Consolidated Statements Of Cash Flows (Unaudited) - USD ($) $ in Thousands	6 Months Ended
	Mar. 31, 2025	Mar. 31, 2024
OPERATING ACTIVITIES
Net Income Available for Common Stock	$ 261,344	$ 299,292
Adjustments to Reconcile Net Income to Net Cash Provided by Operating Activities:
Impairment of Assets	141,802	0
Depreciation, Depletion and Amortization	220,647	234,725
Deferred Income Taxes	25,787	65,187
Premiums Paid on Early Redemption of Debt	2,385	0
Stock-Based Compensation	10,487	10,477
Other	14,317	11,874
Change in:
Receivables and Unbilled Revenue	(197,553)	(50,123)
Gas Stored Underground and Materials and Supplies	27,861	25,675
Unrecovered Purchased Gas Costs	(3,562)	0
Other Current Assets	13,737	15,201
Accounts Payable	17,322	(15,641)
Amounts Payable to Customers	(8,327)	13,327
Customer Advances	(19,373)	(21,003)
Customer Security Deposits	(5,907)	1,836
Other Accruals and Current Liabilities	21,528	26,927
Other Assets	(20,282)	(22,165)
Other Liabilities	(28,343)	(9,328)
Net Cash Provided by Operating Activities	473,870	586,261
INVESTING ACTIVITIES
Capital Expenditures	(434,260)	(481,958)
Other	8,881	(1,189)
Net Cash Used in Investing Activities	(425,379)	(483,147)
FINANCING ACTIVITIES
Changes in Notes Payable to Banks and Commercial Paper	117,700	(8,600)
Net Proceeds from Issuance of Long-Term Debt	989,019	0
Shares Repurchased Under Repurchase Plan	(50,471)	(4,230)
Reduction of Long-Term Debt	(954,086)	0
Dividends Paid on Common Stock	(93,543)	(91,048)
Net Repurchases of Common Stock Under Stock and Benefit Plans	(4,026)	(3,914)
Net Cash Provided by (Used in) Financing Activities	4,593	(107,792)
Net Increase (Decrease) in Cash, Cash Equivalents, and Restricted Cash	53,084	(4,678)
Cash, Cash Equivalents, and Restricted Cash at October 1	38,222	55,447
Cash, Cash Equivalents, and Restricted Cash at March 31	91,306	50,769
Supplemental Disclosure of Cash Flow Information
Non-Cash Capital Expenditures	$ 58,813	$ 62,921