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Regulatory Matters (Tables) | 9 Months Ended
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Sep. 30, 2014
Regulatory Assets [Line Items] |
Regulatory Assets | Regulatory assets were comprised of the following items (in millions):
| Alliant Energy |  | IPL |  | WPL
| September 30, 2014 |  | December 31, 2013 |  | September 30, 2014 |  | December 31, 2013 |  | September 30, 2014 |  | December 31, 2013
Tax-related |  | $937.6 |  |  |  | $829.7 |  |  |  | $910.6 |  |  |  | $798.6 |  |  |  | $27.0 |  |  |  | $31.1 |
Pension and OPEB costs | 345.4 |  |  | 355.3 |  |  | 170.2 |  |  | 174.2 |  |  | 175.2 |  |  | 181.1 |
AROs | 74.6 |  |  | 65.7 |  |  | 43.1 |  |  | 36.7 |  |  | 31.5 |  |  | 29.0 |
Emission allowances | 28.0 |  |  | 30.0 |  |  | 28.0 |  |  | 30.0 |  |  | — |  |  | — |
Environmental-related costs | 26.6 |  |  | 25.0 |  |  | 22.0 |  |  | 21.0 |  |  | 4.6 |  |  | 4.0 |
Derivatives | 23.3 |  |  | 21.1 |  |  | 17.7 |  |  | 5.9 |  |  | 5.6 |  |  | 15.2 |
Other | 88.8 |  |  | 86.4 |  |  | 35.2 |  |  | 47.1 |  |  | 53.6 |  |  | 39.3 |
|  | $1,524.3 |  |  |  | $1,413.2 |  |  |  | $1,226.8 |  |  |  | $1,113.5 |  |  |  | $297.5 |  |  |  | $299.7 |
Regulatory Liabilities | Regulatory liabilities were comprised of the following items (in millions):
| Alliant Energy |  | IPL |  | WPL
| September 30, 2014 |  | December 31, 2013 |  | September 30, 2014 |  | December 31, 2013 |  | September 30, 2014 |  | December 31, 2013
Cost of removal obligations |  | $422.7 |  |  |  | $418.9 |  |  |  | $280.9 |  |  |  | $277.7 |  |  |  | $141.8 |  |  |  | $141.2 |
IPL’s tax benefit riders | 266.3 |  |  | 265.4 |  |  | 266.3 |  |  | 265.4 |  |  | — |  |  | — |
Energy efficiency cost recovery | 67.5 |  |  | 52.7 |  |  | 8.6 |  |  | 9.3 |  |  | 58.9 |  |  | 43.4 |
Derivatives | 41.2 |  |  | 7.2 |  |  | 8.4 |  |  | 3.6 |  |  | 32.8 |  |  | 3.6 |
IPL’s electric transmission cost recovery | 14.1 |  |  | 14.6 |  |  | 14.1 |  |  | 14.6 |  |  | — |  |  | — |
IPL’s electric transmission assets sale | 13.7 |  |  | 21.6 |  |  | 13.7 |  |  | 21.6 |  |  | — |  |  | — |
Other | 51.3 |  |  | 41.1 |  |  | 31.2 |  |  | 22.7 |  |  | 20.1 |  |  | 18.4 |
|  | $876.8 |  |  |  | $821.5 |  |  |  | $623.2 |  |  |  | $614.9 |  |  |  | $253.6 |  |  |  | $206.6 |
Tax Benefit Riders | For the nine months ended September 30, 2014, Alliant Energy and IPL utilized “IPL’s tax benefit riders” regulatory liabilities to credit IPL’s Iowa retail electric and gas customers’ bills as follows (in millions):
Electric tax benefit rider |  | $64 |
Gas tax benefit rider | 9 |
|  | $73 |
Revenue Requirement Adjustment | For the three and nine months ended September 30, the revenue requirement adjustment recognized by both Alliant Energy and IPL is included in the table below (in millions). The revenue requirement adjustment resulted in increases to electric revenues in their income statements and was recognized through the energy adjustment clause as a reduction of the credits on IPL’s Iowa retail electric customers’ bills from the electric tax benefit rider.
