Atmos Energy (ATO) 10-Q 7 May 14 2014 Q2 Quarterly report Financial data

Document_and_Entity_Informatio

Document and Entity Information	6 Months Ended
	Mar. 31, 2014	1-May-14
Document And Entity Information [Abstract]	'	'
Entity Registrant Name	'Atmos Energy Corporation	'
Entity Central Index Key	'0000731802	'
Current Fiscal Year End Date	'--09-30	'
Entity Filer Category	'Large Accelerated Filer	'
Document Type	'10-Q	'
Document Period End Date	31-Mar-14	'
Document Fiscal Year Focus	'2014	'
Document Fiscal Period Focus	'Q2	'
Amendment Flag	'false	'
Entity Common Stock, Shares Outstanding	'	100,186,395
Entity Well-known Seasoned Issuer	'Yes	'
Entity Voluntary Filers	'No	'
Entity Current Reporting Status	'Yes	'

CONDENSED_CONSOLIDATED_BALANCE

CONDENSED CONSOLIDATED BALANCE SHEETS (UNAUDITED) (USD $)	Mar. 31, 2014	Sep. 30, 2013
In Thousands, unless otherwise specified
ASSETS	'	'
Property, plant and equipment	$8,014,440	$7,722,019
Less accumulated depreciation and amortization	1,744,457	1,691,364
Net property, plant and equipment	6,269,983	6,030,655
Current assets	'	'
Cash and cash equivalents	136,740	66,199
Accounts receivable, net	671,021	301,992
Gas stored underground	124,950	244,741
Other current assets	126,450	64,201
Total current assets	1,059,161	677,133
Goodwill	741,363	741,363
Deferred charges and other assets	417,109	485,117
Total assets	8,487,616	7,934,268
Shareholders' equity	'	'
Common stock, no par value (stated at $.005 per share)	501	453
Additional paid-in capital	2,163,144	1,765,811
Retained earnings	924,282	775,267
Accumulated other comprehensive income (loss)	36,834	38,878
Shareholders' equity	3,124,761	2,580,409
Long-term debt	1,955,829	2,455,671
Total capitalization	5,080,590	5,036,080
Current liabilities	'	'
Accounts payable and accrued liabilities	442,816	241,611
Other current liabilities	420,576	368,891
Short-term debt	0	367,984
Current maturities of long-term debt	500,000	0
Total current liabilities	1,363,392	978,486
Deferred income taxes	1,283,551	1,164,053
Regulatory cost of removal obligation	358,262	359,299
Pension and postretirement liabilities	360,851	358,787
Deferred credits and other liabilities	40,970	37,563
Total shareholders' equity and liabilities	$8,487,616	$7,934,268

CONDENSED_CONSOLIDATED_BALANCE1

CONDENSED CONSOLIDATED BALANCE SHEETS (UNAUDITED) (PARENTHETICALS) (USD $)	Mar. 31, 2014	Sep. 30, 2013
Statement of Financial Position [Abstract]	'	'
Common Stock, Par Value Per Share	$0	$0
Common Stock, Stated Value Per Share	$0.01	$0.01
Common Stock, Shares Authorized	200,000,000	200,000,000
Common Stock, Shares, Issued	100,177,825	90,640,211
Common Stock, Shares, Outstanding	100,177,825	90,640,211

CONDENSED_CONSOLIDATED_STATEME

CONDENSED CONSOLIDATED STATEMENTS OF INCOME (UNAUDITED) (USD $)	3 Months Ended		6 Months Ended
Share data in Thousands, except Per Share data, unless otherwise specified	Mar. 31, 2014	Mar. 31, 2013	Mar. 31, 2014	Mar. 31, 2013
Operating revenues	'	'	'	'
Operating revenues	$1,964,322,000	$1,308,996,000	$3,219,470,000	$2,343,151,000
Purchased gas cost	'	'	'	'
Purchased gas cost	1,468,045,000	876,245,000	2,334,236,000	1,548,038,000
Gross profit	496,277,000	432,751,000	885,234,000	795,113,000
Operating expenses	'	'	'	'
Operation and maintenance	124,675,000	111,086,000	240,432,000	217,613,000
Depreciation and amortization	61,307,000	57,180,000	121,776,000	116,759,000
Taxes, other than income	60,215,000	54,307,000	102,226,000	95,641,000
Total operating expenses	246,197,000	222,573,000	464,434,000	430,013,000
Operating income	250,080,000	210,178,000	420,800,000	365,100,000
Miscellaneous income (expense)	-1,516,000	1,712,000	-3,648,000	2,410,000
Interest charges	31,601,000	33,331,000	63,716,000	63,853,000
Income (loss) before income taxes	216,963,000	178,559,000	353,436,000	303,657,000
Income tax expense (benefit)	83,596,000	66,219,000	133,053,000	113,969,000
Income (loss) from continuing operations	133,367,000	112,340,000	220,383,000	189,688,000
Income from discontinued operations, net of tax	0	4,085,000	0	7,202,000
Net income (loss)	133,367,000	116,425,000	220,383,000	196,890,000
Income (Loss) From Continuing Operations Per Basic Share	$1.40	$1.24	$2.36	$2.09
Income (Loss) From Discontinued Operations Net Of Tax Per Basic Share	$0	$0.04	$0	$0.08
Basic net income (loss) per share	$1.40	$1.28	$2.36	$2.17
Income (Loss) From Continuing Operations Per Diluted Share	$1.38	$1.23	$2.34	$2.07
Income (Loss) From Discontinued Operations Net Of Tax Per Diluted Share	$0	$0.04	$0	$0.08
Diluted net income (loss) per share	$1.38	$1.27	$2.34	$2.15
Cash dividends per share	$0.37	$0.35	$0.74	$0.70
Weighted average shares outstanding:	'	'	'	'
Basic weighted average shares outstanding	95,264	90,530	93,049	90,445
Diluted weighted average shares outstanding	96,191	91,492	93,976	91,406
Natural Gas Distribution Segment [Member]	'	'	'	'
Operating revenues	'	'	'	'
Operating revenues	1,290,960,000	905,176,000	2,134,825,000	1,571,963,000
Purchased gas cost	'	'	'	'
Purchased gas cost	905,772,000	558,170,000	1,450,466,000	945,326,000
Gross profit	385,188,000	347,006,000	684,359,000	626,637,000
Operating expenses	'	'	'	'
Operation and maintenance	106,776,000	89,344,000	196,439,000	173,080,000
Depreciation and amortization	50,020,000	47,631,000	99,571,000	97,691,000
Taxes, other than income	60,606,000	49,592,000	97,690,000	86,343,000
Total operating expenses	217,402,000	186,567,000	393,700,000	357,114,000
Operating income	167,786,000	160,439,000	290,659,000	269,523,000
Miscellaneous income (expense)	97,000	2,591,000	-374,000	2,460,000
Interest charges	22,828,000	25,664,000	46,153,000	49,227,000
Income (loss) before income taxes	145,055,000	137,366,000	244,132,000	222,756,000
Income tax expense (benefit)	56,312,000	51,176,000	92,632,000	83,473,000
Income (loss) from continuing operations	'	86,190,000	'	139,283,000
Income from discontinued operations, net of tax	'	4,085,000	'	7,202,000
Net income (loss)	88,743,000	90,275,000	151,500,000	146,485,000
Regulated Transmission and Storage Segment [Member]	'	'	'	'
Operating revenues	'	'	'	'
Operating revenues	73,615,000	61,848,000	144,956,000	122,529,000
Purchased gas cost	'	'	'	'
Purchased gas cost	0	0	0	0
Gross profit	73,615,000	61,848,000	144,956,000	122,529,000
Operating expenses	'	'	'	'
Operation and maintenance	16,595,000	15,390,000	33,895,000	31,710,000
Depreciation and amortization	10,156,000	8,690,000	19,942,000	17,080,000
Taxes, other than income	-1,232,000	4,277,000	3,431,000	8,226,000
Total operating expenses	25,519,000	28,357,000	57,268,000	57,016,000
Operating income	48,096,000	33,491,000	87,688,000	65,513,000
Miscellaneous income (expense)	-1,081,000	-99,000	-2,262,000	-226,000
Interest charges	9,155,000	7,857,000	18,112,000	14,728,000
Income (loss) before income taxes	37,860,000	25,535,000	67,314,000	50,559,000
Income tax expense (benefit)	13,751,000	9,005,000	23,759,000	17,924,000
Income (loss) from continuing operations	'	16,530,000	'	32,635,000
Income from discontinued operations, net of tax	'	0	'	0
Net income (loss)	24,109,000	16,530,000	43,555,000	32,635,000
Nonregulated Segment [Member]	'	'	'	'
Operating revenues	'	'	'	'
Operating revenues	757,683,000	428,948,000	1,205,404,000	828,842,000
Purchased gas cost	'	'	'	'
Purchased gas cost	720,094,000	404,641,000	1,149,249,000	782,076,000
Gross profit	37,589,000	24,307,000	56,155,000	46,766,000
Operating expenses	'	'	'	'
Operation and maintenance	1,419,000	6,763,000	10,334,000	13,645,000
Depreciation and amortization	1,131,000	859,000	2,263,000	1,988,000
Taxes, other than income	841,000	438,000	1,105,000	1,072,000
Total operating expenses	3,391,000	8,060,000	13,702,000	16,705,000
Operating income	34,198,000	16,247,000	42,453,000	30,061,000
Miscellaneous income (expense)	443,000	-91,000	767,000	1,576,000
Interest charges	593,000	498,000	1,230,000	1,295,000
Income (loss) before income taxes	34,048,000	15,658,000	41,990,000	30,342,000
Income tax expense (benefit)	13,533,000	6,038,000	16,662,000	12,572,000
Income (loss) from continuing operations	'	9,620,000	'	17,770,000
Income from discontinued operations, net of tax	'	0	'	0
Net income (loss)	20,515,000	9,620,000	25,328,000	17,770,000
Intersegment Elimination [Member]	'	'	'	'
Operating revenues	'	'	'	'
Operating revenues	-157,936,000	-86,976,000	-265,715,000	-180,183,000
Purchased gas cost	'	'	'	'
Purchased gas cost	-157,821,000	-86,566,000	-265,479,000	-179,364,000
Gross profit	-115,000	-410,000	-236,000	-819,000
Operating expenses	'	'	'	'
Operation and maintenance	-115,000	-411,000	-236,000	-822,000
Depreciation and amortization	0	0	0	0
Taxes, other than income	0	0	0	0
Total operating expenses	-115,000	-411,000	-236,000	-822,000
Operating income	0	1,000	0	3,000
Miscellaneous income (expense)	-975,000	-689,000	-1,779,000	-1,400,000
Interest charges	-975,000	-688,000	-1,779,000	-1,397,000
Income (loss) before income taxes	0	0	0	0
Income tax expense (benefit)	0	0	0	0
Income (loss) from continuing operations	'	0	'	0
Income from discontinued operations, net of tax	'	0	'	0
Net income (loss)	$0	$0	$0	$0

CONDENSED_CONSOLIDATED_STATEME1

CONDENSED CONSOLIDATED STATEMENTS OF INCOME (UNAUDITED) (PARENTHETICALS) (USD $)	3 Months Ended		6 Months Ended
In Thousands, unless otherwise specified	Mar. 31, 2014	Mar. 31, 2013	Mar. 31, 2014	Mar. 31, 2013
Income Statement [Abstract]	'	'	'	'
Discontinued Operation Tax Effect Of Income Loss From Discontinued Operation During Phase Out Period	$0	$2,258	$0	$3,986

CONDENSED_CONSOLIDATED_STATEME2

CONDENSED CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME (UNAUDITED) (USD $)	3 Months Ended		6 Months Ended
In Thousands, unless otherwise specified	Mar. 31, 2014	Mar. 31, 2013	Mar. 31, 2014	Mar. 31, 2013
Statement of Comprehensive Income [Abstract]	'	'	'	'
Net income (loss)	$133,367	$116,425	$220,383	$196,890
Other comprehensive income (loss), net of tax	'	'	'	'
Net unrealized holding gains (losses) on available-for-sale securities, net of tax	-252	-200	2,142	-573
Amortization and unrealized gains (losses) on interest rate agreements, net of tax	-27,047	23,509	-13,105	35,773
Net unrealized gains (losses) on commodity cash flow hedges, net of tax	1,101	8,838	8,919	8,473
Total other comprehensive income (loss)	-26,198	32,147	-2,044	43,673
Total comprehensive income (loss)	$107,169	$148,572	$218,339	$240,563

CONDENSED_CONSOLIDATED_STATEME3

CONDENSED CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME (UNAUDITED) (PARENTHETICALS) (USD $)	3 Months Ended		6 Months Ended
In Thousands, unless otherwise specified	Mar. 31, 2014	Mar. 31, 2013	Mar. 31, 2014	Mar. 31, 2013
Other Comprehensive Income Loss Tax Portion Attributable To Parent Abstract	'	'	'	'
Unrealized holding gains (losses) on available-for-sale securities, tax	($133)	($110)	$1,302	($330)
Amortization and unrealized gains (losses) on interest rate agreements, tax	-15,546	13,513	-7,533	20,562
Net unrealized gains (losses) on commodity cash flow hedging transactions, tax	$703	$5,650	$5,702	$5,417

CONDENSED_CONSOLIDATED_STATEME4

CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS (UNAUDITED) (USD $)	6 Months Ended
In Thousands, unless otherwise specified	Mar. 31, 2014	Mar. 31, 2013
Cash Flows From Operating Activities	'	'
Net income (loss)	$220,383	$196,890
Depreciation and amortization:	'	'
Charged to depreciation and amortization	121,776	118,608
Charged to other accounts	441	265
Other	'	'
Deferred income taxes	119,710	106,891
Other	10,746	5,519
Net Assets Liabilities From Risk Management Activities	836	-14,709
Net change in operating assets and liabilities	17,089	-37,123
Net cash provided by operating activities	490,981	376,341
Cash Flows From Investing Activities	'	'
Capital expenditures	-359,009	-389,117
Other, net	-4,904	-3,700
Net cash used in investing activities	-363,913	-392,817
Cash Flows From Financing Activities	'	'
Net decrease in short-term debt	-369,012	-342,141
Net proceeds from issuance of long-term debt	0	493,793
Settlement of Treasury lock agreements	0	-66,626
Repayments of Long-term Debt	0	-131
Cash dividends paid	-71,380	-64,008
Repurchase of equity awards	-6,317	-3,124
Net proceeds from equity offering	390,205	0
Other	-23	21
Net cash provided by (used in) financing activities	-56,527	17,784
Net increase (decrease) in cash and cash equivalents	70,541	1,308
Cash and cash equivalents at beginning of period	66,199	64,239
Cash and cash equivalents at end of period	$136,740	$65,547

Nature_of_Business

Nature of Business	6 Months Ended
	Mar. 31, 2014
Organization, Consolidation and Presentation of Financial Statements [Abstract]	'
Nature of Business	'
	Nature of Business
	Atmos Energy Corporation (“Atmos Energy” or the “Company”) and our subsidiaries are engaged primarily in the regulated natural gas distribution and transmission and storage businesses as well as certain other nonregulated businesses. For the fiscal year ended September 30, 2013, our regulated businesses generated approximately 95 percent of our consolidated net income.
	Through our natural gas distribution business, we deliver natural gas through sales and transportation arrangements to approximately three million residential, commercial, public authority and industrial customers through our six regulated natural gas distribution divisions, which at March 31, 2014, covered service areas located in eight states. On April 1, 2013, we completed the divestiture of our natural gas distribution operations in Georgia, representing approximately 64,000 customers. In addition, we transport natural gas for others through our distribution system. Our regulated businesses also include our regulated pipeline and storage operations, which include the transportation of natural gas to our North Texas distribution system and the management of our underground storage facilities. Our regulated businesses are subject to federal and state regulation and/or regulation by local authorities in each of the states in which our natural gas distribution divisions operate.
	Our nonregulated businesses operate primarily in the Midwest and Southeast through various wholly-owned subsidiaries of Atmos Energy Holdings, Inc., (AEH). AEH is wholly owned by the Company and based in Houston, Texas. Through AEH, we provide natural gas management and transportation services to municipalities, natural gas distribution companies, including certain divisions of Atmos Energy and third parties.

Unaudited_Financial_Informatio

Unaudited Financial Information	6 Months Ended
	Mar. 31, 2014
Accounting Policies [Abstract]	'
Unaudited Financial Information	'
	Unaudited Financial Information
	These consolidated interim-period financial statements have been prepared in accordance with accounting principles generally accepted in the United States on the same basis as those used for the Company’s audited consolidated financial statements included in our Annual Report on Form 10-K for the fiscal year ended September 30, 2013. In the opinion of management, all material adjustments (consisting of normal recurring accruals) necessary for a fair presentation have been made to the unaudited consolidated interim-period financial statements. These consolidated interim-period financial statements are condensed as permitted by the instructions to Form 10-Q and should be read in conjunction with the audited consolidated financial statements of Atmos Energy Corporation included in our Annual Report on Form 10-K for the fiscal year ended September 30, 2013. Because of seasonal and other factors, the results of operations for the six-month period ended March 31, 2014 are not indicative of our results of operations for the full 2014 fiscal year, which ends September 30, 2014.
	Except as noted in Note 7 and Note 8, no events have occurred subsequent to the balance sheet date that would require recognition or disclosure in the condensed consolidated financial statements.
	Significant accounting policies
	Our accounting policies are described in Note 2 to the consolidated financial statements in our Annual Report on Form 10-K for the fiscal year ended September 30, 2013.
	During the second quarter of fiscal 2014, we completed our annual goodwill impairment assessment. Based on the assessment performed, we determined that our goodwill was not impaired.
	Due to the April 1, 2013 sale of our Georgia distribution operations, prior year financial results for this service area are shown in discontinued operations.
	Disclosure requirements for offsetting arrangements for financial instruments became effective for us beginning on October 1, 2013. We have presented these disclosures in Note 8. In connection with the adoption of this standard, prior-year risk management assets and liabilities have been reclassified to conform with the current-year presentation. The adoption of this standard and reclassification did not have an impact on our financial position, results of operations or cash flows. There were no other significant changes to our accounting policies nor were there new accounting standards announced during the six months ended March 31, 2014 that will become applicable to the Company in future periods.
	Regulatory assets and liabilities
	Accounting principles generally accepted in the United States require cost-based, rate-regulated entities that meet certain criteria to reflect the authorized recovery of costs due to regulatory decisions in their financial statements. As a result, certain costs are permitted to be capitalized rather than expensed because they can be recovered through rates. We record certain costs as regulatory assets when future recovery through customer rates is considered probable. Regulatory liabilities are recorded when it is probable that revenues will be reduced for amounts that will be credited to customers through the ratemaking process. Substantially all of our regulatory assets are recorded as a component of deferred charges and other assets and substantially all of our regulatory liabilities are recorded as a component of deferred credits and other liabilities. Deferred gas costs are recorded either in other current assets or liabilities and the regulatory cost of removal obligation is reported separately.
	Significant regulatory assets and liabilities as of March 31, 2014 and September 30, 2013 included the following:
		March 31,		September 30,
		2014		2013
		(In thousands)
	Regulatory assets:
	Pension and postretirement benefit costs(1)	$	176,616	$	187,977
	Merger and integration costs, net	4,990		5,250
	Deferred gas costs	10,004		15,152
	Regulatory cost of removal asset	9,716		10,008
	Rate case costs	5,037		6,329
	Texas Rule 8.209(2)	40,760		30,364
	APT annual adjustment mechanism	4,084		5,853
	Recoverable loss on reacquired debt	20,156		21,435
	Other	6,393		4,380
		$	277,756	$	286,748
	Regulatory liabilities:
	Deferred gas costs	$	80,330	$	16,481
	Deferred franchise fees	11,523		1,689
	Regulatory cost of removal obligation	425,461		427,524
	Other	11,683		7,887
		$	528,997	$	453,581
	(1)	Includes $18.1 million and $17.4 million of pension and postretirement expense deferred pursuant to regulatory authorization.
	(2)	Texas Rule 8.209 is a Railroad Commission rule that allows for the deferral of all expenses associated with capital expenditures incurred pursuant to this rule, including the recording of interest on the deferred expenses until the next rate proceeding (rate case or annual rate filing), at which time investment and costs would be recovered through base rates.
	Currently authorized rates do not include a return on certain of our merger and integration costs; however, we recover the amortization of these costs. Merger and integration costs, net, are generally amortized on a straight-line basis over estimated useful lives ranging up to 20 years.

Segment_Information

Segment Information	6 Months Ended
	Mar. 31, 2014
Segment Reporting [Abstract]	'
Segment Information	'
	Segment Information
	We operate the Company through the following three segments:
	•	The natural gas distribution segment, which includes our regulated natural gas distribution and related sales operations,
	•	The regulated transmission and storage segment, which includes the regulated pipeline and storage operations of our Atmos Pipeline — Texas Division and
	•	The nonregulated segment, which is comprised of our nonregulated natural gas management, nonregulated natural gas transmission, storage and other services.
	Our determination of reportable segments considers the strategic operating units under which we manage sales of various products and services to customers in differing regulatory environments. Although our natural gas distribution segment operations are geographically dispersed, they are reported as a single segment as each natural gas distribution division has similar economic characteristics. The accounting policies of the segments are the same as those described in the summary of significant accounting policies found in our Annual Report on Form 10-K for the fiscal year ended September 30, 2013. We evaluate performance based on net income or loss of the respective operating units.
	Income statements for the three and six month periods ended March 31, 2014 and 2013 by segment are presented in the following tables:
		Three Months Ended March 31, 2014
		Natural			Regulated			Nonregulated			Eliminations			Consolidated
		Gas			Transmission
		Distribution			and Storage
		(In thousands)
	Operating revenues from external parties	$	1,289,429		$	21,002		$	653,891		$	—		$	1,964,322
	Intersegment revenues	1,531			52,613			103,792			(157,936		)	—
		1,290,960			73,615			757,683			(157,936		)	1,964,322
	Purchased gas cost	905,772			—			720,094			(157,821		)	1,468,045
	Gross profit	385,188			73,615			37,589			(115		)	496,277
	Operating expenses
	Operation and maintenance	106,776			16,595			1,419			(115		)	124,675
	Depreciation and amortization	50,020			10,156			1,131			—			61,307
	Taxes, other than income	60,606			(1,232		)	841			—			60,215
	Total operating expenses	217,402			25,519			3,391			(115		)	246,197
	Operating income	167,786			48,096			34,198			—			250,080
	Miscellaneous income (expense)	97			(1,081		)	443			(975		)	(1,516		)
	Interest charges	22,828			9,155			593			(975		)	31,601
	Income before income taxes	145,055			37,860			34,048			—			216,963
	Income tax expense	56,312			13,751			13,533			—			83,596
	Net income	$	88,743		$	24,109		$	20,515		$	—		$	133,367
	Capital expenditures	$	139,555		$	39,000		$	(113	)	$	—		$	178,442
		Three Months Ended March 31, 2013
		Natural			Regulated			Nonregulated			Eliminations			Consolidated
		Gas			Transmission
		Distribution			and Storage
		(In thousands)
	Operating revenues from external parties	$	904,181		$	19,655		$	385,160		$	—		$	1,308,996
	Intersegment revenues	995			42,193			43,788			(86,976		)	—
		905,176			61,848			428,948			(86,976		)	1,308,996
	Purchased gas cost	558,170			—			404,641			(86,566		)	876,245
	Gross profit	347,006			61,848			24,307			(410		)	432,751
	Operating expenses
	Operation and maintenance	89,344			15,390			6,763			(411		)	111,086
	Depreciation and amortization	47,631			8,690			859			—			57,180
	Taxes, other than income	49,592			4,277			438			—			54,307
	Total operating expenses	186,567			28,357			8,060			(411		)	222,573
	Operating income	160,439			33,491			16,247			1			210,178
	Miscellaneous income (expense)	2,591			(99		)	(91		)	(689		)	1,712
	Interest charges	25,664			7,857			498			(688		)	33,331
	Income from continuing operations before income taxes	137,366			25,535			15,658			—			178,559
	Income tax expense	51,176			9,005			6,038			—			66,219
	Income from continuing operations	86,190			16,530			9,620			—			112,340
	Income from discontinued operations, net of tax	4,085			—			—			—			4,085
	Net income	$	90,275		$	16,530		$	9,620		$	—		$	116,425
	Capital expenditures	$	131,465		$	67,208		$	417		$	—		$	199,090
		Six Months Ended March 31, 2014
		Natural			Regulated			Nonregulated			Eliminations			Consolidated
		Gas			Transmission
		Distribution			and Storage
		(In thousands)
	Operating revenues from external parties	$	2,131,861		$	42,172		$	1,045,437		$	—		$	3,219,470
	Intersegment revenues	2,964			102,784			159,967			(265,715		)	—
		2,134,825			144,956			1,205,404			(265,715		)	3,219,470
	Purchased gas cost	1,450,466			—			1,149,249			(265,479		)	2,334,236
	Gross profit	684,359			144,956			56,155			(236		)	885,234
Operating expenses
Operation and maintenance	196,439			33,895			10,334			(236		)	240,432
Depreciation and amortization	99,571			19,942			2,263			—			121,776
Taxes, other than income	97,690			3,431			1,105			—			102,226
Total operating expenses	393,700			57,268			13,702			(236		)	464,434
Operating income	290,659			87,688			42,453			—			420,800
Miscellaneous income (expense)	(374		)	(2,262		)	767			(1,779		)	(3,648		)
Interest charges	46,153			18,112			1,230			(1,779		)	63,716
Income from before income taxes	244,132			67,314			41,990			—			353,436
Income tax expense	92,632			23,759			16,662			—			133,053
Net income	$	151,500		$	43,555		$	25,328		$	—		$	220,383
Capital expenditures	$	267,061		$	91,921		$	27		$	—		$	359,009
	Six Months Ended March 31, 2013
	Natural			Regulated			Nonregulated			Eliminations			Consolidated
	Gas			Transmission
	Distribution			and Storage
	(In thousands)
Operating revenues from external parties	$	1,569,730		$	38,354		$	735,067		$	—		$	2,343,151
Intersegment revenues	2,233			84,175			93,775			(180,183		)	—
	1,571,963			122,529			828,842			(180,183		)	2,343,151
Purchased gas cost	945,326			—			782,076			(179,364		)	1,548,038
Gross profit	626,637			122,529			46,766			(819		)	795,113
Operating expenses
Operation and maintenance	173,080			31,710			13,645			(822		)	217,613
Depreciation and amortization	97,691			17,080			1,988			—			116,759
Taxes, other than income	86,343			8,226			1,072			—			95,641
Total operating expenses	357,114			57,016			16,705			(822		)	430,013
Operating income	269,523			65,513			30,061			3			365,100
Miscellaneous income (expense)	2,460			(226		)	1,576			(1,400		)	2,410
Interest charges	49,227			14,728			1,295			(1,397		)	63,853
Income from continuing operations before income taxes	222,756			50,559			30,342			—			303,657
Income tax expense	83,473			17,924			12,572			—			113,969
Income from continuing operations	139,283			32,635			17,770			—			189,688
Income from discontinued operations, net of tax	7,202			—			—			—			7,202
Net income	$	146,485		$	32,635		$	17,770		$	—		$	196,890
Capital expenditures	$	277,336		$	111,039		$	742		$	—		$	389,117
Balance sheet information at March 31, 2014 and September 30, 2013 by segment is presented in the following tables.
	31-Mar-14
	Natural			Regulated			Nonregulated			Eliminations			Consolidated
	Gas			Transmission
	Distribution			and Storage
	(In thousands)
ASSETS
Property, plant and equipment, net	$	4,889,160		$	1,322,441		$	58,382		$	—		$	6,269,983
Investment in subsidiaries	908,939			—			(2,096		)	(906,843		)	—
Current assets
Cash and cash equivalents	73,165			—			63,575			—			136,740
Assets from risk management activities	58,746			—			7,940			—			66,686
Other current assets	609,806			14,363			610,515			(378,949		)	855,735
Intercompany receivables	786,428			—			—			(786,428		)	—
Total current assets	1,528,145			14,363			682,030			(1,165,377		)	1,059,161
Goodwill	574,190			132,462			34,711			—			741,363
Noncurrent assets from risk management activities	30,665			—			8,910			—			39,575
Deferred charges and other assets	350,362			19,585			7,587			—			377,534
	$	8,281,461		$	1,488,851		$	789,524		$	(2,072,220	)	$	8,487,616
CAPITALIZATION AND LIABILITIES
Shareholders’ equity	$	3,124,761		$	439,977		$	468,962		$	(908,939	)	$	3,124,761
Long-term debt	1,955,829			—			—			—			1,955,829
Total capitalization	5,080,590			439,977			468,962			(908,939		)	5,080,590
Current liabilities
Current maturities of long-term debt	500,000			—			—			—			500,000
Short-term debt	343,000			—			—			(343,000		)	—
Other current liabilities	658,106			13,654			225,485			(33,853		)	863,392
Intercompany payables	—			708,046			78,382			(786,428		)	—
Total current liabilities	1,501,106			721,700			303,867			(1,163,281		)	1,363,392
Deferred income taxes	943,831			324,879			14,841			—			1,283,551
Regulatory cost of removal obligation	358,262			—			—			—			358,262
Pension and postretirement liabilities	360,851			—			—			—			360,851
Deferred credits and other liabilities	36,821			2,295			1,854			—			40,970
	$	8,281,461		$	1,488,851		$	789,524		$	(2,072,220	)	$	8,487,616
	30-Sep-13
	Natural			Regulated			Nonregulated			Eliminations			Consolidated
	Gas			Transmission
	Distribution			and Storage
	(In thousands)
ASSETS
Property, plant and equipment, net	$	4,719,873		$	1,249,767		$	61,015		$	—		$	6,030,655
Investment in subsidiaries	831,136			—			(2,096		)	(829,040		)	—
Current assets
Cash and cash equivalents	4,237			—			61,962			—			66,199
Assets from risk management activities	1,837			—			10,129			—			11,966
Other current assets	428,366			11,709			452,126			(293,233		)	598,968
Intercompany receivables	783,738			—			—			(783,738		)	—
Total current assets	1,218,178			11,709			524,217			(1,076,971		)	677,133
Goodwill	574,190			132,462			34,711			—			741,363
Noncurrent assets from risk management activities	109,354			—			—			—			109,354
Deferred charges and other assets	347,687			19,227			8,849			—			375,763
	$	7,800,418		$	1,413,165		$	626,696		$	(1,906,011	)	$	7,934,268
CAPITALIZATION AND LIABILITIES
Shareholders’ equity	$	2,580,409		$	396,421		$	434,715		$	(831,136	)	$	2,580,409
Long-term debt	2,455,671			—			—			—			2,455,671
Total capitalization	5,036,080			396,421			434,715			(831,136		)	5,036,080
Current liabilities
Current maturities of long-term debt	—			—			—			—			—
Short-term debt	645,984			—			—			(278,000		)	367,984
Liabilities from risk management activities	1,543			—			—			—			1,543
Other current liabilities	491,681			20,288			110,306			(13,316		)	608,959
Intercompany payables	—			712,768			70,970			(783,738		)	—
Total current liabilities	1,139,208			733,056			181,276			(1,075,054		)	978,486
Deferred income taxes	871,360			283,554			8,960			179			1,164,053
Regulatory cost of removal obligation	359,299			—			—			—			359,299
Pension and postretirement liabilities	358,787			—			—			—			358,787
Deferred credits and other liabilities	35,684			134			1,745			—			37,563
	$	7,800,418		$	1,413,165		$	626,696		$	(1,906,011	)	$	7,934,268

