|
Derivative Instruments (Notional Amounts Of Derivative Instruments) (Details) (Commodity [Member])
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Sep. 30, 2012
MWh
|
|
Electricity (MWhs) [Member] | Alliant Energy [Member]
|
|
| Notional Amount of Derivatives [Line Items] |
|
| Notional Unit Amount Of Derivatives (in MWhs/MWs/Dths/Tons) |
8,134,000 |
|
Electricity (MWhs) [Member] | IPL [Member]
|
|
| Notional Amount of Derivatives [Line Items] |
|
| Notional Unit Amount Of Derivatives (in MWhs/MWs/Dths/Tons) |
3,130,000 |
|
Electricity (MWhs) [Member] | WPL [Member]
|
|
| Notional Amount of Derivatives [Line Items] |
|
| Notional Unit Amount Of Derivatives (in MWhs/MWs/Dths/Tons) |
5,004,000 |
|
FTRs (MWs) [Member] | Alliant Energy [Member]
|
|
| Notional Amount of Derivatives [Line Items] |
|
| Notional Unit Amount Of Derivatives (in MWhs/MWs/Dths/Tons) |
44,000 |
|
FTRs (MWs) [Member] | IPL [Member]
|
|
| Notional Amount of Derivatives [Line Items] |
|
| Notional Unit Amount Of Derivatives (in MWhs/MWs/Dths/Tons) |
23,000 |
|
FTRs (MWs) [Member] | WPL [Member]
|
|
| Notional Amount of Derivatives [Line Items] |
|
| Notional Unit Amount Of Derivatives (in MWhs/MWs/Dths/Tons) |
21,000 |
|
Natural Gas (Dths) [Member] | Alliant Energy [Member]
|
|
| Notional Amount of Derivatives [Line Items] |
|
| Notional Unit Amount Of Derivatives (in MWhs/MWs/Dths/Tons) |
77,379,000 |
|
Natural Gas (Dths) [Member] | IPL [Member]
|
|
| Notional Amount of Derivatives [Line Items] |
|
| Notional Unit Amount Of Derivatives (in MWhs/MWs/Dths/Tons) |
54,818,000 |
|
Natural Gas (Dths) [Member] | WPL [Member]
|
|
| Notional Amount of Derivatives [Line Items] |
|
| Notional Unit Amount Of Derivatives (in MWhs/MWs/Dths/Tons) |
22,561,000 |
|
Coal (Tons) [Member] | Alliant Energy [Member]
|
|
| Notional Amount of Derivatives [Line Items] |
|
| Notional Unit Amount Of Derivatives (in MWhs/MWs/Dths/Tons) |
2,498,000 |
|
Coal (Tons) [Member] | WPL [Member]
|
|
| Notional Amount of Derivatives [Line Items] |
|
| Notional Unit Amount Of Derivatives (in MWhs/MWs/Dths/Tons) |
2,498,000 |
|
2012 [Member] | Electricity (MWhs) [Member] | Alliant Energy [Member]
|
|
| Notional Amount of Derivatives [Line Items] |
|
| Notional Unit Amount Of Derivatives (in MWhs/MWs/Dths/Tons) |
1,280,000 |
|
2012 [Member] | Electricity (MWhs) [Member] | IPL [Member]
|
|
| Notional Amount of Derivatives [Line Items] |
|
| Notional Unit Amount Of Derivatives (in MWhs/MWs/Dths/Tons) |
786,000 |
|
2012 [Member] | Electricity (MWhs) [Member] | WPL [Member]
|
|
| Notional Amount of Derivatives [Line Items] |
|
| Notional Unit Amount Of Derivatives (in MWhs/MWs/Dths/Tons) |
494,000 |
|
2012 [Member] | FTRs (MWs) [Member] | Alliant Energy [Member]
|
|
| Notional Amount of Derivatives [Line Items] |
|
| Notional Unit Amount Of Derivatives (in MWhs/MWs/Dths/Tons) |
16,000 |
|
2012 [Member] | FTRs (MWs) [Member] | IPL [Member]
|
|
| Notional Amount of Derivatives [Line Items] |
|
| Notional Unit Amount Of Derivatives (in MWhs/MWs/Dths/Tons) |
8,000 |
|
2012 [Member] | FTRs (MWs) [Member] | WPL [Member]
|
|
| Notional Amount of Derivatives [Line Items] |
|
| Notional Unit Amount Of Derivatives (in MWhs/MWs/Dths/Tons) |
8,000 |
|
2012 [Member] | Natural Gas (Dths) [Member] | Alliant Energy [Member]
|
|
| Notional Amount of Derivatives [Line Items] |
|
| Notional Unit Amount Of Derivatives (in MWhs/MWs/Dths/Tons) |
26,070,000 |
|
2012 [Member] | Natural Gas (Dths) [Member] | IPL [Member]
