CONDENSED CONSOLIDATED STATEMENTS OF INCOME (UNAUDITED) (USD $) In Thousands, except Per Share data	3 Months Ended		9 Months Ended
	Jun. 30, 2011	Jun. 30, 2010	Jun. 30, 2011	Jun. 30, 2010
Operating revenues
Operating revenues	$ 843,615	$ 761,305	$ 3,558,374	$ 3,941,254
Purchased gas cost
Purchased gas cost	576,810	513,639	2,473,177	2,845,141
Gross profit	266,805	247,666	1,085,197	1,096,113
Operating expenses
Operation and maintenance	112,665	111,559	341,317	348,458
Depreciation and amortization	56,932	51,940	167,176	156,201
Taxes, other than income	52,142	51,908	145,868	152,840
Asset impairments	10,988	0	30,270	0
Total operating expenses	232,727	215,407	684,631	657,499
Operating income	34,078	32,259	400,566	438,614
Miscellaneous income (expense)	(1,430)	(798)	24,046	(905)
Interest charges	35,845	37,267	112,615	115,481
Income (loss) before income taxes	(3,197)	(5,806)	311,997	322,228
Income tax expense (benefit)	(1,723)	(1,577)	114,211	124,199
Income (loss) from continuing operations	(1,474)	(4,229)	197,786	198,029
Discontinued Operation Income Loss From Discontinued Operation During Phase Out Period Net Of Tax	908	1,075	7,854	6,273
Net income (loss)	(566)	(3,154)	205,640	204,302
Income Loss From Continuing Operations Per Basic Share	$ (0.02)	$ (0.04)	$ 2.17	$ 2.12
Income Loss From Discontinued Operations Net Of Tax Per Basic Share	$ 0.01	$ 0.01	$ 0.09	$ 0.07
Basic net income (loss) per share	$ (0.01)	$ (0.03)	$ 2.26	$ 2.19
Income Loss From Continuing Operations Per Diluted Share	$ (0.02)	$ (0.04)	$ 2.16	$ 2.11
Income Loss From Discontinued Operations Net Of Tax Per Diluted Share	$ 0.01	$ 0.01	$ 0.09	$ 0.07
Diluted net income (loss) per share	$ (0.01)	$ (0.03)	$ 2.25	$ 2.18
Cash dividends per share	$ 0.34	$ 0.335	$ 1.02	$ 1.005
Weighted average shares outstanding:
Basic	90,127	92,648	90,233	92,513
Diluted	90,127	92,648	90,530	92,856
Natural Gas Distribution Segment [Member]
Operating revenues
Operating revenues	407,031	396,319	2,187,907	2,512,032
Purchased gas cost
Purchased gas cost	206,839	204,988	1,317,775	1,657,412
Gross profit	200,192	191,331	870,132	854,620
Operating expenses
Operation and maintenance	86,804	87,323	268,299	266,847
Depreciation and amortization	49,099	45,633	145,548	137,580
Taxes, other than income	47,534	47,946	132,070	140,234
Asset impairments	0	0	0	0
Total operating expenses	183,437	180,902	545,917	544,661
Operating income	16,755	10,429	324,215	309,959
Miscellaneous income (expense)	(1,153)	(72)	18,305	1,474
Interest charges	28,042	29,019	87,344	87,877
Income (loss) before income taxes	(12,440)	(18,662)	255,176	223,556
Income tax expense (benefit)	(4,311)	(6,685)	94,323	86,552
Income (loss) from continuing operations	(8,129)	(11,977)	160,853	137,004
Discontinued Operation Income Loss From Discontinued Operation During Phase Out Period Net Of Tax	908	1,075	7,854	6,273
Net income (loss)	(7,221)	(10,902)	168,707	143,277
Regulated Transmission and Storage Segment [Member]
Operating revenues
Operating revenues	53,570	44,957	157,553	146,998
Purchased gas cost
Purchased gas cost	0	0	0	0
Gross profit	53,570	44,957	157,553	146,998
Operating expenses
Operation and maintenance	18,786	16,050	49,591	53,877
Depreciation and amortization	6,790	5,171	18,387	15,395
Taxes, other than income	3,729	3,010	11,395	9,226
Asset impairments	0	0	0	0
Total operating expenses	29,305	24,231	79,373	78,498
Operating income	24,265	20,726	78,180	68,500
Miscellaneous income (expense)	(312)	94	5,267	117
Interest charges	7,653	7,667	23,802	23,589
Income (loss) before income taxes	16,300	13,153	59,645	45,028
Income tax expense (benefit)	5,748	4,688	21,252	16,039
Income (loss) from continuing operations	10,552	8,465	38,393	28,989
Discontinued Operation Income Loss From Discontinued Operation During Phase Out Period Net Of Tax	0	0	0	0
Net income (loss)	10,552	8,465	38,393	28,989
Nonregulated Segment [Member]
Operating revenues
Operating revenues	491,285	427,405	1,550,456	1,652,453
Purchased gas cost
Purchased gas cost	477,880	415,634	1,491,815	1,556,746
Gross profit	13,405	11,771	58,641	95,707
Operating expenses
Operation and maintenance	7,437	8,579	24,556	28,946
Depreciation and amortization	1,043	1,136	3,241	3,226
Taxes, other than income	879	952	2,403	3,380
Asset impairments	10,988	0	30,270	0
Total operating expenses	20,347	10,667	60,470	35,552
Operating income	(6,942)	1,104	(1,829)	60,155
Miscellaneous income (expense)	168	511	764	1,524
Interest charges	283	1,912	1,759	8,035
Income (loss) before income taxes	(7,057)	(297)	(2,824)	53,644
Income tax expense (benefit)	(3,160)	420	(1,364)	21,608
Income (loss) from continuing operations	(3,897)	(717)	(1,460)	32,036
Discontinued Operation Income Loss From Discontinued Operation During Phase Out Period Net Of Tax	0	0	0	0
Net income (loss)	(3,897)	(717)	(1,460)	32,036
Intersegment Elimination [Member]
Operating revenues
Operating revenues	(108,271)	(107,376)	(337,542)	(370,229)
Purchased gas cost
Purchased gas cost	(107,909)	(106,983)	(336,413)	(369,017)
Gross profit	(362)	(393)	(1,129)	(1,212)
Operating expenses
Operation and maintenance	(362)	(393)	(1,129)	(1,212)
Depreciation and amortization	0	0	0	0
Taxes, other than income	0	0	0	0
Asset impairments	0	0	0	0
Total operating expenses	(362)	(393)	(1,129)	(1,212)
Operating income	0	0	0	0
Miscellaneous income (expense)	(133)	(1,331)	(290)	(4,020)
Interest charges	(133)	(1,331)	(290)	(4,020)
Income (loss) before income taxes	0	0	0	0
Income tax expense (benefit)	0	0	0	0
Income (loss) from continuing operations	0	0	0	0
Discontinued Operation Income Loss From Discontinued Operation During Phase Out Period Net Of Tax	0	0	0	0
Net income (loss)	$ 0	$ 0	$ 0	$ 0