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Regulatory Matters - Electric Rates (Details) (USD $) In Millions, unless otherwise specified | Dec. 31, 2012 Municipal Customers [Member] Customers | Dec. 31, 2012 Non-Affiliated Private Utility [Member] Customers | Jun. 01, 2011 MPUC 2010 MN Rate Case [Member] Electric Rates [Member] Retail Customers [Member] | Dec. 31, 2012 FERC-Approved Wholesale Rates [Member] Electric Rates [Member] Municipal Customers [Member] Years Customers | Dec. 31, 2012 FERC-Approved Wholesale Rates [Member] Electric Rates [Member] Non-Affiliated Private Utility [Member] Years MW Customers | Dec. 31, 2012 PSCW 2012 Wisconsin Rate Case [Member] Retail Customers [Member] | Dec. 31, 2012 PSCW 2012 Wisconsin Rate Case [Member] Natural Gas Rates [Member] Retail Customers [Member] | Dec. 31, 2012 PSCW 2012 Wisconsin Rate Case [Member] Electric Rates [Member] Retail Customers [Member] | Dec. 31, 2012 PSCW 2012 Wisconsin Rate Case [Member] Water Rates [Member] Retail Customers [Member]
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Rate Regulation [Line Items] |  |  |  |  |  |  |  |  |
Approved Rate of Return on Common Equity |  |  | 10.38% |  |  | 10.90% |  |  |
Approved Percentage of Capital Structure Related to Equity |  |  | 54.29% |  |  |  |  |  |
Number of Customers | 16 | 1 |  | 16 | 1 |  |  |  |
Length of Notice Required to Terminate (Years) |  |  |  | 3 | 2 |  |  |  |
Average Monthly Demand (in MWs) |  |  |  |  | 17 |  |  |  |
Approved Rate Increase or Decrease |  |  |  |  |  | 2.40% | (2.00%) | 1.20% | 13.80%
Amount Of Estimated Additional Revenue |  |  |  |  |  | $ 1.7 |  |  |

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- Definition Percentage of capital structure related to equity approved by the regulatory commission through a rate case proceeding. + References No definition available. + Details
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- Definition The rate increase or decrease approved by appropriate regulatory body + References No definition available. + Details
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- Definition Rate of return on common equity approved by the regulatory commission through a rate case proceeding. + References No definition available. + Details
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- Definition The Average Monthly Demand (in MWs) + References No definition available. + Details
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- Definition The length of notice required to terminate a contract (in years). + References No definition available. + Details
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- Definition Number of Customers + References No definition available. + Details
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- Details
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