|
|
| Notional Amount of Derivatives [Line Items] |
|
| Notional Unit Amount Of Derivatives (in MWhs/MWs/Dths/Tons) |
19,274,000 |
|
2012 [Member] | Natural Gas (Dths) [Member] | WPL [Member]
|
|
| Notional Amount of Derivatives [Line Items] |
|
| Notional Unit Amount Of Derivatives (in MWhs/MWs/Dths/Tons) |
6,796,000 |
|
2012 [Member] | Coal (Tons) [Member] | Alliant Energy [Member]
|
|
| Notional Amount of Derivatives [Line Items] |
|
| Notional Unit Amount Of Derivatives (in MWhs/MWs/Dths/Tons) |
0 |
|
2012 [Member] | Coal (Tons) [Member] | WPL [Member]
|
|
| Notional Amount of Derivatives [Line Items] |
|
| Notional Unit Amount Of Derivatives (in MWhs/MWs/Dths/Tons) |
0 |
|
2013 [Member] | Electricity (MWhs) [Member] | Alliant Energy [Member]
|
|
| Notional Amount of Derivatives [Line Items] |
|
| Notional Unit Amount Of Derivatives (in MWhs/MWs/Dths/Tons) |
3,860,000 |
|
2013 [Member] | Electricity (MWhs) [Member] | IPL [Member]
|
|
| Notional Amount of Derivatives [Line Items] |
|
| Notional Unit Amount Of Derivatives (in MWhs/MWs/Dths/Tons) |
1,978,000 |
|
2013 [Member] | Electricity (MWhs) [Member] | WPL [Member]
|
|
| Notional Amount of Derivatives [Line Items] |
|
| Notional Unit Amount Of Derivatives (in MWhs/MWs/Dths/Tons) |
1,882,000 |
|
2013 [Member] | FTRs (MWs) [Member] | Alliant Energy [Member]
|
|
| Notional Amount of Derivatives [Line Items] |
|
| Notional Unit Amount Of Derivatives (in MWhs/MWs/Dths/Tons) |
28,000 |
|
2013 [Member] | FTRs (MWs) [Member] | IPL [Member]
|
|
| Notional Amount of Derivatives [Line Items] |
|
| Notional Unit Amount Of Derivatives (in MWhs/MWs/Dths/Tons) |
15,000 |
|
2013 [Member] | FTRs (MWs) [Member] | WPL [Member]
|
|
| Notional Amount of Derivatives [Line Items] |
|
| Notional Unit Amount Of Derivatives (in MWhs/MWs/Dths/Tons) |
13,000 |
|
2013 [Member] | Natural Gas (Dths) [Member] | Alliant Energy [Member]
|
|
| Notional Amount of Derivatives [Line Items] |
|
| Notional Unit Amount Of Derivatives (in MWhs/MWs/Dths/Tons) |
44,899,000 |
|
2013 [Member] | Natural Gas (Dths) [Member] | IPL [Member]
|
|
| Notional Amount of Derivatives [Line Items] |
|
| Notional Unit Amount Of Derivatives (in MWhs/MWs/Dths/Tons) |
32,309,000 |
|
2013 [Member] | Natural Gas (Dths) [Member] | WPL [Member]
|
|
| Notional Amount of Derivatives [Line Items] |
|
| Notional Unit Amount Of Derivatives (in MWhs/MWs/Dths/Tons) |
12,590,000 |
|
2013 [Member] | Coal (Tons) [Member] | Alliant Energy [Member]
|
|
| Notional Amount of Derivatives [Line Items] |
|
| Notional Unit Amount Of Derivatives (in MWhs/MWs/Dths/Tons) |
956,000 |
|
2013 [Member] | Coal (Tons) [Member] | WPL [Member]
|
|
| Notional Amount of Derivatives [Line Items] |
|
| Notional Unit Amount Of Derivatives (in MWhs/MWs/Dths/Tons) |
956,000 |
|
2014 [Member] | Electricity (MWhs) [Member] | Alliant Energy [Member]
|
|
| Notional Amount of Derivatives [Line Items] |
|
| Notional Unit Amount Of Derivatives (in MWhs/MWs/Dths/Tons) |
2,118,000 |
|
2014 [Member] | Electricity (MWhs) [Member] | IPL [Member]
|
|
| Notional Amount of Derivatives [Line Items] |
|
| Notional Unit Amount Of Derivatives (in MWhs/MWs/Dths/Tons) |
366,000 |
|
2014 [Member] | Electricity (MWhs) [Member] | WPL [Member]
|
|
| Notional Amount of Derivatives [Line Items] |
|
| Notional Unit Amount Of Derivatives (in MWhs/MWs/Dths/Tons) |
1,752,000 |
|
2014 [Member] | FTRs (MWs) [Member] | Alliant Energy [Member]
|
|
