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Summary Of Significant Accounting Policies (Narrative) (Details) - Minimum [Member] | Sep. 30, 2015
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New Accounting Pronouncements [Line Items] |
Debt issuance costs percentage, on total long-term debt | 1.00%
IPL [Member] |
New Accounting Pronouncements [Line Items] |
Debt issuance costs percentage, on total long-term debt | 1.00%
WPL [Member] |
New Accounting Pronouncements [Line Items] |
Debt issuance costs percentage, on total long-term debt | 1.00%

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