Consolidated Statements Of Cash Flows - USD ($) $ in Thousands	12 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2019
Operating Activities
Net Income (Loss) Available for Common Stock	$ 363,647	$ (123,772)	$ 304,290
Adjustments to Reconcile Net Income (Loss) to Net Cash Provided by Operating Activities:
Gain on Sale of Timber Properties	(51,066)	0	0
Impairment of Oil and Gas Producing Properties	76,152	449,438	0
Depreciation, Depletion and Amortization	335,303	306,158	275,660
Deferred Income Taxes	105,993	54,313	122,265
Premium Paid on Early Redemption of Debt	15,715	0	0
Stock-Based Compensation	17,065	14,931	21,186
Other	10,896	6,527	8,608
Change in:
Receivables and Unbilled Revenue	(61,413)	(2,578)	6,379
Gas Stored Underground and Materials, Supplies and Emission Allowances	(2,014)	(6,625)	(3,713)
Unrecovered Purchased Gas Costs	(33,128)	2,246	1,958
Other Current Assets	(11,972)	49,367	(29,030)
Accounts Payable	31,352	(4,657)	(24,770)
Amounts Payable to Customers	(10,767)	6,771	623
Customer Advances	1,904	2,275	(565)
Customer Security Deposits	2,093	989	(9,493)
Other Accruals and Current Liabilities	34,314	5,001	10,992
Other Assets	1,250	(24,203)	5,115
Other Liabilities	(33,771)	4,628	4,978
Net Cash Provided by Operating Activities	791,553	740,809	694,483
Investing Activities
Capital Expenditures	(751,734)	(716,153)	(788,938)
Net Proceeds from Sale of Timber Properties	104,582	0	0
Acquisition of Upstream Assets and Midstream Gathering Assets	0	(506,258)	0
Other	13,935	(1,205)	(10,237)
Net Cash Used in Investing Activities	(633,217)	(1,223,616)	(799,175)
Financing Activities
Change in Notes Payable to Banks and Commercial Paper	128,500	(25,200)	55,200
Net Proceeds from Issuance of Long-Term Debt	495,267	493,007	0
Reduction of Long-Term Debt	(515,715)	0	0
Net Repurchases of Common Stock	(3,702)		(8,877)
Net Proceeds from Issuance of Common Stock		161,603
Dividends Paid on Common Stock	(163,089)	(153,322)	(147,418)
Net Cash Provided by (Used in) Financing Activities	(58,739)	476,088	(101,095)
Net Increase (Decrease) in Cash, Cash Equivalents, and Restricted Cash	99,597	(6,719)	(205,787)
Cash, Cash Equivalents and Restricted Cash At Beginning of Year	20,541	27,260	233,047
Cash, Cash Equivalents and Restricted Cash At End of Year	120,138	20,541	27,260
Supplemental Disclosure of Cash Flow Information
Cash Paid for Interest	135,136	103,479	102,920
Cash Refunded for Income Taxes		(82,876)	(17,342)
Cash Paid for Income Taxes	6,374
Supplemental Disclosure of Cash Flow Information, Non-Cash Investing Activities
Non-Cash Capital Expenditures	$ 102,700	$ 87,328	$ 81,121