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, 2020	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Regulated Tariff Sales
Residential									$ 76,798	$ 71,487	$ 69,785
Commercial									15,448	15,198	14,844
Industrial									9,512	9,390	10,183
Fire Protection									12,374	12,291	12,099
Wholesale									15,187	14,319	14,655
Non-Regulated Contract Operations									12,130	11,773	16,374
Total Revenue from Contracts with Customers									141,449	134,458	137,940
Other Regulated Revenues									532	393	335
Other Non-Regulated Revenues									415	404	404
Inter-segment Elimination									(804)	(657)	(602)
Total Revenue	$ 34,626	$ 39,920	$ 35,277	$ 31,769	$ 32,738	$ 37,769	$ 33,393	$ 30,698	$ 141,592	$ 134,598	$ 138,077