Consolidated Statements Of Operations And Comprehensive Income - USD ($) shares in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Consolidated Statements Of Operations And Comprehensive Income [Abstract]
Operating revenues	$ 2,053,824	$ 2,288,032	$ 1,878,144
Operating expenses:
Operations and maintenance	575,518	613,649	550,580
Purchased gas	352,306	601,995	340,262
Depreciation	338,655	315,811	292,191
Amortization	5,040	5,366	5,761
Taxes other than income taxes	90,208	90,024	86,641
Total operating expenses	1,361,727	1,626,845	1,275,435
Operating income	692,097	661,187	602,709
Other expense (income):
Interest expense	283,362	238,116	207,709
Interest income	(3,401)	(3,675)	(2,384)
Allowance for funds used during construction	(16,967)	(23,665)	(20,792)
Gain on sale of other assets	(65)	(991)	(976)
Other	(2,613)	494	(2,848)
Income before income taxes	431,781	450,908	422,000
Income tax benefit	(66,445)	(14,329)	(9,612)
Net income	498,226	465,237	431,612
Comprehensive income	$ 498,226	$ 465,237	$ 431,612
Net income per common share:
Basic	$ 1.86	$ 1.77	$ 1.68
Diluted	$ 1.86	$ 1.77	$ 1.67
Average common shares outstanding during the period:
Basic	267,171	262,246	257,487
Diluted	267,659	262,868	258,180