|
Income Taxes (Schedule Of Deferred Tax Assets And Liabilities) (Details) (USD $)
In Millions, unless otherwise specified
|
Dec. 31, 2012
|
Dec. 31, 2011
|
| Deferred tax liabilities, gross |
$ 2,507.0 |
$ 2,320.4 |
| Deferred tax assets, valuation allowance |
1.9 |
1.2 |
| Deferred tax assets, net of valuation allowance |
743.0 |
751.0 |
| Deferred tax liabilities, net of deferred tax assets and valuation allowance |
1,764.0 |
1,569.4 |
| Other current assets |
(170.2) |
(22.8) |
| Deferred income taxes |
1,934.2 |
1,592.2 |
|
IPL [Member]
|
|
|
| Deferred tax assets, gross |
(383.4) |
(396.5) |
| Deferred tax liabilities, gross |
1,391.4 |
1,319.9 |
| Deferred tax assets and liabilities, net |
1,008.0 |
923.4 |
| Deferred tax liabilities, net of deferred tax assets and valuation allowance |
1,008.0 |
923.4 |
| Other current assets |
(79.3) |
(13.5) |
| Deferred income taxes |
1,087.3 |
936.9 |
|
WPL [Member]
|
|
|
| Deferred tax assets, gross |
(222.8) |
(208.1) |
| Deferred tax liabilities, gross |
981.3 |
874.6 |
| Deferred tax assets and liabilities, net |
758.5 |
666.5 |
| Deferred tax liabilities, net of deferred tax assets and valuation allowance |
758.5 |
666.5 |
| Other current assets |
(85.6) |
(6.0) |
| Deferred income taxes |
844.1 |
672.5 |
|
Property [Member]
|
|
|
| Deferred tax assets, gross |
0 |
0 |
| Deferred tax liabilities, gross |
2,143.8 |
1,926.4 |
| Deferred tax assets and liabilities, net |
2,143.8 |
1,926.4 |
|
Property [Member] | IPL [Member]
|
|
|
| Deferred tax assets, gross |
0 |
0 |
| Deferred tax liabilities, gross |
1,243.9 |
1,134.1 |
| Deferred tax assets and liabilities, net |
1,243.9 |
1,134.1 |
|
Property [Member] | WPL [Member]
|
|
|
| Deferred tax assets, gross |
0 |
0 |
| Deferred tax liabilities, gross |
793.3 |
697.1 |
| Deferred tax assets and liabilities, net |
793.3 |
697.1 |
|
Investment In ATC [Member]
|
|
|
| Deferred tax assets, gross |
0 |
0 |
| Deferred tax liabilities, gross |
104.3 |
93.8 |
| Deferred tax assets and liabilities, net |
104.3 |
93.8 |
|
Investment In ATC [Member] | WPL [Member]
|
|
|
| Deferred tax assets, gross |
0 |
0 |
| Deferred tax liabilities, gross |
104.3 |
93.8 |
| Deferred tax assets and liabilities, net |
104.3 |
93.8 |
|
Pension And Other Postretirement Benefits Obligations [Member] | IPL [Member]
|
|
|
| Deferred tax assets, gross |
0 |
0 |
| Deferred tax liabilities, gross |
64.9 |
67.6 |
| Deferred tax assets and liabilities, net |
64.9 |
67.6 |
|
Pension And Other Postretirement Benefits Obligations [Member] | WPL [Member]
|
|
|
| Deferred tax assets, gross |
0 |
0 |
| Deferred tax liabilities, gross |
46.4 |
49.6 |
| Deferred tax assets and liabilities, net |
46.4 |
49.6 |
|
Deferred Portion of Tax Gain On IPL's Electric Transmission Assets Sale [Member]
|
|
|
| Deferred tax assets, gross |
0 |
0 |
| Deferred tax liabilities, gross |
50.7 |
75.5 |
| Deferred tax assets and liabilities, net |
50.7 |
75.5 |
|
Deferred Portion of Tax Gain On IPL's Electric Transmission Assets Sale [Member] | IPL [Member]
|
|
|
| Deferred tax assets, gross |
0 |
0 |
