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Regulatory Matters - Conservation Improvement Program (Details) - MPUC [Member] - USD ($) $ in Millions		6 Months Ended
	Apr. 02, 2018	Jun. 30, 2017	Jun. 30, 2018
CIP Consolidated Filing [Member] | Minnesota Power [Member]
Regulatory Matters [Line Items]
Requested CIP Financial Incentive	$ 3.3
Approved Financial Incentive		$ 5.5
Minimum [Member]
Regulatory Matters [Line Items]
CIP Spending Minimum - Percentage			1.50%

X

- 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.

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- Definition

Requested CIP Financial Incentive

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- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

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- Definition

The amount of regulated other operating revenues recognized during the period.

+ References

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