Average demand measured for a specified customer, measured in MW.

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- Definition

Discount Provided to EITE Customers

+ References

No definition available.

+ Details

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- Definition

Estimated Discount to be Provided During the Next Twelve Months

+ References

No definition available.

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- Definition

Increase (Decrease) in Annual Depreciation Expense Based on Regulatory Order

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No definition available.

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- Definition

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

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- Definition

Number of Customers

+ References

No definition available.

+ Details

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- Definition

Public Utilities, Approved Rate Increase (Decrease), Reconsideration Amount

+ References

No definition available.

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- Definition

Reserve for Interim Rate Refund

+ References

No definition available.

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- Definition

Cost of electricity purchased as well as fuel used to generate electricity used in operations and sold during the reporting period.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 225
-SubTopic 10
-Section S99
-Paragraph 2
-Subparagraph (SX 210.5-03.2(b))
-URI http://asc.fasb.org/extlink&oid=63488584&loc=d3e20235-122688

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- Definition

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

+ References

No definition available.

+ Details

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- Definition

Amount of public utility's approved rate increase (decrease) by regulatory agency.

+ References

No definition available.

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- Definition

Percentage of public utility's approved return on equity.

+ References

No definition available.

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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.

+ References

No definition available.

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- Definition

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

+ References

No definition available.

+ Details

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- Definition

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

+ References

No definition available.

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- Definition

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

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No definition available.

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- Definition

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

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No definition available.

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

+ References

No definition available.

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- Definition

Percentage of public utility's requested return on equity.

+ References

No definition available.

+ Details

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- Definition

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

+ References

No definition available.

+ Details

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Regulatory Matters - Electric Rates (Details) $ in Millions					1 Months Ended		3 Months Ended		12 Months Ended
Regulatory Matters - Electric Rates (Details) $ in Millions	Apr. 02, 2018 USD ($)	Jan. 18, 2018 USD ($)	Aug. 09, 2017	Apr. 13, 2017 USD ($)	Dec. 31, 2016 USD ($)	Nov. 30, 2016 USD ($)	Mar. 31, 2018 USD ($) Customers Years MW	Mar. 31, 2017 USD ($)	Dec. 31, 2017 USD ($)
Regulatory Matters [Line Items]
Pre-Tax Charge to Fuel, Purchase Power and Gas - Utility							$ 100.9	$ 96.6
MPUC [Member] \| 2016 Minnesota General Rate Case [Member] \| Minnesota Power [Member]
Regulatory Matters [Line Items]
Pre-Tax Charge to Fuel, Purchase Power and Gas - Utility									$ 19.5
MPUC [Member] \| 2016 Minnesota General Rate Case [Member] \| Minnesota Power [Member] \| Boswell Energy Center [Member]
Regulatory Matters [Line Items]
Expected Decrease in Annual Depreciation Expense							25.0
PSCW [Member] \| 2016 Wisconsin General Rate Case [Member] \| SWL&P [Member] \| Retail Customers [Member]
Regulatory Matters [Line Items]
Approved Return on Common Equity			10.50%
Approved Equity Ratio			55.00%
Expected Annualized Collection of Additional Revenue Under Retail Rate Order							$ 2.5
PSCW [Member] \| 2012 Wisconsin Rate Case [Member] \| SWL&P [Member] \| Retail Customers [Member]
Regulatory Matters [Line Items]
Approved Return on Common Equity							10.90%
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							$ 24.1	24.2
Electric Rates [Member] \| MPUC [Member] \| 2016 Minnesota General Rate Case [Member] \| Minnesota Power [Member] \| Retail Customers [Member]
Regulatory Matters [Line Items]
Requested Average Rate Increase						9.00%
Requested Return on Equity						10.25%
Requested Equity Ratio						53.81%
Annual Additional Revenue Generated from Requested Final Rate Increase		$ 13.0				$ 55.0
Annual Additional Revenue Generated from Requested Interim Rate Increase				$ 32.2	$ 34.7	49.0
Annual Additional Revenue Generated from Requested Final Rate Increase, Amended						$ 49.0
Approved Return on Common Equity		9.25%
Approved Equity Ratio		53.81%
Reserve for Interim Rate Refund							41.0		32.0
Electric Rates [Member] \| MPUC [Member] \| 2016 Minnesota General Rate Case [Member] \| Minnesota Power [Member] \| Retail Customers [Member] \| Minimum [Member] \| Subsequent Event [Member]
Regulatory Matters [Line Items]
Requested Reconsideration of Certain Decisions Representing Annualized Additional Revenue	$ 20.0
Electric Rates [Member] \| MPUC [Member] \| 2016 Minnesota General Rate Case [Member] \| Minnesota Power [Member] \| Retail Customers [Member] \| Maximum [Member] \| Subsequent Event [Member]
Regulatory Matters [Line Items]
Requested Reconsideration of Certain Decisions Representing Annualized Additional Revenue	$ 25.0
Electric Rates [Member] \| MPUC [Member] \| Energy-Intensive Trade-Exposed Customer Rates [Member] \| Minnesota Power [Member] \| Retail Customers [Member]
Regulatory Matters [Line Items]
Provided Discounts to EITE Customers							4.3	$ 2.3	$ 8.6
Expected Discounts to EITE Customers Annually							$ 15.0
Electric Rates [Member] \| FERC [Member] \| FERC-Approved Wholesale Rates [Member] \| Minnesota Power [Member] \| Municipal Customers [Member]
Regulatory Matters [Line Items]
Number of Customers \| Customers							16
Length of 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 (Termination Effective June 2019) [Member]
Regulatory Matters [Line Items]
Average Monthly Demand (MW) \| MW							29
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							3
Electric Rates [Member] \| FERC [Member] \| FERC-Approved Wholesale Rates [Member] \| Minnesota Power [Member] \| Municipal Customers [Member] \| Wholesale Electric Contracts (Expire from 2024 through 2029) [Member]
Regulatory Matters [Line Items]
Number of Customers \| Customers							14