Consolidated Statements Of Cash Flows (Unaudited) - USD ($) $ in Thousands	6 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
OPERATING ACTIVITIES
Net Income Available for Common Stock	$ 193,256	$ 290,501
Adjustments to Reconcile Net Income to Net Cash Provided by Operating Activities:
Depreciation, Depletion and Amortization	129,918	116,985
Deferred Income Taxes	90,468	(62,459)
Stock-Based Compensation	10,731	7,862
Other	7,997	8,052
Change in:
Receivables and Unbilled Revenue	(130,377)	(123,954)
Gas Stored Underground and Materials and Supplies	29,093	28,004
Unrecovered Purchased Gas Costs	(1,556)	4,197
Other Current Assets	10,438	(8,819)
Accounts Payable	10,226	10,838
Amounts Payable to Customers	12,069	12,083
Customer Advances	(13,176)	(15,547)
Customer Security Deposits	(7,184)	(1,399)
Other Accruals and Current Liabilities	48,028	37,646
Other Assets	(38,686)	(9,541)
Other Liabilities	(10,410)	(5,767)
Net Cash Provided by Operating Activities	340,835	288,682
INVESTING ACTIVITIES
Capital Expenditures	(386,579)	(261,720)
Net Proceeds from Sale of Oil and Gas Producing Properties	0	17,310
Other	(2,616)	5,355
Net Cash Used in Investing Activities	(389,195)	(239,055)
Financing Activities
Reduction of Long-Term Debt	0	(307,047)
Dividends Paid on Common Stock	(73,197)	(71,091)
Net Repurchases of Common Stock	(8,864)
Net Proceeds from Issuance of Common Stock		2,891
Net Cash Used in Financing Activities	(82,061)	(375,247)
Net Decrease in Cash, Cash Equivalents, and Restricted Cash	(130,421)	(325,620)
Cash, Cash Equivalents and Restricted Cash at October 1	233,047	557,271
Cash, Cash Equivalents and Restricted Cash at March 31	102,626	231,651
Supplemental Disclosure of Cash Flow Information, Non-Cash Investing Activities:
Non-Cash Capital Expenditures	$ 74,929	$ 51,939