v2.4.0.6

Common Equity (Tables) | 12 Months Ended
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Dec. 31, 2012
Schedule of Common Equity [Line Items] |
Common Stock Activity | A summary of Alliant Energy’s common stock activity was as follows:
| 2012 |  | 2011 |  | 2010
Shares outstanding, January 1 | 111,018,821 |  |  | 110,893,901 |  |  | 110,656,498 |
Equity-based compensation plans (Note 6(b)) | 20,195 |  |  | 164,400 |  |  | 260,316 |
Other (a) | (51,616 | ) |  | (39,480 | ) |  | (22,913 | )
Shares outstanding, December 31 | 110,987,400 |  |  | 111,018,821 |  |  | 110,893,901 |
(a) | Includes shares transferred from employees to Alliant Energy to satisfy tax withholding requirements in connection with the vesting of certain restricted stock under the equity-based compensation plans.
Schedule of Restricted Net Assets of Subsidiaries | As of December 31, the amount of net assets of IPL and WPL that were not available to be transferred to their parent company in the form of cash dividends without the consent of IPL’s and WPL’s regulatory authorities was as follows (in billions):
| 2012 |  | 2011
IPL |  | $1.1 |  |  |  | $1.0 |
WPL | 1.5 |  |  | 1.3 |
Capital Transactions with Subsidiaries | IPL, WPL and Resources paid common stock dividends and repayments of capital to their parent company, Alliant Energy, as follows (in millions):
| IPL |  | WPL |  | Resources
| 2012 |  | 2011 |  | 2010 |  | 2012 |  | 2011 |  | 2010 |  | 2012 |  | 2011 |  | 2010
Common stock dividends |  | $122.9 |  |  |  | $73.4 |  |  |  | $— |  |  |  | $112.0 |  |  |  | $112.1 |  |  |  | $109.5 |  |  |  | $— |  |  |  | $— |  |  |  | $— |
Repayments of capital | — |  |  | 100.7 |  |  | 118.2 |  |  | — |  |  | — |  |  | — |  |  | — |  |  | — |  |  | 65.0 |
Total distributions from common equity |  | $122.9 |  |  |  | $174.1 |  |  |  | $118.2 |  |  |  | $112.0 |  |  |  | $112.1 |  |  |  | $109.5 |  |  |  | $— |  |  |  | $— |  |  |  | $65.0 |
Schedule of Capital Contributions | IPL, WPL, Resources and Corporate Services received capital contributions from their parent company, Alliant Energy, as follows (in millions):
| 2012 |  | 2011 |  | 2010
IPL |  | $110.0 |  |  |  | $54.0 |  |  |  | $50.0 |
WPL | 90.0 |  |  | 25.0 |  |  | 75.0 |
Resources | — |  |  | 65.0 |  |  | — |
Corporate Services | 30.0 |  |  | — |  |  | — |
IPL [Member] |
Schedule of Common Equity [Line Items] |
Schedule of Restricted Net Assets of Subsidiaries | As of December 31, the amount of net assets of IPL and WPL that were not available to be transferred to their parent company in the form of cash dividends without the consent of IPL’s and WPL’s regulatory authorities was as follows (in billions):
| 2012 |  | 2011
IPL |  | $1.1 |  |  |  | $1.0 |
WPL | 1.5 |  |  | 1.3 |
Capital Transactions with Subsidiaries | IPL, WPL and Resources paid common stock dividends and repayments of capital to their parent company, Alliant Energy, as follows (in millions):
| IPL |  | WPL |  | Resources
| 2012 |  | 2011 |  | 2010 |  | 2012 |  | 2011 |  | 2010 |  | 2012 |  | 2011 |  | 2010
Common stock dividends |  | $122.9 |  |  |  | $73.4 |  |  |  | $— |  |  |  | $112.0 |  |  |  | $112.1 |  |  |  | $109.5 |  |  |  | $— |  |  |  | $— |  |  |  | $— |
Repayments of capital | — |  |  | 100.7 |  |  | 118.2 |  |  | — |  |  | — |  |  | — |  |  | — |  |  | — |  |  | 65.0 |
Total distributions from common equity |  | $122.9 |  |  |  | $174.1 |  |  |  | $118.2 |  |  |  | $112.0 |  |  |  | $112.1 |  |  |  | $109.5 |  |  |  | $— |  |  |  | $— |  |  |  | $65.0 |
Schedule of Capital Contributions | IPL, WPL, Resources and Corporate Services received capital contributions from their parent company, Alliant Energy, as follows (in millions):
| 2012 |  | 2011 |  | 2010
IPL |  | $110.0 |  |  |  | $54.0 |  |  |  | $50.0 |
WPL | 90.0 |  |  | 25.0 |  |  | 75.0 |
Resources | — |  |  | 65.0 |  |  | — |
Corporate Services | 30.0 |  |  | — |  |  | — |
WPL [Member] |
Schedule of Common Equity [Line Items] |
Schedule of Restricted Net Assets of Subsidiaries | As of December 31, the amount of net assets of IPL and WPL that were not available to be transferred to their parent company in the form of cash dividends without the consent of IPL’s and WPL’s regulatory authorities was as follows (in billions):
| 2012 |  | 2011
IPL |  | $1.1 |  |  |  | $1.0 |
WPL | 1.5 |  |  | 1.3 |
Capital Transactions with Subsidiaries | IPL, WPL and Resources paid common stock dividends and repayments of capital to their parent company, Alliant Energy, as follows (in millions):
| IPL |  | WPL |  | Resources
| 2012 |  | 2011 |  | 2010 |  | 2012 |  | 2011 |  | 2010 |  | 2012 |  | 2011 |  | 2010
Common stock dividends |  | $122.9 |  |  |  | $73.4 |  |  |  | $— |  |  |  | $112.0 |  |  |  | $112.1 |  |  |  | $109.5 |  |  |  | $— |  |  |  | $— |  |  |  | $— |
Repayments of capital | — |  |  | 100.7 |  |  | 118.2 |  |  | — |  |  | — |  |  | — |  |  | — |  |  | — |  |  | 65.0 |
Total distributions from common equity |  | $122.9 |  |  |  | $174.1 |  |  |  | $118.2 |  |  |  | $112.0 |  |  |  | $112.1 |  |  |  | $109.5 |  |  |  | $— |  |  |  | $— |  |  |  | $65.0 |
Schedule of Capital Contributions | IPL, WPL, Resources and Corporate Services received capital contributions from their parent company, Alliant Energy, as follows (in millions):
| 2012 |  | 2011 |  | 2010
IPL |  | $110.0 |  |  |  | $54.0 |  |  |  | $50.0 |
WPL | 90.0 |  |  | 25.0 |  |  | 75.0 |
Resources | — |  |  | 65.0 |  |  | — |
Corporate Services | 30.0 |  |  | — |  |  | — |

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