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Regulatory Matters - Conservation Improvement Program (CIP) (Details) - MPUC [Member] - USD ($) $ in Millions | 12 Months Ended
--- | ---
Dec. 31, 2015 | Dec. 31, 2014 | Dec. 31, 2013
Regulatory Matters [Line Items] |  |  |
Energy CIP Spending Requirement | 1.50% |  |
Annual Energy-Savings Goal | 1.50% |  |
CIP Triennial Filing [Member] | Minnesota Power [Member] |  |  |
Regulatory Matters [Line Items] |  |  |
Investment Goal | $ 7.1 | $ 6.9 | $ 6.0
Actual Spending | 6.6 | 7.2 | 6.4
CIP Annual Filing [Member] | Minnesota Power [Member] |  |  |
Regulatory Matters [Line Items] |  |  |
Financial Incentive | $ 6.2 | $ 8.7 | $ 7.1

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- Definition Conservation improvement program actual annual spend. + References No definition available. + Details
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- Definition Minnesota's Next Generation Act of 2007 introduced an energy-savings goal of 1.5 percent of net gross annual retail electric energy sales beginning with the 2010 program year. + References No definition available. + Details
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- Definition Conservation improvement program financial incentive approved by the public utilities commission. + References No definition available. + Details
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- Definition Conservation improvement program Investment Goal approved by MPUC. + References No definition available. + Details
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- Definition Minnesota's Next Generation Act of 2007 introduced a spend goal of 1.5% of net gross operating revenues from service provided in the state on energy CIPs each year. + References No definition available. + Details
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