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Income Taxes (Tables) | 3 Months Ended
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Mar. 31, 2014
Income Tax [Line Items] |
Schedule Of Effective Income Tax Rates | The overall income tax rates shown in the following table were computed by dividing income tax expense (benefit) by income from continuing operations before income taxes.
| Alliant Energy |  | IPL |  | WPL
Three Months Ended March 31 | 2014 |  | 2013 |  | 2014 |  | 2013 |  | 2014 |  | 2013
Statutory federal income tax rate | 35.0 | % |  | 35.0 | % |  | 35.0 | % |  | 35.0 | % |  | 35.0 | % |  | 35.0 | %
IPL’s tax benefit riders | (11.9 | ) |  | (12.8 | ) |  | (31.2 | ) |  | (37.3 | ) |  | — |  |  | — |
Production tax credits | (6.7 | ) |  | (7.5 | ) |  | (8.3 | ) |  | (9.7 | ) |  | (6.4 | ) |  | (6.9 | )
Effect of rate-making on property-related differences | (5.3 | ) |  | (5.0 | ) |  | (12.4 | ) |  | (14.0 | ) |  | (1.0 | ) |  | (0.3 | )
Other items, net | 4.6 |  |  | 3.0 |  |  | 4.7 |  |  | 2.0 |  |  | 4.8 |  |  | 4.2 |
Overall income tax rate | 15.7 | % |  | 12.7 | % |  | (12.2 | %) |  | (24.0 | %) |  | 32.4 | % |  | 32.0 | %
Production Tax Credits (Net Of State Tax Impacts) | For the three months ended March 31, details regarding production tax credits (net of state tax impacts) related to various wind projects are as follows (dollars in millions):
| End of Production |  | Nameplate |  | Production Tax Credits
| Tax Credit Generation |  | Capacity in MW |  | 2014 |  | 2013
Cedar Ridge (WPL) | December 2018 |  | 68 |  |  |  | $1.2 |  |  |  | $1.2 |
Bent Tree - Phase I (WPL) | February 2021 |  | 201 |  |  | 4.2 |  |  | 3.5 |
Subtotal (WPL) |  |  |  |  | 5.4 |  |  | 4.7 |
Whispering Willow - East (IPL) | December 2019 |  | 200 |  |  | 4.6 |  |  | 3.9 |
|  |  |  |  |  | $10.0 |  |  |  | $8.6 |
Summary Of Tax Credit Carryforwards | At March 31, 2014, tax carryforwards and associated deferred tax assets and expiration dates were estimated as follows (dollars in millions):
Alliant Energy | Carryforward Amount |  | Deferred Tax Assets |  | Earliest Expiration Date
Federal net operating losses |  | $697 |  |  |  | $239 |  |  | 2029
State net operating losses | 681 |  |  | 34 |  |  | 2018
Federal tax credits | 181 |  |  | 178 |  |  | 2022
|  |  |  | $451 |  |  |
IPL | Carryforward Amount |  | Deferred Tax Assets |  | Earliest Expiration Date
Federal net operating losses |  | $303 |  |  |  | $104 |  |  | 2029
State net operating losses | 172 |  |  | 8 |  |  | 2018
Federal tax credits | 59 |  |  | 58 |  |  | 2022
|  |  |  | $170 |  |  |
WPL | Carryforward Amount |  | Deferred Tax Assets |  | Earliest Expiration Date
Federal net operating losses |  | $302 |  |  |  | $103 |  |  | 2029
State net operating losses | 96 |  |  | 5 |  |  | 2018
Federal tax credits | 64 |  |  | 62 |  |  | 2022
|  |  |  | $170 |  |  |
IPL [Member] |
Income Tax [Line Items] |
Schedule Of Effective Income Tax Rates | The overall income tax rates shown in the following table were computed by dividing income tax expense (benefit) by income from continuing operations before income taxes.
