Consolidated Statements Of Operations And Comprehensive Income - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2023	Jun. 30, 2022	Jun. 30, 2023	Jun. 30, 2022
Consolidated Statements Of Operations [Abstract]
Operating revenues	$ 436,700	$ 448,756	$ 1,163,150	$ 1,148,031
Operating expenses:
Operations and maintenance	133,508	134,981	271,502	277,562
Purchased gas	41,933	75,143	298,248	302,855
Depreciation	84,937	77,425	167,860	155,303
Amortization	724	1,751	1,595	2,219
Taxes other than income taxes	20,348	21,720	43,226	44,727
Total operating expenses	281,450	311,020	782,431	782,666
Operating income	155,250	137,736	380,719	365,365
Other expense (income):
Interest expense	69,182	55,221	141,850	108,857
Interest income	(970)	(824)	(1,789)	(1,433)
Allowance for funds used during construction	(3,424)	(6,151)	(9,112)	(11,990)
Gain on sale of other assets	(220)	(478)	(469)	(478)
Other	(323)	(423)	(563)	(2,125)
Income before income taxes	91,005	90,391	250,802	272,534
Provision for income taxes (benefit)	(263)	8,100	(31,900)	(9,133)
Net income	91,268	82,291	282,702	281,667
Comprehensive income	$ 91,268	$ 82,291	$ 282,702	$ 281,667
Net income per common share:
Basic	$ 0.35	$ 0.31	$ 1.07	$ 1.08
Diluted	$ 0.34	$ 0.31	$ 1.07	$ 1.07
Average common shares outstanding during the period:
Basic	264,418,000	262,099,000	264,306,000	262,026,000
Diluted	264,818,000	262,558,000	264,840,000	262,545,000