Aggregate revenue less cost of goods and services sold or operating expenses directly attributable to the revenue generation activity for discontinued operations.

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The total amount of operating revenues recognized during the period for discontinued operations.

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- Definition

After tax income (loss) from operations of a business component (exclusive of any gain or loss on disposal, or provision therefore) during the reporting period, until its disposal.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 144

-Paragraph 43

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 144

-Paragraph 47

-Subparagraph c

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- Definition

Amount of operating income or loss attributable to the disposal group, including a component of the entity (discontinued operation), during the reporting period.

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- Definition

The amount of net income or loss for the period per each share of common stock outstanding during the reporting period.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 04

-Paragraph 21

-Article 9

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 128

-Paragraph 36, 37, 38

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-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 03

-Paragraph 20

-Article 5

Reference 4: http://www.xbrl.org/2003/role/presentationRef

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 04

-Paragraph 18

-Article 7

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- Definition

The amount of net income or loss for the period per each share of common stock and dilutive common stock equivalents outstanding during the reporting period.

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-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 128

-Paragraph 11, 12, 36

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-Name Regulation S-X (SX)

-Number 210

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-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

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-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 04

-Paragraph 21

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Aggregate revenue less cost of goods and services sold or operating expenses directly attributable to the revenue generation activity.

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- Definition

This element represents the income or loss from continuing operations attributable to the economic entity which may also be defined as revenue less expenses and taxes from ongoing operations before extraordinary items, cumulative effects of changes in accounting principles, and noncontrolling interest.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 95

-Paragraph 28

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher AICPA

-Name Accounting Research Bulletin (ARB)

-Number 51

-Paragraph 29

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- Definition

The amount of income (loss) from continuing operations per each share of common stock outstanding during the reporting period.

+ References

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- Definition

The amount of income (loss) from continuing operations available to each share of common stock outstanding during the reporting period and each share that would have been outstanding assuming the issuance of common shares for all dilutive potential common shares outstanding during the reporting period.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 04

-Paragraph 21

-Article 9

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 128

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-Name Statement of Financial Accounting Standard (FAS)

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-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 04

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- Definition

The amount of income (loss) from disposition of discontinued operations, net of related tax effect, per each share of common stock outstanding during the reporting period.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 128

-Paragraph 8, 9, 10, 36, 37, 38

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-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

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-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 04

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Reference 4: http://www.xbrl.org/2003/role/presentationRef

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 04

-Paragraph 21

-Article 9

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- Definition

The amount of income (loss) from discontinued operations, net of related tax effect, per each diluted share of common stock outstanding during the reporting period.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher SEC

-Name Staff Accounting Bulletin (SAB)

-Number Topic 5

-Section E

-Paragraph Question 3

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- Definition

The portion of consolidated profit or loss for the period, net of income taxes, which is attributable to the parent. If the entity does not present consolidated financial statements, the amount of profit or loss for the period, net of income taxes.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 03

-Paragraph 19

-Article 5

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher AICPA

-Name Accounting Research Bulletin (ARB)

-Number 51

-Paragraph 38

-Subparagraph d

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-Publisher AICPA

-Name Accounting Research Bulletin (ARB)

-Number 51

-Paragraph A7

-Appendix A

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-Publisher AICPA

-Name Accounting Research Bulletin (ARB)

-Number 51

-Paragraph 38

-Subparagraph a

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-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 04

-Paragraph 20

-Article 9

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-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 130

-Paragraph 10, 15

Reference 7: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Emerging Issues Task Force (EITF)

-Number 87-21

Reference 8: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 95

-Paragraph 28, 29, 30

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The net result for the period of deducting operating expenses from operating revenues.

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- Definition

The total amount of operating revenues recognized during the period.