Earnings_Per_Share

Earnings Per Share	6 Months Ended
	Mar. 31, 2014
Earnings Per Share [Abstract]	'
Earnings Per Share	'
	Earnings Per Share
	We use the two-class method of computing earnings per share because we have participating securities in the form of non-vested restricted stock units with a nonforfeitable right to dividend equivalents, for which vesting is predicated solely on the passage of time. The calculation of earnings per share using the two-class method excludes income attributable to these participating securities from the numerator and excludes the dilutive impact of those shares from the denominator. Basic and diluted earnings per share for the three and six months ended March 31, 2014 and 2013 are calculated as follows:
		Three Months Ended				Six Months Ended
		March 31				March 31
		2014		2013		2014		2013
		(In thousands, except per share amounts)
	Basic Earnings Per Share from continuing operations
	Income from continuing operations	$	133,367	$	112,340	$	220,383	$	189,688
	Less: Income from continuing operations allocated to participating securities	337		304		578		634
	Income from continuing operations available to common shareholders	$	133,030	$	112,036	$	219,805	$	189,054
	Basic weighted average shares outstanding	95,264		90,530		93,049		90,445
	Income from continuing operations per share — Basic	$	1.4	$	1.24	$	2.36	$	2.09
	Basic Earnings Per Share from discontinued operations
	Income from discontinued operations	$	—	$	4,085	$	—	$	7,202
	Less: Income from discontinued operations allocated to participating securities	—		11		—		24
	Income from discontinued operations available to common shareholders	$	—	$	4,074	$	—	$	7,178
	Basic weighted average shares outstanding	95,264		90,530		93,049		90,445
	Income from discontinued operations per share — Basic	$	—	$	0.04	$	—	$	0.08
	Net income per share — Basic	$	1.4	$	1.28	$	2.36	$	2.17
		Three Months Ended				Six Months Ended
		March 31				March 31
		2014		2013		2014		2013
		(In thousands, except per share amounts)
	Diluted Earnings Per Share from continuing operations
	Income from continuing operations available to common shareholders	$	133,030	$	112,036	$	219,805	$	189,054
	Effect of dilutive stock options and other shares	2		2		4		5
	Income from continuing operations available to common shareholders	$	133,032	$	112,038	$	219,809	$	189,059
	Basic weighted average shares outstanding	95,264		90,530		93,049		90,445
	Additional dilutive stock options and other shares	927		962		927		961
	Diluted weighted average shares outstanding	96,191		91,492		93,976		91,406
	Income from continuing operations per share — Diluted	$	1.38	$	1.23	$	2.34	$	2.07
	Diluted Earnings Per Share from discontinued operations
	Income from discontinued operations available to common shareholders	$	—	$	4,074	$	—	$	7,178
	Effect of dilutive stock options and other shares	—		—		—		—
	Income from discontinued operations available to common shareholders	$	—	$	4,074	$	—	$	7,178
	Basic weighted average shares outstanding	95,264		90,530		93,049		90,445
	Additional dilutive stock options and other shares	927		962		927		961
	Diluted weighted average shares outstanding	96,191		91,492		93,976		91,406
	Income from discontinued operations per share — Diluted	$	—	$	0.04	$	—	$	0.08
	Net income per share — Diluted	$	1.38	$	1.27	$	2.34	$	2.15
	There were no out-of-the-money stock options excluded from the computation of diluted earnings per share for the three and six months ended March 31, 2014 and 2013 as their exercise price was less than the average market price of the common stock during those periods.
	2014 Equity Offering
	On February 18, 2014, we completed the public offering of 9,200,000 shares of our common stock including the underwriters’ exercise of their overallotment option of 1,200,000 shares under our existing shelf registration statement. The offering was priced at $44.00 and generated net proceeds of $390.2 million, which were used to repay short-term debt outstanding under our $950 million commercial paper program, to fund infrastructure spending primarily to enhance the safety and reliability of our system and for general corporate purposes.
	2011 Share Repurchase Program
	We did not repurchase any shares during the six months ended March 31, 2014 and 2013 under our 2011 share repurchase program.

Debt

Debt	6 Months Ended
	Mar. 31, 2014
Debt Disclosure [Abstract]	'
Debt	'
	Debt
	The nature and terms of our debt instruments and credit facilities are described in detail in Note 5 to the consolidated financial statements in our Annual Report on Form 10-K for the fiscal year ended September 30, 2013. Except as noted below, there were no material changes in the terms of our debt instruments during the six months ended March 31, 2014.
	Long-term debt
	Long-term debt at March 31, 2014 and September 30, 2013 consisted of the following:
		31-Mar-14		30-Sep-13
		(In thousands)
	Unsecured 4.95% Senior Notes, due October 2014	$	500,000	$	500,000
	Unsecured 6.35% Senior Notes, due 2017	250,000		250,000
	Unsecured 8.50% Senior Notes, due 2019	450,000		450,000
	Unsecured 5.95% Senior Notes, due 2034	200,000		200,000
	Unsecured 5.50% Senior Notes, due 2041	400,000		400,000
	Unsecured 4.15% Senior Notes, due 2043	500,000		500,000
	Medium-term note Series A, 1995-1, 6.67%, due 2025	10,000		10,000
	Unsecured 6.75% Debentures, due 2028	150,000		150,000
	Total long-term debt	2,460,000		2,460,000
	Less:
	Original issue discount on unsecured senior notes and debentures	4,171		4,329
	Current maturities	500,000		—
		$	1,955,829	$	2,455,671
	Short-term debt
	Our short-term debt is utilized to fund ongoing working capital needs, such as our seasonal requirements for gas supply, general corporate liquidity and capital expenditures. Our short-term borrowing requirements are affected primarily by the seasonal nature of the natural gas business. Changes in the price of natural gas and the amount of natural gas we need to supply our customers’ needs could significantly affect our borrowing requirements. Our short-term borrowings typically reach their highest levels in the winter months.
	We currently finance our short-term borrowing requirements through a combination of a $950 million commercial paper program, four committed revolving credit facilities and one uncommitted revolving credit facility with third-party lenders. These facilities provide approximately $1 billion of working capital funding. At March 31, 2014, there were no short-term debt borrowings outstanding. At September 30, 2013, there was a total of $368.0 million outstanding under our commercial paper program.
	Regulated Operations
	We fund our regulated operations as needed, primarily through our commercial paper program and three committed revolving credit facilities with third-party lenders that provide approximately $985 million of working capital funding, including a five-year $950 million unsecured facility with an accordion feature, which, if utilized would increase the borrowing capacity to $1.2 billion, a $25 million unsecured facility and a $10 million unsecured revolving credit facility, which is used primarily to issue letters of credit. Due to outstanding letters of credit, the total amount available to us under our $10 million revolving credit facility was $4.1 million at March 31, 2014.
	In addition to these third-party facilities, our regulated operations have a $500 million intercompany revolving credit facility with AEH, which bears interest at the lower of (i) the Eurodollar rate under the five-year revolving credit facility or (ii) the rate outstanding under the commercial paper program. Applicable state regulatory commissions have approved our use of this facility through December 31, 2014.
	Nonregulated Operations
	Atmos Energy Marketing, LLC (AEM), which is wholly owned by AEH, had two $25 million 364-day bilateral credit facilities that expired in December 2013. In December 2013, the $25 million 364-day uncommitted bilateral facility was extended to December 2014. In January 2014, this facility was amended to temporarily increase the amount available to $50 million to address the increase in volumes and prices driven by colder than normal weather this winter-heating season.  The maximum available under the facility will return to $25 million on June 30, 2014. The $25 million committed bilateral facility was replaced with a $15 million committed 364-day bilateral credit facility in December 2013. These facilities are used primarily to issue letters of credit. Due to outstanding letters of credit, the total amount available to us under these bilateral credit facilities was $33.7 million at March 31, 2014.
	AEH has a $500 million intercompany demand credit facility with AEC. This facility bears interest at a rate equal to the one-month LIBOR rate plus 3.00 percent or (ii) the rate for AEM's borrowings under its committed credit facility plus 0.75 percent. Applicable state regulatory commissions have approved our use of this facility through December 31, 2014.
	Shelf Registration
	We filed a shelf registration statement with the Securities and Exchange Commission (SEC) on March 28, 2013 that originally permitted us to issue a total of $1.75 billion in common stock and/or debt securities. On February 18, 2014, we completed the public offering of 9,200,000 shares of our common stock, which generated net proceeds of $390.2 million. As of March 31, 2014, $1.35 billion of securities remained available for issuance under the shelf registration statement until March 28, 2016.
	Debt Covenants
	The availability of funds under our regulated credit facilities is subject to conditions specified in the respective credit agreements, all of which we currently satisfy. These conditions include our compliance with financial covenants and the continued accuracy of representations and warranties contained in these agreements. We are required by the financial covenants in each of these facilities to maintain, at the end of each fiscal quarter, a ratio of total debt to total capitalization of no greater than 70 percent. At March 31, 2014, our total-debt-to-total-capitalization ratio, as defined in the agreements, was 46 percent. In addition, both the interest margin and the fee that we pay on unused amounts under certain of these facilities are subject to adjustment depending upon our credit ratings.
	In addition to these financial covenants, our credit facilities and public indentures contain usual and customary covenants for our business, including covenants substantially limiting liens, substantial asset sales and mergers.
	Additionally, our public debt indentures relating to our senior notes and debentures, as well as certain of our revolving credit agreements, each contain a default provision that is triggered if outstanding indebtedness arising out of any other credit agreements in amounts ranging from in excess of $15 million to in excess of $100 million becomes due by acceleration or is not paid at maturity.
	We were in compliance with all of our debt covenants as of March 31, 2014. If we were unable to comply with our debt covenants, we would likely be required to repay our outstanding balances on demand, provide additional collateral or take other corrective actions.

Interim_Pension_and_Other_Post

Interim Pension and Other Postretirement Benefit Plan Information	6 Months Ended
	Mar. 31, 2014
General Discussion of Pension and Other Postretirement Benefits [Abstract]	'
Interim Pension and Postretirement Benefit Plans	'
	Interim Pension and Other Postretirement Benefit Plan Information
	The components of our net periodic pension cost for our pension and other postretirement benefit plans for the three and six months ended March 31, 2014 and 2013 are presented in the following table. Most of these costs are recoverable through our gas distribution rates; however, a portion of these costs is capitalized into our gas distribution rate base. The remaining costs are recorded as a component of operation and maintenance expense. On October 2, 2013, due to the retirement of one of our executive officers, we recognized a settlement loss of $4.5 million associated with our Supplemental Executive Benefits Plan (SEBP). In association with the retirement, on October 2, 2013, we made a $16.8 million benefit payment from the SEBP.
		Three Months Ended March 31
		Pension Benefits								Other Benefits
		2014				2013				2014			2013
		(In thousands)
	Components of net periodic pension cost:
	Service cost	$	4,738			$	5,203			$	4,196		$	4,700
	Interest cost	6,824				6,023				3,988			3,241
	Expected return on assets	(5,900		)		(5,738		)		(1,292		)	(997		)
	Amortization of transition obligation	—				—				68			270
	Amortization of prior service credit	(34		)		(36		)		(362		)	(363		)
	Amortization of actuarial loss	3,930				5,562				158			1,049
	Net periodic pension cost	$	9,558			$	11,014			$	6,756		$	7,900
		Six Months Ended March 31
		Pension Benefits								Other Benefits
		2014				2013				2014			2013
		(In thousands)
	Components of net periodic pension cost:
	Service cost	$	9,476			$	10,405			$	8,392		$	9,400
	Interest cost	13,648				12,048				7,976			6,482
	Expected return on assets	(11,801		)		(11,477		)		(2,584		)	(1,994		)
	Amortization of transition obligation	—				—				136			540
	Amortization of prior service credit	(68		)		(71		)		(725		)	(725		)
	Amortization of actuarial loss	7,862				11,123				316			2,098
	Settlement loss	4,539				—				—			—
	Net periodic pension cost	$	23,656			$	22,028			$	13,511		$	15,801
	The assumptions used to develop our net periodic pension cost for the three and six months ended March 31, 2014 and 2013 are as follows:
		Pension Benefits						Other Benefits
		2014			2013			2014			2013
	Discount rate	4.95	%		4.04	%		4.95	%		4.04	%
	Rate of compensation increase	3.5	%		3.5	%		N/A			N/A
	Expected return on plan assets	7.25	%		7.75	%		4.6	%		4.7	%
	The discount rate used to compute the present value of a plan’s liabilities generally is based on rates of high-grade corporate bonds with maturities similar to the average period over which the benefits will be paid. Generally, our funding policy has been to contribute annually an amount in accordance with the requirements of the Employee Retirement Income Security Act of 1974. In accordance with the Pension Protection Act of 2006 (PPA), we determined the funded status of our plans as of January 1, 2014. During the first six months of fiscal 2014, we contributed $9.1 million to our defined benefit plans and we anticipate contributing approximately $10 million to $35 million during fiscal 2014.
	We contributed $11.6 million to our other post-retirement benefit plans during the six months ended March 31, 2014. We expect to contribute a total of approximately $20 million to $25 million to these plans during fiscal 2014.

Commitments_and_Contingencies

Commitments and Contingencies	6 Months Ended
	Mar. 31, 2014
Commitments and Contingencies Disclosure [Abstract]	'
Commitments and Contingencies	'
	Commitments and Contingencies
	Litigation and Environmental Matters
	With respect to the specific litigation and environmental-related matters or claims that were disclosed in Note 10 to the financial statements in our Annual Report on Form 10-K for the fiscal year ended September 30, 2013, except as noted below, there were no material changes in the status of such litigation and environmental-related matters or claims during the six months ended March 31, 2014.
	Kentucky Litigation
	Since April 2009, Atmos Energy and two subsidiaries of AEH, Atmos Energy Marketing, LLC (AEM) and Atmos Gathering Company, LLC (AGC) (collectively, the Atmos Entities), have been involved in a lawsuit filed in the Circuit Court of Edmonson County, Kentucky related to our Park City Gathering Project. The dispute which gave rise to the litigation involves the amount of royalties due from a third party producer to landowners (who own the mineral rights) for natural gas produced from the landowners’ properties. The third party producer was operating pursuant to leases between the landowners and certain investors/working interest owners. The third party producer filed a petition in bankruptcy, which was subsequently dismissed due to the lack of meaningful assets to reorganize or liquidate.
	Although certain Atmos Energy companies entered into contracts with the third party producer to gather, treat and ultimately sell natural gas produced from the landowners’ properties, no Atmos Energy company had a contractual relationship with the landowners or the investors/working interest owners. After the lawsuit was filed, the landowners were successful in terminating for non-payment of royalties the leases related to the production of natural gas from their properties. Subsequent to termination, the investors/working interest owners under such leases filed additional claims against us for the termination of the leases.
	During the trial, the landowners and the investors/working interest owners requested an award of compensatory damages plus punitive damages against us. On December 17, 2010, the jury returned a verdict in favor of the landowners and investor/working interest owners and awarded compensatory damages of $3.8 million and punitive damages of $27.5 million payable by Atmos Energy and the two AEH subsidiaries.
	A hearing was held on February 28, 2011 to hear a number of motions, including a motion to dismiss the jury verdict and a motion for a new trial. The motions to dismiss the jury verdict and for a new trial were denied. However, the total punitive damages award was reduced from $27.5 million to $24.7 million. On October 17, 2011, we filed our brief of appellants with the Kentucky Court of Appeals, appealing the verdict of the trial court. The appellees in this case subsequently filed their appellees’ brief with the Court of Appeals on January 16, 2012, with our reply brief being filed with the Court of Appeals on March 19, 2012. Oral arguments were held in the case on August 27, 2012.
	In an opinion handed down on January 25, 2013, the Court of Appeals overturned the $28.5 million jury verdict returned against the Atmos Entities. In a unanimous decision by a three-judge panel, the Court of Appeals reversed the claims asserted by the landowners and investors/working interest owners. The Court of Appeals concluded that all of such claims that the Atmos Entities appealed should have been dismissed by the trial court as a matter of law. The Court of Appeals let stand the jury verdict on one claim that Atmos Energy and our subsidiaries chose not to appeal, which was a trespass claim. The jury had awarded a total of $10,000 in compensatory damages to one landowner on that claim. The Court of Appeals vacated all of the other damages awarded by the jury and remanded the case to the trial court for a new trial, solely on the issue of whether punitive damages should be awarded to that landowner and, if so, in what amount.
	The investors/working interest owners, on February 25, 2013, and the landowners, on March 19, 2013, each filed with the Supreme Court of Kentucky, separate motions for discretionary review of the opinion of the Court of Appeals. We filed responses to the motions. The Kentucky Supreme Court denied the motions for discretionary review on  February 12, 2014.  The decision of the Court of Appeals became final on February 21, 2014.  Atmos has filed a motion with the trial court for entry of judgment dismissing all claims against it, except for the trespass claim.  Atmos' motion seeks a ruling by the trial court that the remaining landowner is not entitled to any punitive damages on that claim.  That motion is currently scheduled to be heard on May 19, 2014.
	We had previously accrued what we believed to be an adequate amount for the anticipated resolution of this matter. This accrual was reversed during the second fiscal quarter as the appellate process in this case has been completed.
	In addition, in a related matter, on July 12, 2011, the Atmos Entities filed a lawsuit in the United States District Court, Western District of Kentucky, Atmos Energy Corporation et al.vs. Resource Energy Technologies, LLC and Robert Thorpe and John F. Charles, against the third party producer and its affiliates to recover all costs, including attorneys’ fees, incurred by the Atmos Entities, which are associated with the defense and appeal of the case discussed above as well as for all damages awarded to the plaintiffs in such case against the Atmos Entities. The total amount of damages being claimed in the lawsuit is “open-ended” since the appellate process and related costs are ongoing. This lawsuit is based upon the indemnification provisions agreed to by the third party producer in favor of Atmos Gathering that are contained in an agreement entered into between Atmos Gathering and the third party producer in May 2009. The defendants filed a motion to dismiss the case on August 25, 2011, with Atmos Energy filing a brief in response to such motion on September 19, 2011. On March 27, 2012 the court denied the motion to dismiss. Discovery has been completed, and dispositive motions are due on June 30, 2014.  This case is scheduled for trial beginning October 6, 2014.
	Tennessee Business License Tax
	Atmos Energy, through its affiliate, AEM, has been involved in a dispute with the Tennessee Department of Revenue (TDOR) regarding sales business tax audits over a period of several years. The cumulative assessment approximated $12 million as of March 31, 2014, which AEM has challenged. We had previously accrued in prior years what we believed to be an adequate amount for the anticipated resolution of this matter. With respect to certain issues, AEM and the TDOR filed competing Partial Motions for Summary Judgment with the Chancery Court. On August 2, 2013, the Chancery Court granted the TDOR's Partial Motion for Summary Judgment and denied AEM's Partial Motion for Summary Judgment. A filing deadline was set for filing any cross motions for partial summary judgment as to the remaining issues. On May 2, 2014, the Company and the TDOR executed an agreed order of dismissal with prejudice whereby AEM agreed to pay $6.2 million to resolve all business tax-related liabilities outstanding through September 2014. The order of dismissal will become effective upon approval of the Chancery Court.
	We are a party to other litigation and environmental-related matters or claims that have arisen in the ordinary course of our business. While the results of such litigation and response actions to such environmental-related matters or claims cannot be predicted with certainty, we continue to believe the final outcome of such litigation and matters or claims will not have a material adverse effect on our financial condition, results of operations or cash flows.
	Purchase Commitments
	AEH has commitments to purchase physical quantities of natural gas under contracts indexed to the forward NYMEX strip or fixed price contracts. At March 31, 2014, AEH was committed to purchase 100.5 Bcf within one year, 15.9 Bcf within one to three years and 0.8 Bcf after three years under indexed contracts. AEH is committed to purchase 9.5 Bcf within one year and 0.8 Bcf within one to three years under fixed price contracts with prices ranging from $3.75 to $6.36 per Mcf. Purchases under these contracts totaled $621.1 million and $327.8 million for the three months ended March 31, 2014 and 2013 and $971.3 million and $617.3 million for the six months ended March 31, 2014 and 2013.
	Our natural gas distribution divisions maintain supply contracts with several vendors that generally cover a period of up to one year. Commitments for estimated base gas volumes are established under these contracts on a monthly basis at contractually negotiated prices. Commitments for incremental daily purchases are made as necessary during the month in accordance with the terms of the individual contract.
	Our nonregulated segment maintains long-term contracts related to storage and transportation. The estimated contractual demand fees for contracted storage and transportation under these contracts are detailed in our Annual Report on Form 10-K for the fiscal year ended September 30, 2013. There were no material changes to the estimated storage and transportation fees for the six months ended March 31, 2014.
	Regulatory Matters
	Various regulatory agencies, including the SEC and the Commodities Futures Trading Commission, continue to adopt regulations implementing many of the provisions of the Dodd-Frank Act of 2010. We continue to enact new procedures and modify existing business practices and contractual arrangements to comply with such regulations.  Additional rulemakings are pending which we believe will result in new reporting and disclosure obligations. The costs associated with hedging certain risks inherent in our business may be further increased when these expected additional regulations are adopted.
	As of March 31, 2014, rate cases were in progress in our Kansas, Kentucky, Virginia and West Texas service areas, annual rate filing mechanisms were in progress in Louisiana and Mid-Tex and infrastructure program filings were in progress in Mid-Tex and Atmos Pipeline–Texas. These regulatory proceedings are discussed in further detail below in Management’s Discussion and Analysis — Recent Ratemaking Developments.

