Consolidated Statements Of Cash Flows (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Dec. 31, 2012	Dec. 31, 2011
Operating Activities
Net Income Available for Common Stock	$ 67,944	$ 60,699
Adjustments to Reconcile Net Income to Net Cash Provided by Operating Activities:
Depreciation, Depletion and Amortization	72,331	62,547
Deferred Income Taxes	41,000	39,398
Other	7,923	2,375
Change in:
Hedging Collateral Deposits	364	(5,417)
Receivables and Unbilled Utility Revenue	(55,261)	(51,054)
Gas Stored Underground and Materials and Supplies	3,941	(2,226)
Unrecovered Purchased Gas Costs	0	(3,002)
Other Current Assets	7,013	232
Accounts Payable	6,163	(5,065)
Amounts Payable to Customers	(4,686)	(3,522)
Customer Advances	(1,987)	6,171
Customer Security Deposits	984	364
Other Accruals and Current Liabilities	(5,667)	(3,460)
Other Assets	(597)	(6,244)
Other Liabilities	6,495	3,867
Net Cash Provided by Operating Activities	145,960	95,663
Investing Activities
Capital Expenditures	(162,981)	(249,105)
Other	(3,533)	(966)
Net Cash Used in Investing Activities	(166,514)	(250,071)
Financing Activities
Changes in Notes Payable to Banks and Commercial Paper	67,000	(20,000)
Net Proceeds from Issuance of Long-Term Debt	0	496,085
Reduction of Long-Term Debt	0	(150,000)
Dividends Paid on Common Stock	(60,879)	(29,398)
Net Proceeds from Issuance of Common Stock	956	1,555
Net Cash Provided by Financing Activities	7,077	298,242
Net Increase (Decrease) in Cash and Temporary Cash Investments	(13,477)	143,834
Cash and Temporary Cash Investments at October 1	74,494	80,428
Cash and Temporary Cash Investments at December 31	$ 61,017	$ 224,262