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Quarterly Financial Information (Details) (USD $) In Thousands, except Per Share data	3 Months Ended								12 Months Ended
	Sep. 30, 2011	Jun. 30, 2011	Mar. 31, 2011	Dec. 31, 2010	Sep. 30, 2010	Jun. 30, 2010	Mar. 31, 2010	Dec. 31, 2009	Sep. 30, 2011	Sep. 30, 2010	Sep. 30, 2009
Discontinued Operations Quarterly Information [Abstract]
Discontinued Operations Operating Revenues			$ 35,800	$ 23,700	$ 7,700		$ 32,100	$ 21,100	$ 80,028	$ 69,855	$ 99,969
Discontinued Operations Gross Profit			11,200	8,800	5,200		8,900	7,800	31,269	27,436	27,024
Disposal Group Including Discontinued Operation Operating Income Loss			6,700	4,800	1,700		4,800	4,000	14,415	12,285	11,036
Operating Revenues by Segment [Line Items]
Operating revenues									4,347,634	4,719,835	4,869,111
Selected Quarterly Financial Information Abstract
Gross profit	242,044	266,805	453,668	364,724	241,392	247,666	445,444	403,003	1,327,241	1,337,505	1,319,678
Operating income	41,333	34,078	211,199	155,289	38,537	32,259	219,757	186,598	441,899	477,151	436,366
Income (loss) from continuing operations	1,098	(1,474)	128,160	71,100	244	(4,229)	111,283	90,975	198,884	198,273	183,299
Income (loss) from discontinued operations	863	908	4,049	2,897	1,293	1,075	2,843	2,355	8,717	7,566	7,679
Net income (loss)	1,961	(566)	132,209	73,997	1,537	(3,154)	114,126	93,330	207,601	205,839	190,978
Income (loss) from continuing operations per share - Basic	$ 0.01	$ (0.02)	$ 1.41	$ 0.78	$ 0	$ (0.04)	$ 1.19	$ 0.97	$ 2.18	$ 2.14	$ 1.99
Income (loss) from discontinued operations per share - Basic	$ 0.01	$ 0.01	$ 0.04	$ 0.03	$ 0.02	$ 0.01	$ 0.03	$ 0.03	$ 0.10	$ 0.08	$ 0.09
Basic net income (loss) per share	$ 0.02	$ (0.01)	$ 1.45	$ 0.81	$ 0.02	$ (0.03)	$ 1.22	$ 1.00	$ 2.28	$ 2.22	$ 2.08
Income Loss From Continuing Operations Per Diluted Share	$ 0.01	$ (0.02)	$ 1.41	$ 0.78	$ 0	$ (0.04)	$ 1.19	$ 0.97	$ 2.17	$ 2.12	$ 1.98
Income (loss) from discontinued operations per share - Diluted	$ 0.01	$ 0.01	$ 0.04	$ 0.03	$ 0.02	$ 0.01	$ 0.03	$ 0.03	$ 0.10	$ 0.08	$ 0.09
Diluted net income (loss) per share	$ 0.02	$ (0.01)	$ 1.45	$ 0.81	$ 0.02	$ (0.03)	$ 1.22	$ 1.00	$ 2.27	$ 2.20	$ 2.07
Natural Gas Distribution Segment [Member]
Operating Revenues by Segment [Line Items]
Operating revenues	343,956	407,031	1,077,414	703,462	330,606	396,319	1,333,872	781,841	2,531,863	2,842,638	2,884,796
Selected Quarterly Financial Information Abstract
Gross profit									1,044,364	1,022,011	997,604
Operating income									338,001	310,169	277,978
Income (loss) from continuing operations									154,001	118,383	109,128
Income (loss) from discontinued operations									8,717	7,566	7,679
Net income (loss)									162,718	125,949	116,807
Regulated Transmission and Storage Segment [Member]
Operating Revenues by Segment [Line Items]
Operating revenues	61,820	53,570	54,976	49,007	56,015	44,957	55,181	46,860	219,373	203,013	209,658
Selected Quarterly Financial Information Abstract
Gross profit									219,373	203,013	209,658
Operating income									108,275	97,038	93,163
Income (loss) from continuing operations									52,415	41,486	41,056
Income (loss) from discontinued operations									0	0	0
Net income (loss)									52,415	41,486	41,056
Nonregulated Segment [Member]
Operating Revenues by Segment [Line Items]
Operating revenues	474,437	491,285	583,531	475,640	494,205	427,405	677,032	548,016	2,024,893	2,146,658	2,283,988
Selected Quarterly Financial Information Abstract
Gross profit									65,000	114,091	114,108
Operating income									(4,383)	69,944	64,881
Income (loss) from continuing operations									(7,532)	38,404	33,115
Income (loss) from discontinued operations									0	0	0
Net income (loss)									(7,532)	38,404	33,115
Intersegment Elimination [Member]
Operating Revenues by Segment [Line Items]
Operating revenues	(90,953)	(108,271)	(134,424)	(94,847)	(102,245)	(107,376)	(157,935)	(104,918)	(428,495)	(472,474)	(509,331)
Selected Quarterly Financial Information Abstract
Gross profit									(1,496)	(1,610)	(1,692)
Operating income									6	0	344
Income (loss) from continuing operations									0	0	0
Income (loss) from discontinued operations									0	0	0
Net income (loss)									$ 0	$ 0	$ 0