Regulatory Rate Filings (Details) - USD ($)						6 Months Ended
	Apr. 08, 2019	Apr. 01, 2019	Mar. 19, 2019	Jan. 01, 2019	Sep. 14, 2018	Jun. 30, 2019	Jul. 26, 2019	Jun. 19, 2019	Mar. 29, 2019	Feb. 08, 2019	Jan. 04, 2018	Jun. 06, 2017
Public Utilities, General Disclosures [Line Items]
Regulatory Rate Filings, Requested Rate Increase, Year One											$ 34,288,000
Regulatory Rate Filings, Requested Rate Increase as Percentage of Total Revenue at Time of Request, Year One											9.76%
Regulatory Rate Filings, Requested Rate Increase, Year Two											$ 14,232,000
Regulatory Rate Filings, Proposed Rate Increase, Percent of Authorized Revenue, Year Two											3.70%
Regulatory Rate Filings, Requested Rate Increase, Year Three											$ 20,582,000
Regulatory Rate Filings, Requested Rate Increase, Percent of Authorized Revenue, Year Three											5.17%
Memorandum Account, Requested Recovery											$ 20,725,000
CPED Calculated Double-Billing Refund					$ 4,935,000
Public Utilities, Approved Reimbursement Fee, Percentage		1.23%				1.40%
Minimum
Public Utilities, General Disclosures [Line Items]
CPED Proposed Penalty, Per Offense, Per Day					500
Maximum
Public Utilities, General Disclosures [Line Items]
CPED Proposed Penalty, Per Offense, Per Day					50,000
Advice Letter No. 528/528A [Member]
Public Utilities, General Disclosures [Line Items]
Public Utilities, Approved Rate Decrease, Amount				$ 16,378,000
Public Utilities, Approved Rate Increase (Decrease), Percentage				4.55%
Approved Balancing and Memorandum Accounts, Net				$ 27,045,000
Decision No. 19-06-010 [Member]
Public Utilities, General Disclosures [Line Items]
Approved Balancing and Memorandum Accounts, Net								$ 1,243,000
Advice Letter No. 510 [Member]
Public Utilities, General Disclosures [Line Items]
Requested Service Charge Refund												$ 1,794,000
Advice Letter No. 530 [Member]
Public Utilities, General Disclosures [Line Items]
Approved Service Charge Refund										$ 2,020,000
CPED Calculated Refund 2014-2016
Public Utilities, General Disclosures [Line Items]
CPED Calculated Service Charge Refund					2,061,000
CPED Calculated Refund 1987-2013
Public Utilities, General Disclosures [Line Items]
CPED Calculated Service Charge Refund					$ 1,990,000
CPED Calculated Refund 1987-2011 [Member]
Public Utilities, General Disclosures [Line Items]
CPED Calculated Service Charge Refund	$ 1,757,000		$ 1,847,000
2018 WCMA [Member] | Advice Letter No. 532 [Member]
Public Utilities, General Disclosures [Line Items]
Memorandum Account, Requested Recovery									$ 9,020,000
Subsequent Event [Member] | OII No. 18-09-003 Settlement Agreement [Member]
Public Utilities, General Disclosures [Line Items]
Customer Credit Refund							$ 350,000
Utility Plant Investment Commitment							5,000,000
Subsequent Event [Member] | OII No. 18-09-003 Settlement Agreement [Member] | Minimum
Public Utilities, General Disclosures [Line Items]
Customer Credit Refund							1,757,000
Subsequent Event [Member] | OII No. 18-09-003 Settlement Agreement [Member] | Maximum
Public Utilities, General Disclosures [Line Items]
Customer Credit Refund							$ 2,100,000