Consolidated Statements Of Cash Flows (USD $) In Thousands, unless otherwise specified	9 Months Ended
	Jun. 30, 2013	Jun. 30, 2012
Operating Activities
Net Income Available for Common Stock	$ 212,159	$ 171,275
Adjustments to Reconcile Net Income to Net Cash Provided by Operating Activities:
Depreciation, Depletion and Amortization	240,503	199,925
Deferred Income Taxes	141,007	104,948
Excess Tax Benefits Associated with Stock-Based Compensation Awards	(4,314)	(1,511)
Other	19,744	6,618
Change in:
Hedging Collateral Deposits	(330)	16,309
Receivables and Unbilled Utility Revenue	(43,138)	23,008
Gas Stored Underground and Materials and Supplies	24,551	30,853
Unrecovered Purchased Gas Costs	0	(2,100)
Other Current Assets	14,228	18,190
Accounts Payable	11,241	(5,825)
Amounts Payable to Customers	(7,578)	2,242
Customer Advances	(23,809)	(19,328)
Customer Security Deposits	(1,112)	(474)
Other Accruals and Current Liabilities	3,534	17,083
Other Assets	(5,010)	(1,538)
Other Liabilities	5,557	14,080
Net Cash Provided by Operating Activities	587,233	573,755
Investing Activities
Capital Expenditures	(513,399)	(809,661)
Other	(3,885)	(1,267)
Net Cash Used in Investing Activities	(517,284)	(810,928)
Financing Activities
Changes in Notes Payable to Banks and Commercial Paper	(171,000)	30,200
Excess Tax Benefits Associated with Stock-Based Compensation Awards	4,314	1,511
Net Proceeds from Issuance of Long-Term Debt	495,415	496,085
Reduction of Long-Term Debt	(250,000)	(150,000)
Dividends Paid on Common Stock	(91,364)	(88,404)
Net Proceeds from Issuance of Common Stock	2,774	8,168
Net Cash Provided by (Used in) Financing Activities	(9,861)	297,560
Net Increase in Cash and Temporary Cash Investments	60,088	60,387
Cash and Temporary Cash Investments at October 1	74,494	80,428
Cash and Temporary Cash Investments at June 30	$ 134,582	$ 140,815