CONDENSED CONSOLIDATED STATEMENTS OF INCOME (UNAUDITED) - USD ($) shares in Thousands, $ in Thousands	3 Months Ended		9 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
Operating revenues
Operating revenues	$ 686,401	$ 943,170	$ 3,485,234	$ 4,151,882
Purchased gas cost
Purchased gas cost	304,728	583,637	2,159,538	2,907,115
Gross profit	381,673	359,533	1,325,696	1,244,767
Operating expenses
Operation and maintenance	132,447	125,559	384,489	365,991
Depreciation and amortization	68,444	63,955	204,059	185,731
Taxes, other than income	63,175	63,414	181,606	165,640
Total operating expenses	264,066	252,928	770,154	717,362
Operating income	117,607	106,605	555,542	527,405
Miscellaneous income (expense)	634	(374)	(2,634)	(4,022)
Interest charges	27,955	31,840	85,166	95,556
Income (loss) before income taxes	90,286	74,391	467,742	427,827
Income tax expense (benefit)	34,005	28,670	176,182	161,723
Net income (loss)	$ 56,281	$ 45,721	$ 291,560	$ 266,104
Basic net income (loss) per share	$ 0.55	$ 0.45	$ 2.86	$ 2.76
Diluted net income (loss) per share	0.55	0.45	2.86	2.76
Cash dividends per share	$ 0.39	$ 0.37	$ 1.17	$ 1.11
Weighted average shares outstanding:
Basic weighted average shares outstanding	102,000	101,162	101,776	96,392
Diluted weighted average shares outstanding	102,000	101,163	101,776	96,394
Regulated Distribution Segment [Member]
Operating revenues
Operating revenues	$ 416,794	$ 517,707	$ 2,394,179	$ 2,652,532
Purchased gas cost
Purchased gas cost	149,775	260,042	1,397,113	1,710,508
Gross profit	267,019	257,665	997,066	942,024
Operating expenses
Operation and maintenance	98,552	92,994	288,962	289,433
Depreciation and amortization	55,491	52,542	165,730	152,113
Taxes, other than income	56,176	57,596	162,759	155,286
Total operating expenses	210,219	203,132	617,451	596,832
Operating income	56,800	54,533	379,615	345,192
Miscellaneous income (expense)	1,045	678	(1,221)	304
Interest charges	19,961	23,649	60,914	69,802
Income (loss) before income taxes	37,884	31,562	317,480	275,694
Income tax expense (benefit)	15,420	13,033	121,776	105,665
Net income (loss)	22,464	18,529	195,704	170,029
Regulated Pipeline Segment [Member]
Operating revenues
Operating revenues	97,008	87,189	272,305	232,145
Purchased gas cost
Purchased gas cost	0	0	0	0
Gross profit	97,008	87,189	272,305	232,145
Operating expenses
Operation and maintenance	26,572	23,570	74,029	57,465
Depreciation and amortization	11,816	10,281	34,945	30,223
Taxes, other than income	6,193	5,054	16,296	8,485
Total operating expenses	44,581	38,905	125,270	96,173
Operating income	52,427	48,284	147,035	135,972
Miscellaneous income (expense)	(211)	(489)	(842)	(2,751)
Interest charges	8,299	9,162	25,014	27,274
Income (loss) before income taxes	43,917	38,633	121,179	105,947
Income tax expense (benefit)	15,349	13,695	42,894	37,454
Net income (loss)	28,568	24,938	78,285	68,493
Nonregulated Segment [Member]
Operating revenues
Operating revenues	278,769	465,485	1,179,379	1,660,131
Purchased gas cost
Purchased gas cost	260,990	450,672	1,122,655	1,589,163
Gross profit	17,779	14,813	56,724	70,968
Operating expenses
Operation and maintenance	7,456	9,129	21,897	19,463
Depreciation and amortization	1,137	1,132	3,384	3,395
Taxes, other than income	806	764	2,551	1,869
Total operating expenses	9,399	11,025	27,832	24,727
Operating income	8,380	3,788	28,892	46,241
Miscellaneous income (expense)	345	1,018	897	1,785
Interest charges	240	610	706	1,840
Income (loss) before income taxes	8,485	4,196	29,083	46,186
Income tax expense (benefit)	3,236	1,942	11,512	18,604
Net income (loss)	5,249	2,254	17,571	27,582
Intersegment Elimination [Member]
Operating revenues
Operating revenues	(106,170)	(127,211)	(360,629)	(392,926)
Purchased gas cost
Purchased gas cost	(106,037)	(127,077)	(360,230)	(392,556)
Gross profit	(133)	(134)	(399)	(370)
Operating expenses
Operation and maintenance	(133)	(134)	(399)	(370)
Depreciation and amortization	0	0	0	0
Taxes, other than income	0	0	0	0
Total operating expenses	(133)	(134)	(399)	(370)
Operating income	0	0	0	0
Miscellaneous income (expense)	(545)	(1,581)	(1,468)	(3,360)
Interest charges	(545)	(1,581)	(1,468)	(3,360)
Income (loss) before income taxes	0	0	0	0
Income tax expense (benefit)	0	0	0	0
Net income (loss)	$ 0	$ 0	$ 0	$ 0