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NDPSC (Details 3) - Electric - NDPSC [Member] - Montana-Dakota Utilities Co. [Member] - Subsequent Event [Member] $ in Millions	Nov. 01, 2021 USD ($)
Public Utilities, General Disclosures [Line Items]
Total Transmission Cost Adjustment Rider	$ 14.5
Public Utilities, Requested Rate Increase (Decrease), Amount	(1.1)
Transmission Capital Projects Increase (Decrease)	$ 5.1

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- Definition

Total Transmission Cost Adjustment Rider

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- Definition

Transmission Capital Projects Increase (Decrease)

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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 requested rate increase (decrease) with regulatory agency.

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