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Discontinued Operations and Assets and Liabilities Held For Sale (Components Of Assets And Liabilities Held For Sale In Consolidated Balance Sheets) (Details) - Alliant Energy and IPL [Member] - Gas Distribution [Member] $ in Millions | Dec. 31, 2014 USD ($)
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Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items] |
Current assets | $ 1.1
Property, plant and equipment, net | 11.0
Non-current regulatory assets | 7.0
Total assets held for sale | 19.1
Current liabilities | 1.0
Other liabilities | 7.1
Total liabilities held for sale | 8.1
Net assets held for sale | $ 11.0

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