XML 174 R88.htm IDEA: XBRL DOCUMENT
v2.4.1.9

Debt (Schedule Of Debt-To-Capital Ratios) (Details) | Dec. 31, 2014
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Actual | 52.00%lnt_DebtToCapitalRatiosActualStatus
IPL [Member] |
Actual | 47.00%lnt_DebtToCapitalRatiosActualStatus / dei_LegalEntityAxis = lnt_IplMember
WPL [Member] |
Actual | 49.00%lnt_DebtToCapitalRatiosActualStatus / dei_LegalEntityAxis = lnt_WplMember
Maximum [Member] |
Requirement, not to exceed | 65.00%lnt_DebtToCapitalRatiosBasePercentage / us-gaap_RangeAxis = us-gaap_MaximumMember
Maximum [Member] | IPL [Member] |
Requirement, not to exceed | 58.00%lnt_DebtToCapitalRatiosBasePercentage / dei_LegalEntityAxis = lnt_IplMember / us-gaap_RangeAxis = us-gaap_MaximumMember
Maximum [Member] | WPL [Member] |
Requirement, not to exceed | 58.00%lnt_DebtToCapitalRatiosBasePercentage / dei_LegalEntityAxis = lnt_WplMember / us-gaap_RangeAxis = us-gaap_MaximumMember

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

X
- Details
Name: | dei_LegalEntityAxis=lnt_IplMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | dei_LegalEntityAxis=lnt_WplMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_RangeAxis=us-gaap_MaximumMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |