Revenue Recognition (Schedule Of Disaggregation Of Revenue) (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Disaggregation of Revenue [Line Items]
Revenue	$ 384,468	$ 218,892	$ 640,053	$ 420,024
Water [Member]
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	200,523	188,459	385,584	360,547
Revenue	200,863	188,776	385,643	360,828
Water [Member] | Residential [Member]
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	146,621	126,550	273,635	240,597
Water [Member] | Commercial [Member]
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	31,318	35,155	66,618	65,446
Water [Member] | Fire Protection [Member]
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	8,769	8,260	17,414	16,338
Water [Member] | Industrial [Member]
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	7,120	7,456	14,062	14,321
Water [Member] | Other Water [Member]
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	6,695	11,038	13,855	23,845
Water [Member] | Alternative Revenue Program [Member]
Disaggregation of Revenue [Line Items]
Revenue	340	317	59	281
Wastewater [Member]
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	30,232	25,970	58,468	51,361
Revenue	30,149	25,868	58,363	51,146
Wastewater [Member] | Residential [Member]
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	23,631	20,263	46,246	40,210
Wastewater [Member] | Commercial [Member]
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	4,942	3,797	9,393	7,364
Wastewater [Member] | Industrial [Member]
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	396	487	842	968
Wastewater [Member] | Other Wastewater [Member]
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	1,263	1,423	1,987	2,819
Wastewater [Member] | Alternative Revenue Program [Member]
Disaggregation of Revenue [Line Items]
Revenue	(83)	(102)	(105)	(215)
Natural Gas [Member]
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	145,954		183,907
Revenue	146,880		184,915
Natural Gas [Member] | Residential [Member]
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	86,191		109,091
Natural Gas [Member] | Commercial [Member]
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	11,964		15,893
Natural Gas [Member] | Industrial [Member]
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	1,880		2,314
Natural Gas [Member] | Gas Transportation [Member]
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	40,235		49,704
Natural Gas [Member] | Alternative Revenue Program [Member]
Disaggregation of Revenue [Line Items]
Revenue	72		154
Natural Gas [Member] | Other Utility [Member]
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	5,684		6,905
Natural Gas [Member] | Other And Eliminations [Member]
Disaggregation of Revenue [Line Items]
Revenue	854		854
Other [Member]
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	5,831	3,362	9,544	6,252
Revenue	6,576	4,248	11,132	8,050
Other [Member] | Other Utility [Member]
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	5,831	3,362	9,544	6,252
Other [Member] | Other And Eliminations [Member]
Disaggregation of Revenue [Line Items]
Revenue	$ 745	$ 886	$ 1,588	$ 1,798