Consolidated Statements Of Income And Earnings Reinvested In The Business - USD ($) $ in Thousands	12 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2013
INCOME
Operating Revenues	$ 1,760,913	$ 2,113,081	$ 1,829,551
Operating Expenses
Purchased Gas	349,984	605,838	460,432
Operation and Maintenance	470,003	463,078	442,090
Property, Franchise and Other Taxes	89,564	90,711	82,431
Depreciation, Depletion and Amortization	336,158	383,781	326,760
Impairment of Oil and Gas Producing Properties	1,126,257	0	0
Total Operating Expenses	2,371,966	1,543,408	1,311,713
Operating Income (Loss)	(611,053)	569,673	517,838
Other Income (Expense):
Other Income	8,039	9,461	4,697
Interest Income	3,922	4,170	4,335
Interest Expense on Long-Term Debt	(95,916)	(90,194)	(90,273)
Other Interest Expense	(3,555)	(4,083)	(3,838)
Income (Loss) Before Income Taxes	(698,563)	489,027	432,759
Income Tax Expense (Benefit)	(319,136)	189,614	172,758
Net Income (Loss) Available for Common Stock	(379,427)	299,413	260,001
EARNINGS REINVESTED IN THE BUSINESS
Balance at Beginning of Year	1,614,361	1,442,617	1,306,284
Beginning Retained Earnings Unappropriated And Current Period Net Income Loss	1,234,934	1,742,030	1,566,285
Dividends on Common Stock	(131,734)	(127,669)	(123,668)
Balance at End of Year	$ 1,103,200	$ 1,614,361	$ 1,442,617
Earnings Per Common Share, Basic:
Net Income (Loss) Available for Common Stock (in usd per share)	$ (4.50)	$ 3.57	$ 3.11
Earnings Per Common Share, Diluted:
Net Income (Loss) Available for Common Stock (in usd per share)	$ (4.50)	$ 3.52	$ 3.08
Weighted Average Number of Shares Outstanding:
Used in Basic Calculation	84,387,755	83,929,989	83,518,857
Used in Diluted Calculation	84,387,755	84,952,347	84,341,220