Financial_Instruments

Financial Instruments	6 Months Ended
	Mar. 31, 2014
Derivative Instruments and Hedging Activities Disclosure [Abstract]	'
Financial Instruments	'
	Financial Instruments
	We use financial instruments to mitigate commodity price risk and interest rate risk. The objectives and strategies for using financial instruments have been tailored to our regulated and nonregulated businesses. The accounting for these financial instruments is fully described in Note 2 to the consolidated financial statements in our Annual Report on Form 10-K for the fiscal year ended September 30, 2013. During the six months ended March 31, 2014 there were no changes in our objectives, strategies and accounting for these financial instruments. Currently, we utilize financial instruments in our natural gas distribution and nonregulated segments. We currently do not manage commodity price risk with financial instruments in our regulated transmission and storage segment.
	Our financial instruments do not contain any credit-risk-related or other contingent features that could cause payments to be accelerated when our financial instruments are in net liability positions.
	Regulated Commodity Risk Management Activities
	Although our purchased gas cost adjustment mechanisms essentially insulate our natural gas distribution segment from commodity price risk, our customers are exposed to the effects of volatile natural gas prices. We manage this exposure through a combination of physical storage, fixed-price forward contracts and financial instruments, primarily over-the-counter swap and option contracts, in an effort to minimize the impact of natural gas price volatility on our customers during the winter heating season.
	Our natural gas distribution gas supply department is responsible for executing this segment’s commodity risk management activities in conformity with regulatory requirements. In jurisdictions where we are permitted to mitigate commodity price risk through financial instruments, the relevant regulatory authorities may establish the level of heating season gas purchases that can be hedged. Historically, if the regulatory authority does not establish this level, we seek to hedge between 25 and 50 percent of anticipated heating season gas purchases using financial instruments. For the 2013-2014 heating season (generally October through March), in the jurisdictions where we are permitted to utilize financial instruments, we hedged approximately 32 percent, or 24.6 Bcf of the winter flowing gas requirements. We have not designated these financial instruments as hedges for accounting purposes.
	The costs associated with the gains and losses arising from the use of financial instruments to mitigate commodity price risk are included in our purchased gas cost adjustment mechanisms in accordance with regulatory requirements. Therefore, changes in the fair value of these financial instruments are initially recorded as a component of deferred gas costs and recognized in the consolidated statement of income as a component of purchased gas cost when the related costs are recovered through our rates and recognized in revenue in accordance with applicable authoritative accounting guidance. Accordingly, there is no earnings impact on our natural gas distribution segment as a result of the use of financial instruments.
	Nonregulated Commodity Risk Management Activities
	Our nonregulated operations aggregate and purchase gas supply, arrange transportation and/or storage logistics and ultimately deliver gas to our customers at competitive prices. To provide these services, we utilize proprietary and customer-owned transportation and storage assets to provide the various services our customers request. In an effort to offset the demand fees paid to contract for storage capacity and to maximize the value of this capacity, AEH sells financial instruments to earn a gross profit margin through the arbitrage of pricing differences in various locations and by recognizing pricing differences that occur over time.
	As a result of these activities, our nonregulated segment is exposed to risks associated with changes in the market price of natural gas. We manage our exposure to such risks through a combination of physical storage and financial instruments, including futures, over-the-counter and exchange-traded options and swap contracts with counterparties. Future contracts provide the right, but not the obligation, to buy or sell the commodity at a fixed price. Option contracts provide the right, but not the requirement, to buy or sell the commodity at a fixed price. Swap contracts require receipt of payment for the commodity based on the difference between a fixed price and the market price on the settlement date.
	We use financial instruments, designated as cash flow hedges of anticipated purchases and sales at index prices, to mitigate the commodity price risk in our nonregulated operations associated with deliveries under fixed-priced forward contracts to deliver gas to customers. These financial instruments have maturity dates ranging from one to 49 months. We use financial instruments, designated as fair value hedges, to hedge our natural gas inventory used in asset optimization activities in our nonregulated segment.
	Our nonregulated operations also use storage swaps and futures to capture additional storage arbitrage opportunities that arise subsequent to the execution of the original fair value hedge associated with our physical natural gas inventory, basis swaps to insulate and protect the economic value of our fixed price and storage books and various over-the-counter and exchange-traded options. These financial instruments have not been designated as hedges for accounting purposes.
	Interest Rate Risk Management Activities
	We periodically manage interest rate risk by entering into financial instruments to effectively fix the Treasury yield component of the interest cost associated with anticipated financings.
	As of March 31, 2014, we had forward starting interest rate swaps to effectively fix the Treasury yield component associated with the anticipated issuance of $500 million and $250 million unsecured senior notes in fiscal 2015 and fiscal 2017, at 3.129% and 3.37%, which we designated as cash flow hedges at the time the agreements were executed. In April and May 2014, we entered into forward starting interest rate swaps to effectively fix the Treasury yield component associated with $250 million of the anticipated issuance of $450 million unsecured senior notes in fiscal 2019 at 3.95%, which we designated as cash flow hedges at the time the agreements were executed. Accordingly, unrealized gains and losses associated with the forward starting interest rate swaps are being recorded as a component of accumulated other comprehensive income (loss). When the forward starting interest rate swaps settle, the realized gain or loss will be recorded as a component of accumulated other comprehensive income (loss) and recognized as a component of interest expense over the life of the related financing arrangement. Hedge ineffectiveness to the extent incurred is reported as a component of interest expense.
	In prior years, we entered into Treasury lock agreements to fix the Treasury yield component of the interest cost of financing various issuances of long-term debt and senior notes. The gains and losses realized upon settlement of these Treasury locks were recorded as a component of accumulated other comprehensive income (loss) when they were settled and are being recognized as a component of interest expense over the life of the associated notes from the date of settlement. As of March 31, 2014, the remaining amortization periods for the settled Treasury locks extend through fiscal 2043.
	Quantitative Disclosures Related to Financial Instruments
	The following tables present detailed information concerning the impact of financial instruments on our condensed consolidated balance sheet and income statements.
	As of March 31, 2014, our financial instruments were comprised of both long and short commodity positions. A long position is a contract to purchase the commodity, while a short position is a contract to sell the commodity. As of March 31, 2014, we had net long/(short) commodity contracts outstanding in the following quantities:
	Contract Type		Hedge Designation		Natural Gas			Nonregulated
					Distribution
					Quantity (MMcf)
	Commodity contracts		Fair Value		—			(5,770	)
			Cash Flow		—			21,795
			Not designated		8,428			45,975
					8,428			62,000
	Financial Instruments on the Balance Sheet
	The following tables present the fair value and balance sheet classification of our financial instruments by operating segment as of March 31, 2014 and September 30, 2013. The gross amounts of recognized assets and liabilities are netted within our unaudited Condensed Consolidated Balance Sheets to the extent that we have netting arrangements with the counterparties.
				Natural Gas Distribution								Nonregulated
		Balance Sheet Location		Assets				Liabilities				Assets				Liabilities
				(In thousands)
	31-Mar-14
	Designated As Hedges:
	Commodity contracts	Other current assets /		$	—			$	—			$	11,398			$	(6,849	)
		Other current liabilities
	Interest rate contracts	Other current assets /		54,093				—				—				—
		Other current liabilities
	Commodity contracts	Deferred charges and other assets /		—				—				557				(944		)
		Deferred credits and other liabilities
	Interest rate contracts	Deferred charges and other assets /		30,665				—				—				—
		Deferred credits and other liabilities
	Total			84,758				—				11,955				(7,793		)
	Not Designated As Hedges:
	Commodity contracts	Other current assets /		4,653				—				48,402				(56,065		)
		Other current liabilities
	Commodity contracts	Deferred charges and other assets /		—				—				34,017				(24,720		)
		Deferred credits and other liabilities
	Total			4,653				—				82,419				(80,785		)
	Gross Financial Instruments			89,411				—				94,374				(88,578		)
	Gross Amounts Offset on Consolidated Balance Sheet:
	Contract netting			—				—				(85,464		)		85,464
	Net Financial Instruments			89,411				—				8,910				(3,114		)
	Cash collateral			—				—				7,940				3,114
	Net Assets/Liabilities from Risk Management Activities			$	89,411			$	—			$	16,850			$	—
				Natural Gas Distribution								Nonregulated
		Balance Sheet Location		Assets				Liabilities				Assets				Liabilities
				(In thousands)
	30-Sep-13
	Designated As Hedges:
	Commodity contracts	Other current assets /		$	—			$	—			$	9,094			$	(12,173	)
		Other current liabilities
	Commodity contracts	Deferred charges and other assets /		—				—				416				(1,639		)
		Deferred credits and other liabilities
Interest rate contracts	Deferred charges and other assets /		107,512				—				—				—
	Deferred credits and other liabilities
Total			107,512				—				9,510				(13,812		)
Not Designated As Hedges:
Commodity contracts	Other current assets /		1,837				(1,543		)		65,388				(70,876		)
	Other current liabilities
Commodity contracts	Deferred charges and other assets /		1,842				—				40,982				(45,892		)
	Deferred credits and other liabilities
Total			3,679				(1,543		)		106,370				(116,768		)
Gross Financial Instruments			111,191				(1,543		)		115,880				(130,580		)
Gross Amounts Offset on Consolidated Balance Sheet:
Contract netting			—				—				(115,875		)		115,875
Net Financial Instruments			111,191				(1,543		)		5				(14,705		)
Cash collateral			—				—				10,124				14,705
Net Assets/Liabilities from Risk Management Activities			$	111,191			$	(1,543	)		$	10,129			$	—
Impact of Financial Instruments on the Income Statement
Hedge ineffectiveness for our nonregulated segment is recorded as a component of unrealized gross profit and primarily results from differences in the location and timing of the derivative instrument and the hedged item. Hedge ineffectiveness could materially affect our results of operations for the reported period. For the three months ended March 31, 2014 and 2013 we recognized a gain (loss) arising from fair value and cash flow hedge ineffectiveness of $(3.7) million and $1.7 million. For the six months ended March 31, 2014 and 2013, we recognized a gain arising from fair value and cash flow hedge ineffectiveness of $1.4 million and $17.8 million. Additional information regarding ineffectiveness recognized in the income statement is included in the tables below.
Fair Value Hedges
The impact of our nonregulated commodity contracts designated as fair value hedges and the related hedged item on our condensed consolidated income statement for the three and six months ended March 31, 2014 and 2013 is presented below.
	Three Months Ended
	March 31
	2014				2013
	(In thousands)
Commodity contracts	$	3,587			$	(17,846	)
Fair value adjustment for natural gas inventory designated as the hedged item	(7,450		)		19,586
Total (increase) decrease in purchased gas cost	$	(3,863	)		$	1,740
The (increase) decrease in purchased gas cost is comprised of the following:
Basis ineffectiveness	$	(579	)		$	1,458
Timing ineffectiveness	(3,284		)		282
	$	(3,863	)		$	1,740
	Six Months Ended
	March 31
	2014				2013
	(In thousands)
Commodity contracts	$	(4,974	)		$	(10,532	)
Fair value adjustment for natural gas inventory designated as the hedged item	6,329				28,405
Total decrease in purchased gas cost	$	1,355			$	17,873
The (increase) decrease in purchased gas cost is comprised of the following:
Basis ineffectiveness	$	(1,199	)		$	1,218
Timing ineffectiveness	2,554				16,655
	$	1,355			$	17,873
Basis ineffectiveness arises from natural gas market price differences between the locations of the hedged inventory and the delivery location specified in the hedge instruments. Timing ineffectiveness arises due to changes in the difference between the spot price and the futures price, as well as the difference between the timing of the settlement of the futures and the valuation of the underlying physical commodity. As the commodity contract nears the settlement date, spot-to-forward price differences should converge, which should reduce or eliminate the impact of this ineffectiveness on purchased gas cost. To the extent that the Company’s natural gas inventory does not qualify as a hedged item in a fair-value hedge, or has not been designated as such, the natural gas inventory is valued at the lower of cost or market.
Cash Flow Hedges
The impact of cash flow hedges on our condensed consolidated income statements for the three and six months ended March 31, 2014 and 2013 is presented below. Note that this presentation does not reflect the financial impact arising from the hedged physical transaction. Therefore, this presentation is not indicative of the economic gross profit we realized when the underlying physical and financial transactions were settled.
	Three Months Ended March 31, 2014
	Natural				Nonregulated				Consolidated
	Gas
	Distribution
	(In thousands)
Gain reclassified from AOCI for effective portion of commodity contracts	$	—			$	7,184			$	7,184
Gain arising from ineffective portion of commodity contracts	—				142				142
Total impact on purchased gas cost	—				7,326				7,326
Net loss on settled interest rate agreements reclassified from AOCI into interest expense	(1,057		)		—				(1,057		)
Total Impact from Cash Flow Hedges	$	(1,057	)		$	7,326			$	6,269
	Three Months Ended March 31, 2013
	Natural				Nonregulated				Consolidated
	Gas
	Distribution
	(In thousands)
Loss reclassified from AOCI for effective portion of commodity contracts	$	—			$	(5,199	)		$	(5,199	)
Loss arising from ineffective portion of commodity contracts	—				(83		)		(83		)
Total impact on purchased gas cost	—				(5,282		)		(5,282		)
Net loss on settled interest rate agreements reclassified from AOCI into interest expense	(873		)		—				(873		)
Total Impact from Cash Flow Hedges	$	(873	)		$	(5,282	)		$	(6,155	)
	Six Months Ended March 31, 2014
	Natural				Nonregulated				Consolidated
	Gas
	Distribution
	(In thousands)
Gain reclassified from AOCI for effective portion of commodity contracts	$	—			$	4,574			$	4,574
Gain arising from ineffective portion of commodity contracts	—				24				24
Total impact on purchased gas cost	—				4,598				4,598
Loss on settled interest rate agreements reclassified from AOCI into interest expense	(2,115		)		—				(2,115		)
Total Impact from Cash Flow Hedges	$	(2,115	)		$	4,598			$	2,483
	Six Months Ended March 31, 2013
	Natural Gas				Nonregulated				Consolidated
	Distribution
	(In thousands)
Loss reclassified from AOCI for effective portion of commodity contracts	$	—			$	(10,359	)		$	(10,359	)
Loss arising from ineffective portion of commodity contracts	—				(102		)		(102		)
Total impact on purchased gas cost	—				(10,461		)		(10,461		)
Loss on settled interest rate agreements reclassified from AOCI into interest expense	(1,375		)		—				(1,375		)
Total Impact from Cash Flow Hedges	$	(1,375	)		$	(10,461	)		$	(11,836	)
The following table summarizes the gains and losses arising from hedging transactions that were recognized as a component of other comprehensive income (loss), net of taxes, for the three and six months ended March 31, 2014 and 2013. The amounts included in the table below exclude gains and losses arising from ineffectiveness because those amounts are immediately recognized in the income statement as incurred.
	Three Months Ended								Six Months Ended
	March 31								March 31
	2014				2013				2014				2013
	(In thousands)
Increase (decrease) in fair value:
Interest rate agreements	$	(27,718	)		$	22,955			$	(14,448	)		$	34,900
Forward commodity contracts	5,483				5,666				11,709				2,153
Recognition of (gains) losses in earnings due to settlements:
Interest rate agreements	671				554				1,343				873
Forward commodity contracts	(4,382		)		3,172				(2,790		)		6,320
Total other comprehensive income (loss) from hedging, net of tax(1)	$	(25,946	)		$	32,347			$	(4,186	)		$	44,246
(1)	Utilizing an income tax rate ranging from 37 percent to 39 percent based on the effective rates in each taxing jurisdiction.
Deferred gains (losses) recorded in accumulated other comprehensive income (AOCI) associated with our interest rate agreements are recognized in earnings as they are amortized over the terms of the underlying debt instruments, while deferred gains (losses) associated with commodity contracts are recognized in earnings upon settlement. The following amounts, net of deferred taxes, represent the expected recognition in earnings of the deferred gains (losses) recorded in AOCI associated with our financial instruments, based upon the fair values of these financial instruments as of March 31, 2014. However, the table below does not include the expected recognition in earnings of our outstanding interest rate agreements as those instruments have not yet settled.
	Interest Rate				Commodity				Total
	Agreements				Contracts
	(In thousands)
Next twelve months	$	(1,830	)		$	4,682			$	2,852
Thereafter	(27,191		)		(239		)		(27,430		)
Total(1)	$	(29,021	)		$	4,443			$	(24,578	)
(1)	Utilizing an income tax rate ranging from 37 percent to 39 percent based on the effective rates in each taxing jurisdiction.
Financial Instruments Not Designated as Hedges
The impact of financial instruments that have not been designated as hedges on our condensed consolidated income statements for the three months ended March 31, 2014 and 2013 was an increase (decrease) in gross profit of $(9.3) million and $6.8 million. For the six months ended March 31, 2014 and 2013 gross profit increased (decreased) by $(10.1) million and $6.7 million. Note that this presentation does not reflect the expected gains or losses arising from the underlying physical transactions associated with these financial instruments. Therefore, this presentation is not indicative of the economic gross profit we realized when the underlying physical and financial transactions were settled.
As discussed above, financial instruments used in our natural gas distribution segment are not designated as hedges. However, there is no earnings impact on our natural gas distribution segment as a result of the use of these financial instruments because the gains and losses arising from the use of these financial instruments are recognized in the consolidated statement of income as a component of purchased gas cost when the related costs are recovered through our rates and recognized in revenue. Accordingly, the impact of these financial instruments is excluded from this presentation.

Accumulated_Other_Comprehensiv

Accumulated Other Comprehensive Income	6 Months Ended
	Mar. 31, 2014
Equity [Abstract]	'
Accumulated Other Comprehensive Income	'
	Accumulated Other Comprehensive Income
	We record deferred gains (losses) in accumulated other comprehensive income (AOCI) related to available-for-sale securities, interest rate agreement cash flow hedges and commodity contract cash flow hedges. Deferred gains (losses) for our available-for-sale securities and commodity contract cash flow hedges are recognized in earnings upon settlement, while deferred gains (losses) related to our interest rate agreement cash flow hedges are recognized in earnings as they are amortized. The following tables provide the components of our accumulated other comprehensive income (loss) balances, net of the related tax effects allocated to each component of other comprehensive income.
		Available-			Interest			Commodity			Total
		for-Sale			Rate			Contracts
		Securities			Agreement			Cash Flow
					Cash Flow			Hedges
					Hedges
		(In thousands)
	30-Sep-13	$	5,448		$	37,906		$	(4,476	)	$	38,878
	Other comprehensive income before reclassifications	2,369			(14,448		)	11,709			(370		)
	Amounts reclassified from accumulated other comprehensive income	(227		)	1,343			(2,790		)	(1,674		)
	Net current-period other comprehensive income	2,142			(13,105		)	8,919			(2,044		)
	31-Mar-14	$	7,590		$	24,801		$	4,443		$	36,834
		Available-			Interest			Commodity			Total
		for-Sale			Rate			Contracts
		Securities			Agreement			Cash Flow
					Cash Flow			Hedges
					Hedges
		(In thousands)
	30-Sep-12	$	5,661		$	(44,273	)	$	(8,995	)	$	(47,607	)
	Other comprehensive income before reclassifications	1,135			34,900			2,153			38,188
	Amounts reclassified from accumulated other comprehensive income	(1,708		)	873			6,320			5,485
	Net current-period other comprehensive income	(573		)	35,773			8,473			43,673
	31-Mar-13	$	5,088		$	(8,500	)	$	(522	)	$	(3,934	)
	The following tables detail reclassifications out of AOCI for the three and six months ended March 31, 2014 and 2013. Amounts in parentheses below indicate decreases to net income in the statement of income.
		Three Months Ended March 31, 2014
	Accumulated Other Comprehensive Income Components	Amount Reclassified from			Affected Line Item in the
		Accumulated Other			Statement of Income
		Comprehensive Income
		(In thousands)
	Available-for-sale securities	$	358		Operation and maintenance expense
		358			Total before tax
		(131		)	Tax expense
		$	227		Net of tax
	Cash flow hedges
	Interest rate agreements	$	(1,057	)	Interest charges
	Commodity contracts	7,184			Purchased gas cost
		6,127			Total before tax
		(2,416		)	Tax expense
		$	3,711		Net of tax
	Total reclassifications	$	3,938		Net of tax
		Three Months Ended March 31, 2013
	Accumulated Other Comprehensive Income Components	Amount Reclassified from			Affected Line Item in the
		Accumulated Other			Statement of Income
		Comprehensive Income
		(In thousands)
	Available-for-sale securities	$	2,689		Operation and maintenance expense
		2,689			Total before tax
		(981		)	Tax expense
		$	1,708		Net of tax
	Cash flow hedges
	Interest rate agreements	$	(873	)	Interest charges
	Commodity contracts	(5,201		)	Purchased gas cost
		(6,074		)	Total before tax
		2,348			Tax benefit
		$	(3,726	)	Net of tax
	Total reclassifications	$	(2,018	)	Net of tax
		Six Months Ended March 31, 2014
	Accumulated Other Comprehensive Income Components	Amount Reclassified from			Affected Line Item in  the
		Accumulated Other			Statement of Income
		Comprehensive Income
		(In thousands)
	Available-for-sale securities	$	358		Operation and maintenance expense
	358			Total before tax
	(131		)	Tax expense
	$	227		Net of tax
Cash flow hedges
Interest rate agreements	$	(2,115	)	Interest charges
Commodity contracts	4,574			Purchased gas cost
	2,459			Total before tax
	(1,012		)	Tax expense
	$	1,447		Net of tax
Total reclassifications	$	1,674		Net of tax
	Six Months Ended March 31, 2013
Accumulated Other Comprehensive Income Components	Amount Reclassified from			Affected Line Item in  the
	Accumulated Other			Statement of Income
	Comprehensive Income
	(In thousands)
Available-for-sale securities	$	2,689		Operation and maintenance expense
	2,689			Total before tax
	(981		)	Tax expense
	$	1,708		Net of tax
Cash flow hedges
Interest rate agreements	$	(1,375	)	Interest charges
Commodity contracts	(10,361		)	Purchased gas cost
	(11,736		)	Total before tax
	4,543			Tax benefit
	$	(7,193	)	Net of tax
Total reclassifications	$	(5,485	)	Net of tax

