Regulatory matters - MTPSC (Details) - Pending Rate Case - Natural gas distribution - MTPSC - Montana-Dakota Utilities Co. - Subsequent Event $ in Millions	Jul. 15, 2024 USD ($)
Public Utilities, General Disclosures [Line Items]
Public utilities, requested rate increase (decrease), amount	$ 9.4
Public utilities, requested rate increase (decrease), percentage	11.10%

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