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Common Equity (Tables) | 3 Months Ended
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Mar. 31, 2016
Stockholders' Equity Note [Abstract] |
Pro Forma Earnings Per Share | For the three months ended March 31, pro forma basic and diluted EPS attributable to Alliant Energy common shareowners to reflect the two-for-one common stock split is as follows:
| 2016 |  | 2015
Basic and diluted EPS: |  |  |
As reported |  | $0.85 |  |  |  | $0.87 |
Pro forma | 0.43 |  |  | 0.43 |
Common Share Activity | A summary of Alliant Energy’s common stock activity was as follows:
Shares outstanding, January 1, 2016 | 113,459,216 |
Shareowner Direct Plan issuances | 92,231 |
Equity-based compensation plans (Note 9(b)) | 11,204 |
Shares outstanding, March 31, 2016 | 113,562,651 |

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