Fair_Value_Measurements

Fair Value Measurements	6 Months Ended
	Mar. 31, 2014
Fair Value Disclosures [Abstract]	'
Fair Value Measurements	'
	Fair Value Measurements
	We report certain assets and liabilities at fair value, which is defined as the price that would be received to sell an asset or paid to transfer a liability in an orderly transaction between market participants at the measurement date (exit price). We record cash and cash equivalents, accounts receivable and accounts payable at carrying value, which substantially approximates fair value due to the short-term nature of these assets and liabilities. For other financial assets and liabilities, we primarily use quoted market prices and other observable market pricing information to minimize the use of unobservable pricing inputs in our measurements when determining fair value. The methods used to determine fair value for our assets and liabilities are fully described in Note 2 to the financial statements in our Annual Report on Form 10-K for the fiscal year ended September 30, 2013. During the six months ended March 31, 2014, there were no changes in these methods.
	Fair value measurements also apply to the valuation of our pension and postretirement plan assets. Current accounting guidance requires employers to annually disclose information about fair value measurements of the assets of a defined benefit pension or other postretirement plan. The fair value of these assets is presented in Note 6 to the financial statements in our Annual Report on Form 10-K for the fiscal year ending September 30, 2013.
	Quantitative Disclosures
	Financial Instruments
	The classification of our fair value measurements requires judgment regarding the degree to which market data are observable or corroborated by observable market data. Authoritative accounting literature establishes a fair value hierarchy that prioritizes the inputs used to measure fair value based on observable and unobservable data. The hierarchy categorizes the inputs into three levels, with the highest priority given to unadjusted quoted prices in active markets for identical assets and liabilities (Level 1), with the lowest priority given to unobservable inputs (Level 3). The following tables summarize, by level within the fair value hierarchy, our assets and liabilities that were accounted for at fair value on a recurring basis as of March 31, 2014 and September 30, 2013. Assets and liabilities are categorized in their entirety based on the lowest level of input that is significant to the fair value measurement.
		Quoted		Significant		Significant			Netting and			31-Mar-14
		Prices in		Other		Other			Cash
		Active		Observable		Unobservable			Collateral(2)
		Markets		Inputs		Inputs
		(Level 1)		(Level 2)(1)		(Level 3)
		(In thousands)
	Assets:
	Financial instruments
	Natural gas distribution segment	$	—	$	89,411	$	—		$	—		$	89,411
	Nonregulated segment	89		94,285		—			(77,524		)	16,850
	Total financial instruments	89		183,696		—			(77,524		)	106,261
	Hedged portion of gas stored underground	23,570		—		—			—			23,570
	Available-for-sale securities
	Money market funds	—		2,904		—			—			2,904
	Registered investment companies	44,263		—		—			—			44,263
	Bonds	—		28,503		—			—			28,503
	Total available-for-sale securities	44,263		31,407		—			—			75,670
	Total assets	$	67,922	$	215,103	$	—		$	(77,524	)	$	205,501
	Liabilities:
	Financial instruments
	Natural gas distribution segment	$	—	$	—	$	—		$	—		$	—
	Nonregulated segment	1,297		87,281		—			(88,578		)	—
	Total liabilities	$	1,297	$	87,281	$	—		$	(88,578	)	$	—
		Quoted		Significant		Significant			Netting and			30-Sep-13
		Prices in		Other		Other			Cash
		Active		Observable		Unobservable			Collateral(3)
		Markets		Inputs		Inputs
		(Level 1)		(Level 2)(1)		(Level 3)
		(In thousands)
	Assets:
	Financial instruments
	Natural gas distribution segment	$	—	$	111,191	$	—		$	—		$	111,191
	Nonregulated segment	745		115,135		—			(105,751		)	10,129
	Total financial instruments	745		226,326		—			(105,751		)	121,320
	Hedged portion of gas stored underground	44,758		—		—			—			44,758
	Available-for-sale securities
	Money market funds	—		4,428		—			—			4,428
	Registered investment companies	40,094		—		—			—			40,094
	Bonds	—		28,160		—			—			28,160
	Total available-for-sale securities	40,094		32,588		—			—			72,682
	Total assets	$	85,597	$	258,914	$	—		$	(105,751	)	$	238,760
	Liabilities:
	Financial instruments
	Natural gas distribution segment	$	—	$	1,543	$	—		$	—		$	1,543
	Nonregulated segment	158		130,422		—			(130,580		)	—
	Total liabilities	$	158	$	131,965	$	—		$	(130,580	)	$	1,543
	(1)	Our Level 2 measurements consist of over-the-counter options and swaps which are valued using a market-based approach in which observable market prices are adjusted for criteria specific to each instrument, such as the strike price, notional amount or basis differences, municipal and corporate bonds which are valued based on the most recent available quoted market prices and money market funds which are valued at cost.
	(2)	This column reflects adjustments to our gross financial instrument assets and liabilities to reflect netting permitted under our master netting agreements and the relevant authoritative accounting literature. In addition, as of March 31, 2014, we had $11.1 million of cash held in margin accounts to collateralize certain financial instruments. Of this amount, $3.1 million was used to offset current risk management liabilities under master netting arrangements and the remaining $8.0 million is classified as current risk management assets.
	(3)	This column reflects adjustments to our gross financial instrument assets and liabilities to reflect netting permitted under our master netting agreements and the relevant authoritative accounting literature. In addition, as of September 30, 2013 we had $24.8 million of cash held in margin accounts to collateralize certain financial instruments. Of this amount, $14.7 million was used to offset current and noncurrent risk management liabilities under master netting arrangements and the remaining $10.1 million is classified as current risk management assets.
	Available-for-sale securities are comprised of the following:
		Amortized		Gross		Gross			Fair
		Cost		Unrealized		Unrealized			Value
				Gain		Loss
		(In thousands)
	As of March 31, 2014
	Domestic equity mutual funds	$	27,226	$	10,052	$	—		$	37,278
	Foreign equity mutual funds	5,118		1,867		—			6,985
Bonds	28,320		191		(8		)	28,503
Money market funds	2,904		—		—			2,904
	$	63,568	$	12,110	$	(8	)	$	75,670
As of September 30, 2013
Domestic equity mutual funds	$	27,043	$	7,476	$	(23	)	$	34,496
Foreign equity mutual funds	4,536		1,062		—			5,598
Bonds	28,016		168		(24		)	28,160
Money market funds	4,428		—		—			4,428
	$	64,023	$	8,706	$	(47	)	$	72,682
At March 31, 2014 and September 30, 2013, our available-for-sale securities included $47.2 million and $44.5 million related to assets held in separate rabbi trusts for our supplemental executive benefit plans. At March 31, 2014, we maintained investments in bonds that have contractual maturity dates ranging from April 2014 through July 2017. During the six months ended March 31, 2013, we recognized a gain of $2.7 million on the sale of certain assets in the rabbi trusts.
These securities are reported at market value with unrealized gains and losses shown as a component of accumulated other comprehensive income (loss). We regularly evaluate the performance of these investments on a fund by fund basis for impairment, taking into consideration the fund’s purpose, volatility and current returns. If a determination is made that a decline in fair value is other than temporary, the related fund is written down to its estimated fair value and the other-than-temporary impairment is recognized in the income statement.
Other Fair Value Measures
Our debt is recorded at carrying value. The fair value of our debt is determined using third party market value quotations, which are considered Level 1 fair value measurements for debt instruments with a recent, observable trade or Level 2 fair value measurements for debt instruments where fair value is determined using the most recent available quoted market price. The following table presents the carrying value and fair value of our debt as of March 31, 2014 and September 30, 2013:
	31-Mar-14		30-Sep-13
	(In thousands)
Carrying Amount	$	2,460,000	$	2,460,000
Fair Value	$	2,739,091	$	2,676,487

Concentration_of_Credit_Risk

Concentration of Credit Risk	6 Months Ended
	Mar. 31, 2014
Risks and Uncertainties [Abstract]	'
Concentration of Credit Risk	'
	Concentration of Credit Risk
	Information regarding our concentration of credit risk is disclosed in Note 15 to the financial statements in our Annual Report on Form 10-K for the fiscal year ended September 30, 2013. During the six months ended March 31, 2014, there were no material changes in our concentration of credit risk.

Discontinued_Operations

Discontinued Operations	6 Months Ended
	Mar. 31, 2014
Discontinued Operations and Disposal Groups [Abstract]	'
Discontinued Operations	'
	Discontinued Operations
	On April 1, 2013, we completed the sale of substantially all of our natural gas distribution assets and certain related nonregulated assets located in Georgia to Liberty Energy (Georgia) Corp., an affiliate of Algonquin Power & Utilities Corp. for a cash price of approximately $153 million. In connection with the sale, we recognized a net of tax gain of $5.3 million.
	For the three and six months ended March 31, 2013, net income from discontinued operations includes the operating results of our Georgia operations. As required under generally accepted accounting principles, the operating results from our discontinued Georgia operations have been aggregated and reported on the condensed consolidated statements of income as income from discontinued operations, net of income tax. Expenses related to general corporate overhead and interest expense allocated to their operations are not included in discontinued operations.
	The table below sets forth statement of income data related to discontinued operations. At March 31, 2014 and September 30, 2013 we did not have any assets or liabilities held for sale.
		Three Months Ended				Six Months Ended
		March 31				March 31
		2014		2013		2014		2013
		(In thousands)
	Operating revenues	$	—	$	21,678	$	—	$	37,962
	Purchased gas cost	—		12,497		—		21,464
	Gross profit	—		9,181		—		16,498
	Operating expenses	—		3,038		—		5,858
	Operating income	—		6,143		—		10,640
	Other nonoperating income	—		200		—		548
	Income from discontinued operations before income taxes	—		6,343		—		11,188
	Income tax expense	—		2,258		—		3,986
	Net income from discontinued operations	$	—	$	4,085	$	—	$	7,202

Accounting_Policies_Policy

Accounting Policies (Policy)	6 Months Ended
	Mar. 31, 2014
Accounting Policies [Abstract]	'
Regulatory assets and liabilities	'Regulatory assets and liabilitiesAccounting principles generally accepted in the United States require cost-based, rate-regulated entities that meet certain criteria to reflect the authorized recovery of costs due to regulatory decisions in their financial statements. As a result, certain costs are permitted to be capitalized rather than expensed because they can be recovered through rates. We record certain costs as regulatory assets when future recovery through customer rates is considered probable. Regulatory liabilities are recorded when it is probable that revenues will be reduced for amounts that will be credited to customers through the ratemaking process. Substantially all of our regulatory assets are recorded as a component of deferred charges and other assets and substantially all of our regulatory liabilities are recorded as a component of deferred credits and other liabilities. Deferred gas costs are recorded either in other current assets or liabilities and the regulatory cost of removal obligation is reported separately.
Segment Reporting	'
	Segment Information
	We operate the Company through the following three segments:
	•	The natural gas distribution segment, which includes our regulated natural gas distribution and related sales operations,
	•	The regulated transmission and storage segment, which includes the regulated pipeline and storage operations of our Atmos Pipeline — Texas Division and
	•	The nonregulated segment, which is comprised of our nonregulated natural gas management, nonregulated natural gas transmission, storage and other services.
	Our determination of reportable segments considers the strategic operating units under which we manage sales of various products and services to customers in differing regulatory environments. Although our natural gas distribution segment operations are geographically dispersed, they are reported as a single segment as each natural gas distribution division has similar economic characteristics. The accounting policies of the segments are the same as those described in the summary of significant accounting policies found in our Annual Report on Form 10-K for the fiscal year ended September 30, 2013. We evaluate performance based on net income or loss of the respective operating units.
Earnings Per Share	'
	We use the two-class method of computing earnings per share because we have participating securities in the form of non-vested restricted stock units with a nonforfeitable right to dividend equivalents, for which vesting is predicated solely on the passage of time. The calculation of earnings per share using the two-class method excludes income attributable to these participating securities from the numerator and excludes the dilutive impact of those shares from the denominator.
Fair Value Measurements	'
	Fair Value Measurements
	We report certain assets and liabilities at fair value, which is defined as the price that would be received to sell an asset or paid to transfer a liability in an orderly transaction between market participants at the measurement date (exit price). We record cash and cash equivalents, accounts receivable and accounts payable at carrying value, which substantially approximates fair value due to the short-term nature of these assets and liabilities. For other financial assets and liabilities, we primarily use quoted market prices and other observable market pricing information to minimize the use of unobservable pricing inputs in our measurements when determining fair value. The methods used to determine fair value for our assets and liabilities are fully described in Note 2 to the financial statements in our Annual Report on Form 10-K for the fiscal year ended September 30, 2013. During the six months ended March 31, 2014, there were no changes in these methods.

Unaudited_Financial_Informatio1

Unaudited Financial Information (Table)	6 Months Ended
	Mar. 31, 2014
Regulatory Assets And Liabilities Table [Abstract]	'
Regulatory assets and liabilities table	'
	Significant regulatory assets and liabilities as of March 31, 2014 and September 30, 2013 included the following:
		March 31,		September 30,
		2014		2013
		(In thousands)
	Regulatory assets:
	Pension and postretirement benefit costs(1)	$	176,616	$	187,977
	Merger and integration costs, net	4,990		5,250
	Deferred gas costs	10,004		15,152
	Regulatory cost of removal asset	9,716		10,008
	Rate case costs	5,037		6,329
	Texas Rule 8.209(2)	40,760		30,364
	APT annual adjustment mechanism	4,084		5,853
	Recoverable loss on reacquired debt	20,156		21,435
	Other	6,393		4,380
		$	277,756	$	286,748
	Regulatory liabilities:
	Deferred gas costs	$	80,330	$	16,481
	Deferred franchise fees	11,523		1,689
	Regulatory cost of removal obligation	425,461		427,524
	Other	11,683		7,887
		$	528,997	$	453,581
	(1)	Includes $18.1 million and $17.4 million of pension and postretirement expense deferred pursuant to regulatory authorization.
	(2)	Texas Rule 8.209 is a Railroad Commission rule that allows for the deferral of all expenses associated with capital expenditures incurred pursuant to this rule, including the recording of interest on the deferred expenses until the next rate proceeding (rate case or annual rate filing), at which time investment and costs would be recovered through base rates.

Segment_Information_Table

Segment Information (Table)	6 Months Ended
	Mar. 31, 2014
Segment Reporting [Abstract]	'
Schedule of Segment Reporting Information, by Segment	'
	Income statements for the three and six month periods ended March 31, 2014 and 2013 by segment are presented in the following tables:
		Three Months Ended March 31, 2014
		Natural			Regulated			Nonregulated			Eliminations			Consolidated
		Gas			Transmission
		Distribution			and Storage
		(In thousands)
	Operating revenues from external parties	$	1,289,429		$	21,002		$	653,891		$	—		$	1,964,322
	Intersegment revenues	1,531			52,613			103,792			(157,936		)	—
		1,290,960			73,615			757,683			(157,936		)	1,964,322
	Purchased gas cost	905,772			—			720,094			(157,821		)	1,468,045
	Gross profit	385,188			73,615			37,589			(115		)	496,277
	Operating expenses
	Operation and maintenance	106,776			16,595			1,419			(115		)	124,675
	Depreciation and amortization	50,020			10,156			1,131			—			61,307
	Taxes, other than income	60,606			(1,232		)	841			—			60,215
	Total operating expenses	217,402			25,519			3,391			(115		)	246,197
	Operating income	167,786			48,096			34,198			—			250,080
	Miscellaneous income (expense)	97			(1,081		)	443			(975		)	(1,516		)
	Interest charges	22,828			9,155			593			(975		)	31,601
	Income before income taxes	145,055			37,860			34,048			—			216,963
	Income tax expense	56,312			13,751			13,533			—			83,596
	Net income	$	88,743		$	24,109		$	20,515		$	—		$	133,367
	Capital expenditures	$	139,555		$	39,000		$	(113	)	$	—		$	178,442
		Three Months Ended March 31, 2013
		Natural			Regulated			Nonregulated			Eliminations			Consolidated
		Gas			Transmission
		Distribution			and Storage
		(In thousands)
	Operating revenues from external parties	$	904,181		$	19,655		$	385,160		$	—		$	1,308,996
	Intersegment revenues	995			42,193			43,788			(86,976		)	—
		905,176			61,848			428,948			(86,976		)	1,308,996
	Purchased gas cost	558,170			—			404,641			(86,566		)	876,245
	Gross profit	347,006			61,848			24,307			(410		)	432,751
	Operating expenses
	Operation and maintenance	89,344			15,390			6,763			(411		)	111,086
	Depreciation and amortization	47,631			8,690			859			—			57,180
	Taxes, other than income	49,592			4,277			438			—			54,307
	Total operating expenses	186,567			28,357			8,060			(411		)	222,573
	Operating income	160,439			33,491			16,247			1			210,178
	Miscellaneous income (expense)	2,591			(99		)	(91		)	(689		)	1,712
	Interest charges	25,664			7,857			498			(688		)	33,331
	Income from continuing operations before income taxes	137,366			25,535			15,658			—			178,559
	Income tax expense	51,176			9,005			6,038			—			66,219
	Income from continuing operations	86,190			16,530			9,620			—			112,340
	Income from discontinued operations, net of tax	4,085			—			—			—			4,085
	Net income	$	90,275		$	16,530		$	9,620		$	—		$	116,425
	Capital expenditures	$	131,465		$	67,208		$	417		$	—		$	199,090
		Six Months Ended March 31, 2014
		Natural			Regulated			Nonregulated			Eliminations			Consolidated
		Gas			Transmission
		Distribution			and Storage
		(In thousands)
	Operating revenues from external parties	$	2,131,861		$	42,172		$	1,045,437		$	—		$	3,219,470
	Intersegment revenues	2,964			102,784			159,967			(265,715		)	—
		2,134,825			144,956			1,205,404			(265,715		)	3,219,470
	Purchased gas cost	1,450,466			—			1,149,249			(265,479		)	2,334,236
	Gross profit	684,359			144,956			56,155			(236		)	885,234
	Operating expenses
	Operation and maintenance	196,439			33,895			10,334			(236		)	240,432
	Depreciation and amortization	99,571			19,942			2,263			—			121,776
	Taxes, other than income	97,690			3,431			1,105			—			102,226
	Total operating expenses	393,700			57,268			13,702			(236		)	464,434
	Operating income	290,659			87,688			42,453			—			420,800
Miscellaneous income (expense)	(374		)	(2,262		)	767			(1,779		)	(3,648		)
Interest charges	46,153			18,112			1,230			(1,779		)	63,716
Income from before income taxes	244,132			67,314			41,990			—			353,436
Income tax expense	92,632			23,759			16,662			—			133,053
Net income	$	151,500		$	43,555		$	25,328		$	—		$	220,383
Capital expenditures	$	267,061		$	91,921		$	27		$	—		$	359,009
	Six Months Ended March 31, 2013
	Natural			Regulated			Nonregulated			Eliminations			Consolidated
	Gas			Transmission
	Distribution			and Storage
	(In thousands)
Operating revenues from external parties	$	1,569,730		$	38,354		$	735,067		$	—		$	2,343,151
Intersegment revenues	2,233			84,175			93,775			(180,183		)	—
	1,571,963			122,529			828,842			(180,183		)	2,343,151
Purchased gas cost	945,326			—			782,076			(179,364		)	1,548,038
Gross profit	626,637			122,529			46,766			(819		)	795,113
Operating expenses
Operation and maintenance	173,080			31,710			13,645			(822		)	217,613
Depreciation and amortization	97,691			17,080			1,988			—			116,759
Taxes, other than income	86,343			8,226			1,072			—			95,641
Total operating expenses	357,114			57,016			16,705			(822		)	430,013
Operating income	269,523			65,513			30,061			3			365,100
Miscellaneous income (expense)	2,460			(226		)	1,576			(1,400		)	2,410
Interest charges	49,227			14,728			1,295			(1,397		)	63,853
Income from continuing operations before income taxes	222,756			50,559			30,342			—			303,657
Income tax expense	83,473			17,924			12,572			—			113,969
Income from continuing operations	139,283			32,635			17,770			—			189,688
Income from discontinued operations, net of tax	7,202			—			—			—			7,202
Net income	$	146,485		$	32,635		$	17,770		$	—		$	196,890
Capital expenditures	$	277,336		$	111,039		$	742		$	—		$	389,117
Balance sheet information at March 31, 2014 and September 30, 2013 by segment is presented in the following tables.
	31-Mar-14
	Natural			Regulated			Nonregulated			Eliminations			Consolidated
	Gas			Transmission
	Distribution			and Storage
	(In thousands)
ASSETS
Property, plant and equipment, net	$	4,889,160		$	1,322,441		$	58,382		$	—		$	6,269,983
Investment in subsidiaries	908,939			—			(2,096		)	(906,843		)	—
Current assets
Cash and cash equivalents	73,165			—			63,575			—			136,740
Assets from risk management activities	58,746			—			7,940			—			66,686
Other current assets	609,806			14,363			610,515			(378,949		)	855,735
Intercompany receivables	786,428			—			—			(786,428		)	—
Total current assets	1,528,145			14,363			682,030			(1,165,377		)	1,059,161
Goodwill	574,190			132,462			34,711			—			741,363
Noncurrent assets from risk management activities	30,665			—			8,910			—			39,575
Deferred charges and other assets	350,362			19,585			7,587			—			377,534
	$	8,281,461		$	1,488,851		$	789,524		$	(2,072,220	)	$	8,487,616
CAPITALIZATION AND LIABILITIES
Shareholders’ equity	$	3,124,761		$	439,977		$	468,962		$	(908,939	)	$	3,124,761
Long-term debt	1,955,829			—			—			—			1,955,829
Total capitalization	5,080,590			439,977			468,962			(908,939		)	5,080,590
Current liabilities
Current maturities of long-term debt	500,000			—			—			—			500,000
Short-term debt	343,000			—			—			(343,000		)	—
Other current liabilities	658,106			13,654			225,485			(33,853		)	863,392
Intercompany payables	—			708,046			78,382			(786,428		)	—
Total current liabilities	1,501,106			721,700			303,867			(1,163,281		)	1,363,392
Deferred income taxes	943,831			324,879			14,841			—			1,283,551
Regulatory cost of removal obligation	358,262			—			—			—			358,262
Pension and postretirement liabilities	360,851			—			—			—			360,851
Deferred credits and other liabilities	36,821			2,295			1,854			—			40,970
	$	8,281,461		$	1,488,851		$	789,524		$	(2,072,220	)	$	8,487,616
	30-Sep-13
	Natural			Regulated			Nonregulated			Eliminations			Consolidated
	Gas			Transmission
	Distribution			and Storage
	(In thousands)
ASSETS
Property, plant and equipment, net	$	4,719,873		$	1,249,767		$	61,015		$	—		$	6,030,655
Investment in subsidiaries	831,136			—			(2,096		)	(829,040		)	—
Current assets
Cash and cash equivalents	4,237			—			61,962			—			66,199
Assets from risk management activities	1,837			—			10,129			—			11,966
Other current assets	428,366			11,709			452,126			(293,233		)	598,968
Intercompany receivables	783,738			—			—			(783,738		)	—
Total current assets	1,218,178			11,709			524,217			(1,076,971		)	677,133
Goodwill	574,190			132,462			34,711			—			741,363
Noncurrent assets from risk management activities	109,354			—			—			—			109,354
Deferred charges and other assets	347,687			19,227			8,849			—			375,763
	$	7,800,418		$	1,413,165		$	626,696		$	(1,906,011	)	$	7,934,268
CAPITALIZATION AND LIABILITIES
Shareholders’ equity	$	2,580,409		$	396,421		$	434,715		$	(831,136	)	$	2,580,409
Long-term debt	2,455,671			—			—			—			2,455,671
Total capitalization	5,036,080			396,421			434,715			(831,136		)	5,036,080
Current liabilities
Current maturities of long-term debt	—			—			—			—			—
Short-term debt	645,984			—			—			(278,000		)	367,984
Liabilities from risk management activities	1,543			—			—			—			1,543
Other current liabilities	491,681			20,288			110,306			(13,316		)	608,959
Intercompany payables	—			712,768			70,970			(783,738		)	—
Total current liabilities	1,139,208			733,056			181,276			(1,075,054		)	978,486
Deferred income taxes	871,360			283,554			8,960			179			1,164,053
Regulatory cost of removal obligation	359,299			—			—			—			359,299
Pension and postretirement liabilities	358,787			—			—			—			358,787
Deferred credits and other liabilities	35,684			134			1,745			—			37,563
	$	7,800,418		$	1,413,165		$	626,696		$	(1,906,011	)	$	7,934,268

Earnings_Per_Share_Table

Earnings Per Share (Table)	6 Months Ended
	Mar. 31, 2014
Earnings Per Share [Abstract]	'
Earnings per share table	'
	Basic and diluted earnings per share for the three and six months ended March 31, 2014 and 2013 are calculated as follows:
		Three Months Ended				Six Months Ended
		March 31				March 31
		2014		2013		2014		2013
		(In thousands, except per share amounts)
	Basic Earnings Per Share from continuing operations
	Income from continuing operations	$	133,367	$	112,340	$	220,383	$	189,688
	Less: Income from continuing operations allocated to participating securities	337		304		578		634
	Income from continuing operations available to common shareholders	$	133,030	$	112,036	$	219,805	$	189,054
	Basic weighted average shares outstanding	95,264		90,530		93,049		90,445
	Income from continuing operations per share — Basic	$	1.4	$	1.24	$	2.36	$	2.09
	Basic Earnings Per Share from discontinued operations
	Income from discontinued operations	$	—	$	4,085	$	—	$	7,202
	Less: Income from discontinued operations allocated to participating securities	—		11		—		24
	Income from discontinued operations available to common shareholders	$	—	$	4,074	$	—	$	7,178
	Basic weighted average shares outstanding	95,264		90,530		93,049		90,445
	Income from discontinued operations per share — Basic	$	—	$	0.04	$	—	$	0.08
	Net income per share — Basic	$	1.4	$	1.28	$	2.36	$	2.17
		Three Months Ended				Six Months Ended
		March 31				March 31
		2014		2013		2014		2013
		(In thousands, except per share amounts)
	Diluted Earnings Per Share from continuing operations
	Income from continuing operations available to common shareholders	$	133,030	$	112,036	$	219,805	$	189,054
	Effect of dilutive stock options and other shares	2		2		4		5
	Income from continuing operations available to common shareholders	$	133,032	$	112,038	$	219,809	$	189,059
	Basic weighted average shares outstanding	95,264		90,530		93,049		90,445
	Additional dilutive stock options and other shares	927		962		927		961
	Diluted weighted average shares outstanding	96,191		91,492		93,976		91,406
	Income from continuing operations per share — Diluted	$	1.38	$	1.23	$	2.34	$	2.07
	Diluted Earnings Per Share from discontinued operations
	Income from discontinued operations available to common shareholders	$	—	$	4,074	$	—	$	7,178
	Effect of dilutive stock options and other shares	—		—		—		—
	Income from discontinued operations available to common shareholders	$	—	$	4,074	$	—	$	7,178
	Basic weighted average shares outstanding	95,264		90,530		93,049		90,445
	Additional dilutive stock options and other shares	927		962		927		961
	Diluted weighted average shares outstanding	96,191		91,492		93,976		91,406
	Income from discontinued operations per share — Diluted	$	—	$	0.04	$	—	$	0.08
	Net income per share — Diluted	$	1.38	$	1.27	$	2.34	$	2.15

Debt_Table

Debt (Table)	6 Months Ended
	Mar. 31, 2014
Debt Disclosure [Abstract]	'
Components of Debt	'
	Long-term debt at March 31, 2014 and September 30, 2013 consisted of the following:
		31-Mar-14		30-Sep-13
		(In thousands)
	Unsecured 4.95% Senior Notes, due October 2014	$	500,000	$	500,000
	Unsecured 6.35% Senior Notes, due 2017	250,000		250,000
	Unsecured 8.50% Senior Notes, due 2019	450,000		450,000
	Unsecured 5.95% Senior Notes, due 2034	200,000		200,000
	Unsecured 5.50% Senior Notes, due 2041	400,000		400,000
	Unsecured 4.15% Senior Notes, due 2043	500,000		500,000
	Medium-term note Series A, 1995-1, 6.67%, due 2025	10,000		10,000
	Unsecured 6.75% Debentures, due 2028	150,000		150,000
	Total long-term debt	2,460,000		2,460,000
	Less:
	Original issue discount on unsecured senior notes and debentures	4,171		4,329
	Current maturities	500,000		—
		$	1,955,829	$	2,455,671

