Business Segment Data (Details) $ in Thousands	3 Months Ended
	Mar. 31, 2021 USD ($)	Mar. 31, 2020 USD ($)	Dec. 31, 2020 USD ($)
Segment Reporting Information [Line Items]
Number of Reportable Segments	2
Operating Revenues	$ 32,541	$ 31,769
Operating Income	5,634	6,527
Net Income	6,907	7,668
Capital Expenditures	22,033	25,147
Assets	986,210		$ 976,470
Regulated [Member]
Segment Reporting Information [Line Items]
Operating Revenues	29,421	28,937
Operating Income	4,716	5,843
Net Income	6,240	7,181
Capital Expenditures	21,963	24,968
Assets	1,004,405		998,932
Non - Regulated [Member]
Segment Reporting Information [Line Items]
Operating Revenues	3,257	2,961
Operating Income	918	684
Net Income	667	487
Capital Expenditures	70	179
Assets	7,918		8,289
Inter-segment Elimination [Member]
Segment Reporting Information [Line Items]
Operating Revenues	(137)	$ (129)
Assets	$ (26,113)		$ (30,751)