Revenue Recognition (Schedule Of Disaggregation Of Revenue) (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Disaggregation of Revenue [Line Items]
Revenue	$ 348,647	$ 243,626	$ 988,700	$ 663,650
Water [Member]
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	222,404	213,153	607,988	573,701
Revenue	222,063	213,088	607,707	573,918
Water [Member] | Residential [Member]
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	157,387	145,643	431,022	386,240
Water [Member] | Commercial [Member]
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	41,693	42,883	108,311	108,329
Water [Member] | Fire Protection [Member]
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	8,535	8,565	26,437	24,903
Water [Member] | Industrial [Member]
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	9,022	8,730	22,597	23,052
Water [Member] | Other Water [Member]
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	9,524	7,332	23,378	31,177
Water [Member] | Customer Rate Credits [Member]
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	(3,757)		(3,757)
Water [Member] | Alternative Revenue Program [Member]
Disaggregation of Revenue [Line Items]
Revenue	(341)	(65)	(281)	217
Wastewater [Member]
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	30,496	26,622	88,963	77,983
Revenue	30,353	26,784	88,715	77,930
Wastewater [Member] | Residential [Member]
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	24,175	21,437	70,421	61,647
Wastewater [Member] | Commercial [Member]
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	4,794	4,037	14,186	11,400
Wastewater [Member] | Industrial [Member]
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	388	390	1,230	1,358
Wastewater [Member] | Other Wastewater [Member]
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	1,462	758	3,449	3,578
Wastewater [Member] | Customer Rate Credits [Member]
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	(323)		(323)
Wastewater [Member] | Alternative Revenue Program [Member]
Disaggregation of Revenue [Line Items]
Revenue	(143)	162	(248)	(53)
Natural Gas [Member]
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	88,324		272,235
Revenue	88,880		273,798
Natural Gas [Member] | Residential [Member]
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	46,913		156,004
Natural Gas [Member] | Commercial [Member]
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	7,993		23,887
Natural Gas [Member] | Industrial [Member]
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	1,407		3,721
Natural Gas [Member] | Gas Transportation [Member]
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	26,248		75,951
Natural Gas [Member] | Alternative Revenue Program [Member]
Disaggregation of Revenue [Line Items]
Revenue			154
Natural Gas [Member] | Other Utility [Member]
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	5,763		12,672
Natural Gas [Member] | Other And Eliminations [Member]
Disaggregation of Revenue [Line Items]
Revenue	556		1,409
Other [Member]
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	6,548	2,984	16,088	9,234
Revenue	7,351	3,754	18,480	11,802
Other [Member] | Other Utility [Member]
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	6,548	2,984	16,088	9,234
Other [Member] | Other And Eliminations [Member]
Disaggregation of Revenue [Line Items]
Revenue	$ 803	$ 770	$ 2,392	$ 2,568