Interim_Pension_and_Other_Post1

Interim Pension and Other Postretirement Benefits (Table)	6 Months Ended
	Mar. 31, 2014
General Discussion of Pension and Other Postretirement Benefits [Abstract]	'
Components of net periodic pension cost table	'
	The components of our net periodic pension cost for our pension and other postretirement benefit plans for the three and six months ended March 31, 2014 and 2013 are presented in the following table. Most of these costs are recoverable through our gas distribution rates; however, a portion of these costs is capitalized into our gas distribution rate base. The remaining costs are recorded as a component of operation and maintenance expense. On October 2, 2013, due to the retirement of one of our executive officers, we recognized a settlement loss of $4.5 million associated with our Supplemental Executive Benefits Plan (SEBP). In association with the retirement, on October 2, 2013, we made a $16.8 million benefit payment from the SEBP.
		Three Months Ended March 31
		Pension Benefits								Other Benefits
		2014				2013				2014			2013
		(In thousands)
	Components of net periodic pension cost:
	Service cost	$	4,738			$	5,203			$	4,196		$	4,700
	Interest cost	6,824				6,023				3,988			3,241
	Expected return on assets	(5,900		)		(5,738		)		(1,292		)	(997		)
	Amortization of transition obligation	—				—				68			270
	Amortization of prior service credit	(34		)		(36		)		(362		)	(363		)
	Amortization of actuarial loss	3,930				5,562				158			1,049
	Net periodic pension cost	$	9,558			$	11,014			$	6,756		$	7,900
		Six Months Ended March 31
		Pension Benefits								Other Benefits
		2014				2013				2014			2013
		(In thousands)
	Components of net periodic pension cost:
	Service cost	$	9,476			$	10,405			$	8,392		$	9,400
	Interest cost	13,648				12,048				7,976			6,482
	Expected return on assets	(11,801		)		(11,477		)		(2,584		)	(1,994		)
	Amortization of transition obligation	—				—				136			540
	Amortization of prior service credit	(68		)		(71		)		(725		)	(725		)
	Amortization of actuarial loss	7,862				11,123				316			2,098
	Settlement loss	4,539				—				—			—
	Net periodic pension cost	$	23,656			$	22,028			$	13,511		$	15,801
Schedule of assumptions used table text block	'
	The assumptions used to develop our net periodic pension cost for the three and six months ended March 31, 2014 and 2013 are as follows:
		Pension Benefits						Other Benefits
		2014			2013			2014			2013
	Discount rate	4.95	%		4.04	%		4.95	%		4.04	%
	Rate of compensation increase	3.5	%		3.5	%		N/A			N/A
	Expected return on plan assets	7.25	%		7.75	%		4.6	%		4.7	%

Financial_Instruments_Table

Financial Instruments (Table)	6 Months Ended
	Mar. 31, 2014
Derivative Instruments and Hedging Activities Disclosure [Abstract]	'
Oustanding commodity contracts volumes table	'
	As of March 31, 2014, we had net long/(short) commodity contracts outstanding in the following quantities:
	Contract Type		Hedge Designation		Natural Gas			Nonregulated
					Distribution
					Quantity (MMcf)
	Commodity contracts		Fair Value		—			(5,770	)
			Cash Flow		—			21,795
			Not designated		8,428			45,975
					8,428			62,000
Financial instruments on the balance sheet	'
				Natural Gas Distribution								Nonregulated
		Balance Sheet Location		Assets				Liabilities				Assets				Liabilities
				(In thousands)
	30-Sep-13
	Designated As Hedges:
	Commodity contracts	Other current assets /		$	—			$	—			$	9,094			$	(12,173	)
		Other current liabilities
	Commodity contracts	Deferred charges and other assets /		—				—				416				(1,639		)
		Deferred credits and other liabilities
	Interest rate contracts	Deferred charges and other assets /		107,512				—				—				—
		Deferred credits and other liabilities
	Total			107,512				—				9,510				(13,812		)
	Not Designated As Hedges:
	Commodity contracts	Other current assets /		1,837				(1,543		)		65,388				(70,876		)
		Other current liabilities
	Commodity contracts	Deferred charges and other assets /		1,842				—				40,982				(45,892		)
		Deferred credits and other liabilities
	Total			3,679				(1,543		)		106,370				(116,768		)
	Gross Financial Instruments			111,191				(1,543		)		115,880				(130,580		)
	Gross Amounts Offset on Consolidated Balance Sheet:
	Contract netting			—				—				(115,875		)		115,875
	Net Financial Instruments			111,191				(1,543		)		5				(14,705		)
	Cash collateral			—				—				10,124				14,705
	Net Assets/Liabilities from Risk Management Activities			$	111,191			$	(1,543	)		$	10,129			$	—
	The following tables present the fair value and balance sheet classification of our financial instruments by operating segment as of March 31, 2014 and September 30, 2013. The gross amounts of recognized assets and liabilities are netted within our unaudited Condensed Consolidated Balance Sheets to the extent that we have netting arrangements with the counterparties.
				Natural Gas Distribution								Nonregulated
		Balance Sheet Location		Assets				Liabilities				Assets				Liabilities
				(In thousands)
	31-Mar-14
	Designated As Hedges:
	Commodity contracts	Other current assets /		$	—			$	—			$	11,398			$	(6,849	)
		Other current liabilities
	Interest rate contracts	Other current assets /		54,093				—				—				—
		Other current liabilities
	Commodity contracts	Deferred charges and other assets /		—				—				557				(944		)
		Deferred credits and other liabilities
	Interest rate contracts	Deferred charges and other assets /		30,665				—				—				—
		Deferred credits and other liabilities
	Total			84,758				—				11,955				(7,793		)
	Not Designated As Hedges:
	Commodity contracts	Other current assets /		4,653				—				48,402				(56,065		)
		Other current liabilities
	Commodity contracts	Deferred charges and other assets /		—				—				34,017				(24,720		)
		Deferred credits and other liabilities
	Total			4,653				—				82,419				(80,785		)
	Gross Financial Instruments			89,411				—				94,374				(88,578		)
	Gross Amounts Offset on Consolidated Balance Sheet:
	Contract netting			—				—				(85,464		)		85,464
	Net Financial Instruments			89,411				—				8,910				(3,114		)
	Cash collateral			—				—				7,940				3,114
	Net Assets/Liabilities from Risk Management Activities			$	89,411			$	—			$	16,850			$	—
Fair value hedges table	'
	The impact of our nonregulated commodity contracts designated as fair value hedges and the related hedged item on our condensed consolidated income statement for the three and six months ended March 31, 2014 and 2013 is presented below.
		Three Months Ended
		March 31
		2014				2013
		(In thousands)
	Commodity contracts	$	3,587			$	(17,846	)
	Fair value adjustment for natural gas inventory designated as the hedged item	(7,450		)		19,586
	Total (increase) decrease in purchased gas cost	$	(3,863	)		$	1,740
	The (increase) decrease in purchased gas cost is comprised of the following:
	Basis ineffectiveness	$	(579	)		$	1,458
	Timing ineffectiveness	(3,284		)		282
		$	(3,863	)		$	1,740
		Six Months Ended
		March 31
		2014				2013
		(In thousands)
	Commodity contracts	$	(4,974	)		$	(10,532	)
	Fair value adjustment for natural gas inventory designated as the hedged item	6,329				28,405
	Total decrease in purchased gas cost	$	1,355			$	17,873
	The (increase) decrease in purchased gas cost is comprised of the following:
	Basis ineffectiveness	$	(1,199	)		$	1,218
	Timing ineffectiveness	2,554				16,655
		$	1,355			$	17,873
Cash flow hedges	'
	The impact of cash flow hedges on our condensed consolidated income statements for the three and six months ended March 31, 2014 and 2013 is presented below. Note that this presentation does not reflect the financial impact arising from the hedged physical transaction. Therefore, this presentation is not indicative of the economic gross profit we realized when the underlying physical and financial transactions were settled.
		Three Months Ended March 31, 2014
		Natural				Nonregulated				Consolidated
		Gas
		Distribution
		(In thousands)
	Gain reclassified from AOCI for effective portion of commodity contracts	$	—			$	7,184			$	7,184
	Gain arising from ineffective portion of commodity contracts	—				142				142
	Total impact on purchased gas cost	—				7,326				7,326
	Net loss on settled interest rate agreements reclassified from AOCI into interest expense	(1,057		)		—				(1,057		)
	Total Impact from Cash Flow Hedges	$	(1,057	)		$	7,326			$	6,269
		Three Months Ended March 31, 2013
		Natural				Nonregulated				Consolidated
		Gas
		Distribution
		(In thousands)
	Loss reclassified from AOCI for effective portion of commodity contracts	$	—			$	(5,199	)		$	(5,199	)
	Loss arising from ineffective portion of commodity contracts	—				(83		)		(83		)
	Total impact on purchased gas cost	—				(5,282		)		(5,282		)
	Net loss on settled interest rate agreements reclassified from AOCI into interest expense	(873		)		—				(873		)
	Total Impact from Cash Flow Hedges	$	(873	)		$	(5,282	)		$	(6,155	)
		Six Months Ended March 31, 2014
		Natural				Nonregulated				Consolidated
		Gas
		Distribution
		(In thousands)
	Gain reclassified from AOCI for effective portion of commodity contracts	$	—			$	4,574			$	4,574
	Gain arising from ineffective portion of commodity contracts	—				24				24
	Total impact on purchased gas cost	—				4,598				4,598
	Loss on settled interest rate agreements reclassified from AOCI into interest expense	(2,115		)		—				(2,115		)
	Total Impact from Cash Flow Hedges	$	(2,115	)		$	4,598			$	2,483
		Six Months Ended March 31, 2013
		Natural Gas				Nonregulated				Consolidated
		Distribution
		(In thousands)
	Loss reclassified from AOCI for effective portion of commodity contracts	$	—			$	(10,359	)		$	(10,359	)
	Loss arising from ineffective portion of commodity contracts	—				(102		)		(102		)
	Total impact on purchased gas cost	—				(10,461		)		(10,461		)
	Loss on settled interest rate agreements reclassified from AOCI into interest expense	(1,375		)		—				(1,375		)
	Total Impact from Cash Flow Hedges	$	(1,375	)		$	(10,461	)		$	(11,836	)
Other comprehensive income from hedging table	'
	The following table summarizes the gains and losses arising from hedging transactions that were recognized as a component of other comprehensive income (loss), net of taxes, for the three and six months ended March 31, 2014 and 2013. The amounts included in the table below exclude gains and losses arising from ineffectiveness because those amounts are immediately recognized in the income statement as incurred.
		Three Months Ended								Six Months Ended
		March 31								March 31
		2014				2013				2014				2013
		(In thousands)
	Increase (decrease) in fair value:
	Interest rate agreements	$	(27,718	)		$	22,955			$	(14,448	)		$	34,900
	Forward commodity contracts	5,483				5,666				11,709				2,153
	Recognition of (gains) losses in earnings due to settlements:
	Interest rate agreements	671				554				1,343				873
	Forward commodity contracts	(4,382		)		3,172				(2,790		)		6,320
	Total other comprehensive income (loss) from hedging, net of tax(1)	$	(25,946	)		$	32,347			$	(4,186	)		$	44,246
	(1)	Utilizing an income tax rate ranging from 37 percent to 39 percent based on the effective rates in each taxing jurisdiction.
Expected recognition in earnings of deferred gains/(losses) in AOCI table	'
	The following amounts, net of deferred taxes, represent the expected recognition in earnings of the deferred gains (losses) recorded in AOCI associated with our financial instruments, based upon the fair values of these financial instruments as of March 31, 2014. However, the table below does not include the expected recognition in earnings of our outstanding interest rate agreements as those instruments have not yet settled.
		Interest Rate				Commodity				Total
		Agreements				Contracts
		(In thousands)
	Next twelve months	$	(1,830	)		$	4,682			$	2,852
	Thereafter	(27,191		)		(239		)		(27,430		)
	Total(1)	$	(29,021	)		$	4,443			$	(24,578	)
	(1)	Utilizing an income tax rate ranging from 37 percent to 39 percent based on the effective rates in each taxing jurisdiction.

Accumulated_Other_Comprehensiv1

Accumulated Other Comprehensive Income (Table)	6 Months Ended
	Mar. 31, 2014
Equity [Abstract]	'
Schedule of Accumulated Other Comprehensive Income (Loss)	'
	The following tables provide the components of our accumulated other comprehensive income (loss) balances, net of the related tax effects allocated to each component of other comprehensive income.
		Available-			Interest			Commodity			Total
		for-Sale			Rate			Contracts
		Securities			Agreement			Cash Flow
					Cash Flow			Hedges
					Hedges
		(In thousands)
	30-Sep-13	$	5,448		$	37,906		$	(4,476	)	$	38,878
	Other comprehensive income before reclassifications	2,369			(14,448		)	11,709			(370		)
	Amounts reclassified from accumulated other comprehensive income	(227		)	1,343			(2,790		)	(1,674		)
	Net current-period other comprehensive income	2,142			(13,105		)	8,919			(2,044		)
	31-Mar-14	$	7,590		$	24,801		$	4,443		$	36,834
		Available-			Interest			Commodity			Total
		for-Sale			Rate			Contracts
		Securities			Agreement			Cash Flow
					Cash Flow			Hedges
					Hedges
		(In thousands)
	30-Sep-12	$	5,661		$	(44,273	)	$	(8,995	)	$	(47,607	)
	Other comprehensive income before reclassifications	1,135			34,900			2,153			38,188
	Amounts reclassified from accumulated other comprehensive income	(1,708		)	873			6,320			5,485
	Net current-period other comprehensive income	(573		)	35,773			8,473			43,673
	31-Mar-13	$	5,088		$	(8,500	)	$	(522	)	$	(3,934	)
Reclassification out of Accumulated Other Comprehensive Income	'
	The following tables detail reclassifications out of AOCI for the three and six months ended March 31, 2014 and 2013. Amounts in parentheses below indicate decreases to net income in the statement of income.
		Three Months Ended March 31, 2014
	Accumulated Other Comprehensive Income Components	Amount Reclassified from			Affected Line Item in the
		Accumulated Other			Statement of Income
		Comprehensive Income
		(In thousands)
	Available-for-sale securities	$	358		Operation and maintenance expense
		358			Total before tax
		(131		)	Tax expense
		$	227		Net of tax
	Cash flow hedges
	Interest rate agreements	$	(1,057	)	Interest charges
	Commodity contracts	7,184			Purchased gas cost
		6,127			Total before tax
		(2,416		)	Tax expense
		$	3,711		Net of tax
	Total reclassifications	$	3,938		Net of tax
		Three Months Ended March 31, 2013
	Accumulated Other Comprehensive Income Components	Amount Reclassified from			Affected Line Item in the
		Accumulated Other			Statement of Income
		Comprehensive Income
		(In thousands)
	Available-for-sale securities	$	2,689		Operation and maintenance expense
		2,689			Total before tax
		(981		)	Tax expense
		$	1,708		Net of tax
	Cash flow hedges
	Interest rate agreements	$	(873	)	Interest charges
	Commodity contracts	(5,201		)	Purchased gas cost
		(6,074		)	Total before tax
		2,348			Tax benefit
		$	(3,726	)	Net of tax
	Total reclassifications	$	(2,018	)	Net of tax
		Six Months Ended March 31, 2014
	Accumulated Other Comprehensive Income Components	Amount Reclassified from			Affected Line Item in  the
		Accumulated Other			Statement of Income
		Comprehensive Income
		(In thousands)
	Available-for-sale securities	$	358		Operation and maintenance expense
		358			Total before tax
		(131		)	Tax expense
		$	227		Net of tax
	Cash flow hedges
	Interest rate agreements	$	(2,115	)	Interest charges
	Commodity contracts	4,574			Purchased gas cost
		2,459			Total before tax
		(1,012		)	Tax expense
		$	1,447		Net of tax
	Total reclassifications	$	1,674		Net of tax
		Six Months Ended March 31, 2013
	Accumulated Other Comprehensive Income Components	Amount Reclassified from			Affected Line Item in  the
		Accumulated Other			Statement of Income
		Comprehensive Income
		(In thousands)
	Available-for-sale securities	$	2,689		Operation and maintenance expense
		2,689			Total before tax
		(981		)	Tax expense
		$	1,708		Net of tax
	Cash flow hedges
	Interest rate agreements	$	(1,375	)	Interest charges
	Commodity contracts	(10,361		)	Purchased gas cost
		(11,736		)	Total before tax
		4,543			Tax benefit
	$	(7,193	)	Net of tax
Total reclassifications	$	(5,485	)	Net of tax

Fair_Value_Measurements_Table

Fair Value Measurements (Table)	6 Months Ended
	Mar. 31, 2014
Fair Value Disclosures [Abstract]	'
Fair value measurements table	'
	The following tables summarize, by level within the fair value hierarchy, our assets and liabilities that were accounted for at fair value on a recurring basis as of March 31, 2014 and September 30, 2013. Assets and liabilities are categorized in their entirety based on the lowest level of input that is significant to the fair value measurement.
		Quoted		Significant		Significant			Netting and			31-Mar-14
		Prices in		Other		Other			Cash
		Active		Observable		Unobservable			Collateral(2)
		Markets		Inputs		Inputs
		(Level 1)		(Level 2)(1)		(Level 3)
		(In thousands)
	Assets:
	Financial instruments
	Natural gas distribution segment	$	—	$	89,411	$	—		$	—		$	89,411
	Nonregulated segment	89		94,285		—			(77,524		)	16,850
	Total financial instruments	89		183,696		—			(77,524		)	106,261
	Hedged portion of gas stored underground	23,570		—		—			—			23,570
	Available-for-sale securities
	Money market funds	—		2,904		—			—			2,904
	Registered investment companies	44,263		—		—			—			44,263
	Bonds	—		28,503		—			—			28,503
	Total available-for-sale securities	44,263		31,407		—			—			75,670
	Total assets	$	67,922	$	215,103	$	—		$	(77,524	)	$	205,501
	Liabilities:
	Financial instruments
	Natural gas distribution segment	$	—	$	—	$	—		$	—		$	—
	Nonregulated segment	1,297		87,281		—			(88,578		)	—
	Total liabilities	$	1,297	$	87,281	$	—		$	(88,578	)	$	—
		Quoted		Significant		Significant			Netting and			30-Sep-13
		Prices in		Other		Other			Cash
		Active		Observable		Unobservable			Collateral(3)
		Markets		Inputs		Inputs
		(Level 1)		(Level 2)(1)		(Level 3)
		(In thousands)
	Assets:
	Financial instruments
	Natural gas distribution segment	$	—	$	111,191	$	—		$	—		$	111,191
	Nonregulated segment	745		115,135		—			(105,751		)	10,129
	Total financial instruments	745		226,326		—			(105,751		)	121,320
	Hedged portion of gas stored underground	44,758		—		—			—			44,758
	Available-for-sale securities
	Money market funds	—		4,428		—			—			4,428
	Registered investment companies	40,094		—		—			—			40,094
	Bonds	—		28,160		—			—			28,160
	Total available-for-sale securities	40,094		32,588		—			—			72,682
	Total assets	$	85,597	$	258,914	$	—		$	(105,751	)	$	238,760
	Liabilities:
	Financial instruments
	Natural gas distribution segment	$	—	$	1,543	$	—		$	—		$	1,543
	Nonregulated segment	158		130,422		—			(130,580		)	—
	Total liabilities	$	158	$	131,965	$	—		$	(130,580	)	$	1,543
	(1)	Our Level 2 measurements consist of over-the-counter options and swaps which are valued using a market-based approach in which observable market prices are adjusted for criteria specific to each instrument, such as the strike price, notional amount or basis differences, municipal and corporate bonds which are valued based on the most recent available quoted market prices and money market funds which are valued at cost.
	(2)	This column reflects adjustments to our gross financial instrument assets and liabilities to reflect netting permitted under our master netting agreements and the relevant authoritative accounting literature. In addition, as of March 31, 2014, we had $11.1 million of cash held in margin accounts to collateralize certain financial instruments. Of this amount, $3.1 million was used to offset current risk management liabilities under master netting arrangements and the remaining $8.0 million is classified as current risk management assets.
	(3)	This column reflects adjustments to our gross financial instrument assets and liabilities to reflect netting permitted under our master netting agreements and the relevant authoritative accounting literature. In addition, as of September 30, 2013 we had $24.8 million of cash held in margin accounts to collateralize certain financial instruments. Of this amount, $14.7 million was used to offset current and noncurrent risk management liabilities under master netting arrangements and the remaining $10.1 million is classified as current risk management assets.
Schedule of Available-for-sale Securities Reconciliation [Table Text Block]	'
	Available-for-sale securities are comprised of the following:
		Amortized		Gross		Gross			Fair
		Cost		Unrealized		Unrealized			Value
				Gain		Loss
		(In thousands)
	As of March 31, 2014
	Domestic equity mutual funds	$	27,226	$	10,052	$	—		$	37,278
	Foreign equity mutual funds	5,118		1,867		—			6,985
	Bonds	28,320		191		(8		)	28,503
	Money market funds	2,904		—		—			2,904
		$	63,568	$	12,110	$	(8	)	$	75,670
	As of September 30, 2013
	Domestic equity mutual funds	$	27,043	$	7,476	$	(23	)	$	34,496
	Foreign equity mutual funds	4,536		1,062		—			5,598
	Bonds	28,016		168		(24		)	28,160
	Money market funds	4,428		—		—			4,428
		$	64,023	$	8,706	$	(47	)	$	72,682
Other fair value measurements table	'
	The following table presents the carrying value and fair value of our debt as of March 31, 2014 and September 30, 2013:
		31-Mar-14		30-Sep-13
		(In thousands)
	Carrying Amount	$	2,460,000	$	2,460,000
	Fair Value	$	2,739,091	$	2,676,487

Discontinued_Operations_Table

Discontinued Operations (Table)	6 Months Ended
	Mar. 31, 2014
Discontinued Operations and Disposal Groups [Abstract]	'
Discontinued operations income statement detail table	'
	The table below sets forth statement of income data related to discontinued operations. At March 31, 2014 and September 30, 2013 we did not have any assets or liabilities held for sale.
		Three Months Ended				Six Months Ended
		March 31				March 31
		2014		2013		2014		2013
		(In thousands)
	Operating revenues	$	—	$	21,678	$	—	$	37,962
	Purchased gas cost	—		12,497		—		21,464
	Gross profit	—		9,181		—		16,498
	Operating expenses	—		3,038		—		5,858
	Operating income	—		6,143		—		10,640
	Other nonoperating income	—		200		—		548
	Income from discontinued operations before income taxes	—		6,343		—		11,188
	Income tax expense	—		2,258		—		3,986
	Net income from discontinued operations	$	—	$	4,085	$	—	$	7,202

Nature_of_Business_Details

Nature of Business (Details)	Mar. 31, 2014
	state
	regulated_gas_distributions_divisions
	customers
Organization, Consolidation and Presentation of Financial Statements [Abstract]	'
Number of Customers, Natural Gas Distribution	3,000,000
Number of Divisions, Natural Gas Distribution	6
Number of States in which Entity Operates	8
Number of Customers, discontinued operations	64,000

Unaudited_Interim_Financial_In

Unaudited Interim Financial Information (Details) (USD $)	3 Months Ended
	Mar. 31, 2014		Sep. 30, 2013
Regulatory Asset [Line Items]	'		'
Regulatory assets	$277,756,000		$286,748,000
Regulatory Liabilities [Line Items]	'		'
Regulatory liabilities	528,997,000		453,581,000
Regulatory asset - future recoverable pension costs	18,100,000		17,400,000
Regulatory noncurrent asset, amortization period	'20		'
Deferred Gas Costs [Member]	'		'
Regulatory Liabilities [Line Items]	'		'
Regulatory liabilities	80,330,000		16,481,000
Deferred Franchise Fees [Member]	'		'
Regulatory Liabilities [Line Items]	'		'
Regulatory liabilities	11,523,000		1,689,000
Regulatory Cost of Removal Obligation [Member]	'		'
Regulatory Liabilities [Line Items]	'		'
Regulatory liabilities	425,461,000		427,524,000
Other [Member]	'		'
Regulatory Liabilities [Line Items]	'		'
Regulatory liabilities	11,683,000		7,887,000
Pension And Postretirement Benefit Costs [Member]	'		'
Regulatory Asset [Line Items]	'		'
Regulatory assets	176,616,000	[1]	187,977,000	[1]
Merger And Integration Costs Net [Member]	'		'
Regulatory Asset [Line Items]	'		'
Regulatory assets	4,990,000		5,250,000
Deferred Gas Costs Asset [Member]	'		'
Regulatory Asset [Line Items]	'		'
Regulatory assets	10,004,000		15,152,000
Regulatory Cost of Removal Asset [Member]	'		'
Regulatory Asset [Line Items]	'		'
Regulatory assets	9,716,000		10,008,000
Rate Case Costs [Member]	'		'
Regulatory Asset [Line Items]	'		'
Regulatory assets	5,037,000		6,329,000
Texas 8.209 [Member]	'		'
Regulatory Asset [Line Items]	'		'
Regulatory assets	40,760,000	[2]	30,364,000	[2]
APT Annual Adjustment Mechanism [Member]	'		'
Regulatory Asset [Line Items]	'		'
Regulatory assets	4,084,000		5,853,000
Recoverable Loss On Reacquired Debt [Member]	'		'
Regulatory Asset [Line Items]	'		'
Regulatory assets	20,156,000		21,435,000
Other [Member]	'		'
Regulatory Asset [Line Items]	'		'
Regulatory assets	$6,393,000		$4,380,000
[1]	Includes $18.1 million and $17.4 million of pension and postretirement expense deferred pursuant to regulatory authorization.
[2]	Texas Rule 8.209 is a Railroad Commission rule that allows for the deferral of all expenses associated with capital expenditures incurred pursuant to this rule, including the recording of interest on the deferred expenses until the next rate proceeding (rate case or annual rate filing), at which time investment and costs would be recovered through base rates.

