Segment Information (Company's Segment Information, Continuing Operations) (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2023	Mar. 31, 2022	Dec. 31, 2022
Segment Reporting Information [Line Items]
Operating revenues	$ 726,450	$ 699,275
Operations and maintenance expense	137,994	142,581
Purchased gas	256,315	227,712
Depreciation and amortization	83,794	78,346
Taxes other than income taxes	22,878	23,007
Operating income	225,469	227,629
Interest expense, net	71,849	53,027
Allowance for funds used during construction	(5,688)	(5,839)
Income before income taxes	159,797	182,143
Provision for income taxes (benefit)	(31,637)	(17,233)
Net income (loss)	191,434	199,376
Capital expenditures	243,730	183,322
Total assets	15,818,266		$ 15,719,107
Water [Member] | Regulated [Member]
Segment Reporting Information [Line Items]
Operating revenues	267,300	239,198
Operations and maintenance expense	82,802	86,088
Depreciation and amortization	53,467	48,716
Interest expense, net	29,713	27,554
Allowance for funds used during construction	(4,946)	(5,149)
Provision for income taxes (benefit)	13,514	7,499
Net income (loss)	77,402	60,543
Capital expenditures	159,394	100,803
Total assets	8,893,947		8,792,633
Natural Gas [Member] | Regulated [Member]
Segment Reporting Information [Line Items]
Operating revenues	441,295	445,183
Operations and maintenance expense	57,150	59,452
Purchased gas	241,856	217,306
Depreciation and amortization	30,128	29,704
Interest expense, net	27,507	20,652
Allowance for funds used during construction	(742)	(690)
Provision for income taxes (benefit)	(43,484)	(26,474)
Net income (loss)	123,546	139,486
Capital expenditures	81,669	82,122
Total assets	6,556,182		6,528,654
Other [Member]
Segment Reporting Information [Line Items]
Operating revenues	17,855	14,894
Operations and maintenance expense	(1,958)	(2,959)
Purchased gas	14,459	10,406
Depreciation and amortization	199	(74)
Interest expense, net	14,629	4,821
Provision for income taxes (benefit)	(1,667)	1,742
Net income (loss)	(9,514)	(653)
Capital expenditures	2,667	$ 397
Total assets	$ 368,137		$ 397,820