Consolidated Statements Of Cash Flows - USD ($) $ in Thousands	12 Months Ended
	Sep. 30, 2022	Sep. 30, 2021	Sep. 30, 2020
Operating Activities
Net Income (Loss) Available for Common Stock	$ 566,021	$ 363,647	$ (123,772)
Adjustments to Reconcile Net Income (Loss) to Net Cash Provided by Operating Activities:
Gain on Sale of Assets	(12,736)	(51,066)	0
Impairment of Oil and Gas Producing Properties	0	76,152	449,438
Depreciation, Depletion and Amortization	369,790	335,303	306,158
Deferred Income Taxes	104,415	105,993	54,313
Premium Paid on Early Redemption of Debt	0	15,715	0
Stock-Based Compensation	19,506	17,065	14,931
Reduction of Other Post-Retirement Regulatory Liability	(18,533)	0	0
Other	31,983	10,896	6,527
Change in:
Receivables and Unbilled Revenue	(168,769)	(61,413)	(2,578)
Gas Stored Underground and Materials, Supplies and Emission Allowances	3,109	(2,014)	(6,625)
Unrecovered Purchased Gas Costs	(66,214)	(33,128)	2,246
Other Current Assets	291	(11,972)	49,367
Accounts Payable	11,907	31,352	(4,657)
Amounts Payable to Customers	398	(10,767)	6,771
Customer Advances	8,885	1,904	2,275
Customer Security Deposits	4,991	2,093	989
Other Accruals and Current Liabilities	34,260	34,314	5,001
Other Assets	(58,924)	1,250	(24,203)
Other Liabilities	(17,859)	(33,771)	4,628
Net Cash Provided by Operating Activities	812,521	791,553	740,809
Investing Activities
Capital Expenditures	(811,826)	(751,734)	(716,153)
Net Proceeds from Sale of Oil and Gas Producing Properties	254,439	0	0
Net Proceeds from Sale of Timber Properties	0	104,582	0
Sale of Fixed Income Mutual Fund Shares in Grantor Trust	30,000	0	0
Acquisition of Upstream Assets and Midstream Gathering Assets	0	0	(506,258)
Other	8,683	13,935	(1,205)
Net Cash Used in Investing Activities	(518,704)	(633,217)	(1,223,616)
Financing Activities
Change in Notes Payable to Banks and Commercial Paper	(98,500)	128,500	(25,200)
Net Proceeds from Issuance of Long-Term Debt	0	495,267	493,007
Reduction of Long-Term Debt	0	(515,715)	0
Net Repurchases of Common Stock	(9,590)	(3,702)
Net Proceeds from Issuance of Common Stock			161,603
Dividends Paid on Common Stock	(168,147)	(163,089)	(153,322)
Net Cash Provided by (Used in) Financing Activities	(276,237)	(58,739)	476,088
Net Increase (Decrease) in Cash, Cash Equivalents, and Restricted Cash	17,580	99,597	(6,719)
Cash, Cash Equivalents and Restricted Cash At Beginning of Year	120,138	20,541	27,260
Cash, Cash Equivalents and Restricted Cash At End of Year	137,718	120,138	20,541
Supplemental Disclosure of Cash Flow Information
Cash Paid for Interest	124,312	135,136	103,479
Cash Paid for Income Taxes	16,680	6,374
Cash Refunded for Income Taxes			(82,876)
Supplemental Disclosure of Cash Flow Information, Non-Cash Investing Activities
Non-Cash Capital Expenditures	120,262	102,700	87,328
Non-Cash Contingent Consideration for Asset Sale	$ 12,571	$ 0	$ 0