| Three Months |  | Nine Months
| 2014 |  | 2013 |  | 2014 |  | 2013
Revenue requirement adjustment |  | $4 |  |  |  | $7 |  |  |  | $11 |  |  |  | $18 |
IPL [Member] |
Regulatory Assets [Line Items] |
Regulatory Assets | Regulatory assets were comprised of the following items (in millions):
| Alliant Energy |  | IPL |  | WPL
| September 30, 2014 |  | December 31, 2013 |  | September 30, 2014 |  | December 31, 2013 |  | September 30, 2014 |  | December 31, 2013
Tax-related |  | $937.6 |  |  |  | $829.7 |  |  |  | $910.6 |  |  |  | $798.6 |  |  |  | $27.0 |  |  |  | $31.1 |
Pension and OPEB costs | 345.4 |  |  | 355.3 |  |  | 170.2 |  |  | 174.2 |  |  | 175.2 |  |  | 181.1 |
AROs | 74.6 |  |  | 65.7 |  |  | 43.1 |  |  | 36.7 |  |  | 31.5 |  |  | 29.0 |
Emission allowances | 28.0 |  |  | 30.0 |  |  | 28.0 |  |  | 30.0 |  |  | — |  |  | — |
Environmental-related costs | 26.6 |  |  | 25.0 |  |  | 22.0 |  |  | 21.0 |  |  | 4.6 |  |  | 4.0 |
Derivatives | 23.3 |  |  | 21.1 |  |  | 17.7 |  |  | 5.9 |  |  | 5.6 |  |  | 15.2 |
Other | 88.8 |  |  | 86.4 |  |  | 35.2 |  |  | 47.1 |  |  | 53.6 |  |  | 39.3 |
|  | $1,524.3 |  |  |  | $1,413.2 |  |  |  | $1,226.8 |  |  |  | $1,113.5 |  |  |  | $297.5 |  |  |  | $299.7 |
Regulatory Liabilities | Regulatory liabilities were comprised of the following items (in millions):
| Alliant Energy |  | IPL |  | WPL
| September 30, 2014 |  | December 31, 2013 |  | September 30, 2014 |  | December 31, 2013 |  | September 30, 2014 |  | December 31, 2013
Cost of removal obligations |  | $422.7 |  |  |  | $418.9 |  |  |  | $280.9 |  |  |  | $277.7 |  |  |  | $141.8 |  |  |  | $141.2 |
IPL’s tax benefit riders | 266.3 |  |  | 265.4 |  |  | 266.3 |  |  | 265.4 |  |  | — |  |  | — |
Energy efficiency cost recovery | 67.5 |  |  | 52.7 |  |  | 8.6 |  |  | 9.3 |  |  | 58.9 |  |  | 43.4 |
Derivatives | 41.2 |  |  | 7.2 |  |  | 8.4 |  |  | 3.6 |  |  | 32.8 |  |  | 3.6 |
IPL’s electric transmission cost recovery | 14.1 |  |  | 14.6 |  |  | 14.1 |  |  | 14.6 |  |  | — |  |  | — |
IPL’s electric transmission assets sale | 13.7 |  |  | 21.6 |  |  | 13.7 |  |  | 21.6 |  |  | — |  |  | — |
Other | 51.3 |  |  | 41.1 |  |  | 31.2 |  |  | 22.7 |  |  | 20.1 |  |  | 18.4 |
|  | $876.8 |  |  |  | $821.5 |  |  |  | $623.2 |  |  |  | $614.9 |  |  |  | $253.6 |  |  |  | $206.6 |
Tax Benefit Riders | For the nine months ended September 30, 2014, Alliant Energy and IPL utilized “IPL’s tax benefit riders” regulatory liabilities to credit IPL’s Iowa retail electric and gas customers’ bills as follows (in millions):
Electric tax benefit rider |  | $64 |
Gas tax benefit rider | 9 |
|  | $73 |
Revenue Requirement Adjustment | For the three and nine months ended September 30, the revenue requirement adjustment recognized by both Alliant Energy and IPL is included in the table below (in millions). The revenue requirement adjustment resulted in increases to electric revenues in their income statements and was recognized through the energy adjustment clause as a reduction of the credits on IPL’s Iowa retail electric customers’ bills from the electric tax benefit rider.
