Consolidated Statements Of Operations And Comprehensive Income - USD ($) shares in Thousands, $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2022	Jun. 30, 2021	Jun. 30, 2022	Jun. 30, 2021
Consolidated Statements Of Operations [Abstract]
Operating revenues	$ 448,756	$ 397,032	$ 1,148,031	$ 980,597
Operating expenses:
Operations and maintenance	134,981	127,515	277,562	252,590
Purchased gas	75,143	44,897	302,855	177,050
Depreciation	77,425	72,764	155,303	144,401
Amortization	1,751	1,408	2,219	2,715
Taxes other than income taxes	21,720	21,120	44,727	42,161
Total operating expenses	311,020	267,704	782,666	618,917
Operating income	137,736	129,328	365,365	361,680
Other expense (income):
Interest expense	55,221	52,036	108,857	102,805
Interest income	(824)	(338)	(1,433)	(725)
Allowance for funds used during construction	(6,151)	(4,906)	(11,990)	(7,840)
Gain on sale of other assets	(478)	(223)	(478)	(303)
Other	(423)	(1,941)	(2,125)	(5,412)
Income before income taxes	90,391	84,700	272,534	273,155
Provision for income taxes (benefit)	8,100	3,786	(9,133)	8,552
Net income	82,291	80,914	281,667	264,603
Comprehensive income	$ 82,291	$ 80,914	$ 281,667	$ 264,603
Net income per common share:
Basic	$ 0.31	$ 0.32	$ 1.08	$ 1.04
Diluted	$ 0.31	$ 0.32	$ 1.07	$ 1.04
Average common shares outstanding during the period:
Basic	262,099	254,769	262,026	254,667
Diluted	262,558	255,441	262,545	255,268