Consolidated Statements Of Operations And Comprehensive Income - USD ($) shares in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Consolidated Statements Of Operations And Comprehensive Income [Abstract]
Operating revenues	$ 2,288,032	$ 1,878,144	$ 1,462,698
Operating expenses:
Operations and maintenance	613,649	550,580	528,611
Purchased gas	601,995	340,262	165,745
Depreciation	315,811	292,191	251,443
Amortization	5,366	5,761	5,616
Taxes other than income taxes	90,024	86,641	76,597
Total operating expenses	1,626,845	1,275,435	1,028,012
Operating income	661,187	602,709	434,686
Other expense (income):
Interest expense	238,116	207,709	188,435
Interest income	(3,675)	(2,384)	(5,363)
Allowance for funds used during construction	(23,665)	(20,792)	(12,687)
Gain on sale of other assets	(991)	(976)	(661)
Equity loss in joint venture			3,374
Other	494	(2,848)	(3,383)
Income before income taxes	450,908	422,000	264,971
Income tax benefit	(14,329)	(9,612)	(19,878)
Net income	465,237	431,612	284,849
Comprehensive income	$ 465,237	$ 431,612	$ 284,849
Net income per common share:
Basic	$ 1.77	$ 1.68	$ 1.14
Diluted	$ 1.77	$ 1.67	$ 1.12
Average common shares outstanding during the period:
Basic	262,246	257,487	249,768
Diluted	262,868	258,180	254,629