Revenue Recognition (Schedule Of Disaggregation Of Revenue) (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Disaggregation of Revenue [Line Items]
Revenue	$ 361,860	$ 348,647	$ 1,342,457	$ 988,700
Water [Member]
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	222,187	222,404	626,472	607,988
Revenue	222,714	222,063	627,829	607,707
Water [Member] | Residential [Member]
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	148,247	157,387	425,519	431,022
Water [Member] | Commercial [Member]
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	42,318	41,693	113,473	108,311
Water [Member] | Fire Protection [Member]
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	8,866	8,535	26,830	26,437
Water [Member] | Industrial [Member]
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	8,217	9,022	22,954	22,597
Water [Member] | Other Water [Member]
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	14,539	9,524	37,696	23,378
Water [Member] | Customer Rate Credits [Member]
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers				(3,757)
Water [Member] | Alternative Revenue Program [Member]
Disaggregation of Revenue [Line Items]
Revenue	527	(341)	1,357	(281)
Wastewater [Member]
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	33,882	30,496	97,986	88,963
Revenue	33,904	30,353	98,004	88,715
Wastewater [Member] | Residential [Member]
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	25,147	24,175	73,820	70,421
Wastewater [Member] | Commercial [Member]
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	5,839	4,794	16,102	14,186
Wastewater [Member] | Industrial [Member]
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	401	388	1,256	1,230
Wastewater [Member] | Other Wastewater [Member]
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	2,495	1,462	6,808	3,449
Wastewater [Member] | Customer Rate Credits [Member]
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers				(323)
Wastewater [Member] | Alternative Revenue Program [Member]
Disaggregation of Revenue [Line Items]
Revenue	22	(143)	18	(248)
Natural Gas [Member]
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	95,069	88,324	581,114	272,235
Revenue	95,069	88,880	581,320	273,798
Natural Gas [Member] | Residential [Member]
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	49,838	46,913	347,790	156,004
Natural Gas [Member] | Commercial [Member]
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	9,534	7,993	65,404	23,887
Natural Gas [Member] | Industrial [Member]
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	415	1,407	1,894	3,721
Natural Gas [Member] | Gas Transportation [Member]
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	27,794	26,248	143,387	75,951
Natural Gas [Member] | Other Utility [Member]
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	7,488	5,763	22,639	12,672
Natural Gas [Member] | Alternative Revenue Program [Member]
Disaggregation of Revenue [Line Items]
Revenue			206	154
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	3,241	6,548	10,556	16,088
Revenue	10,173	7,351	35,304	18,480
Other [Member] | Other Utility [Member]
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	3,241	6,548	10,556	16,088
Other [Member] | Other And Eliminations [Member]
Disaggregation of Revenue [Line Items]
Revenue	$ 6,932	$ 803	$ 24,748	$ 2,392