Consolidated Statements Of Cash Flows (Unaudited) (USD $) In Thousands, unless otherwise specified	9 Months Ended
	Jun. 30, 2014	Jun. 30, 2013
OPERATING ACTIVITIES
Net Income Available for Common Stock	$ 241,983	$ 212,159
Adjustments to Reconcile Net Income to Net Cash Provided by Operating Activities:
Depreciation, Depletion and Amortization	279,876	240,503
Deferred Income Taxes	119,395	141,007
Excess Tax Benefits Associated with Stock-Based Compensation Awards	(4,641)	(4,314)
Stock-Based Compensation	12,438	9,706
Other	10,969	10,038
Change in:
Hedging Collateral Deposits	1,094	(330)
Receivables and Unbilled Revenue	(72,082)	(43,138)
Gas Stored Underground and Materials and Supplies	35,503	24,551
Unrecovered Purchased Gas Costs	12,408	0
Other Current Assets	5,376	14,228
Accounts Payable	26,386	11,241
Amounts Payable to Customers	19,977	(7,578)
Customer Advances	(21,878)	(23,809)
Customer Security Deposits	(17)	(1,112)
Other Accruals and Current Liabilities	17,590	3,534
Other Assets	25,449	(5,010)
Other Liabilities	15,743	5,557
Net Cash Provided by Operating Activities	725,569	587,233
INVESTING ACTIVITIES
Capital Expenditures	(609,427)	(513,399)
Other	4,696	(3,885)
Net Cash Used in Investing Activities	(604,731)	(517,284)
Financing Activities
Changes in Notes Payable to Banks and Commercial Paper	0	(171,000)
Excess Tax Benefits Associated with Stock-Based Compensation Awards	4,641	4,314
Net Proceeds from Issuance of Long-Term Debt	0	495,415
Reduction of Long-Term Debt	0	(250,000)
Dividends Paid on Common Stock	(94,269)	(91,364)
Net Proceeds from Issuance of Common Stock	6,585	2,774
Net Cash Used in Financing Activities	(83,043)	(9,861)
Net Increase in Cash and Temporary Cash Investments	37,795	60,088
Cash and Temporary Cash Investments at October 1	64,858	74,494
Cash and Temporary Cash Investments at June 30	102,653	134,582
Supplemental Disclosure of Cash Flow Information, Non-Cash Investing Activities:
Non-Cash Capital Expenditures	$ 135,747	$ 58,632