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OPUC (Details 4) - Tax Cuts and Jobs Act [Member] - OPUC [Member] - USD ($) | Jan. 22, 2019 | May 31, 2018
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Public Utilities, General Disclosures [Line Items] |  |
Public utilities, requested rate increase (decrease), amount |  | $ 2,300,000
Public utilities, requested rate increase (decrease), percentage |  | 3.50%
Subsequent event [Member] | Natural gas rate proceeding [Member] |  |
Public Utilities, General Disclosures [Line Items] |  |
Public utilities, requested rate increase (decrease), amount | $ 1,200,000 |
Public Utilities, Requested Rate Increase (Decrease) in Revenues Only, Amount | 1,700,000 |
Public Utilities, Requested Rate Increase (Decrease) in Taxes Only, Amount | $ (500,000) |

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