Segment Information (Company's Segment Information, Continuing Operations) (Details) - USD ($) $ in Thousands	3 Months Ended						9 Months Ended
	Sep. 30, 2022	Jun. 30, 2022	Mar. 31, 2022	Sep. 30, 2021	Jun. 30, 2021	Mar. 31, 2021	Sep. 30, 2022	Sep. 30, 2021	Dec. 31, 2021
Segment Reporting Information [Line Items]
Operating revenues	$ 434,618			$ 361,860			$ 1,582,649	$ 1,342,457
Operations and maintenance expense	151,361			139,355			428,923	391,945
Purchased gas	52,041			25,488			354,896	202,538
Depreciation and amortization	82,730			74,507			240,252	221,623
Taxes other than income taxes	22,625			21,058			67,352	63,219
Operating income	125,861			101,452			491,226	463,132
Interest expense, net	58,978			51,567			166,402	153,647
Allowance for funds used during construction	(5,812)			(6,082)			(17,802)	(13,922)
Other	(740)			3,699			(3,343)	(2,016)
Income before income taxes	73,435			52,268			345,969	325,423
Provision for income taxes	4,797			1,765			(4,336)	10,317
Net income	68,638	$ 82,291	$ 199,376	50,503	$ 80,914	$ 183,689	350,305	315,106
Capital expenditures							719,688	675,845
Total assets	15,279,792						15,279,792		$ 14,658,278
Water [Member] | Regulated [Member]
Segment Reporting Information [Line Items]
Operating revenues	301,335			259,859			809,888	736,389
Operations and maintenance expense	94,854			86,923			273,757	243,071
Depreciation and amortization	51,522			45,506			150,498	136,189
Taxes other than income taxes	16,809			16,291			48,262	47,756
Operating income	138,150			111,139			337,371	309,373
Interest expense, net	27,762			27,389			82,920	80,971
Allowance for funds used during construction	(5,161)			(5,407)			(15,657)	(13,091)
Other	(2,219)			(1,896)			(5,891)	(5,265)
Income before income taxes	117,768			91,053			275,999	246,758
Provision for income taxes	19,182			9,230			40,528	22,056
Net income	98,586			81,823			235,471	224,702
Capital expenditures							382,853	404,894
Total assets	8,666,230						8,666,230		8,403,586
Natural Gas [Member] | Regulated [Member]
Segment Reporting Information [Line Items]
Operating revenues	118,985			94,752			731,897	579,429
Operations and maintenance expense	51,850			53,954			156,209	157,614
Purchased gas	41,124			20,386			321,822	183,062
Depreciation and amortization	30,295			28,194			89,130	83,905
Taxes other than income taxes	5,073			4,271			16,878	13,356
Operating income	(9,357)			(12,053)			147,858	141,492
Interest expense, net	20,323			18,406			60,146	56,125
Allowance for funds used during construction	(651)			(675)			(2,145)	(831)
Other	838			5,329			404	4,462
Income before income taxes	(29,867)			(35,113)			89,453	81,736
Provision for income taxes	(12,734)			(6,821)			(44,378)	(11,128)
Net income	(17,133)			(28,292)			133,831	92,864
Capital expenditures							335,738	269,958
Total assets	6,163,931						6,163,931		5,960,602
Other [Member]
Segment Reporting Information [Line Items]
Operating revenues	14,298			7,249			40,864	26,639
Operations and maintenance expense	4,657			(1,522)			(1,043)	(8,740)
Purchased gas	10,917			5,102			33,074	19,476
Depreciation and amortization	913			807			624	1,529
Taxes other than income taxes	743			496			2,212	2,107
Operating income	(2,932)			2,366			5,997	12,267
Interest expense, net	10,893			5,772			23,336	16,551
Other	641			266			2,144	(1,213)
Income before income taxes	(14,466)			(3,672)			(19,483)	(3,071)
Provision for income taxes	(1,651)			(644)			(486)	(611)
Net income	(12,815)			$ (3,028)			(18,997)	(2,460)
Capital expenditures							1,097	$ 993
Total assets	$ 449,631						$ 449,631		$ 294,090