| Notional Amount of Derivatives [Line Items] |
|
| Notional Unit Amount Of Derivatives (in MWhs/MWs/Dths/Tons) |
0 |
|
2014 [Member] | FTRs (MWs) [Member] | IPL [Member]
|
|
| Notional Amount of Derivatives [Line Items] |
|
| Notional Unit Amount Of Derivatives (in MWhs/MWs/Dths/Tons) |
0 |
|
2014 [Member] | FTRs (MWs) [Member] | WPL [Member]
|
|
| Notional Amount of Derivatives [Line Items] |
|
| Notional Unit Amount Of Derivatives (in MWhs/MWs/Dths/Tons) |
0 |
|
2014 [Member] | Natural Gas (Dths) [Member] | Alliant Energy [Member]
|
|
| Notional Amount of Derivatives [Line Items] |
|
| Notional Unit Amount Of Derivatives (in MWhs/MWs/Dths/Tons) |
6,410,000 |
|
2014 [Member] | Natural Gas (Dths) [Member] | IPL [Member]
|
|
| Notional Amount of Derivatives [Line Items] |
|
| Notional Unit Amount Of Derivatives (in MWhs/MWs/Dths/Tons) |
3,235,000 |
|
2014 [Member] | Natural Gas (Dths) [Member] | WPL [Member]
|
|
| Notional Amount of Derivatives [Line Items] |
|
| Notional Unit Amount Of Derivatives (in MWhs/MWs/Dths/Tons) |
3,175,000 |
|
2014 [Member] | Coal (Tons) [Member] | Alliant Energy [Member]
|
|
| Notional Amount of Derivatives [Line Items] |
|
| Notional Unit Amount Of Derivatives (in MWhs/MWs/Dths/Tons) |
981,000 |
|
2014 [Member] | Coal (Tons) [Member] | WPL [Member]
|
|
| Notional Amount of Derivatives [Line Items] |
|
| Notional Unit Amount Of Derivatives (in MWhs/MWs/Dths/Tons) |
981,000 |
|
2015 [Member] | Electricity (MWhs) [Member] | Alliant Energy [Member]
|
|
| Notional Amount of Derivatives [Line Items] |
|
| Notional Unit Amount Of Derivatives (in MWhs/MWs/Dths/Tons) |
876,000 |
|
2015 [Member] | Electricity (MWhs) [Member] | IPL [Member]
|
|
| Notional Amount of Derivatives [Line Items] |
|
| Notional Unit Amount Of Derivatives (in MWhs/MWs/Dths/Tons) |
0 |
|
2015 [Member] | Electricity (MWhs) [Member] | WPL [Member]
|
|
| Notional Amount of Derivatives [Line Items] |
|
| Notional Unit Amount Of Derivatives (in MWhs/MWs/Dths/Tons) |
876,000 |
|
2015 [Member] | FTRs (MWs) [Member] | Alliant Energy [Member]
|
|
| Notional Amount of Derivatives [Line Items] |
|
| Notional Unit Amount Of Derivatives (in MWhs/MWs/Dths/Tons) |
0 |
|
2015 [Member] | FTRs (MWs) [Member] | IPL [Member]
|
|
| Notional Amount of Derivatives [Line Items] |
|
| Notional Unit Amount Of Derivatives (in MWhs/MWs/Dths/Tons) |
0 |
|
2015 [Member] | FTRs (MWs) [Member] | WPL [Member]
|
|
| Notional Amount of Derivatives [Line Items] |
|
| Notional Unit Amount Of Derivatives (in MWhs/MWs/Dths/Tons) |
0 |
|
2015 [Member] | Natural Gas (Dths) [Member] | Alliant Energy [Member]
|
|
| Notional Amount of Derivatives [Line Items] |
|
| Notional Unit Amount Of Derivatives (in MWhs/MWs/Dths/Tons) |
0 |
|
2015 [Member] | Natural Gas (Dths) [Member] | IPL [Member]
|
|
| Notional Amount of Derivatives [Line Items] |
|
| Notional Unit Amount Of Derivatives (in MWhs/MWs/Dths/Tons) |
0 |
|
2015 [Member] | Natural Gas (Dths) [Member] | WPL [Member]
|
|
| Notional Amount of Derivatives [Line Items] |
|
| Notional Unit Amount Of Derivatives (in MWhs/MWs/Dths/Tons) |
0 |
|
2015 [Member] | Coal (Tons) [Member] | Alliant Energy [Member]
|
|
| Notional Amount of Derivatives [Line Items] |
|
| Notional Unit Amount Of Derivatives (in MWhs/MWs/Dths/Tons) |
561,000 |
|
2015 [Member] | Coal (Tons) [Member] | WPL [Member]
|
|
| Notional Amount of Derivatives [Line Items] |
|
| Notional Unit Amount Of Derivatives (in MWhs/MWs/Dths/Tons) |
561,000 |