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Regulatory Matters - Conservation Improvement Program (CIP) (Details) - USD ($) $ in Millions | 12 Months Ended
--- | ---
Dec. 31, 2021 | Dec. 31, 2020
Regulatory Matters [Line Items] |  |
Conservation Improvement Program Goal, Next Fiscal Year | $ 10.7 |
Conservation Improvement Program Goal, In 2 Years | 10.9 |
MPUC [Member] | CIP Consolidated Filing [Member] | Minnesota Power [Member] |  |
Regulatory Matters [Line Items] |  |
CIP Financial Incentive | $ 2.4 | $ 2.4
MPUC [Member] | Minimum [Member] |  |
Regulatory Matters [Line Items] |  |
CIP Spending Minimum - Percentage | 1.50% |

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- Definition Minnesota 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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