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Regulatory matters - MTPSC (Details) - Pending Rate Case - Natural gas distribution - MTPSC - Montana-Dakota Utilities Co. - USD ($) $ in Millions | Oct. 15, 2024 | Jul. 15, 2024
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Public Utilities, General Disclosures [Line Items] |  |
Public utilities, requested rate increase (decrease), amount |  | $ 9.4
Public utilities, requested rate increase (decrease), percentage |  | 11.10%
Subsequent Event |  |
Public Utilities, General Disclosures [Line Items] |  |
Public utilities, requested rate increase (decrease), amount | $ 8.0 |
Public utilities, requested rate increase (decrease), percentage | 10.20% |

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