Consolidated Statements Of Income And Earnings Reinvested In The Business - USD ($) $ in Thousands	12 Months Ended
	Sep. 30, 2022	Sep. 30, 2021	Sep. 30, 2020
INCOME
Operating Revenues	$ 2,186,046	$ 1,742,659	$ 1,546,291
Operating Expenses:
Purchased Gas	392,093	171,827	233,890
Property, Franchise and Other Taxes	101,182	94,713	88,400
Depreciation, Depletion and Amortization	369,790	335,303	306,158
Impairment of Oil and Gas Producing Properties	0	76,152	449,438
Total Operating Expenses	1,384,266	1,153,801	1,516,433
Gain on Sale of Assets	(12,736)	(51,066)	0
Operating Income	814,516	639,924	29,858
Other Income (Expense):
Other Income (Deductions)	(1,509)	(15,238)	(17,814)
Interest Expense on Long-Term Debt	(120,507)	(141,457)	(110,012)
Other Interest Expense	(9,850)	(4,900)	(7,065)
Income (Loss) Before Income Taxes	682,650	478,329	(105,033)
Income Tax Expense	116,629	114,682	18,739
Net Income (Loss) Available for Common Stock	566,021	363,647	(123,772)
EARNINGS REINVESTED IN THE BUSINESS
Balance at Beginning of Year	1,191,175	991,630	1,272,601
Beginning Retained Earnings Unappropriated And Current Period Net Income	1,757,196	1,355,277	1,148,829
Dividends on Common Stock	(170,111)	(164,102)	(156,249)
Balance at End of Year	$ 1,587,085	$ 1,191,175	$ 991,630
Earnings (Loss) Per Common Share, Basic:
Net Income (Loss) Available for Common Stock (in dollars per share)	$ 6.19	$ 3.99	$ (1.41)
Earnings (Loss) Per Common Share, Diluted:
Net Income (Loss) Available for Common Stock (in dollars per share)	$ 6.15	$ 3.97	$ (1.41)
Weighted Average Number of Shares Outstanding:
Used in Basic Calculation	91,410,625	91,130,941	87,968,895
Used in Diluted Calculation	92,107,066	91,684,583	87,968,895
Utility and Energy Marketing [Member]
INCOME
Operating Revenues	$ 897,916	$ 667,549	$ 728,336
Operating Expenses:
Operation and Maintenance	193,058	179,547	181,051
Exploration and Production and Other [Member]
INCOME
Operating Revenues	1,010,629	837,597	611,885
Operating Expenses:
Operation and Maintenance	191,572	173,041	148,856
Pipeline and Storage and Gathering [Member]
INCOME
Operating Revenues	277,501	237,513	206,070
Operating Expenses:
Operation and Maintenance	136,571	123,218	108,640
Guidance for Hedging [Member] | Cumulative Effect of Adoption of Authoritative Guidance [Member]
EARNINGS REINVESTED IN THE BUSINESS
Balance at Beginning of Year	$ 0	0	(950)
Balance at End of Year		$ 0	$ 0