| Deferred tax liabilities, gross |
50.7 |
75.5 |
| Deferred tax assets and liabilities, net |
50.7 |
75.5 |
|
Net Operating Losses Carryforward - State [Member]
|
|
|
| Deferred tax assets, gross |
(46.8) |
(39.9) |
| Deferred tax liabilities, gross |
0 |
0 |
| Deferred tax assets and liabilities, net |
(46.8) |
(39.9) |
|
Customer Advances [Member] | WPL [Member]
|
|
|
| Deferred tax assets, gross |
(9.6) |
(11.6) |
| Deferred tax liabilities, gross |
0 |
0 |
| Deferred tax assets and liabilities, net |
(9.6) |
(11.6) |
|
Federal Credit Carryforward [Member]
|
|
|
| Deferred tax assets, gross |
(133.8) |
(107.4) |
| Deferred tax liabilities, gross |
0 |
0 |
| Deferred tax assets and liabilities, net |
(133.8) |
(107.4) |
|
Federal Credit Carryforward [Member] | IPL [Member]
|
|
|
| Deferred tax assets, gross |
(37.4) |
(25.0) |
| Deferred tax liabilities, gross |
0 |
0 |
| Deferred tax assets and liabilities, net |
(37.4) |
(25.0) |
|
Federal Credit Carryforward [Member] | WPL [Member]
|
|
|
| Deferred tax assets, gross |
(39.4) |
(26.1) |
| Deferred tax liabilities, gross |
0 |
0 |
| Deferred tax assets and liabilities, net |
(39.4) |
(26.1) |
|
Regulatory Liability, IPL's Tax Benefit Rider [Member]
|
|
|
| Deferred tax assets, gross |
(144.6) |
(140.6) |
| Deferred tax liabilities, gross |
0 |
0 |
| Deferred tax assets and liabilities, net |
(144.6) |
(140.6) |
|
Regulatory Liability, IPL's Tax Benefit Rider [Member] | IPL [Member]
|
|
|
| Deferred tax assets, gross |
(144.6) |
(140.6) |
| Deferred tax liabilities, gross |
0 |
0 |
| Deferred tax assets and liabilities, net |
(144.6) |
(140.6) |
|
Net Operating Losses Carryforward - Federal [Member]
|
|
|
| Deferred tax assets, gross |
(306.0) |
(336.1) |
| Deferred tax liabilities, gross |
0 |
0 |
| Deferred tax assets and liabilities, net |
(306.0) |
(336.1) |
|
Net Operating Losses Carryforward - Federal [Member] | IPL [Member]
|
|
|
| Deferred tax assets, gross |
(131.0) |
(154.4) |
| Deferred tax liabilities, gross |
0 |
0 |
| Deferred tax assets and liabilities, net |
(131.0) |
(154.4) |
|
Net Operating Losses Carryforward - Federal [Member] | WPL [Member]
|
|
|
| Deferred tax assets, gross |
(142.2) |
(141.1) |
| Deferred tax liabilities, gross |
0 |
0 |
| Deferred tax assets and liabilities, net |
(142.2) |
(141.1) |
|
Other [Member]
|
|
|
| Deferred tax assets, gross |
(113.7) |
(128.2) |
| Deferred tax liabilities, gross |
208.2 |
224.7 |
| Deferred tax assets and liabilities, net |
94.5 |
96.5 |
|
Other [Member] | IPL [Member]
|
|
|
| Deferred tax assets, gross |
(70.4) |
(76.5) |
| Deferred tax liabilities, gross |
31.9 |
42.7 |
| Deferred tax assets and liabilities, net |
(38.5) |
(33.8) |
|
Other [Member] | WPL [Member]
|
|
|
| Deferred tax assets, gross |
(31.6) |
(29.3) |
| Deferred tax liabilities, gross |
37.3 |
34.1 |
| Deferred tax assets and liabilities, net |
5.7 |
4.8 |
|
Subtotal [Member]
|
|
|
| Deferred tax assets, gross |
(744.9) |
(752.2) |
| Deferred tax liabilities, gross |
2,507.0 |
2,320.4 |
| Deferred tax assets and liabilities, net |
$ 1,762.1 |
$ 1,568.2 |