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Alternative Revenue Program, Required Collection Period

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- Definition

Commission Approved Refund

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- Definition

Deferred Interim Rates

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- Definition

Estimated Market Value - Reservoir Land to be Sold

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- Definition

Forced Outage Costs

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- Definition

The length of notice required to terminate a contract (in years).

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- Definition

Number of Customers

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- Definition

Proposed Ongoing Customer Rate Increase

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- Definition

Public Utilities Reserve for Interim Rates (Recorded During Period)

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- Definition

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

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- Definition

Percentage of public utility's approved return on equity.

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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

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

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- Definition

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

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- Definition

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

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- Definition

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

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- Definition

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

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- Definition

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) $ in Millions					3 Months Ended	4 Months Ended	8 Months Ended	12 Months Ended			18 Months Ended
Regulatory Matters - Electric Rates (Details) $ in Millions	Jan. 13, 2022 USD ($)	Nov. 01, 2021 USD ($)	Nov. 01, 2019 USD ($)	Dec. 20, 2018	Jun. 30, 2020 USD ($)	Apr. 30, 2020 USD ($)	Dec. 31, 2020	Dec. 31, 2021 USD ($) Customers Years	Dec. 31, 2020 USD ($)	Dec. 31, 2019 USD ($)	Dec. 31, 2019 USD ($)
Cost Recovery Riders [Member]
Regulatory Matters [Line Items]
Alternative Revenue Program, Required Collection Period								2 years
MPUC [Member] \| Fuel Adjustment Clause Filing [Member] \| Minnesota Power [Member]
Regulatory Matters [Line Items]
Forced Outage Costs											$ 8.0
Administrative Law Judge Recommended Refund								$ 5.0
MPUC [Member] \| Fuel Adjustment Clause Filing [Member] \| Minnesota Power [Member] \| Subsequent Event [Member]
Regulatory Matters [Line Items]
Commission Approved Refund	$ 5.0
MPUC [Member] \| Minnesota Power Land Sales \| Minnesota Power [Member]
Regulatory Matters [Line Items]
Estimated Market Value - Reservoir Land to be Sold								100.0
PSCW [Member] \| 2018 Wisconsin General Rate Case [Member] \| SWL&P [Member] \| Retail Customers [Member]
Regulatory Matters [Line Items]
Approved Return on Common Equity				10.40%
Approved Equity Ratio				55.00%
Electric Rates [Member] \| MPUC [Member] \| Minnesota Cost Recovery Riders [Member] \| Minnesota Power [Member] \| Retail Customers [Member]
Regulatory Matters [Line Items]
Revenue from Cost Recovery Riders								$ 38.9	$ 29.9	$ 31.8
Electric Rates [Member] \| MPUC [Member] \| 2020 Minnesota General Rate Review [Member] \| Minnesota Power [Member] \| Retail Customers [Member]
Regulatory Matters [Line Items]
Requested Average Rate Increase			10.60%
Requested Return on Equity			10.05%
Requested Equity Ratio			53.81%
Annual Additional Revenue Generated from Requested Final Rate Increase			$ 66.0
Public Utilities, Interim Rate Increase (Decrease), Amount						$ 36.1
Proposed Ongoing Customer Rate Increase							4.10%
Public Utilities, Interim Rate Increase (Decrease), Percentage						5.80%
Public Utilities Reserve for Interim Rates (Recorded During Period)					$ 11.7
Electric Rates [Member] \| MPUC [Member] \| 2022 Minnesota General Rate Review \| Minnesota Power [Member] \| Retail Customers [Member]
Regulatory Matters [Line Items]
Requested Average Rate Increase		18.00%
Requested Return on Equity		10.25%
Requested Equity Ratio		53.81%
Annual Additional Revenue Generated from Requested Final Rate Increase		$ 108.0
Public Utilities, Interim Rate Increase (Decrease), Amount		80.0
Electric Rates [Member] \| MPUC [Member] \| 2022 Minnesota General Rate Review \| Minnesota Power [Member] \| Residential [Member]
Regulatory Matters [Line Items]
Deferred Interim Rates		$ 8.0
Electric Rates [Member] \| FERC [Member] \| FERC-Approved Wholesale Rates [Member] \| Minnesota Power [Member] \| Municipal Customers [Member]
Regulatory Matters [Line Items]
Number of Customers \| Customers								15
Notice Required to Terminate (Years) \| Years								3
Electric Rates [Member] \| FERC [Member] \| FERC-Approved Wholesale Rates [Member] \| Minnesota Power [Member] \| Municipal Customers [Member] \| Wholesale Electric Contract (Cost-Based Formula Methodology for Entire Term) [Member]
Regulatory Matters [Line Items]
Number of Customers \| Customers								2
Electric Rates [Member] \| FERC [Member] \| FERC-Approved Wholesale Rates [Member] \| Minnesota Power [Member] \| Municipal Customers [Member] \| Wholesale Electric Contracts (expire December 2024) [Member]
Regulatory Matters [Line Items]
Number of Customers \| Customers								1
Electric Rates [Member] \| FERC [Member] \| FERC-Approved Wholesale Rates [Member] \| Minnesota Power [Member] \| Municipal Customers [Member] \| Wholesale Electric Contracts (Through 2029)
Regulatory Matters [Line Items]
Number of Customers \| Customers								13