Consolidated Statements Of Cash Flows (Unaudited) - USD ($) $ in Thousands	6 Months Ended
	Mar. 31, 2024	Mar. 31, 2023
OPERATING ACTIVITIES
Net Income Available for Common Stock	$ 299,292	$ 310,570
Adjustments to Reconcile Net Income to Net Cash Provided by Operating Activities:
Depreciation, Depletion and Amortization	234,725	197,564
Deferred Income Taxes	65,187	80,745
Stock-Based Compensation	10,477	11,286
Other	11,874	10,758
Change in:
Receivables and Unbilled Revenue	(50,123)	71,760
Gas Stored Underground and Materials and Supplies	25,675	21,243
Unrecovered Purchased Gas Costs	0	72,491
Other Current Assets	15,201	(15,864)
Accounts Payable	(15,641)	(29,169)
Amounts Payable to Customers	13,327	2,411
Customer Advances	(21,003)	(26,108)
Customer Security Deposits	1,836	10,099
Other Accruals and Current Liabilities	26,927	28,741
Other Assets	(22,165)	(26,901)
Other Liabilities	(9,328)	(8,417)
Net Cash Provided by Operating Activities	586,261	711,209
INVESTING ACTIVITIES
Capital Expenditures	(481,958)	(496,362)
Deposit Paid for Upstream Assets	0	(12,700)
Sale of Fixed Income Mutual Fund Shares in Grantor Trust	0	10,000
Other	(1,189)	14,413
Net Cash Used in Investing Activities	(483,147)	(484,649)
FINANCING ACTIVITIES
Proceeds from Issuance of Short-Term Note Payable to Bank	0	250,000
Net Change in Other Short-Term Notes Payable to Banks and Commercial Paper	(8,600)	100,000
Shares Repurchased Under Repurchase Plan	(4,230)	0
Reduction of Long-Term Debt	0	(549,000)
Dividends Paid on Common Stock	(91,048)	(87,051)
Net Repurchases of Common Stock Under Stock and Benefit Plans	(3,914)	(6,694)
Net Cash Used in Financing Activities	(107,792)	(292,745)
Net Decrease in Cash, Cash Equivalents, and Restricted Cash	(4,678)	(66,185)
Cash, Cash Equivalents, and Restricted Cash at October 1	55,447	137,718
Cash, Cash Equivalents, and Restricted Cash at March 31	50,769	71,533
Supplemental Disclosure of Cash Flow Information
Non-Cash Capital Expenditures	$ 62,921	$ 64,495