v2.4.0.6

Debt (Schedule Of Debt-To-Capital Ratios) (Details) | Dec. 31, 2012
--- | ---
Actual | 50.00%
IPL [Member] |
Actual | 45.00%
WPL [Member] |
Actual | 48.00%
Maximum [Member] |
Requirement | 65.00%
Maximum [Member] | IPL [Member] |
Requirement | 58.00%
Maximum [Member] | WPL [Member] |
Requirement | 58.00%

X
- Definition Debt to capital ratios actual status + References No definition available. + Details
Name: | lnt_DebtToCapitalRatiosActualStatus
Namespace Prefix: | lnt_
Data Type: | num:percentItemType
Balance Type: | na
Period Type: | instant

X
- Definition Debt to capital ratios base percentage + References No definition available. + Details
Name: | lnt_DebtToCapitalRatiosBasePercentage
Namespace Prefix: | lnt_
Data Type: | num:percentItemType
Balance Type: | na
Period Type: | instant