Consolidated Statements Of Income And Earnings Reinvested In The Business (Unaudited) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015
INCOME
Operating Revenues	$ 335,617	$ 339,815	$ 1,159,943	$ 1,459,851
Operating Expenses:
Purchased Gas	23,477	27,038	147,168	344,728
Property, Franchise and Other Taxes	20,261	22,717	61,923	68,561
Depreciation, Depletion and Amortization	58,802	79,865	193,300	265,298
Impairment of Oil and Gas Producing Properties	82,658	588,712	915,552	709,060
Total Operating Expenses	290,456	829,029	1,657,706	1,744,172
Operating Income (Loss)	45,161	(489,214)	(497,763)	(284,321)
Other Income (Expense):
Interest Income	564	327	2,640	1,631
Other Income	1,519	2,066	7,173	4,638
Interest Expense on Long-Term Debt	(28,897)	(22,213)	(88,263)	(66,900)
Other Interest Expense	(1,321)	(1,007)	(3,938)	(3,382)
Income (Loss) Before Income Taxes	17,026	(510,041)	(580,151)	(348,334)
Income Tax Expense (Benefit)	8,740	(216,907)	(251,641)	(156,610)
Net Income (Loss) Available for Common Stock	8,286	(293,134)	(328,510)	(191,724)
EARNINGS REINVESTED IN THE BUSINESS
Balance at Beginning of Period	699,399	1,650,840	1,103,200	1,614,361
Beginning Retained Earnings Unappropriated And Current Period Net Income Loss	707,685	1,357,706	774,690	1,422,637
Dividends on Common Stock	(34,404)	(33,388)	(101,409)	(98,319)
Balance at June 30	$ 673,281	$ 1,324,318	$ 673,281	$ 1,324,318
Earnings Per Common Share, Basic:
Net Income (Loss) Available for Common Stock (in dollars per share)	$ 0.10	$ (3.47)	$ (3.87)	$ (2.27)
Earnings Per Common Share, Diluted:
Net Income (Loss) Available for Common Stock (in dollars per share)	$ 0.10	$ (3.44)	$ (3.87)	$ (2.25)
Weighted Average Common Shares Outstanding:
Used in Basic Calculation (shares)	84,917,664	84,453,602	84,791,447	84,326,182
Used in Diluted Calculation (shares)	85,470,216	85,248,281	84,791,447	85,237,514
Dividends Per Common Share:
Dividends Declared (in dollars per share)	$ 0.405	$ 0.395	$ 1.195	$ 1.165
Utility and Energy Marketing [Member]
INCOME
Operating Revenues	$ 123,976	$ 132,422	$ 540,981	$ 772,802
Operating Expenses:
Operation and Maintenance	46,616	44,263	151,474	156,724
Exploration and Production and Other [Member]
INCOME
Operating Revenues	158,578	160,256	456,032	532,173
Operating Expenses:
Operation and Maintenance	35,427	46,162	123,965	140,564
Pipeline and Storage and Gathering [Member]
INCOME
Operating Revenues	53,063	47,137	162,930	154,876
Operating Expenses:
Operation and Maintenance	$ 23,215	$ 20,272	$ 64,324	$ 59,237