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MTPSC (Details 2) - MTPSC - USD ($) | Apr. 24, 2019 | Mar. 07, 2019 | Sep. 28, 2018
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Electric rate proceeding |  |  |
Public Utilities, General Disclosures [Line Items] |  |  |
Public utilities, requested rate increase (decrease), amount | $ 9,000,000.0 |  | $ 11,900,000
Public utilities, requested rate increase (decrease), percentage |  |  | 18.90%
Public utilities, interim rate increase (decrease), amount |  | $ 7,900,000 |
Public utilities, interim rate increase (decrease), percentage |  | 12.80% |
Future Electric Rate Proceeding [Member] |  |  |
Public Utilities, General Disclosures [Line Items] |  |  |
Public utilities, requested rate increase (decrease), amount | $ 300,000 |  |

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