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Legal Proceedings Narrative (Details) - USD ($) $ in Thousands | Jul. 26, 2019 | Feb. 08, 2019
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Advice Letter No. 530 [Member] |  |
Loss Contingencies [Line Items] |  |
Approved Service Charge Refund |  | $ 2,020
Subsequent Event [Member] | OII No. 18-09-003 Settlement Agreement [Member] |  |
Loss Contingencies [Line Items] |  |
Customer Credit Refund | $ 350 |
Utility Plant Investment Commitment | 5,000 |
Maximum | Subsequent Event [Member] | OII No. 18-09-003 Settlement Agreement [Member] |  |
Loss Contingencies [Line Items] |  |
Customer Credit Refund | 2,100 |
Minimum | Subsequent Event [Member] | OII No. 18-09-003 Settlement Agreement [Member] |  |
Loss Contingencies [Line Items] |  |
Customer Credit Refund | $ 1,757 |

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