Segment_Information_Details

Segment Information (Details) (USD $)	0 Months Ended	3 Months Ended		6 Months Ended
	Apr. 02, 2013	Mar. 31, 2014	Mar. 31, 2013	Mar. 31, 2014	Mar. 31, 2013	Sep. 30, 2013	Sep. 30, 2012
				segment
Segment Reporting Information [Line Items]	'	'	'	'	'	'	'
Number of operating segments	'	'	'	3	'	'	'
Segment Reporting Information Profit Loss [Abstract]	'	'	'	'	'	'	'
Total operating revenues	'	$1,964,322,000	$1,308,996,000	$3,219,470,000	$2,343,151,000	'	'
Purchased gas cost	'	1,468,045,000	876,245,000	2,334,236,000	1,548,038,000	'	'
Gross profit	'	496,277,000	432,751,000	885,234,000	795,113,000	'	'
Operating expenses	'	'	'	'	'	'	'
Operation and maintenance	'	124,675,000	111,086,000	240,432,000	217,613,000	'	'
Depreciation and amortization	'	61,307,000	57,180,000	121,776,000	116,759,000	'	'
Taxes, other than income	'	60,215,000	54,307,000	102,226,000	95,641,000	'	'
Total operating expenses	'	246,197,000	222,573,000	464,434,000	430,013,000	'	'
Operating income	'	250,080,000	210,178,000	420,800,000	365,100,000	'	'
Miscellaneous income (expense)	'	-1,516,000	1,712,000	-3,648,000	2,410,000	'	'
Interest charges	'	31,601,000	33,331,000	63,716,000	63,853,000	'	'
Income (loss) before income taxes	'	216,963,000	178,559,000	353,436,000	303,657,000	'	'
Income tax expense (benefit)	'	83,596,000	66,219,000	133,053,000	113,969,000	'	'
Income (loss) from continuing operations	'	133,367,000	112,340,000	220,383,000	189,688,000	'	'
Income from discontinued operations, net of tax	'	0	4,085,000	0	7,202,000	'	'
Gain (loss) on sale of discontinued operations, net of tax	5,300,000	'	'	'	'	'	'
Net income (loss)	'	133,367,000	116,425,000	220,383,000	196,890,000	'	'
Capital expenditures	'	178,442,000	199,090,000	359,009,000	389,117,000	'	'
ASSETS	'	'	'	'	'	'	'
Net property, plant and equipment	'	6,269,983,000	'	6,269,983,000	'	6,030,655,000	'
Investment in subsidiaries	'	0	'	0	'	0	'
Current assets	'	'	'	'	'	'	'
Cash and cash equivalents	'	136,740,000	65,547,000	136,740,000	65,547,000	66,199,000	64,239,000
Assets from risk management activities	'	66,686,000	'	66,686,000	'	11,966,000	'
Other current assets	'	855,735,000	'	855,735,000	'	598,968,000	'
Intercompany receivables	'	0	'	0	'	0	'
Total current assets	'	1,059,161,000	'	1,059,161,000	'	677,133,000	'
Goodwill	'	741,363,000	'	741,363,000	'	741,363,000	'
Noncurrent assets from risk management activities	'	39,575,000	'	39,575,000	'	109,354,000	'
Deferred charges and other assets	'	377,534,000	'	377,534,000	'	375,763,000	'
Total Assets	'	8,487,616,000	'	8,487,616,000	'	7,934,268,000	'
CAPITALIZATION AND LIABILITIES	'	'	'	'	'	'	'
Shareholders' equity	'	3,124,761,000	'	3,124,761,000	'	2,580,409,000	'
Long-term debt	'	1,955,829,000	'	1,955,829,000	'	2,455,671,000	'
Total capitalization	'	5,080,590,000	'	5,080,590,000	'	5,036,080,000	'
Current liabilities	'	'	'	'	'	'	'
Current maturities of long-term debt	'	500,000,000	'	500,000,000	'	0	'
Short-term debt	'	0	'	0	'	367,984,000	'
Liabilities from risk management activities	'	'	'	'	'	1,543,000	'
Other current liabilities	'	863,392,000	'	863,392,000	'	608,959,000	'
Intercompany payables	'	0	'	0	'	0	'
Total current liabilities	'	1,363,392,000	'	1,363,392,000	'	978,486,000	'
Deferred income taxes	'	1,283,551,000	'	1,283,551,000	'	1,164,053,000	'
Regulatory cost of removal obligation	'	358,262,000	'	358,262,000	'	359,299,000	'
Pension and postretirement liabilities	'	360,851,000	'	360,851,000	'	358,787,000	'
Deferred credits and other liabilities	'	40,970,000	'	40,970,000	'	37,563,000	'
Total Equity and Liabilities	'	8,487,616,000	'	8,487,616,000	'	7,934,268,000	'
Reportable Subsegments [Member]	'	'	'	'	'	'	'
Segment Reporting Information Profit Loss [Abstract]	'	'	'	'	'	'	'
Revenues from external customers	'	1,964,322,000	1,308,996,000	3,219,470,000	2,343,151,000	'	'
Intersubsegment Eliminations [Member]	'	'	'	'	'	'	'
Segment Reporting Information Profit Loss [Abstract]	'	'	'	'	'	'	'
Revenues from external customers	'	0	0	0	0	'	'
Natural Gas Distribution Segment [Member]	'	'	'	'	'	'	'
Segment Reporting Information Profit Loss [Abstract]	'	'	'	'	'	'	'
Total operating revenues	'	1,290,960,000	905,176,000	2,134,825,000	1,571,963,000	'	'
Purchased gas cost	'	905,772,000	558,170,000	1,450,466,000	945,326,000	'	'
Gross profit	'	385,188,000	347,006,000	684,359,000	626,637,000	'	'
Operating expenses	'	'	'	'	'	'	'
Operation and maintenance	'	106,776,000	89,344,000	196,439,000	173,080,000	'	'
Depreciation and amortization	'	50,020,000	47,631,000	99,571,000	97,691,000	'	'
Taxes, other than income	'	60,606,000	49,592,000	97,690,000	86,343,000	'	'
Total operating expenses	'	217,402,000	186,567,000	393,700,000	357,114,000	'	'
Operating income	'	167,786,000	160,439,000	290,659,000	269,523,000	'	'
Miscellaneous income (expense)	'	97,000	2,591,000	-374,000	2,460,000	'	'
Interest charges	'	22,828,000	25,664,000	46,153,000	49,227,000	'	'
Income (loss) before income taxes	'	145,055,000	137,366,000	244,132,000	222,756,000	'	'
Income tax expense (benefit)	'	56,312,000	51,176,000	92,632,000	83,473,000	'	'
Income (loss) from continuing operations	'	'	86,190,000	'	139,283,000	'	'
Income from discontinued operations, net of tax	'	'	4,085,000	'	7,202,000	'	'
Net income (loss)	'	88,743,000	90,275,000	151,500,000	146,485,000	'	'
Capital expenditures	'	139,555,000	131,465,000	267,061,000	277,336,000	'	'
ASSETS	'	'	'	'	'	'	'
Net property, plant and equipment	'	4,889,160,000	'	4,889,160,000	'	4,719,873,000	'
Investment in subsidiaries	'	908,939,000	'	908,939,000	'	831,136,000	'
Current assets	'	'	'	'	'	'	'
Cash and cash equivalents	'	73,165,000	'	73,165,000	'	4,237,000	'
Assets from risk management activities	'	58,746,000	'	58,746,000	'	1,837,000	'
Other current assets	'	609,806,000	'	609,806,000	'	428,366,000	'
Intercompany receivables	'	786,428,000	'	786,428,000	'	783,738,000	'
Total current assets	'	1,528,145,000	'	1,528,145,000	'	1,218,178,000	'
Goodwill	'	574,190,000	'	574,190,000	'	574,190,000	'
Noncurrent assets from risk management activities	'	30,665,000	'	30,665,000	'	109,354,000	'
Deferred charges and other assets	'	350,362,000	'	350,362,000	'	347,687,000	'
Total Assets	'	8,281,461,000	'	8,281,461,000	'	7,800,418,000	'
CAPITALIZATION AND LIABILITIES	'	'	'	'	'	'	'
Shareholders' equity	'	3,124,761,000	'	3,124,761,000	'	2,580,409,000	'
Long-term debt	'	1,955,829,000	'	1,955,829,000	'	2,455,671,000	'
Total capitalization	'	5,080,590,000	'	5,080,590,000	'	5,036,080,000	'
Current liabilities	'	'	'	'	'	'	'
Current maturities of long-term debt	'	500,000,000	'	500,000,000	'	0	'
Short-term debt	'	343,000,000	'	343,000,000	'	645,984,000	'
Liabilities from risk management activities	'	'	'	'	'	1,543,000	'
Other current liabilities	'	658,106,000	'	658,106,000	'	491,681,000	'
Intercompany payables	'	0	'	0	'	0	'
Total current liabilities	'	1,501,106,000	'	1,501,106,000	'	1,139,208,000	'
Deferred income taxes	'	943,831,000	'	943,831,000	'	871,360,000	'
Regulatory cost of removal obligation	'	358,262,000	'	358,262,000	'	359,299,000	'
Pension and postretirement liabilities	'	360,851,000	'	360,851,000	'	358,787,000	'
Deferred credits and other liabilities	'	36,821,000	'	36,821,000	'	35,684,000	'
Total Equity and Liabilities	'	8,281,461,000	'	8,281,461,000	'	7,800,418,000	'
Natural Gas Distribution Segment [Member] | Reportable Subsegments [Member]	'	'	'	'	'	'	'
Segment Reporting Information Profit Loss [Abstract]	'	'	'	'	'	'	'
Revenues from external customers	'	1,289,429,000	904,181,000	2,131,861,000	1,569,730,000	'	'
Natural Gas Distribution Segment [Member] | Intersubsegment Eliminations [Member]	'	'	'	'	'	'	'
Segment Reporting Information Profit Loss [Abstract]	'	'	'	'	'	'	'
Revenues from external customers	'	1,531,000	995,000	2,964,000	2,233,000	'	'
Regulated Transmission and Storage Segment [Member]	'	'	'	'	'	'	'
Segment Reporting Information Profit Loss [Abstract]	'	'	'	'	'	'	'
Total operating revenues	'	73,615,000	61,848,000	144,956,000	122,529,000	'	'
Purchased gas cost	'	0	0	0	0	'	'
Gross profit	'	73,615,000	61,848,000	144,956,000	122,529,000	'	'
Operating expenses	'	'	'	'	'	'	'
Operation and maintenance	'	16,595,000	15,390,000	33,895,000	31,710,000	'	'
Depreciation and amortization	'	10,156,000	8,690,000	19,942,000	17,080,000	'	'
Taxes, other than income	'	-1,232,000	4,277,000	3,431,000	8,226,000	'	'
Total operating expenses	'	25,519,000	28,357,000	57,268,000	57,016,000	'	'
Operating income	'	48,096,000	33,491,000	87,688,000	65,513,000	'	'
Miscellaneous income (expense)	'	-1,081,000	-99,000	-2,262,000	-226,000	'	'
Interest charges	'	9,155,000	7,857,000	18,112,000	14,728,000	'	'
Income (loss) before income taxes	'	37,860,000	25,535,000	67,314,000	50,559,000	'	'
Income tax expense (benefit)	'	13,751,000	9,005,000	23,759,000	17,924,000	'	'
Income (loss) from continuing operations	'	'	16,530,000	'	32,635,000	'	'
Income from discontinued operations, net of tax	'	'	0	'	0	'	'
Net income (loss)	'	24,109,000	16,530,000	43,555,000	32,635,000	'	'
Capital expenditures	'	39,000,000	67,208,000	91,921,000	111,039,000	'	'
ASSETS	'	'	'	'	'	'	'
Net property, plant and equipment	'	1,322,441,000	'	1,322,441,000	'	1,249,767,000	'
Investment in subsidiaries	'	0	'	0	'	0	'
Current assets	'	'	'	'	'	'	'
Cash and cash equivalents	'	0	'	0	'	0	'
Assets from risk management activities	'	0	'	0	'	0	'
Other current assets	'	14,363,000	'	14,363,000	'	11,709,000	'
Intercompany receivables	'	0	'	0	'	0	'
Total current assets	'	14,363,000	'	14,363,000	'	11,709,000	'
Goodwill	'	132,462,000	'	132,462,000	'	132,462,000	'
Noncurrent assets from risk management activities	'	0	'	0	'	0	'
Deferred charges and other assets	'	19,585,000	'	19,585,000	'	19,227,000	'
Total Assets	'	1,488,851,000	'	1,488,851,000	'	1,413,165,000	'
CAPITALIZATION AND LIABILITIES	'	'	'	'	'	'	'
Shareholders' equity	'	439,977,000	'	439,977,000	'	396,421,000	'
Long-term debt	'	0	'	0	'	0	'
Total capitalization	'	439,977,000	'	439,977,000	'	396,421,000	'
Current liabilities	'	'	'	'	'	'	'
Current maturities of long-term debt	'	0	'	0	'	0	'
Short-term debt	'	0	'	0	'	0	'
Liabilities from risk management activities	'	'	'	'	'	0	'
Other current liabilities	'	13,654,000	'	13,654,000	'	20,288,000	'
Intercompany payables	'	708,046,000	'	708,046,000	'	712,768,000	'
Total current liabilities	'	721,700,000	'	721,700,000	'	733,056,000	'
Deferred income taxes	'	324,879,000	'	324,879,000	'	283,554,000	'
Regulatory cost of removal obligation	'	0	'	0	'	0	'
Pension and postretirement liabilities	'	0	'	0	'	0	'
Deferred credits and other liabilities	'	2,295,000	'	2,295,000	'	134,000	'
Total Equity and Liabilities	'	1,488,851,000	'	1,488,851,000	'	1,413,165,000	'
Regulated Transmission and Storage Segment [Member] | Reportable Subsegments [Member]	'	'	'	'	'	'	'
Segment Reporting Information Profit Loss [Abstract]	'	'	'	'	'	'	'
Revenues from external customers	'	21,002,000	19,655,000	42,172,000	38,354,000	'	'
Regulated Transmission and Storage Segment [Member] | Intersubsegment Eliminations [Member]	'	'	'	'	'	'	'
Segment Reporting Information Profit Loss [Abstract]	'	'	'	'	'	'	'
Revenues from external customers	'	52,613,000	42,193,000	102,784,000	84,175,000	'	'
Nonregulated Segment [Member]	'	'	'	'	'	'	'
Segment Reporting Information Profit Loss [Abstract]	'	'	'	'	'	'	'
Total operating revenues	'	757,683,000	428,948,000	1,205,404,000	828,842,000	'	'
Purchased gas cost	'	720,094,000	404,641,000	1,149,249,000	782,076,000	'	'
Gross profit	'	37,589,000	24,307,000	56,155,000	46,766,000	'	'
Operating expenses	'	'	'	'	'	'	'
Operation and maintenance	'	1,419,000	6,763,000	10,334,000	13,645,000	'	'
Depreciation and amortization	'	1,131,000	859,000	2,263,000	1,988,000	'	'
Taxes, other than income	'	841,000	438,000	1,105,000	1,072,000	'	'
Total operating expenses	'	3,391,000	8,060,000	13,702,000	16,705,000	'	'
Operating income	'	34,198,000	16,247,000	42,453,000	30,061,000	'	'
Miscellaneous income (expense)	'	443,000	-91,000	767,000	1,576,000	'	'
Interest charges	'	593,000	498,000	1,230,000	1,295,000	'	'
Income (loss) before income taxes	'	34,048,000	15,658,000	41,990,000	30,342,000	'	'
Income tax expense (benefit)	'	13,533,000	6,038,000	16,662,000	12,572,000	'	'
Income (loss) from continuing operations	'	'	9,620,000	'	17,770,000	'	'
Income from discontinued operations, net of tax	'	'	0	'	0	'	'
Net income (loss)	'	20,515,000	9,620,000	25,328,000	17,770,000	'	'
Capital expenditures	'	-113,000	417,000	27,000	742,000	'	'
ASSETS	'	'	'	'	'	'	'
Net property, plant and equipment	'	58,382,000	'	58,382,000	'	61,015,000	'
Investment in subsidiaries	'	-2,096,000	'	-2,096,000	'	-2,096,000	'
Current assets	'	'	'	'	'	'	'
Cash and cash equivalents	'	63,575,000	'	63,575,000	'	61,962,000	'
Assets from risk management activities	'	7,940,000	'	7,940,000	'	10,129,000	'
Other current assets	'	610,515,000	'	610,515,000	'	452,126,000	'
Intercompany receivables	'	0	'	0	'	0	'
Total current assets	'	682,030,000	'	682,030,000	'	524,217,000	'
Goodwill	'	34,711,000	'	34,711,000	'	34,711,000	'
Noncurrent assets from risk management activities	'	8,910,000	'	8,910,000	'	0	'
Deferred charges and other assets	'	7,587,000	'	7,587,000	'	8,849,000	'
Total Assets	'	789,524,000	'	789,524,000	'	626,696,000	'
CAPITALIZATION AND LIABILITIES	'	'	'	'	'	'	'
Shareholders' equity	'	468,962,000	'	468,962,000	'	434,715,000	'
Long-term debt	'	0	'	0	'	0	'
Total capitalization	'	468,962,000	'	468,962,000	'	434,715,000	'
Current liabilities	'	'	'	'	'	'	'
Current maturities of long-term debt	'	0	'	0	'	0	'
Short-term debt	'	0	'	0	'	0	'
Liabilities from risk management activities	'	'	'	'	'	0	'
Other current liabilities	'	225,485,000	'	225,485,000	'	110,306,000	'
Intercompany payables	'	78,382,000	'	78,382,000	'	70,970,000	'
Total current liabilities	'	303,867,000	'	303,867,000	'	181,276,000	'
Deferred income taxes	'	14,841,000	'	14,841,000	'	8,960,000	'
Regulatory cost of removal obligation	'	0	'	0	'	0	'
Pension and postretirement liabilities	'	0	'	0	'	0	'
Deferred credits and other liabilities	'	1,854,000	'	1,854,000	'	1,745,000	'
Total Equity and Liabilities	'	789,524,000	'	789,524,000	'	626,696,000	'
Nonregulated Segment [Member] | Reportable Subsegments [Member]	'	'	'	'	'	'	'
Segment Reporting Information Profit Loss [Abstract]	'	'	'	'	'	'	'
Revenues from external customers	'	653,891,000	385,160,000	1,045,437,000	735,067,000	'	'
Nonregulated Segment [Member] | Intersubsegment Eliminations [Member]	'	'	'	'	'	'	'
Segment Reporting Information Profit Loss [Abstract]	'	'	'	'	'	'	'
Revenues from external customers	'	103,792,000	43,788,000	159,967,000	93,775,000	'	'
Intersegment Elimination [Member]	'	'	'	'	'	'	'
Segment Reporting Information Profit Loss [Abstract]	'	'	'	'	'	'	'
Total operating revenues	'	-157,936,000	-86,976,000	-265,715,000	-180,183,000	'	'
Purchased gas cost	'	-157,821,000	-86,566,000	-265,479,000	-179,364,000	'	'
Gross profit	'	-115,000	-410,000	-236,000	-819,000	'	'
Operating expenses	'	'	'	'	'	'	'
Operation and maintenance	'	-115,000	-411,000	-236,000	-822,000	'	'
Depreciation and amortization	'	0	0	0	0	'	'
Taxes, other than income	'	0	0	0	0	'	'
Total operating expenses	'	-115,000	-411,000	-236,000	-822,000	'	'
Operating income	'	0	1,000	0	3,000	'	'
Miscellaneous income (expense)	'	-975,000	-689,000	-1,779,000	-1,400,000	'	'
Interest charges	'	-975,000	-688,000	-1,779,000	-1,397,000	'	'
Income (loss) before income taxes	'	0	0	0	0	'	'
Income tax expense (benefit)	'	0	0	0	0	'	'
Income (loss) from continuing operations	'	'	0	'	0	'	'
Income from discontinued operations, net of tax	'	'	0	'	0	'	'
Net income (loss)	'	0	0	0	0	'	'
Capital expenditures	'	0	0	0	0	'	'
ASSETS	'	'	'	'	'	'	'
Net property, plant and equipment	'	0	'	0	'	0	'
Investment in subsidiaries	'	-906,843,000	'	-906,843,000	'	-829,040,000	'
Current assets	'	'	'	'	'	'	'
Cash and cash equivalents	'	0	'	0	'	0	'
Assets from risk management activities	'	0	'	0	'	0	'
Other current assets	'	-378,949,000	'	-378,949,000	'	-293,233,000	'
Intercompany receivables	'	-786,428,000	'	-786,428,000	'	-783,738,000	'
Total current assets	'	-1,165,377,000	'	-1,165,377,000	'	-1,076,971,000	'
Goodwill	'	0	'	0	'	0	'
Noncurrent assets from risk management activities	'	0	'	0	'	0	'
Deferred charges and other assets	'	0	'	0	'	0	'
Total Assets	'	-2,072,220,000	'	-2,072,220,000	'	-1,906,011,000	'
CAPITALIZATION AND LIABILITIES	'	'	'	'	'	'	'
Shareholders' equity	'	-908,939,000	'	-908,939,000	'	-831,136,000	'
Long-term debt	'	0	'	0	'	0	'
Total capitalization	'	-908,939,000	'	-908,939,000	'	-831,136,000	'
Current liabilities	'	'	'	'	'	'	'
Current maturities of long-term debt	'	0	'	0	'	0	'
Short-term debt	'	-343,000,000	'	-343,000,000	'	-278,000,000	'
Liabilities from risk management activities	'	'	'	'	'	0	'
Other current liabilities	'	-33,853,000	'	-33,853,000	'	-13,316,000	'
Intercompany payables	'	-786,428,000	'	-786,428,000	'	-783,738,000	'
Total current liabilities	'	-1,163,281,000	'	-1,163,281,000	'	-1,075,054,000	'
Deferred income taxes	'	0	'	0	'	179,000	'
Regulatory cost of removal obligation	'	0	'	0	'	0	'
Pension and postretirement liabilities	'	0	'	0	'	0	'
Deferred credits and other liabilities	'	0	'	0	'	0	'
Total Equity and Liabilities	'	-2,072,220,000	'	-2,072,220,000	'	-1,906,011,000	'
Intersegment Elimination [Member] | Reportable Subsegments [Member]	'	'	'	'	'	'	'
Segment Reporting Information Profit Loss [Abstract]	'	'	'	'	'	'	'
Revenues from external customers	'	0	0	0	0	'	'
Intersegment Elimination [Member] | Intersubsegment Eliminations [Member]	'	'	'	'	'	'	'
Segment Reporting Information Profit Loss [Abstract]	'	'	'	'	'	'	'
Revenues from external customers	'	($157,936,000)	($86,976,000)	($265,715,000)	($180,183,000)	'	'

Earnings_Per_Share_Details

Earnings Per Share (Details) (USD $)	0 Months Ended	3 Months Ended		6 Months Ended
	Feb. 18, 2014	Mar. 31, 2014	Mar. 31, 2013	Mar. 31, 2014	Mar. 31, 2013
Earnings Per Share [Abstract]	'	'	'	'	'
Stock Issued During Period, Shares, New Issues	9,200,000	'	'	'	'
Shares Issued At Overallotment Option	1,200,000	'	'	'	'
Share Price	$44	'	'	'	'
Net proceeds from equity offering	$390,200,000	'	'	$390,205,000	$0
Basic Earnings per Share from Continuing Operations	'	'	'	'	'
Income from continuing operations	'	133,367,000	112,340,000	220,383,000	189,688,000
Less: Income from continuing operations allocated to participating securities	'	337,000	304,000	578,000	634,000
Income from continuing operations available to common shareholders	'	133,030,000	112,036,000	219,805,000	189,054,000
Basic weighted average shares outstanding	'	95,264,000	90,530,000	93,049,000	90,445,000
Income from continuing operations per share - Basic	'	$1.40	$1.24	$2.36	$2.09
Basic Earnings per Share from Discontinued Operations	'	'	'	'	'
Income from discontinued operations, net of tax	'	0	4,085,000	0	7,202,000
Less: Income from discontinued operations allocated to participating securities	'	0	11,000	0	24,000
Income from discontinued operations available to common shareholders	'	0	4,074,000	0	7,178,000
Basic weighted average shares outstanding	'	95,264,000	90,530,000	93,049,000	90,445,000
Income from discontinued operations per share - Basic	'	$0	$0.04	$0	$0.08
Net income per share - Basic	'	$1.40	$1.28	$2.36	$2.17
Diluted Earnings per Share from Continuing Operations	'	'	'	'	'
Income from continuing operations available to common shareholders	'	133,030,000	112,036,000	219,805,000	189,054,000
Effect of dilutive stock options and other shares	'	2,000	2,000	4,000	5,000
Income from continuing operations available to common shareholders	'	133,032,000	112,038,000	219,809,000	189,059,000
Basic weighted average shares outstanding	'	95,264,000	90,530,000	93,049,000	90,445,000
Additional dilutive stock options and other shares	'	927,000	962,000	927,000	961,000
Diluted weighted average shares outstanding	'	96,191,000	91,492,000	93,976,000	91,406,000
Income from continuing operations per share - Diluted	'	$1.38	$1.23	$2.34	$2.07
Diluted Earnings per Share from Discontinued Operations	'	'	'	'	'
Income from discontinued operations available to common shareholders	'	0	4,074,000	0	7,178,000
Effect of dilutive stock options and other shares	'	0	0	0	0
Net Income Loss From Discontinued Operations Available To Common Stockholders Diluted	'	0	4,074,000	0	7,178,000
Basic weighted average shares outstanding	'	95,264,000	90,530,000	93,049,000	90,445,000
Additional dilutive stock options and other shares	'	927,000	962,000	927,000	961,000
Diluted weighted average shares outstanding	'	96,191,000	91,492,000	93,976,000	91,406,000
Income from discontinued operations per share - Diluted	'	$0	$0.04	$0	$0.08
Net income per share - Diluted	'	$1.38	$1.27	$2.34	$2.15
Earnings Per Share Diluted Other Disclosures Abstract	'	'	'	'	'
Anti-dilutive stock options excluded from computation of diluted earnings per share (in shares)	'	0	0	0	0
Share Repurchase Program - Shares Purchased	'	'	'	0	0
Share Repurchase Program - Amount Purchased	'	'	'	$0	$0

