NDPSC (Details 3) - Pending Rate Case [Member] - Electric - NDPSC [Member] - Montana-Dakota Utilities Co. [Member] - Subsequent Event [Member] $ in Millions	Jul. 17, 2020 USD ($)
Public Utilities, General Disclosures [Line Items]
Total Transmission Cost Adjustment Rider	$ 15.5
Public Utilities, Requested Rate Increase (Decrease), Amount	6.3
Transmission Capital Projects Increase (Decrease)	$ 3.3

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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