CONDENSED CONSOLIDATED STATEMENTS OF INCOME (UNAUDITED) (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended		9 Months Ended
	Jun. 30, 2013	Jun. 30, 2012	Jun. 30, 2013	Jun. 30, 2012
Operating revenues
Operating revenues	$ 857,935	$ 576,414	$ 3,201,086	$ 2,885,917
Purchased gas cost
Purchased gas cost	541,438	283,243	2,089,476	1,811,567
Gross profit	316,497	293,171	1,111,610	1,074,350
Operating expenses
Operation and maintenance	121,258	106,045	338,871	329,989
Depreciation and amortization	58,129	58,956	174,888	176,742
Taxes, other than income	50,714	46,624	146,355	144,170
Total operating expenses	230,101	211,625	660,114	650,901
Operating income	86,396	81,546	451,496	423,449
Miscellaneous income (expense)	(467)	(2,075)	1,943	(3,585)
Interest charges	32,741	34,909	96,594	107,278
Income (loss) before income taxes	53,188	44,562	356,845	312,586
Income tax expense (benefit)	19,714	16,548	133,683	120,104
Income (loss) from continuing operations	33,474	28,014	223,162	192,482
Income from disconnected operations, net of tax	0	3,118	7,202	16,268
Gain on sale of discontinued operations, net of tax	5,294	0	5,294	0
Net income (loss)	38,768	31,132	235,658	208,750
Income Loss From Continuing Operations Per Basic Share	$ 0.37	$ 0.31	$ 2.46	$ 2.13
Income Loss From Discontinued Operations Net Of Tax Per Basic Share	$ 0.06	$ 0.03	$ 0.14	$ 0.18
Basic net income (loss) per share	$ 0.43	$ 0.34	$ 2.60	$ 2.31
Income Loss From Continuing Operations Per Diluted Share	$ 0.36	$ 0.31	$ 2.43	$ 2.10
Income Loss From Discontinued Operations Net Of Tax Per Diluted Share	$ 0.06	$ 0.03	$ 0.14	$ 0.18
Diluted net income (loss) per share	$ 0.42	$ 0.34	$ 2.57	$ 2.28
Cash dividends per share	$ 0.35	$ 0.345	$ 1.05	$ 1.035
Weighted average shares outstanding:
Basic weighted average shares outstanding	90,603	90,118	90,497	90,131
Diluted weighted average shares outstanding	91,550	90,993	91,445	91,006
Natural Gas Distribution Segment [Member]
Operating revenues
Operating revenues	467,144	315,634	2,039,107	1,862,814
Purchased gas cost
Purchased gas cost	227,649	120,575	1,172,975	1,011,832
Gross profit	239,495	195,059	866,132	850,982
Operating expenses
Operation and maintenance	93,490	82,224	266,570	262,255
Depreciation and amortization	48,368	50,157	146,059	151,042
Taxes, other than income	45,686	42,011	132,029	130,232
Total operating expenses	187,544	174,392	544,658	543,529
Operating income	51,951	20,667	321,474	307,453
Miscellaneous income (expense)	268	(1,053)	2,728	(2,327)
Interest charges	25,001	27,820	74,228	84,775
Income (loss) before income taxes	27,218	(8,206)	249,974	220,351
Income tax expense (benefit)	11,401	(3,299)	94,874	86,282
Income (loss) from continuing operations	15,817	(4,907)	155,100	134,069
Income from disconnected operations, net of tax	0	3,118	7,202	16,268
Gain on sale of discontinued operations, net of tax	5,649		5,649
Net income (loss)	21,466	(1,789)	167,951	150,337
Regulated Transmission and Storage Segment [Member]
Operating revenues
Operating revenues	74,041	67,073	196,570	181,869
Purchased gas cost
Purchased gas cost	0	0	0	0
Gross profit	74,041	67,073	196,570	181,869
Operating expenses
Operation and maintenance	17,035	16,427	48,745	49,239
Depreciation and amortization	8,676	7,797	25,756	23,240
Taxes, other than income	4,287	3,839	12,513	11,538
Total operating expenses	29,998	28,063	87,014	84,017
Operating income	44,043	39,010	109,556	97,852
Miscellaneous income (expense)	(247)	(298)	(473)	(634)
Interest charges	8,049	7,353	22,777	22,176
Income (loss) before income taxes	35,747	31,359	86,306	75,042
Income tax expense (benefit)	12,650	11,215	30,574	26,864
Income (loss) from continuing operations	23,097	20,144	55,732	48,178
Income from disconnected operations, net of tax	0	0	0	0
Gain on sale of discontinued operations, net of tax	0		0
Net income (loss)	23,097	20,144	55,732	48,178
Nonregulated Segment [Member]
Operating revenues
Operating revenues	421,808	256,250	1,250,650	1,071,189
Purchased gas cost
Purchased gas cost	418,548	224,829	1,200,624	1,028,592
Gross profit	3,260	31,421	50,026	42,597
Operating expenses
Operation and maintenance	11,034	7,777	24,679	19,597
Depreciation and amortization	1,085	1,002	3,073	2,460
Taxes, other than income	741	774	1,813	2,400
Total operating expenses	12,860	9,553	29,565	24,457
Operating income	(9,600)	21,868	20,461	18,140
Miscellaneous income (expense)	215	136	1,791	739
Interest charges	392	595	1,687	1,686
Income (loss) before income taxes	(9,777)	21,409	20,565	17,193
Income tax expense (benefit)	(4,337)	8,632	8,235	6,958
Income (loss) from continuing operations	(5,440)	12,777	12,330	10,235
Income from disconnected operations, net of tax	0	0	0	0
Gain on sale of discontinued operations, net of tax	(355)		(355)
Net income (loss)	(5,795)	12,777	11,975	10,235
Intersegment Elimination [Member]
Operating revenues
Operating revenues	(105,058)	(62,543)	(285,241)	(229,955)
Purchased gas cost
Purchased gas cost	(104,759)	(62,161)	(284,123)	(228,857)
Gross profit	(299)	(382)	(1,118)	(1,098)
Operating expenses
Operation and maintenance	(301)	(383)	(1,123)	(1,102)
Depreciation and amortization	0	0	0	0
Taxes, other than income	0	0	0	0
Total operating expenses	(301)	(383)	(1,123)	(1,102)
Operating income	2	1	5	4
Miscellaneous income (expense)	(703)	(860)	(2,103)	(1,363)
Interest charges	(701)	(859)	(2,098)	(1,359)
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
Income from disconnected operations, net of tax	0	0	0	0
Gain on sale of discontinued operations, net of tax	0		0
Net income (loss)	$ 0	$ 0	$ 0	$ 0