Consolidated Statements Of Income And Earnings Reinvested In The Business (USD $) In Thousands, except Share data, unless otherwise specified	3 Months Ended		6 Months Ended
	Mar. 31, 2012	Mar. 31, 2011	Mar. 31, 2012	Mar. 31, 2011
INCOME
Operating Revenues	$ 552,309	$ 660,881	$ 984,732	$ 1,111,829
Operating Expenses
Purchased Gas	208,537	306,595	340,730	469,633
Operation and Maintenance	118,047	116,721	218,106	214,171
Property, Franchise and Other Taxes	30,477	23,798	49,707	43,534
Depreciation, Depletion and Amortization	63,151	60,011	125,698	113,324
Total Operating Expenses	420,212	507,125	734,241	840,662
Operating Income	132,097	153,756	250,491	271,167
Other Income (Expense):
Gain on Sale of Unconsolidated Subsidiaries	0	50,879	0	50,879
Interest Income	192	68	1,297	951
Other Income	1,654	2,424	2,990	2,317
Interest Expense on Long-Term Debt	(20,425)	(17,926)	(39,066)	(38,118)
Other Interest Expense	(1,253)	(1,454)	(2,023)	(2,855)
Income Before Income Taxes	112,265	187,747	213,689	284,341
Income Tax Expense	44,873	72,136	85,598	110,187
Net Income Available for Common Stock	67,392	115,611	128,091	174,154
EARNINGS REINVESTED IN THE BUSINESS
Beginning Balance	1,237,242	1,093,398	1,206,022	1,063,262
Beginning Retained Earnings Unappropriated And Current Period Net Income Loss	1,304,634	1,209,009	1,334,113	1,237,416
Dividends on Common Stock	(29,527)	(28,478)	(59,006)	(56,885)
Balance at March 31	$ 1,275,107	$ 1,180,531	$ 1,275,107	$ 1,180,531
Earnings Per Common Share, Basic:
Net Income Available for Common Stock	$ 0.81	$ 1.40	$ 1.54	$ 2.12
Diluted:
Net Income Available for Common Stock	$ 0.81	$ 1.38	$ 1.53	$ 2.08
Weighted Average Common Shares Outstanding:
Used in Basic Calculation	83,107,884	82,400,851	82,988,750	82,311,162
Used in Diluted Calculation	83,678,261	83,673,977	83,712,681	83,561,775