| Three Months |  | Nine Months
| 2014 |  | 2013 |  | 2014 |  | 2013
Revenue requirement adjustment |  | $4 |  |  |  | $7 |  |  |  | $11 |  |  |  | $18 |
WPL [Member] |
Regulatory Assets [Line Items] |
Regulatory Assets | Regulatory assets were comprised of the following items (in millions):
| Alliant Energy |  | IPL |  | WPL
| September 30, 2014 |  | December 31, 2013 |  | September 30, 2014 |  | December 31, 2013 |  | September 30, 2014 |  | December 31, 2013
Tax-related |  | $937.6 |  |  |  | $829.7 |  |  |  | $910.6 |  |  |  | $798.6 |  |  |  | $27.0 |  |  |  | $31.1 |
Pension and OPEB costs | 345.4 |  |  | 355.3 |  |  | 170.2 |  |  | 174.2 |  |  | 175.2 |  |  | 181.1 |
AROs | 74.6 |  |  | 65.7 |  |  | 43.1 |  |  | 36.7 |  |  | 31.5 |  |  | 29.0 |
Emission allowances | 28.0 |  |  | 30.0 |  |  | 28.0 |  |  | 30.0 |  |  | — |  |  | — |
Environmental-related costs | 26.6 |  |  | 25.0 |  |  | 22.0 |  |  | 21.0 |  |  | 4.6 |  |  | 4.0 |
Derivatives | 23.3 |  |  | 21.1 |  |  | 17.7 |  |  | 5.9 |  |  | 5.6 |  |  | 15.2 |
Other | 88.8 |  |  | 86.4 |  |  | 35.2 |  |  | 47.1 |  |  | 53.6 |  |  | 39.3 |
|  | $1,524.3 |  |  |  | $1,413.2 |  |  |  | $1,226.8 |  |  |  | $1,113.5 |  |  |  | $297.5 |  |  |  | $299.7 |
Regulatory Liabilities | Regulatory liabilities were comprised of the following items (in millions):
| Alliant Energy |  | IPL |  | WPL
| September 30, 2014 |  | December 31, 2013 |  | September 30, 2014 |  | December 31, 2013 |  | September 30, 2014 |  | December 31, 2013
Cost of removal obligations |  | $422.7 |  |  |  | $418.9 |  |  |  | $280.9 |  |  |  | $277.7 |  |  |  | $141.8 |  |  |  | $141.2 |
IPL’s tax benefit riders | 266.3 |  |  | 265.4 |  |  | 266.3 |  |  | 265.4 |  |  | — |  |  | — |
Energy efficiency cost recovery | 67.5 |  |  | 52.7 |  |  | 8.6 |  |  | 9.3 |  |  | 58.9 |  |  | 43.4 |
Derivatives | 41.2 |  |  | 7.2 |  |  | 8.4 |  |  | 3.6 |  |  | 32.8 |  |  | 3.6 |
IPL’s electric transmission cost recovery | 14.1 |  |  | 14.6 |  |  | 14.1 |  |  | 14.6 |  |  | — |  |  | — |
IPL’s electric transmission assets sale | 13.7 |  |  | 21.6 |  |  | 13.7 |  |  | 21.6 |  |  | — |  |  | — |
Other | 51.3 |  |  | 41.1 |  |  | 31.2 |  |  | 22.7 |  |  | 20.1 |  |  | 18.4 |
|  | $876.8 |  |  |  | $821.5 |  |  |  | $623.2 |  |  |  | $614.9 |  |  |  | $253.6 |  |  |  | $206.6 |

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- Definition Tabular disclosure of assets that are created when regulatory agencies permit public utilities to defer certain costs included in rate-setting to the balance sheet. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 980 -SubTopic 340 -Section 50 -Paragraph 1 -URI http://asc.fasb.org/extlink&oid=6499975&loc=d3e44250-110382 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 980 -SubTopic 715 -Section 50 -Paragraph 1 -URI http://asc.fasb.org/extlink&oid=6501251&loc=d3e52485-110419 Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 980 -SubTopic 340 -Section 50 -Paragraph 2 -URI http://asc.fasb.org/extlink&oid=6499975&loc=d3e44264-110382 + Details
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