Consolidated Statements Of Income And Earnings Reinvested In The Business (Unaudited) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Mar. 31, 2023	Mar. 31, 2022	Mar. 31, 2023	Mar. 31, 2022
INCOME
Operating Revenues	$ 717,261	$ 701,720	$ 1,376,119	$ 1,248,277
Operating Expenses:
Purchased Gas	243,839	199,592	415,035	301,219
Property, Franchise and Other Taxes	25,367	27,717	51,572	52,219
Depreciation, Depletion and Amortization	100,964	91,245	197,564	179,823
Total Operating Expenses	495,884	455,354	900,371	792,252
Operating Income	221,377	246,366	475,748	456,025
Other Income (Expense):
Other Income (Deductions)	2,884	10,018	9,203	8,940
Interest Expense on Long-Term Debt	(27,583)	(30,079)	(57,188)	(60,209)
Other Interest Expense	(5,861)	(1,519)	(9,704)	(2,680)
Income Before Income Taxes	190,817	224,786	418,059	402,076
Income Tax Expense	49,937	57,458	107,489	102,356
Net Income Available for Common Stock	140,880	167,328	310,570	299,720
EARNINGS REINVESTED IN THE BUSINESS
Balance at Beginning of Period	1,713,176	1,281,963	1,587,085	1,191,175
Beginning Retained Earnings Unappropriated And Current Period Net Income	1,854,056	1,449,291	1,897,655	1,490,895
Dividends on Common Stock	(43,602)	(41,608)	(87,201)	(83,212)
Balance at March 31	$ 1,810,454	$ 1,407,683	$ 1,810,454	$ 1,407,683
Earnings Per Common Share, Basic:
Net Income Available for Common Stock (in dollars per share)	$ 1.53	$ 1.83	$ 3.39	$ 3.28
Earnings Per Common Share, Diluted:
Net Income Available for Common Stock (in dollars per share)	$ 1.53	$ 1.82	$ 3.37	$ 3.26
Weighted Average Common Shares Outstanding:
Used in Basic Calculation (shares)	91,794,765	91,444,638	91,686,110	91,354,488
Used in Diluted Calculation (shares)	92,256,348	92,064,711	92,264,717	92,047,467
Dividends Per Common Share:
Dividends Declared (in dollars per share)	$ 0.475	$ 0.455	$ 0.950	$ 0.910
Utility [Member]
INCOME
Operating Revenues	$ 406,758	$ 369,092	$ 718,376	$ 605,776
Operating Expenses:
Operation and Maintenance	56,453	53,476	106,805	100,120
Exploration and Production and Other [Member]
INCOME
Operating Revenues	244,552	261,676	521,525	505,957
Operating Expenses:
Operation and Maintenance	31,782	49,806	58,655	95,425
Pipeline and Storage and Gathering [Member]
INCOME
Operating Revenues	65,951	70,952	136,218	136,544
Operating Expenses:
Operation and Maintenance	$ 37,479	$ 33,518	$ 70,740	$ 63,446