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NDPSC (Details 3) - Electric - NDPSC [Member] - Montana-Dakota Utilities Co. [Member] - USD ($) $ in Millions	Apr. 26, 2023	Jul. 14, 2022	May 16, 2022
Public Utilities, General Disclosures [Line Items]
Public Utilities, Interim Rate Increase (Decrease), Amount		$ 10.9
Public Utilities, Interim Rate Increase (Decrease), Percentage		5.30%
Pending Rate Case [Member]
Public Utilities, General Disclosures [Line Items]
Public Utilities, Requested Rate Increase (Decrease), Amount			$ 25.4
Public Utilities, Requested Rate Increase (Decrease), Percentage			12.30%
Pending Rate Case [Member] | Subsequent Event [Member]
Public Utilities, General Disclosures [Line Items]
Public Utilities, Requested Rate Increase (Decrease), Amended, Amount	$ 15.3
Public Utilities, Requested Rate Increase (Decrease), Amended, Percentage	7.40%
Public Utilities, Requested Return on Equity, Percentage	9.75%

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