Segment Information (Company's Segment Information, Continuing Operations) (Details) - USD ($) $ in Thousands	3 Months Ended						9 Months Ended
	Sep. 30, 2023	Jun. 30, 2023	Mar. 31, 2023	Sep. 30, 2022	Jun. 30, 2022	Mar. 31, 2022	Sep. 30, 2023	Sep. 30, 2022
Segment Reporting Information [Line Items]
Operating revenues	$ 411,255			$ 434,618			$ 1,574,405	$ 1,582,649
Operations and maintenance expense	147,018			151,361			418,520	428,923
Purchased gas	16,590			52,041			314,838	354,896
Depreciation and amortization	86,035			82,730			255,490	240,252
Interest expense, net	67,648			58,978			207,709	166,402
Allowance for funds used during construction	(5,455)			(5,812)			(14,567)	(17,802)
Provision for income taxes (benefit)	(3,711)			4,797			(35,611)	(4,336)
Net income (loss)	80,076	$ 91,268	$ 191,434	68,638	$ 82,291	$ 199,376	362,778	350,305
Capital expenditures							874,491	719,688
Regulated Water [Member] | Regulated [Member]
Segment Reporting Information [Line Items]
Operating revenues	310,591			301,335			871,563	809,888
Operations and maintenance expense	98,695			94,854			274,724	273,757
Depreciation and amortization	54,695			51,522			161,393	150,498
Interest expense, net	30,867			27,762			91,103	82,920
Allowance for funds used during construction	(4,643)			(5,161)			(12,529)	(15,657)
Provision for income taxes (benefit)	16,186			19,182			45,559	40,528
Net income (loss)	99,916			98,586			267,345	235,471
Capital expenditures							493,851	382,853
Regulated Natural Gas [Member] | Regulated [Member]
Segment Reporting Information [Line Items]
Operating revenues	94,798			118,985			675,076	731,897
Operations and maintenance expense	50,006			51,850			148,270	156,209
Purchased gas	14,408			41,124			295,929	321,822
Depreciation and amortization	31,141			30,295			93,457	89,130
Interest expense, net	19,405			20,323			67,894	60,146
Allowance for funds used during construction	(812)			(651)			(2,038)	(2,145)
Provision for income taxes (benefit)	(16,905)			(12,734)			(73,703)	(44,378)
Net income (loss)	(9,776)			(17,133)			127,400	133,831
Capital expenditures							377,562	335,738
Other [Member]
Segment Reporting Information [Line Items]
Operating revenues	5,866			14,298			27,766	40,864
Operations and maintenance expense	(1,683)			4,657			(4,474)	(1,043)
Purchased gas	2,182			10,917			18,909	33,074
Depreciation and amortization	199			913			640	624
Interest expense, net	17,376			10,893			48,712	23,336
Provision for income taxes (benefit)	(2,992)			(1,651)			(7,467)	(486)
Net income (loss)	$ (10,064)			$ (12,815)			(31,967)	(18,997)
Capital expenditures							$ 3,078	$ 1,097