STATEMENTS OF 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
Regulated Operating Revenue	$ 428,975	$ 315,646	$ 1,400,434	$ 940,939
Cost of natural gas	188,251	93,701	828,197	407,770
Operating expenses
Operations and maintenance	110,579	103,534	225,674	214,420
Depreciation and amortization	55,043	50,872	112,180	103,138
General taxes	16,533	16,437	35,057	34,164
Total operating expenses	182,155	170,843	372,911	351,722
Operating income	58,569	51,102	199,326	181,447
Other income (expense), net	(3,983)	451	(8,128)	46
Interest expense, net	(16,320)	(14,996)	(31,915)	(30,436)
Income before income taxes	38,266	36,557	159,283	151,057
Income taxes	(6,191)	(6,464)	(28,274)	(25,389)
Net income	$ 32,075	$ 30,093	$ 131,009	$ 125,668
Earnings per share
Basic	$ 0.59	$ 0.56	$ 2.42	$ 2.35
Diluted	$ 0.59	$ 0.56	$ 2.42	$ 2.35
Weighted Average Number of Shares Outstanding, Basic [Abstract]
Basic	54,262	53,466	54,092	53,419
Weighted Average Number of Shares Outstanding, Diluted [Abstract]
Diluted	54,335	53,548	54,183	53,531
Dividends declared per share of stock	$ 0.62	$ 0.58	$ 1.24	$ 1.16