Consolidated Statements Of Operations And Comprehensive Income - USD ($) shares in Thousands, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2022	Sep. 30, 2021	Sep. 30, 2022	Sep. 30, 2021
Consolidated Statements Of Operations [Abstract]
Operating revenues	$ 434,618	$ 361,860	$ 1,582,649	$ 1,342,457
Operating expenses:
Operations and maintenance	151,361	139,355	428,923	391,945
Purchased gas	52,041	25,488	354,896	202,538
Depreciation	80,471	72,606	235,774	217,007
Amortization	2,259	1,901	4,478	4,616
Taxes other than income taxes	22,625	21,058	67,352	63,219
Total operating expenses	308,757	260,408	1,091,423	879,325
Operating income	125,861	101,452	491,226	463,132
Other expense (income):
Interest expense	60,488	52,132	169,345	154,937
Interest income	(1,510)	(565)	(2,943)	(1,290)
Allowance for funds used during construction	(5,812)	(6,082)	(17,802)	(13,922)
Gain on sale of other assets	(299)	(320)	(777)	(623)
Other	(441)	4,019	(2,566)	(1,393)
Income before income taxes	73,435	52,268	345,969	325,423
Provision for income taxes (benefit)	4,797	1,765	(4,336)	10,317
Net income	68,638	50,503	350,305	315,106
Comprehensive income	$ 68,638	$ 50,503	$ 350,305	$ 315,106
Net income per common share:
Basic	$ 0.26	$ 0.20	$ 1.34	$ 1.23
Diluted	$ 0.26	$ 0.19	$ 1.33	$ 1.23
Average common shares outstanding during the period:
Basic	262,213	258,773	262,089	256,051
Diluted	262,754	259,437	262,641	256,763