 |
Amounts attributable to Alliant Energy common shareowners: |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Income from continuing operations, net of tax | 120.9 |  |  | 100.4 |  |  | 205.5 |  |  | 85.3 |  |  | 99.0 |  |  | 94.3 |  |  | 168.8 |  |  | 93.8 |
Income from discontinued operations, net of tax | — |  |  | — |  |  | — |  |  | — |  |  | 1.4 |  |  | — |  |  | — |  |  | — |
Net income | 120.9 |  |  | 100.4 |  |  | 205.5 |  |  | 85.3 |  |  | 100.4 |  |  | 94.3 |  |  | 168.8 |  |  | 93.8 |
Earnings per weighted average common share attributable to Alliant Energy common shareowners: |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Income from continuing operations, net of tax | 0.52 |  |  | 0.43 |  |  | 0.87 |  |  | 0.36 |  |  | 0.43 |  |  | 0.41 |  |  | 0.73 |  |  | 0.41 |
Income from discontinued operations, net of tax | — |  |  | — |  |  | — |  |  | — |  |  | 0.01 |  |  | — |  |  | — |  |  | — |
Net income | 0.52 |  |  | 0.43 |  |  | 0.87 |  |  | 0.36 |  |  | 0.44 |  |  | 0.41 |  |  | 0.73 |  |  | 0.41 |
IPL [Member] |
Components Of Selected Consolidated Quarterly Financial Data | Earnings per share data is not disclosed for IPL given Alliant Energy is the sole shareowner of all shares of IPL’s common stock outstanding during the periods presented.
| 2018 |  | 2017
| March 31 |  | June 30 |  | Sep. 30 |  | Dec. 31 |  | March 31 |  | June 30 |  | Sep. 30 |  | Dec. 31
| (in millions)
Revenues |  | $525.8 |  |  |  | $474.8 |  |  |  | $547.6 |  |  |  | $494.1 |  |  |  | $450.5 |  |  |  | $420.2 |  |  |  | $527.4 |  |  |  | $472.2 |
Operating income | 75.6 |  |  | 77.7 |  |  | 143.1 |  |  | 54.4 |  |  | 51.3 |  |  | 68.1 |  |  | 133.8 |  |  | 50.9 |
Net income | 49.3 |  |  | 54.2 |  |  | 129.1 |  |  | 41.6 |  |  | 39.8 |  |  | 45.3 |  |  | 123.0 |  |  | 18.9 |
Earnings available for common stock | 46.7 |  |  | 51.7 |  |  | 126.5 |  |  | 39.1 |  |  | 37.2 |  |  | 42.8 |  |  | 120.4 |  |  | 16.4 |
WPL [Member] |
Components Of Selected Consolidated Quarterly Financial Data | Earnings per share data is not disclosed for WPL given Alliant Energy is the sole shareowner of all shares of WPL’s common stock outstanding during the periods presented.
| 2018 |  | 2017
| March 31 |  | June 30 |  | Sep. 30 |  | Dec. 31 |  | March 31 |  | June 30 |  | Sep. 30 |  | Dec. 31
| (in millions)
Revenues |  | $381.7 |  |  |  | $330.8 |  |  |  | $370.7 |  |  |  | $369.4 |  |  |  | $393.1 |  |  |  | $334.8 |  |  |  | $370.2 |  |  |  | $374.7 |
Operating income | 84.0 |  |  | 63.4 |  |  | 104.2 |  |  | 61.3 |  |  | 88.6 |  |  | 76.2 |  |  | 93.5 |  |  | 75.4 |
Net income | 54.0 |  |  | 39.8 |  |  | 76.3 |  |  | 38.0 |  |  | 45.5 |  |  | 38.1 |  |  | 49.8 |  |  | 53.2 |
Earnings available for common stock | 54.0 |  |  | 39.8 |  |  | 76.3 |  |  | 38.0 |  |  | 45.5 |  |  | 38.1 |  |  | 49.8 |  |  | 53.2 |

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- Definition Tabular disclosure of quarterly financial data. Includes, but is not limited to, financial information for fiscal quarters, cumulative effect of a change in accounting principle and earnings per share data. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 270 -SubTopic 10 -Section 50 -Paragraph 1 -Subparagraph (a)-(j) -URI http://asc.fasb.org/extlink&oid=84173487&loc=d3e1280-108306 + Details
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