STATEMENTS OF INCOME - USD ($) shares in Thousands, $ in Thousands	3 Months Ended
	Mar. 31, 2022	Mar. 31, 2021
Regulated Operating Revenue	$ 971,459	$ 625,293
Cost of natural gas	639,946	314,069
Operating expenses
Operations and maintenance	115,095	110,886
Depreciation and amortization	57,137	52,266
General taxes	18,524	17,727
Total operating expenses	190,756	180,879
Operating income	140,757	130,345
Other expense, net	(4,145)	(405)
Interest expense, net	(15,595)	(15,440)
Income before income taxes	121,017	114,500
Income taxes	(22,083)	(18,925)
Net income	$ 98,934	$ 95,575
Earnings per share
Basic	$ 1.83	$ 1.79
Diluted	$ 1.83	$ 1.79
Weighted Average Number of Shares Outstanding, Basic [Abstract]
Basic	53,922	53,372
Weighted Average Number of Shares Outstanding, Diluted [Abstract]
Diluted	54,030	53,515
Common Stock, Dividends, Per Share, Declared	$ 0.62	$ 0.58