Organization, Summary of Significant Accounting Policies and Recent Developments (Schedule of Operating Revenues) (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Regulated Tariff Sales
Residential									$ 71,487	$ 69,785	$ 66,483
Commercial									15,198	14,844	13,956
Industrial									9,390	10,183	9,321
Fire Protection									12,291	12,099	11,812
Wholesale									14,319	14,655	13,553
Non-Regulated Contract Operations									11,773	16,374	15,508
Total Revenue from Contracts with Customers									134,458	137,940	130,633
Other Regulated Revenues									393	335	329
Other Non-Regulated Revenues									404	404	404
Inter-segment Elimination									(657)	(602)	(591)
Total Revenue	$ 32,738	$ 37,769	$ 33,393	$ 30,698	$ 33,268	$ 38,713	$ 34,919	$ 31,177	$ 134,598	$ 138,077	$ 130,775