- Definition

Estimated Annual Reduction to Revenue Due to Idled Customers net of associated expense savings such as fuel costs for Keetac and Verso.

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Forced Outage Costs

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- Definition

Proposed Ongoing Customer Rate Increase

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- Definition

Public Utilities Reserve for Interim Rates

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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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Amount of public utility's interim rate increase (decrease) allowed while waiting final decision of regulatory agency.

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Percentage of public utility's interim rate increase (decrease) allowed while waiting final decision of regulatory agency.

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Percentage of public utility's requested equity to capital, including debt and equity.

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Amount of public utility's requested rate increase (decrease) with regulatory agency.

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Percentage of public utility's requested rate increase (decrease) with regulatory agency.

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Percentage of public utility's requested return on equity.

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- Definition

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

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Regulatory Matters - Electric Rates (Details) - MPUC [Member] - Minnesota Power [Member] - USD ($) $ in Millions				4 Months Ended	6 Months Ended		18 Months Ended
	Apr. 01, 2021	May 01, 2020	Nov. 01, 2019	Apr. 30, 2020	Jun. 30, 2021	Jun. 30, 2020	Dec. 31, 2019	Dec. 31, 2020
CIP Consolidated Filing [Member]
Regulatory Matters [Line Items]
Revenue from Cost Recovery Riders and Other Regulatory Programs	$ 2.4
Fuel Adjustment Clause Filing [Member]
Regulatory Matters [Line Items]
Forced Outage Costs							$ 8.0
COVID-19 Related Deferred Accounting [Member]
Regulatory Matters [Line Items]
Estimated Annual Reduction to Revenue Due to Idled Customers Keetac and Verso					$ 30.0
Electric Rates [Member] \| Minnesota Cost Recovery Riders [Member] \| Retail Customers [Member]
Regulatory Matters [Line Items]
Revenue from Cost Recovery Riders and Other Regulatory Programs					$ 22.1	$ 14.9
Electric Rates [Member] \| 2020 Minnesota General Rate Case [Member] \| Retail Customers [Member]
Regulatory Matters [Line Items]
Annual Additional Revenue Generated from Requested Final Rate Increase			$ 66.0
Requested Rate Increase Percent			10.60%
Interim Rate Increase				$ 36.1
Requested Return on Equity			10.05%
Requested Equity Capital Structure			53.81%
Ongoing Customer Rate Increase		4.10%
Public Utilities, Interim Rate Increase (Decrease), Percentage				5.80%
Public Utilities Reserve for Interim Rates								$ 11.7