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