Debt_Details

Debt (Details) (USD $)	0 Months Ended	3 Months Ended	6 Months Ended
	Feb. 18, 2014	Mar. 31, 2014	Mar. 31, 2014	Mar. 31, 2013	Sep. 30, 2013
Debt Instrument [Line Items]	'	'	'	'	'
Debt Instrument Carrying Amount	'	$2,460,000,000	$2,460,000,000	'	$2,460,000,000
Debt Instrument, Unamortized Discount	'	4,171,000	4,171,000	'	4,329,000
Current maturities of long-term debt	'	500,000,000	500,000,000	'	0
Long-term debt	'	1,955,829,000	1,955,829,000	'	2,455,671,000
Line Of Credit Facility [Line Items]	'	'	'	'	'
Line Of Credit Facility Maximum Borrowing Capacity	'	1,000,000,000	1,000,000,000	'	'
Long Term Debt Other Disclosures [Abstract]	'	'	'	'	'
Authorized Commercial Paper	'	950,000,000	950,000,000	'	'
Commercial Paper	'	0	0	'	368,000,000
Debt and Equity Securities Authorized for Issuance	'	1,750,000,000	1,750,000,000	'	'
Debt And Equity Securities Available For Issuance	'	1,350,000,000	1,350,000,000	'	'
Regulated Operations Line of Credit Facilities, Covenant Terms	'	'We are required by the financial covenants in each of these facilities to maintain, at the end of each fiscal quarter, a ratio of total debt to total capitalization of no greater than 70 percent.	'	'	'
Ratio of Total Debt to Total Capital	'	46.00%	46.00%	'	'
Debt Instrument Covenant Description	'	'In addition to these financial covenants, our credit facilities and public indentures contain usual and customary covenants for our business, including covenants substantially limiting liens, substantial asset sales and mergers. Additionally, our public debt indentures relating to our senior notes and debentures, as well as our revolving credit agreements, each contain a default provision that is triggered if outstanding indebtedness arising out of any other credit agreements in amounts ranging from in excess of $15 million to in excess of $100 million becomes due by acceleration or is not paid at maturity.	'	'	'
Debt Instrument Covenant Compliance	'	'We were in compliance with all of our debt covenants as of March 31, 2014.	'	'	'
Stock Issued During Period, Shares, New Issues	9,200,000	'	'	'	'
Net proceeds from equity offering	390,200,000	'	390,205,000	0	'
Minimum [Member]	'	'	'	'	'
Line Of Credit Facility [Line Items]	'	'	'	'	'
Debt Instrument, Covenant, Excess Debt Trigger	'	15,000,000	15,000,000	'	'
Maximum [Member]	'	'	'	'	'
Line Of Credit Facility [Line Items]	'	'	'	'	'
Debt Instrument, Covenant, Excess Debt Trigger	'	100,000,000	100,000,000	'	'
First Facility Regulated Operations [Member]	'	'	'	'	'
Line Of Credit Facility [Line Items]	'	'	'	'	'
Line Of Credit Facility Maximum Borrowing Capacity	'	950,000,000	950,000,000	'	'
Line of Credit Facility, Maximum Borrowing Capacity with Accordion Feature	'	1,200,000,000	1,200,000,000	'	'
Second Facility Regulated Operations [Member]	'	'	'	'	'
Line Of Credit Facility [Line Items]	'	'	'	'	'
Line Of Credit Facility Maximum Borrowing Capacity	'	25,000,000	25,000,000	'	'
Third Facility Regulated Operations [Member]	'	'	'	'	'
Line Of Credit Facility [Line Items]	'	'	'	'	'
Line Of Credit Facility Maximum Borrowing Capacity	'	10,000,000	10,000,000	'	'
Line of Credit Facility, Current Available Borrowing Capacity	'	4,100,000	4,100,000	'	'
Intercompany Facility Regulated Operations [Member]	'	'	'	'	'
Line Of Credit Facility [Line Items]	'	'	'	'	'
Line Of Credit Facility Maximum Borrowing Capacity	'	500,000,000	500,000,000	'	'
Line Of Credit Facility Description	'	'which bears interest at the lower of (i)B the Eurodollar rate under the five-year revolving credit facility or (ii)B the rate outstanding under the commercial paper program	'	'	'
Committed Facility Nonregulated Operations [Member]	'	'	'	'	'
Line Of Credit Facility [Line Items]	'	'	'	'	'
Line Of Credit Facility Maximum Borrowing Capacity	'	15,000,000	15,000,000	'	25,000,000
Uncommitted Facility Nonregulated Operations [Member]	'	'	'	'	'
Line Of Credit Facility [Line Items]	'	'	'	'	'
Line Of Credit Facility Maximum Borrowing Capacity	'	25,000,000	25,000,000	'	'
Line of Credit Facility, Amended Maximum Borrowing Capacity	'	50,000,000	50,000,000	'	'
Intercompany Facility Nonregulated Operations [Member]	'	'	'	'	'
Line Of Credit Facility [Line Items]	'	'	'	'	'
Line Of Credit Facility Maximum Borrowing Capacity	'	500,000,000	500,000,000	'	'
Line Of Credit Facility Description	'	'This facility bears interest at a rate equal to the one-month LIBOR rate plus 3.00 percent or (ii) the rate for AEM's borrowings under its committed credit facility plus 0.75 percent.	'	'	'
Nonregulated Facilities [Member]	'	'	'	'	'
Line Of Credit Facility [Line Items]	'	'	'	'	'
Line of Credit Facility, Current Available Borrowing Capacity	'	33,700,000	33,700,000	'	'
Regulated Facilities [Member]	'	'	'	'	'
Line Of Credit Facility [Line Items]	'	'	'	'	'
Line Of Credit Facility Maximum Borrowing Capacity	'	985,000,000	985,000,000	'	'
Unsecured Senior Notes Due 2014 [Member]	'	'	'	'	'
Debt Instrument [Line Items]	'	'	'	'	'
Debt Instrument Carrying Amount	'	500,000,000	500,000,000	'	500,000,000
Debt Instrument, Interest Rate, Stated Percentage	'	4.95%	4.95%	'	'
Debt Instrument, Maturity Date	'	15-Oct-14	'	'	'
Unsecured Senior Notes Due 2017 [Member]	'	'	'	'	'
Debt Instrument [Line Items]	'	'	'	'	'
Debt Instrument Carrying Amount	'	250,000,000	250,000,000	'	250,000,000
Debt Instrument, Interest Rate, Stated Percentage	'	6.35%	6.35%	'	'
Debt Instrument, Maturity Date	'	15-Jun-17	'	'	'
Unsecured Senior Notes Due 2019 [Member]	'	'	'	'	'
Debt Instrument [Line Items]	'	'	'	'	'
Debt Instrument Carrying Amount	'	450,000,000	450,000,000	'	450,000,000
Debt Instrument, Interest Rate, Stated Percentage	'	8.50%	8.50%	'	'
Debt Instrument, Maturity Date	'	15-Mar-19	'	'	'
Unsecured Senior Notes Due 2034 [Member]	'	'	'	'	'
Debt Instrument [Line Items]	'	'	'	'	'
Debt Instrument Carrying Amount	'	200,000,000	200,000,000	'	200,000,000
Debt Instrument, Interest Rate, Stated Percentage	'	5.95%	5.95%	'	'
Debt Instrument, Maturity Date	'	15-Oct-34	'	'	'
Unsecured Senior Notes Due 2041 [Member]	'	'	'	'	'
Debt Instrument [Line Items]	'	'	'	'	'
Debt Instrument Carrying Amount	'	400,000,000	400,000,000	'	400,000,000
Debt Instrument, Interest Rate, Stated Percentage	'	5.50%	5.50%	'	'
Debt Instrument, Maturity Date	'	15-Jun-41	'	'	'
Unsecured Senior Notes Due 2043 [Member]	'	'	'	'	'
Debt Instrument [Line Items]	'	'	'	'	'
Debt Instrument Carrying Amount	'	500,000,000	500,000,000	'	500,000,000
Debt Instrument, Interest Rate, Stated Percentage	'	4.15%	4.15%	'	'
Debt Instrument, Maturity Date	'	15-Jan-43	'	'	'
Medium Term Notes Due 2025 [Member]	'	'	'	'	'
Debt Instrument [Line Items]	'	'	'	'	'
Debt Instrument Carrying Amount	'	10,000,000	10,000,000	'	10,000,000
Debt Instrument, Interest Rate, Stated Percentage	'	6.67%	6.67%	'	'
Debt Instrument, Maturity Date	'	15-Dec-25	'	'	'
Unsecured Debentures Due 2028 [Member]	'	'	'	'	'
Debt Instrument [Line Items]	'	'	'	'	'
Debt Instrument Carrying Amount	'	$150,000,000	$150,000,000	'	$150,000,000
Debt Instrument, Interest Rate, Stated Percentage	'	6.75%	6.75%	'	'
Debt Instrument, Maturity Date	'	15-Jul-28	'	'	'

Interim_Pension_and_Other_Post2

Interim Pension and Other Postretirement Benefits (Details) (USD $)	0 Months Ended	3 Months Ended		6 Months Ended
	Oct. 02, 2013	Mar. 31, 2014	Mar. 31, 2013	Mar. 31, 2014	Mar. 31, 2013
Pension Benefits [Member]	'	'	'	'	'
Components of net periodic pension cost [Abstract]	'	'	'	'	'
Service Cost	'	$4,738,000	$5,203,000	$9,476,000	$10,405,000
Interest Cost	'	6,824,000	6,023,000	13,648,000	12,048,000
Expected return on assets	'	-5,900,000	-5,738,000	-11,801,000	-11,477,000
Amortization of transition (asset)/obligation	'	0	0	0	0
Amortization of prior service (credit)/cost	'	-34,000	-36,000	-68,000	-71,000
Amortization of actuarial (gain) loss	'	3,930,000	5,562,000	7,862,000	11,123,000
Settlement loss	4,539,000	'	'	4,539,000	0
Net periodic pension cost	'	9,558,000	11,014,000	23,656,000	22,028,000
Defined Benefit Plan Weighted Average Assumptions Used In Calculating Net Periodic Benefit Cost Abstract	'	'	'	'	'
Discount Rate	'	4.95%	4.04%	4.95%	4.04%
Rate of compensation increase	'	3.50%	3.50%	3.50%	3.50%
Expected return on plan assets	'	7.25%	7.75%	7.25%	7.75%
Current Year Benefit Plan Contributions [Abstract]	'	'	'	'	'
Contributions Actual	'	'	'	9,100,000	'
Benefit Payment	16,800,000	'	'	'	'
Pension Benefits [Member] | Minimum [Member]	'	'	'	'	'
Current Year Benefit Plan Contributions [Abstract]	'	'	'	'	'
Defined Benefit Plan, Expected Contributions in Current Fiscal Year	'	'	'	10,000,000	'
Pension Benefits [Member] | Maximum [Member]	'	'	'	'	'
Current Year Benefit Plan Contributions [Abstract]	'	'	'	'	'
Defined Benefit Plan, Expected Contributions in Current Fiscal Year	'	'	'	35,000,000	'
Other Benefits [Member]	'	'	'	'	'
Components of net periodic pension cost [Abstract]	'	'	'	'	'
Service Cost	'	4,196,000	4,700,000	8,392,000	9,400,000
Interest Cost	'	3,988,000	3,241,000	7,976,000	6,482,000
Expected return on assets	'	-1,292,000	-997,000	-2,584,000	-1,994,000
Amortization of transition (asset)/obligation	'	68,000	270,000	136,000	540,000
Amortization of prior service (credit)/cost	'	-362,000	-363,000	-725,000	-725,000
Amortization of actuarial (gain) loss	'	158,000	1,049,000	316,000	2,098,000
Settlement loss	'	'	'	0	0
Net periodic pension cost	'	6,756,000	7,900,000	13,511,000	15,801,000
Defined Benefit Plan Weighted Average Assumptions Used In Calculating Net Periodic Benefit Cost Abstract	'	'	'	'	'
Discount Rate	'	4.95%	4.04%	4.95%	4.04%
Expected return on plan assets	'	4.60%	4.70%	4.60%	4.70%
Current Year Benefit Plan Contributions [Abstract]	'	'	'	'	'
Contributions Actual	'	'	'	11,600,000	'
Other Benefits [Member] | Minimum [Member]	'	'	'	'	'
Current Year Benefit Plan Contributions [Abstract]	'	'	'	'	'
Defined Benefit Plan, Expected Contributions in Current Fiscal Year	'	'	'	20,000,000	'
Other Benefits [Member] | Maximum [Member]	'	'	'	'	'
Current Year Benefit Plan Contributions [Abstract]	'	'	'	'	'
Defined Benefit Plan, Expected Contributions in Current Fiscal Year	'	'	'	$25,000,000	'

Commitments_and_Contingencies_

Commitments and Contingencies (Details) (USD $)	0 Months Ended		3 Months Ended		6 Months Ended
	2-May-14	Jan. 25, 2013	Mar. 31, 2014	Mar. 31, 2013	Mar. 31, 2014	Mar. 31, 2013
Loss Contingency Information About Litigation Matters Abstract	'	'	'	'	'	'
Description of Pending Litigation	'	'	'	'	'Since April 2009, Atmos Energy and two subsidiaries of AEH, Atmos Energy Marketing, LLC (AEM) and Atmos Gathering Company, LLC (AGC) (collectively, the Atmos Entities), have been involved in a lawsuit filed in the Circuit Court of Edmonson County, Kentucky related to our Park City Gathering Project. The dispute which gave rise to the litigation involves the amount of royalties due from a third party producer to landowners (who own the mineral rights) for natural gas produced from the landownersb properties. The third party producer was operating pursuant to leases between the landowners and certain investors/working interest owners. The third party producer filed a petition in bankruptcy, which was subsequently dismissed due to the lack of meaningful assets to reorganize or liquidate.Although certain Atmos Energy companies entered into contracts with the third party producer to gather, treat and ultimately sell natural gas produced from the landownersb properties, no Atmos Energy company had a contractual relationship with the landowners or the investors/working interest owners. After the lawsuit was filed, the landowners were successful in terminating for non-payment of royalties the leases related to the production of natural gas from their properties. Subsequent to termination, the investors/working interest owners under such leases filed additional claims against us for the termination of the leases.During the trial, the landowners and the investors/working interest owners requested an award of compensatory damages plus punitive damages against us. On DecemberB 17, 2010, the jury returned a verdict in favor of the landowners and investor/working interest owners and awarded compensatory damages of $3.8 million and punitive damages of $27.5 million payable by Atmos Energy and the two AEH subsidiaries.A hearing was held on FebruaryB 28, 2011 to hear a number of motions, including a motion to dismiss the jury verdict and a motion for a new trial. The motions to dismiss the jury verdict and for a new trial were denied. However, the total punitive damages award was reduced from $27.5 million to $24.7 million. On OctoberB 17, 2011, we filed our brief of appellants with the Kentucky Court of Appeals, appealing the verdict of the trial court. The appellees in this case subsequently filed their appelleesb brief with the Court of Appeals on JanuaryB 16, 2012, with our reply brief being filed with the Court of Appeals on MarchB 19, 2012. Oral arguments were held in the case on AugustB 27, 2012.In an opinion handed down on JanuaryB 25, 2013, the Court of Appeals overturned the $28.5 million jury verdict returned against the Atmos Entities. In a unanimous decision by a three-judge panel, the Court of Appeals reversed the claims asserted by the landowners and investors/working interest owners. The Court of Appeals concluded that all of such claims that the Atmos Entities appealed should have been dismissed by the trial court as a matter of law. The Court of Appeals let stand the jury verdict on one claim that Atmos Energy and our subsidiaries chose not to appeal, which was a trespass claim. The jury had awarded a total of $10,000 in compensatory damages to one landowner on that claim. The Court of Appeals vacated all of the other damages awarded by the jury and remanded the case to the trial court for a new trial, solely on the issue of whether punitive damages should be awarded to that landowner and, if so, in what amount.The investors/working interest owners, on FebruaryB 25, 2013, and the landowners, on MarchB 19, 2013, each filed with the Supreme Court of Kentucky, separate motions for discretionary review of the opinion of the Court of Appeals. We filed responses to the motions. The Kentucky Supreme Court denied the motions for discretionary review on B February 12, 2014.B The decision of the Court of Appeals became final on February 21, 2014.B Atmos has filed a motion with the trial court for entry of judgment dismissing all claims against it, except for the trespass claim.B Atmos' motion seeks a ruling by the trial court that the remaining landowner is not entitled to any punitive damages on that claim. B That motion is currently scheduled to be heard on May 19, 2014.We had previously accrued what we believed to be an adequate amount for the anticipated resolution of this matter. This accrual was reversed during the second fiscal quarter as the appellate process in this case has been completed. In addition, in a related matter, on JulyB 12, 2011, the Atmos Entities filed a lawsuit in the United States District Court, Western District of Kentucky, Atmos Energy Corporation et al.vs. Resource Energy Technologies, LLC and Robert Thorpe and John F. Charles, against the third party producer and its affiliates to recover all costs, including attorneysb fees, incurred by the Atmos Entities, which are associated with the defense and appeal of the case discussed above as well as for all damages awarded to the plaintiffs in such case against the Atmos Entities. The total amount of damages being claimed in the lawsuit is bopen-endedb since the appellate process and related costs are ongoing. This lawsuit is based upon the indemnification provisions agreed to by the third party producer in favor of Atmos Gathering that are contained in an agreement entered into between Atmos Gathering and the third party producer in May 2009. The defendants filed a motion to dismiss the case on AugustB 25, 2011, with Atmos Energy filing a brief in response to such motion on SeptemberB 19, 2011. On MarchB 27, 2012 the court denied the motion to dismiss. Discovery has been completed, and dispositive motions are due on June 30, 2014.B This case is scheduled for trial beginning October 6, 2014	'
Loss Contingency, Compensatory Damages Awarded, Value	'	$10,000	'	'	'	'
Business License Tax [Abstract]	'	'	'	'	'	'
Business License Tax Examination, Description	'	'	'	'	'Atmos Energy, through its affiliate, AEM, has been involved in a dispute with the Tennessee Department of Revenue (TDOR) regarding sales business tax audits over a period of several years. The cumulative assessment approximated $12 million as of March 31, 2014, which AEM has challenged. We had previously accrued in prior years what we believed to be an adequate amount for the anticipated resolution of this matter. With respect to certain issues, AEM and the TDOR filed competing Partial Motions for Summary Judgment with the Chancery Court. On August 2, 2013, the Chancery Court granted the TDOR's Partial Motion for Summary Judgment and denied AEM's Partial Motion for Summary Judgment. A filing deadline was set for filing any cross motions for partial summary judgment as to the remaining issues. On May 2, 2014, the Company and the TDOR executed an agreed order of dismissal with prejudice whereby AEM agreed to pay $6.2 million to resolve all business tax-related liabilities outstanding through September 2014. The order of dismissal will become effective upon approval of the Chancery Court.	'
Business License Tax Examination, Settlement Amount	6,200,000	'	'	'	'	'
Long Term Purchase Commitment [Line Items]	'	'	'	'	'	'
Significant Purchase Commitment Amount	'	'	$621,100,000	$327,800,000	$971,300,000	$617,300,000
Inventories Under Indexed Contracts [Member]	'	'	'	'	'	'
Long Term Purchase Commitment [Line Items]	'	'	'	'	'	'
Long Term Purchase Commitment Minimum Quantity Required Within One Year	'	'	100,500	'	100,500	'
Long Term Purchase Commitment Minimum Quantity Required One To Three Years	'	'	15,900	'	15,900	'
Long Term Purchase Commitment Minimum Quantity Required After Three Years	'	'	800	'	800	'
Inventories Under Fixed Price Contracts [Member]	'	'	'	'	'	'
Long Term Purchase Commitment [Line Items]	'	'	'	'	'	'
Long Term Purchase Commitment Minimum Quantity Required Within One Year	'	'	9,500	'	9,500	'
Long Term Purchase Commitment Minimum Quantity Required One To Three Years	'	'	800	'	800	'
Purchase Commitment Amount Minimum	'	'	3.75	'	3.75	'
Purchase Commitment Amount Maximum	'	'	6.36	'	6.36	'

Financial_Instruments_Descript

Financial Instruments Descriptions (Details) (USD $)	3 Months Ended		6 Months Ended
In Millions, unless otherwise specified	Mar. 31, 2014	Mar. 31, 2013	Mar. 31, 2014	Mar. 31, 2013
			MMcf
General Discussion Of Derivative Instruments And Hedging Activities [Abstract]	'	'	'	'
Minimum Hedge Percentage Of Anticipated Heating Season Gas	'	'	25.00%	'
Maximum Hedge Percentage Of Anticipated Heating Season Gas	'	'	50.00%	'
Hedge Percentage Of Actual Heating Season Gas	'	'	32.00%	'
Hedge Volume Of Actual Heating Season Gas	'	'	24,600	'
Minimum Length Of Time Hedged In Cash Flow Hedge	'1 month	'	'	'
Maximum Length Of Time Hedged In Cash Flow Hedge	'49 months	'	'	'
Gain (Loss) On Hedge Ineffectiveness	($3.70)	$1.70	$1.40	$17.80
Regulated Segments Effective Income Tax Rate Reconciliation At Federal Statutory Income Tax Rate	'	'	37.00%	'
Nonregulated Segment Effective Income Tax Rate Reconciliation At Federal Statutory Income Tax Rate	'	'	39.00%	'
Gain (Loss) On Derivative Instruments Not Designated Hedges Net Pretax	-9.3	6.8	-10.1	6.7
Interest Rate Hedges, Senior Notes 2015 Issuance [Member]	'	'	'	'
Derivative [Line Items]	'	'	'	'
Notional Amount of Interest Rate Cash Flow Hedge Derivatives	500	'	500	'
Anticipated Debt Issuance, Amount	500	'	500	'
Derivative, Average Forward Interest Rate	3.13%	'	3.13%	'
Interest Rate Hedges, Senior Notes 2017 Issuance [Member]	'	'	'	'
Derivative [Line Items]	'	'	'	'
Notional Amount of Interest Rate Cash Flow Hedge Derivatives	250	'	250	'
Anticipated Debt Issuance, Amount	250	'	250	'
Derivative, Average Forward Interest Rate	3.37%	'	3.37%	'
Interest Rate Hedges, Senior Notes 2019 Issuance [Member]	'	'	'	'
Derivative [Line Items]	'	'	'	'
Notional Amount of Interest Rate Cash Flow Hedge Derivatives	250	'	250	'
Anticipated Debt Issuance, Amount	$450	'	$450	'
Derivative, Average Forward Interest Rate	3.95%	'	3.95%	'

Financial_Instruments_Commodit

Financial Instruments Commodity Contract Volume (Details)	Mar. 31, 2014
	MMcf
Natural Gas Distribution Segment [Member]	'
Commodity Contract Outstanding Volumes [Line Items]	'
Investment Contract Volume	8,428
Natural Gas Distribution Segment [Member] | Nondesignated [Member]	'
Commodity Contract Outstanding Volumes [Line Items]	'
Investment Contract Volume	8,428
Natural Gas Distribution Segment [Member] | Fair Value Hedging [Member]	'
Commodity Contract Outstanding Volumes [Line Items]	'
Investment Contract Volume	0
Natural Gas Distribution Segment [Member] | Cash Flow Hedging [Member]	'
Commodity Contract Outstanding Volumes [Line Items]	'
Investment Contract Volume	0
Nonregulated Segment [Member]	'
Commodity Contract Outstanding Volumes [Line Items]	'
Investment Contract Volume	62,000
Nonregulated Segment [Member] | Nondesignated [Member]	'
Commodity Contract Outstanding Volumes [Line Items]	'
Investment Contract Volume	45,975
Nonregulated Segment [Member] | Fair Value Hedging [Member]	'
Commodity Contract Outstanding Volumes [Line Items]	'
Investment Contract Volume	-5,770
Nonregulated Segment [Member] | Cash Flow Hedging [Member]	'
Commodity Contract Outstanding Volumes [Line Items]	'
Investment Contract Volume	21,795

