Total Transmission Cost Adjustment Rider

No definition available.

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- Definition

Transmission Capital Projects Increase (Decrease)

+ References

No definition available.

+ Details

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- Definition

Under-Recovered Balance, Transmission Cost Adjustment Rider

+ References

No definition available.

+ Details

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Data Type:	xbrli:monetaryItemType
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- Definition

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

+ References

No definition available.

+ Details

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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.

+ Details

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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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Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

Percentage 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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Namespace Prefix:	us-gaap_
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Period Type:	duration

- Definition

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

+ References

No definition available.

+ Details

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

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

+ References

No definition available.

+ Details

Name:	us-gaap_PublicUtilitiesRequestedRateIncreaseDecreasePercentage
Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Details

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- Details

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- Details

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- Details

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- Details

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- Details

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NDPSC (Details 3) - NDPSC [Member] - Montana-Dakota Utilities Co. [Member] - USD ($) $ in Millions	Jan. 01, 2021	Nov. 01, 2020	Aug. 26, 2020
Electric \| Subsequent Event [Member]
Public Utilities, General Disclosures [Line Items]
Total Transmission Cost Adjustment Rider		$ 15.5
Transmission Capital Projects Increase (Decrease)		3.3
Public Utilities, Approved Rate Increase (Decrease), Amount		6.3
COVID-19 [Member] \| Electric \| Subsequent Event [Member]
Public Utilities, General Disclosures [Line Items]
Under-Recovered Balance, Transmission Cost Adjustment Rider		$ 1.6
Pending Rate Case [Member] \| Gas Distribution [Member]
Public Utilities, General Disclosures [Line Items]
Public Utilities, Requested Rate Increase (Decrease), Amount			$ 9.0
Public Utilities, Requested Rate Increase (Decrease), Percentage			7.80%
Pending Rate Case [Member] \| Gas Distribution [Member] \| Subsequent Event [Member]
Public Utilities, General Disclosures [Line Items]
Public Utilities, Interim Rate Increase (Decrease), Amount	$ 6.9
Public Utilities, Interim Rate Increase (Decrease), Percentage	6.00%