NDPSC (Details 3) $ in Millions	Oct. 28, 2019 USD ($)
NDPSC \| Electricity [Member] \| Montana-Dakota Utilities Co. [Member] \| Subsequent Event [Member]
Public Utilities, General Disclosures [Line Items]
Public Utilities, Approved Rate Increase (Decrease), Amount	$ 1.5

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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