STATEMENTS OF INCOME - USD ($) shares in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2024	Dec. 31, 2023	Dec. 31, 2022
Regulated Operating Revenue	$ 2,083,558	$ 2,371,990	$ 2,578,005
Cost of natural gas	778,333	1,134,510	1,459,087
Operating expenses
Operations and maintenance	530,111	508,399	472,265
Depreciation and amortization	296,699	279,830	228,479
General taxes	79,371	71,661	68,217
Total operating expenses	906,181	859,890	768,961
Operating income	399,044	377,590	349,957
Other Nonoperating Income (Expense)	7,427	9,476	(4,183)
Interest expense, net	(147,235)	(115,339)	(77,506)
Income before income taxes	259,236	271,727	268,268
Income taxes	(36,386)	(40,495)	(46,526)
Net income	$ 222,850	$ 231,232	$ 221,742
Earnings per share
Basic	$ 3.92	$ 4.16	$ 4.09
Diluted	$ 3.91	$ 4.14	$ 4.08
Weighted Average Number of Shares Outstanding, Basic [Abstract]
Basic	56,826	55,600	54,207
Weighted Average Number of Shares Outstanding, Diluted [Abstract]
Diluted	57,033	55,860	54,338
Common Stock, Dividends, Per Share, Declared	$ 2.64	$ 2.60	$ 2.48