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WYPSC (Details 5) - Distribution - Montana-Dakota Utilities Co. [Member] - Pending Rate Case [Member] - WYPSC [Member] - USD ($) | Dec. 17, 2019 | May 23, 2019
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Public Utilities, General Disclosures [Line Items] |  |
Public Utilities, Requested Rate Increase (Decrease), Amount |  | $ 1,100,000
Public Utilities, Requested Rate Increase (Decrease), Percentage |  | 7.00%
Public Utilities, Requested Rate Increase (Decrease), Amended, Amount | $ 830,000 |
Public Utilities, Requested Rate Increase (Decrease), Amended, Percentage | 5.50% |

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