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Regulatory Matters - Conservation Improvement Program (Details) - MPUC [Member] - USD ($) $ in Millions | 3 Months Ended |
--- | --- | ---
Jun. 30, 2017 | Sep. 30, 2016 | Sep. 30, 2017
Minimum [Member] |  |  |
Regulatory Matters [Line Items] |  |  |
CIP Spending Requirement |  |  | 1.50%
CIP Annual Filing [Member] | Minnesota Power [Member] |  |  |
Regulatory Matters [Line Items] |  |  |
Financial Incentive | $ 5.5 | $ 7.5 |

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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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- Details
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