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Common Equity (Tables) | 12 Months Ended
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Dec. 31, 2020
Schedule of Common Equity [Line Items] |
Common Stock Activity | A summary of Alliant Energy’s common stock activity was as follows:
| 2020 |  | 2019 |  | 2018
Shares outstanding, January 1 | 245,022,800 |  |  | 236,063,279 |  |  | 231,348,646 |
Equity forward agreements | 4,275,127 |  |  | 8,358,973 |  |  | — |
At-the-market offering programs | — |  |  | — |  |  | 4,171,013 |
Shareowner Direct Plan | 472,283 |  |  | 501,808 |  |  | 576,965 |
Equity-based compensation plans | 98,205 |  |  | 101,478 |  |  | 5,078 |
Other | — |  |  | (2,738) |  |  | (38,423) |
Shares outstanding, December 31 | 249,868,415 |  |  | 245,022,800 |  |  | 236,063,279 |

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- Definition Tabular disclosure of an entity's capital units or capital shares, including the value of capital units or capital shares, units authorized, units outstanding and other information necessary to a fair presentation. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 946 -SubTopic 210 -Section S99 -Paragraph 1 -Subparagraph (SX 210.6-04.16) -URI http://asc.fasb.org/extlink&oid=120401414&loc=d3e603758-122996 + Details
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