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Summary Of Significant Accounting Policies (Schedule Of Allowance For Funds Used During Construction Recovery Rate) (Details) | 12 Months Ended
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Dec. 31, 2013 | Dec. 31, 2012 | Dec. 31, 2011
IPL [Member] | IPL (FERC formula) [Member] |  |  |  |  |  |
Public Utility, Property, Plant and Equipment [Line Items] |  |  |  |  |  |
Recovery rates | 8.20% |  | 8.20% |  | 8.50% |
WPL [Member] | WPL (PSCW formula - retail jurisdiction) [Member] |  |  |  |  |  |
Public Utility, Property, Plant and Equipment [Line Items] |  |  |  |  |  |
Recovery rates | 8.20% | [1] | 8.80% | [1] | 8.80% | [1]
WPL [Member] | WPL (FERC formula - wholesale jurisdiction) [Member] |  |  |  |  |  |
Public Utility, Property, Plant and Equipment [Line Items] |  |  |  |  |  |
Recovery rates | 4.50% |  | 7.90% |  | 6.20% |
WPL [Member] | Edgewater Unit 5 and Columbia Units 1 and 2 [Member] |  |  |  |  |  |
Public Utility, Property, Plant and Equipment [Line Items] |  |  |  |  |  |
Accrual recorded, percentage of estimated CWIP | 100.00% |  |  |  |  |
WPL [Member] | Columbia Units 1-2 [Member] |  |  |  |  |  |
Public Utility, Property, Plant and Equipment [Line Items] |  |  |  |  |  |
Accrual recorded, percentage of estimated CWIP | 50.00% |  |  |  |  |
Return earned, expected percentage of estimated CWIP | 50.00% |  |  |  |  |
[1] | Consistent with the PSCW’s retail rate case order issued in 2009, WPL accrued AFUDC on 100% of CWIP related to the Edgewater Unit 5 SCR emission controls project and the Columbia Units 1 and 2 scrubber and baghouse emission controls project in 2012 and 2011. Consistent with the PSCW’s retail rate case order issued in 2012, WPL earned a return on 50% of the estimated CWIP related to its Columbia Units 1 and 2 scrubber and baghouse emission controls project for 2013 and accrued AFUDC on the remaining 50% in 2013.

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- Definition Public Utilities, Allowance for Funds Used During Construction, Accrual Recorded, Percentage of Estimated Construction Work-in-process + References No definition available. + Details
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- Definition Public Utilities, Allowance for Funds Used During Construction, Return Earned, Expected Percentage of Estimated Construction Work-in-process, Next Twelve Months + References No definition available. + Details
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- Definition Effective rate, including composite rate, of cost of financing additions to qualifying regulated assets, commonly called allowance for funds used during construction. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 980 -SubTopic 835 -Section 45 -Paragraph 1 -URI http://asc.fasb.org/extlink&oid=6501662&loc=d3e56162-110433 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 980 -SubTopic 835 -Section 25 -Paragraph 1 -URI http://asc.fasb.org/extlink&oid=6501569&loc=d3e55921-110430 + Details
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