Consolidated Statements Of Cash Flows - USD ($) $ in Thousands	12 Months Ended
	Sep. 30, 2024	Sep. 30, 2023	Sep. 30, 2022
Operating Activities
Net Income Available for Common Stock	$ 77,513	$ 476,866	$ 566,021
Adjustments to Reconcile Net Income to Net Cash Provided by Operating Activities:
Gain on Sale of Assets	0	0	(12,736)
Impairment of Assets	519,129	0	0
Depreciation, Depletion and Amortization	457,026	409,573	369,790
Deferred Income Taxes	(2,610)	151,403	104,415
Stock-Based Compensation	22,080	20,630	19,506
Reduction of Other Post-Retirement Regulatory Liability	0	0	(18,533)
Other	24,411	19,647	31,983
Change in:
Receivables and Unbilled Revenue	34,369	213,579	(168,769)
Gas Stored Underground and Materials, Supplies and Emission Allowances	1,738	(8,406)	3,109
Unrecovered Purchased Gas Costs	0	99,342	(66,214)
Other Current Assets	8,144	(41,077)	291
Accounts Payable	5,616	(37,095)	11,907
Amounts Payable to Customers	(16,299)	58,600	398
Customer Advances	(1,630)	(5,105)	8,885
Customer Security Deposits	7,501	4,481	4,991
Other Accruals and Current Liabilities	2,637	(67,664)	34,260
Other Assets	(48,183)	(26,564)	(58,924)
Other Liabilities	(25,481)	(31,135)	(17,859)
Net Cash Provided by Operating Activities	1,065,961	1,237,075	812,521
Investing Activities
Capital Expenditures	(931,236)	(1,009,868)	(811,826)
Net Proceeds from Sale of Exploration and Production Properties	0	0	254,439
Sale of Fixed Income Mutual Fund Shares in Grantor Trust	0	10,000	30,000
Acquisition of Upstream Assets	0	(124,758)	0
Other	(2,669)	12,279	8,683
Net Cash Used in Investing Activities	(933,905)	(1,112,347)	(518,704)
Financing Activities
Proceeds from Issuance of Short-Term Note Payable to Bank	0	250,000	0
Repayment of Short-Term Note Payable to Bank	0	(250,000)	0
Net Change in Other Short-Term Notes Payable to Banks and Commercial Paper	(196,800)	227,500	(98,500)
Net Proceeds from Issuance of Long-Term Debt	299,359	297,306	0
Shares Repurchased Under Repurchase Plan	(64,086)	0	0
Reduction of Long-Term Debt	0	(549,000)	0
Net Repurchases of Common Stock Under Stock and Benefit Plans	(3,956)	(6,709)	(9,590)
Dividends Paid on Common Stock	(183,798)	(176,096)	(168,147)
Net Cash Used in Financing Activities	(149,281)	(206,999)	(276,237)
Net Increase (Decrease) in Cash, Cash Equivalents, and Restricted Cash	(17,225)	(82,271)	17,580
Cash, Cash Equivalents and Restricted Cash At Beginning of Year	55,447	137,718	120,138
Cash, Cash Equivalents and Restricted Cash At End of Year	38,222	55,447	137,718
Cash Paid For:
Interest	125,130	124,441	124,312
Income Taxes	4,132	38,098	16,680
Non-Cash Investing Activities:
Non-Cash Capital Expenditures	119,988	109,208	120,262
Non-Cash Contingent Consideration for Asset Sale	$ 0	$ 0	$ 12,571