Financial_Instruments_Balance_

Financial Instruments Balance Sheet Location (Details) (USD $)	Mar. 31, 2014	Sep. 30, 2013
In Thousands, unless otherwise specified
Derivatives Fair Value [Line Items]	'	'
Derivative, Collateral, Right to Reclaim Cash	$8,000	$10,100
Derivative Liability, Collateral, Right to Reclaim Cash, Offset	3,100	14,700
Natural Gas Distribution Segment [Member]	'	'
Derivatives Fair Value [Line Items]	'	'
Derivative Asset, Fair Value, Gross Asset	89,411	111,191
Derivative Asset, Contract Netting	0	0
Derivative Asset, Net of Contract Netting	89,411	111,191
Derivative, Collateral, Right to Reclaim Cash	0	0
Derivative Asset	89,411	111,191
Derivative Liability, Fair Value, Gross Liability	0	-1,543
Derivative Liability, Contract Netting	0	0
Derivative Liability, Net of Contract Netting	0	-1,543
Derivative Liability, Collateral, Right to Reclaim Cash, Offset	0	0
Derivative Liability	0	-1,543
Nonregulated Segment [Member]	'	'
Derivatives Fair Value [Line Items]	'	'
Derivative Asset, Fair Value, Gross Asset	94,374	115,880
Derivative Asset, Contract Netting	-85,464	-115,875
Derivative Asset, Net of Contract Netting	8,910	5
Derivative, Collateral, Right to Reclaim Cash	7,940	10,124
Derivative Asset	16,850	10,129
Derivative Liability, Fair Value, Gross Liability	-88,578	-130,580
Derivative Liability, Contract Netting	85,464	115,875
Derivative Liability, Net of Contract Netting	-3,114	-14,705
Derivative Liability, Collateral, Right to Reclaim Cash, Offset	3,114	14,705
Derivative Liability	0	0
Designated As Hedging Instrument [Member] | Natural Gas Distribution Segment [Member]	'	'
Derivatives Fair Value [Line Items]	'	'
Derivative Asset, Fair Value, Gross Asset	84,758	107,512
Derivative Liability, Fair Value, Gross Liability	0	0
Designated As Hedging Instrument [Member] | Natural Gas Distribution Segment [Member] | Other Current Assets [Member] | Interest Rate Contract [Member]	'	'
Derivatives Fair Value [Line Items]	'	'
Derivative Asset, Fair Value, Gross Asset	54,093	'
Designated As Hedging Instrument [Member] | Natural Gas Distribution Segment [Member] | Other Current Assets [Member] | Commodity Contract [Member]	'	'
Derivatives Fair Value [Line Items]	'	'
Derivative Asset, Fair Value, Gross Asset	0	0
Designated As Hedging Instrument [Member] | Natural Gas Distribution Segment [Member] | Deferred Charges And Other Assets [Member] | Interest Rate Contract [Member]	'	'
Derivatives Fair Value [Line Items]	'	'
Derivative Asset, Fair Value, Gross Asset	30,665	107,512
Designated As Hedging Instrument [Member] | Natural Gas Distribution Segment [Member] | Deferred Charges And Other Assets [Member] | Commodity Contract [Member]	'	'
Derivatives Fair Value [Line Items]	'	'
Derivative Asset, Fair Value, Gross Asset	0	0
Designated As Hedging Instrument [Member] | Natural Gas Distribution Segment [Member] | Other Current Liabilities [Member] | Interest Rate Contract [Member]	'	'
Derivatives Fair Value [Line Items]	'	'
Derivative Liability, Fair Value, Gross Liability	0	'
Designated As Hedging Instrument [Member] | Natural Gas Distribution Segment [Member] | Other Current Liabilities [Member] | Commodity Contract [Member]	'	'
Derivatives Fair Value [Line Items]	'	'
Derivative Liability, Fair Value, Gross Liability	0	0
Designated As Hedging Instrument [Member] | Natural Gas Distribution Segment [Member] | Deferred Credits And Other Liabilities [Member] | Interest Rate Contract [Member]	'	'
Derivatives Fair Value [Line Items]	'	'
Derivative Liability, Fair Value, Gross Liability	0	0
Designated As Hedging Instrument [Member] | Natural Gas Distribution Segment [Member] | Deferred Credits And Other Liabilities [Member] | Commodity Contract [Member]	'	'
Derivatives Fair Value [Line Items]	'	'
Derivative Liability, Fair Value, Gross Liability	0	0
Designated As Hedging Instrument [Member] | Nonregulated Segment [Member]	'	'
Derivatives Fair Value [Line Items]	'	'
Derivative Asset, Fair Value, Gross Asset	11,955	9,510
Derivative Liability, Fair Value, Gross Liability	-7,793	-13,812
Designated As Hedging Instrument [Member] | Nonregulated Segment [Member] | Other Current Assets [Member] | Interest Rate Contract [Member]	'	'
Derivatives Fair Value [Line Items]	'	'
Derivative Asset, Fair Value, Gross Asset	0	'
Designated As Hedging Instrument [Member] | Nonregulated Segment [Member] | Other Current Assets [Member] | Commodity Contract [Member]	'	'
Derivatives Fair Value [Line Items]	'	'
Derivative Asset, Fair Value, Gross Asset	11,398	9,094
Designated As Hedging Instrument [Member] | Nonregulated Segment [Member] | Deferred Charges And Other Assets [Member] | Interest Rate Contract [Member]	'	'
Derivatives Fair Value [Line Items]	'	'
Derivative Asset, Fair Value, Gross Asset	0	0
Designated As Hedging Instrument [Member] | Nonregulated Segment [Member] | Deferred Charges And Other Assets [Member] | Commodity Contract [Member]	'	'
Derivatives Fair Value [Line Items]	'	'
Derivative Asset, Fair Value, Gross Asset	557	416
Designated As Hedging Instrument [Member] | Nonregulated Segment [Member] | Other Current Liabilities [Member] | Interest Rate Contract [Member]	'	'
Derivatives Fair Value [Line Items]	'	'
Derivative Liability, Fair Value, Gross Liability	0	'
Designated As Hedging Instrument [Member] | Nonregulated Segment [Member] | Other Current Liabilities [Member] | Commodity Contract [Member]	'	'
Derivatives Fair Value [Line Items]	'	'
Derivative Liability, Fair Value, Gross Liability	-6,849	-12,173
Designated As Hedging Instrument [Member] | Nonregulated Segment [Member] | Deferred Credits And Other Liabilities [Member] | Interest Rate Contract [Member]	'	'
Derivatives Fair Value [Line Items]	'	'
Derivative Liability, Fair Value, Gross Liability	0	0
Designated As Hedging Instrument [Member] | Nonregulated Segment [Member] | Deferred Credits And Other Liabilities [Member] | Commodity Contract [Member]	'	'
Derivatives Fair Value [Line Items]	'	'
Derivative Liability, Fair Value, Gross Liability	-944	-1,639
Nondesignated [Member] | Natural Gas Distribution Segment [Member]	'	'
Derivatives Fair Value [Line Items]	'	'
Derivative Asset, Fair Value, Gross Asset	4,653	3,679
Derivative Liability, Fair Value, Gross Liability	0	-1,543
Nondesignated [Member] | Natural Gas Distribution Segment [Member] | Other Current Assets [Member] | Commodity Contract [Member]	'	'
Derivatives Fair Value [Line Items]	'	'
Derivative Asset, Fair Value, Gross Asset	4,653	1,837
Nondesignated [Member] | Natural Gas Distribution Segment [Member] | Deferred Charges And Other Assets [Member] | Commodity Contract [Member]	'	'
Derivatives Fair Value [Line Items]	'	'
Derivative Asset, Fair Value, Gross Asset	0	1,842
Nondesignated [Member] | Natural Gas Distribution Segment [Member] | Other Current Liabilities [Member] | Commodity Contract [Member]	'	'
Derivatives Fair Value [Line Items]	'	'
Derivative Liability, Fair Value, Gross Liability	0	-1,543
Nondesignated [Member] | Natural Gas Distribution Segment [Member] | Deferred Credits And Other Liabilities [Member] | Commodity Contract [Member]	'	'
Derivatives Fair Value [Line Items]	'	'
Derivative Liability, Fair Value, Gross Liability	0	0
Nondesignated [Member] | Nonregulated Segment [Member]	'	'
Derivatives Fair Value [Line Items]	'	'
Derivative Asset, Fair Value, Gross Asset	82,419	106,370
Derivative Liability, Fair Value, Gross Liability	-80,785	-116,768
Nondesignated [Member] | Nonregulated Segment [Member] | Other Current Assets [Member] | Commodity Contract [Member]	'	'
Derivatives Fair Value [Line Items]	'	'
Derivative Asset, Fair Value, Gross Asset	48,402	65,388
Nondesignated [Member] | Nonregulated Segment [Member] | Deferred Charges And Other Assets [Member] | Commodity Contract [Member]	'	'
Derivatives Fair Value [Line Items]	'	'
Derivative Asset, Fair Value, Gross Asset	34,017	40,982
Nondesignated [Member] | Nonregulated Segment [Member] | Other Current Liabilities [Member] | Commodity Contract [Member]	'	'
Derivatives Fair Value [Line Items]	'	'
Derivative Liability, Fair Value, Gross Liability	-56,065	-70,876
Nondesignated [Member] | Nonregulated Segment [Member] | Deferred Credits And Other Liabilities [Member] | Commodity Contract [Member]	'	'
Derivatives Fair Value [Line Items]	'	'
Derivative Liability, Fair Value, Gross Liability	($24,720)	($45,892)

Financial_Instruments_Fair_Val

Financial Instruments Fair Value Hedges and Cash Flow Hedges (Details) (USD $)	3 Months Ended		6 Months Ended
In Thousands, unless otherwise specified	Mar. 31, 2014	Mar. 31, 2013	Mar. 31, 2014	Mar. 31, 2013
Effect of Fair Value Hedges on Results of Operations [Abstract]	'	'	'	'
Commodity contracts	$3,587	($17,846)	($4,974)	($10,532)
Fair value adjustment for natural gas inventory designated as the hedged item	-7,450	19,586	6,329	28,405
Total (increase) decrease to purchased gas cost	-3,863	1,740	1,355	17,873
Basis ineffectiveness	-579	1,458	-1,199	1,218
Timing ineffectiveness	-3,284	282	2,554	16,655
Cash Flow Hedge [Line Items]	'	'	'	'
Gain (loss) reclassified from AOCI into purchased gas cost for effective portion of commodity contracts	7,184	-5,199	4,574	-10,359
Gain (loss) arising from ineffective portion of commodity contracts	142	-83	24	-102
Total impact on purchased gas cost	7,326	-5,282	4,598	-10,461
Loss on settled Treasury Lock agreements reclassified from AOCI into interest expense	-1,057	-873	-2,115	-1,375
Total Impact from Cash Flow Hedges	6,269	-6,155	2,483	-11,836
Natural Gas Distribution Segment [Member]	'	'	'	'
Cash Flow Hedge [Line Items]	'	'	'	'
Gain (loss) reclassified from AOCI into purchased gas cost for effective portion of commodity contracts	0	0	0	0
Gain (loss) arising from ineffective portion of commodity contracts	0	0	0	0
Total impact on purchased gas cost	0	0	0	0
Loss on settled Treasury Lock agreements reclassified from AOCI into interest expense	-1,057	-873	-2,115	-1,375
Total Impact from Cash Flow Hedges	-1,057	-873	-2,115	-1,375
Nonregulated Segment [Member]	'	'	'	'
Cash Flow Hedge [Line Items]	'	'	'	'
Gain (loss) reclassified from AOCI into purchased gas cost for effective portion of commodity contracts	7,184	-5,199	4,574	-10,359
Gain (loss) arising from ineffective portion of commodity contracts	142	-83	24	-102
Total impact on purchased gas cost	7,326	-5,282	4,598	-10,461
Loss on settled Treasury Lock agreements reclassified from AOCI into interest expense	0	0	0	0
Total Impact from Cash Flow Hedges	$7,326	($5,282)	$4,598	($10,461)

Financial_Instruments_Other_Co

Financial Instruments Other Comprehensive Income (Details) (USD $)	3 Months Ended				6 Months Ended
In Thousands, unless otherwise specified	Mar. 31, 2014		Mar. 31, 2013		Mar. 31, 2014		Mar. 31, 2013
Other Comprehensive Income (Loss), Net of Tax [Abstract]	'		'		'		'
Interest rate agreements fair value	($27,718)		$22,955		($14,448)		$34,900
Forward commodity contracts fair value	5,483		5,666		11,709		2,153
Interest rate agreements	671		554		1,343		873
Forward commodity contracts	-4,382		3,172		-2,790		6,320
Total other comprehensive income (loss) from hedging, net of tax	-25,946	[1]	32,347	[1]	-4,186	[1]	44,246	[1]
Expected Earnings [Line Items]	'		'		'		'
Interest Rate Agreement Gain (Loss) Reclassified To Earnings	'		'		-29,021	[2]	'
Commodity Contract Gain (Loss) Reclassified To Earnings	'		'		4,443	[2]	'
Total Hedge Gain (Loss) Reclassified To Earnings	'		'		-24,578		'
Next Twelve Months [Member]	'		'		'		'
Expected Earnings [Line Items]	'		'		'		'
Interest Rate Agreement Gain (Loss) Reclassified To Earnings	'		'		-1,830		'
Commodity Contract Gain (Loss) Reclassified To Earnings	'		'		4,682		'
Total Hedge Gain (Loss) Reclassified To Earnings	'		'		2,852		'
Thereafter [Member]	'		'		'		'
Expected Earnings [Line Items]	'		'		'		'
Interest Rate Agreement Gain (Loss) Reclassified To Earnings	'		'		-27,191		'
Commodity Contract Gain (Loss) Reclassified To Earnings	'		'		-239		'
Total Hedge Gain (Loss) Reclassified To Earnings	'		'		($27,430)		'
[1]	Utilizing an income tax rate ranging from 37 percent to 39 percent based on the effective rates in each taxing jurisdiction.
[2]	(1)B Utilizing an income tax rate ranging from 37 percent to 39 percent based on the effective rates in each taxing jurisdiction.

Accumulated_Other_Comprehensiv2

Accumulated Other Comprehensive Income Components (Details) (USD $)	6 Months Ended
In Thousands, unless otherwise specified	Mar. 31, 2014	Mar. 31, 2013
Accumulated Other Comprehensive Income (Loss) [Line Items]	'	'
Accumulated other comprehensive income (loss), beginning balance	$38,878	($47,607)
Other comprehensive income (loss) before reclassifications	-370	38,188
Amounts reclassified from accumulated other comprehensive income	-1,674	5,485
Net current-period other comprehensive income (loss)	-2,044	43,673
Accumulated other comprehensive income (loss), ending balance	36,834	-3,934
Accumulated Net Unrealized Investment Gain (Loss) [Member]	'	'
Accumulated Other Comprehensive Income (Loss) [Line Items]	'	'
Accumulated other comprehensive income (loss), beginning balance	5,448	5,661
Other comprehensive income (loss) before reclassifications	2,369	1,135
Amounts reclassified from accumulated other comprehensive income	-227	-1,708
Net current-period other comprehensive income (loss)	2,142	-573
Accumulated other comprehensive income (loss), ending balance	7,590	5,088
Accumulated Net Gain (Loss) from Interest Rate Hedges [Member] [Member]	'	'
Accumulated Other Comprehensive Income (Loss) [Line Items]	'	'
Accumulated other comprehensive income (loss), beginning balance	37,906	-44,273
Other comprehensive income (loss) before reclassifications	-14,448	34,900
Amounts reclassified from accumulated other comprehensive income	1,343	873
Net current-period other comprehensive income (loss)	-13,105	35,773
Accumulated other comprehensive income (loss), ending balance	24,801	-8,500
Accumulated Net Gain (Loss) from Commodity Contracts Cash Flow Hedges [Member] [Member]	'	'
Accumulated Other Comprehensive Income (Loss) [Line Items]	'	'
Accumulated other comprehensive income (loss), beginning balance	-4,476	-8,995
Other comprehensive income (loss) before reclassifications	11,709	2,153
Amounts reclassified from accumulated other comprehensive income	-2,790	6,320
Net current-period other comprehensive income (loss)	8,919	8,473
Accumulated other comprehensive income (loss), ending balance	$4,443	($522)

Accumulated_Other_Comprehensiv3

Accumulated Other Comprehensive Income Affected Line Item in the Statement of Income (Details) (USD $)	3 Months Ended		6 Months Ended
In Thousands, unless otherwise specified	Mar. 31, 2014	Mar. 31, 2013	Mar. 31, 2014	Mar. 31, 2013
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]	'	'	'	'
Operation and maintenance	($124,675)	($111,086)	($240,432)	($217,613)
Income (Loss) from Continuing Operations before Equity Method Investments, Income Taxes, Extraordinary Items, Noncontrolling Interest	216,963	178,559	353,436	303,657
Income Tax Expense	-83,596	-66,219	-133,053	-113,969
Income (loss) from continuing operations	133,367	112,340	220,383	189,688
Interest charges	-31,601	-33,331	-63,716	-63,853
Purchased gas cost	-1,468,045	-876,245	-2,334,236	-1,548,038
Reclassification out of Accumulated Other Comprehensive Income [Member]	'	'	'	'
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]	'	'	'	'
Income (loss) from continuing operations	3,938	-2,018	1,674	-5,485
Reclassification out of Accumulated Other Comprehensive Income [Member] | Accumulated Net Unrealized Investment Gain (Loss) [Member]	'	'	'	'
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]	'	'	'	'
Operation and maintenance	358	2,689	358	2,689
Income (Loss) from Continuing Operations before Equity Method Investments, Income Taxes, Extraordinary Items, Noncontrolling Interest	358	2,689	358	2,689
Income Tax Expense	-131	-981	-131	-981
Income (loss) from continuing operations	227	1,708	227	1,708
Reclassification out of Accumulated Other Comprehensive Income [Member] | Accumulated Net Gain (Loss) from Interest Rate Hedges [Member] [Member]	'	'	'	'
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]	'	'	'	'
Interest charges	-1,057	-873	-2,115	-1,375
Reclassification out of Accumulated Other Comprehensive Income [Member] | Accumulated Net Gain (Loss) from Commodity Contracts Cash Flow Hedges [Member] [Member]	'	'	'	'
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]	'	'	'	'
Purchased gas cost	7,184	-5,201	4,574	-10,361
Reclassification out of Accumulated Other Comprehensive Income [Member] | Accumulated Net Gain (Loss) from Designated or Qualifying Cash Flow Hedges [Member]	'	'	'	'
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]	'	'	'	'
Income (Loss) from Continuing Operations before Equity Method Investments, Income Taxes, Extraordinary Items, Noncontrolling Interest	6,127	-6,074	2,459	-11,736
Income Tax Expense	-2,416	2,348	-1,012	4,543
Income (loss) from continuing operations	$3,711	($3,726)	$1,447	($7,193)

Fair_Value_Measurements_Detail

Fair Value Measurements (Details) (USD $)	Mar. 31, 2014	Sep. 30, 2013
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]	'	'
Financial instruments, assets	$106,261,000	$121,320,000
Hedged portion of gas stored underground	23,570,000	44,758,000
Available-for-sale Securities	75,670,000	72,682,000
Total assets	205,501,000	238,760,000
Financial instruments, liabilities	0	1,543,000
Fair Value [Abstract]	'	'
Derivative, Cash Collateral	11,100,000	24,800,000
Cash Held In Margin Accounts Classified Current Risk Management Asset	8,000,000	10,100,000
Cash Held In Margin Accounts Offset Current Risk Management Liabilities	3,100,000	14,700,000
Debt Instrument Carrying Amount	2,460,000,000	2,460,000,000
Debt Instrument Fair Value	2,739,091,000	2,676,487,000
Money Market Funds [Member]	'	'
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]	'	'
Available-for-sale Securities	2,904,000	4,428,000
Equity Securities [Member]	'	'
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]	'	'
Available-for-sale Securities	44,263,000	40,094,000
Debt Securities [Member]	'	'
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]	'	'
Available-for-sale Securities	28,503,000	28,160,000
Natural Gas Distribution Segment [Member]	'	'
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]	'	'
Financial instruments, assets	89,411,000	111,191,000
Financial instruments, liabilities	0	1,543,000
Fair Value [Abstract]	'	'
Cash Held In Margin Accounts Classified Current Risk Management Asset	0	0
Cash Held In Margin Accounts Offset Current Risk Management Liabilities	0	0
Nonregulated Segment [Member]	'	'
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]	'	'
Financial instruments, assets	16,850,000	10,129,000
Financial instruments, liabilities	0	0
Fair Value [Abstract]	'	'
Cash Held In Margin Accounts Classified Current Risk Management Asset	7,940,000	10,124,000
Cash Held In Margin Accounts Offset Current Risk Management Liabilities	3,114,000	14,705,000
Fair Value Inputs Level 1 [Member]	'	'
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]	'	'
Financial instruments, assets	89,000	745,000
Hedged portion of gas stored underground	23,570,000	44,758,000
Available-for-sale Securities	44,263,000	40,094,000
Total assets	67,922,000	85,597,000
Financial instruments, liabilities	1,297,000	158,000
Fair Value Inputs Level 1 [Member] | Money Market Funds [Member]	'	'
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]	'	'
Available-for-sale Securities	0	0
Fair Value Inputs Level 1 [Member] | Equity Securities [Member]	'	'
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]	'	'
Available-for-sale Securities	44,263,000	40,094,000
Fair Value Inputs Level 1 [Member] | Debt Securities [Member]	'	'
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]	'	'
Available-for-sale Securities	0	0
Fair Value Inputs Level 1 [Member] | Natural Gas Distribution Segment [Member]	'	'
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]	'	'
Financial instruments, assets	0	0
Financial instruments, liabilities	0	0
Fair Value Inputs Level 1 [Member] | Nonregulated Segment [Member]	'	'
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]	'	'
Financial instruments, assets	89,000	745,000
Financial instruments, liabilities	1,297,000	158,000
Fair Value Inputs Level 2 [Member]	'	'
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]	'	'
Financial instruments, assets	183,696,000	226,326,000
Hedged portion of gas stored underground	0	0
Available-for-sale Securities	31,407,000	32,588,000
Total assets	215,103,000	258,914,000
Financial instruments, liabilities	87,281,000	131,965,000
Fair Value Inputs Level 2 [Member] | Money Market Funds [Member]	'	'
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]	'	'
Available-for-sale Securities	2,904,000	4,428,000
Fair Value Inputs Level 2 [Member] | Equity Securities [Member]	'	'
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]	'	'
Available-for-sale Securities	0	0
Fair Value Inputs Level 2 [Member] | Debt Securities [Member]	'	'
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]	'	'
Available-for-sale Securities	28,503,000	28,160,000
Fair Value Inputs Level 2 [Member] | Natural Gas Distribution Segment [Member]	'	'
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]	'	'
Financial instruments, assets	89,411,000	111,191,000
Financial instruments, liabilities	0	1,543,000
Fair Value Inputs Level 2 [Member] | Nonregulated Segment [Member]	'	'
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]	'	'
Financial instruments, assets	94,285,000	115,135,000
Financial instruments, liabilities	87,281,000	130,422,000
Fair Value Inputs Level 3 [Member]	'	'
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]	'	'
Financial instruments, assets	0	0
Hedged portion of gas stored underground	0	0
Available-for-sale Securities	0	0
Total assets	0	0
Financial instruments, liabilities	0	0
Fair Value Inputs Level 3 [Member] | Money Market Funds [Member]	'	'
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]	'	'
Available-for-sale Securities	0	0
Fair Value Inputs Level 3 [Member] | Equity Securities [Member]	'	'
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]	'	'
Available-for-sale Securities	0	0
Fair Value Inputs Level 3 [Member] | Debt Securities [Member]	'	'
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]	'	'
Available-for-sale Securities	0	0
Fair Value Inputs Level 3 [Member] | Natural Gas Distribution Segment [Member]	'	'
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]	'	'
Financial instruments, assets	0	0
Financial instruments, liabilities	0	0
Fair Value Inputs Level 3 [Member] | Nonregulated Segment [Member]	'	'
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]	'	'
Financial instruments, assets	0	0
Financial instruments, liabilities	0	0
Netting And Collateral [Member]	'	'
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]	'	'
Financial instruments, assets	-77,524,000	-105,751,000
Hedged portion of gas stored underground	0	0
Available-for-sale Securities	0	0
Total assets	-77,524,000	-105,751,000
Financial instruments, liabilities	-88,578,000	-130,580,000
Netting And Collateral [Member] | Money Market Funds [Member]	'	'
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]	'	'
Available-for-sale Securities	0	0
Netting And Collateral [Member] | Equity Securities [Member]	'	'
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]	'	'
Available-for-sale Securities	0	0
Netting And Collateral [Member] | Debt Securities [Member]	'	'
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]	'	'
Available-for-sale Securities	0	0
Netting And Collateral [Member] | Natural Gas Distribution Segment [Member]	'	'
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]	'	'
Financial instruments, assets	0	0
Financial instruments, liabilities	0	0
Netting And Collateral [Member] | Nonregulated Segment [Member]	'	'
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]	'	'
Financial instruments, assets	-77,524,000	-105,751,000
Financial instruments, liabilities	($88,578,000)	($130,580,000)

Fair_Value_Measurements_Availa

Fair Value Measurements Available-For-Sale Securities (Details) (USD $)	6 Months Ended
	Mar. 31, 2013	Mar. 31, 2014	Sep. 30, 2013
Schedule Of Available For Sale Securities [Line Items]	'	'	'
Available For Sale Securities Amortized Cost	'	$63,568,000	$64,023,000
Gross Unrealized Gain	'	12,110,000	8,706,000
Gross Unrealized Loss	'	-8,000	-47,000
Fair value	'	75,670,000	72,682,000
Available-for-sale Securities, Other Disclosure Items [Abstract]	'	'	'
Available-for-sale Securities, Supplemental Executive Benefit Plans	'	47,200,000	44,500,000
Available-for-sale Securities, Gross Realized Gains	2,700,000	'	'
Equity Funds Domestic [Member]	'	'	'
Schedule Of Available For Sale Securities [Line Items]	'	'	'
Available For Sale Securities Amortized Cost	'	27,226,000	27,043,000
Gross Unrealized Gain	'	10,052,000	7,476,000
Gross Unrealized Loss	'	0	-23,000
Fair value	'	37,278,000	34,496,000
Equity Funds Foreign [Member]	'	'	'
Schedule Of Available For Sale Securities [Line Items]	'	'	'
Available For Sale Securities Amortized Cost	'	5,118,000	4,536,000
Gross Unrealized Gain	'	1,867,000	1,062,000
Gross Unrealized Loss	'	0	0
Fair value	'	6,985,000	5,598,000
Debt Securities [Member]	'	'	'
Schedule Of Available For Sale Securities [Line Items]	'	'	'
Available For Sale Securities Amortized Cost	'	28,320,000	28,016,000
Gross Unrealized Gain	'	191,000	168,000
Gross Unrealized Loss	'	-8,000	-24,000
Fair value	'	28,503,000	28,160,000
Money Market Funds [Member]	'	'	'
Schedule Of Available For Sale Securities [Line Items]	'	'	'
Available For Sale Securities Amortized Cost	'	2,904,000	4,428,000
Gross Unrealized Gain	'	0	0
Gross Unrealized Loss	'	0	0
Fair value	'	$2,904,000	$4,428,000

Discontinued_Operations_Detail

Discontinued Operations (Details) (USD $)	0 Months Ended	3 Months Ended		6 Months Ended
	Apr. 02, 2013	Mar. 31, 2014	Mar. 31, 2013	Mar. 31, 2014	Mar. 31, 2013
Discontinued Operations and Disposal Groups [Abstract]	'	'	'	'	'
Discontinued Operation, Cash Price Received from Disposal of Discontinued Operation	$153,000,000	'	'	'	'
Discontinued Operation, Income (Loss) from Discontinued Operation Disclosures [Abstract]	'	'	'	'	'
Operating revenues	'	0	21,678,000	0	37,962,000
Purchased gas cost	'	0	12,497,000	0	21,464,000
Gross profit	'	0	9,181,000	0	16,498,000
Operating expenses	'	0	3,038,000	0	5,858,000
Operating income	'	0	6,143,000	0	10,640,000
Miscellaneous income (expense)	'	0	200,000	0	548,000
Income from discontinued operations before income taxes	'	0	6,343,000	0	11,188,000
Income tax expense	'	0	2,258,000	0	3,986,000
Income (loss) from discontinued operations	'	0	4,085,000	0	7,202,000
Gain (loss) on sale of discontinued operations, net of tax	5,300,000	'	'	'	'
Net income (loss) from discontinued operations	'	$0	$4,085,000	$0	$7,202,000