| Alliant Energy |  | IPL |  | WPL
Three Months Ended March 31 | 2014 |  | 2013 |  | 2014 |  | 2013 |  | 2014 |  | 2013
Statutory federal income tax rate | 35.0 | % |  | 35.0 | % |  | 35.0 | % |  | 35.0 | % |  | 35.0 | % |  | 35.0 | %
IPL’s tax benefit riders | (11.9 | ) |  | (12.8 | ) |  | (31.2 | ) |  | (37.3 | ) |  | — |  |  | — |
Production tax credits | (6.7 | ) |  | (7.5 | ) |  | (8.3 | ) |  | (9.7 | ) |  | (6.4 | ) |  | (6.9 | )
Effect of rate-making on property-related differences | (5.3 | ) |  | (5.0 | ) |  | (12.4 | ) |  | (14.0 | ) |  | (1.0 | ) |  | (0.3 | )
Other items, net | 4.6 |  |  | 3.0 |  |  | 4.7 |  |  | 2.0 |  |  | 4.8 |  |  | 4.2 |
Overall income tax rate | 15.7 | % |  | 12.7 | % |  | (12.2 | %) |  | (24.0 | %) |  | 32.4 | % |  | 32.0 | %
Production Tax Credits (Net Of State Tax Impacts) | For the three months ended March 31, details regarding production tax credits (net of state tax impacts) related to various wind projects are as follows (dollars in millions):
| End of Production |  | Nameplate |  | Production Tax Credits
| Tax Credit Generation |  | Capacity in MW |  | 2014 |  | 2013
Cedar Ridge (WPL) | December 2018 |  | 68 |  |  |  | $1.2 |  |  |  | $1.2 |
Bent Tree - Phase I (WPL) | February 2021 |  | 201 |  |  | 4.2 |  |  | 3.5 |
Subtotal (WPL) |  |  |  |  | 5.4 |  |  | 4.7 |
Whispering Willow - East (IPL) | December 2019 |  | 200 |  |  | 4.6 |  |  | 3.9 |
|  |  |  |  |  | $10.0 |  |  |  | $8.6 |
Summary Of Tax Credit Carryforwards | At March 31, 2014, tax carryforwards and associated deferred tax assets and expiration dates were estimated as follows (dollars in millions):
Alliant Energy | Carryforward Amount |  | Deferred Tax Assets |  | Earliest Expiration Date
Federal net operating losses |  | $697 |  |  |  | $239 |  |  | 2029
State net operating losses | 681 |  |  | 34 |  |  | 2018
Federal tax credits | 181 |  |  | 178 |  |  | 2022
|  |  |  | $451 |  |  |
IPL | Carryforward Amount |  | Deferred Tax Assets |  | Earliest Expiration Date
Federal net operating losses |  | $303 |  |  |  | $104 |  |  | 2029
State net operating losses | 172 |  |  | 8 |  |  | 2018
Federal tax credits | 59 |  |  | 58 |  |  | 2022
|  |  |  | $170 |  |  |
WPL | Carryforward Amount |  | Deferred Tax Assets |  | Earliest Expiration Date
Federal net operating losses |  | $302 |  |  |  | $103 |  |  | 2029
State net operating losses | 96 |  |  | 5 |  |  | 2018
Federal tax credits | 64 |  |  | 62 |  |  | 2022
|  |  |  | $170 |  |  |
WPL [Member] |
Income Tax [Line Items] |
Schedule Of Effective Income Tax Rates | The overall income tax rates shown in the following table were computed by dividing income tax expense (benefit) by income from continuing operations before income taxes.
| Alliant Energy |  | IPL |  | WPL
Three Months Ended March 31 | 2014 |  | 2013 |  | 2014 |  | 2013 |  | 2014 |  | 2013
Statutory federal income tax rate | 35.0 | % |  | 35.0 | % |  | 35.0 | % |  | 35.0 | % |  | 35.0 | % |  | 35.0 | %
IPL’s tax benefit riders | (11.9 | ) |  | (12.8 | ) |  | (31.2 | ) |  | (37.3 | ) |  | — |  |  | — |
Production tax credits | (6.7 | ) |  | (7.5 | ) |  | (8.3 | ) |  | (9.7 | ) |  | (6.4 | ) |  | (6.9 | )
Effect of rate-making on property-related differences | (5.3 | ) |  | (5.0 | ) |  | (12.4 | ) |  | (14.0 | ) |  | (1.0 | ) |  | (0.3 | )
Other items, net | 4.6 |  |  | 3.0 |  |  | 4.7 |  |  | 2.0 |  |  | 4.8 |  |  | 4.2 |
Overall income tax rate | 15.7 | % |  | 12.7 | % |  | (12.2 | %) |  | (24.0 | %) |  | 32.4 | % |  | 32.0 | %
Production Tax Credits (Net Of State Tax Impacts) | For the three months ended March 31, details regarding production tax credits (net of state tax impacts) related to various wind projects are as follows (dollars in millions):
| End of Production |  | Nameplate |  | Production Tax Credits
| Tax Credit Generation |  | Capacity in MW |  | 2014 |  | 2013
Cedar Ridge (WPL) | December 2018 |  | 68 |  |  |  | $1.2 |  |  |  | $1.2 |
Bent Tree - Phase I (WPL) | February 2021 |  | 201 |  |  | 4.2 |  |  | 3.5 |
Subtotal (WPL) |  |  |  |  | 5.4 |  |  | 4.7 |
Whispering Willow - East (IPL) | December 2019 |  | 200 |  |  | 4.6 |  |  | 3.9 |
|  |  |  |  |  | $10.0 |  |  |  | $8.6 |
Summary Of Tax Credit Carryforwards | At March 31, 2014, tax carryforwards and associated deferred tax assets and expiration dates were estimated as follows (dollars in millions):
Alliant Energy | Carryforward Amount |  | Deferred Tax Assets |  | Earliest Expiration Date
Federal net operating losses |  | $697 |  |  |  | $239 |  |  | 2029
State net operating losses | 681 |  |  | 34 |  |  | 2018
Federal tax credits | 181 |  |  | 178 |  |  | 2022
|  |  |  | $451 |  |  |
IPL | Carryforward Amount |  | Deferred Tax Assets |  | Earliest Expiration Date
Federal net operating losses |  | $303 |  |  |  | $104 |  |  | 2029
State net operating losses | 172 |  |  | 8 |  |  | 2018
Federal tax credits | 59 |  |  | 58 |  |  | 2022
|  |  |  | $170 |  |  |
WPL | Carryforward Amount |  | Deferred Tax Assets |  | Earliest Expiration Date
Federal net operating losses |  | $302 |  |  |  | $103 |  |  | 2029
State net operating losses | 96 |  |  | 5 |  |  | 2018
Federal tax credits | 64 |  |  | 62 |  |  | 2022
|  |  |  | $170 |  |  |

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