Atmos Energy (ATO) 10-K 6 Nov 15 2015 FY Annual report Financial data

Document and Entity Information

Document and Entity Information - USD ($)	12 Months Ended
	Sep. 30, 2015	Oct. 30, 2015	Mar. 31, 2015
Document And Entity Information [Abstract]
Entity Registrant Name	Atmos Energy Corporation
Entity Central Index Key	731,802
Current Fiscal Year End Date	--09-30
Entity Filer Category	Large Accelerated Filer
Document Type	10-K
Document Period End Date	Sep. 30, 2015
Document Fiscal Year Focus	2,015
Document Fiscal Period Focus	FY
Amendment Flag	false
Entity Common Stock Shares Outstanding		101,506,645
Entity Well Known Seasoned Issuer	Yes
Entity Voluntary Filers	No
Entity Current Reporting Status	Yes
Entity Public Float			$ 5,500,632,050

CONSOLIDATED BALANCE SHEETS

CONSOLIDATED BALANCE SHEETS - USD ($) $ in Thousands		Sep. 30, 2015	Sep. 30, 2014
ASSETS
Property, plant and equipment		$ 8,959,702	$ 8,200,121
Construction in progress		280,398	247,579
Total property, plant and equipment and construction in progress		9,240,100	8,447,700
Less accumulated depreciation and amortization		1,809,520	1,721,794
Net property, plant and equipment	[1]	7,430,580	6,725,906
Current assets
Cash and cash equivalents		28,653	42,258
Accounts receivable, less allowance for doubtful accounts of $15,283 in 2015 and $23,992 in 2014		295,160	343,400
Gas stored underground		236,603	278,917
Other current assets		70,569	111,265
Total current assets		630,985	775,840
Goodwill		742,702	742,029
Deferred charges and other assets		288,678	350,929
Total assets		9,092,945	8,594,704
Shareholders' equity
Common stock, no par value (stated at $.005 per share); 200,000,000 shares authorized; issued and outstanding: 2015 — 101,478,818 shares, 2014 — 100,388,092 shares		507	502
Additional paid-in capital		2,230,591	2,180,151
Accumulated other comprehensive loss		(109,330)	(12,393)
Retained earnings		1,073,029	917,972
Shareholders' equity		3,194,797	3,086,232
Long-term debt		2,455,388	2,455,986
Total capitalization		5,650,185	5,542,218
Current liabilities
Accounts payable and accrued liabilities		238,942	308,086
Other current liabilities		457,954	405,869
Short-term debt		457,927	196,695
Total current liabilities		1,154,823	910,650
Deferred income taxes		1,411,315	1,286,616
Regulatory cost of removal obligation		427,553	445,387
Pension and postretirement liabilities		287,373	340,963
Deferred credits and other liabilities		161,696	68,870
Total shareholders' equity and liabilities		$ 9,092,945	$ 8,594,704
[1]	Net property, plant and equipment includes plant acquisition adjustments of $(68.1) million and $(76.4) million at September 30, 2015 and 2014.

CONSOLIDATED BALANCE SHEETS (PA

CONSOLIDATED BALANCE SHEETS (PARENTHETICALS) - USD ($) $ in Thousands	Sep. 30, 2015	Sep. 30, 2014
Statement of Financial Position [Abstract]
Allowance for doubtful accounts	$ 15,283	$ 23,992
Common Stock, Stated Value Per Share	$ 0.005	$ 0.005
Common Stock, Shares Authorized	200,000,000	200,000,000
Common Stock, Shares, Issued	101,478,818	100,388,092

CONSOLIDATED STATEMENTS OF INCO

CONSOLIDATED STATEMENTS OF INCOME - USD ($) shares in Thousands, $ in Thousands	3 Months Ended								12 Months Ended
	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2013	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2013
Operating revenues
Operating revenues	$ 656,902	$ 686,401	$ 1,540,068	$ 1,258,765	$ 789,034	$ 943,170	$ 1,964,854	$ 1,243,858	$ 4,142,136	$ 4,940,916	$ 3,875,460
Purchased gas cost
Purchased gas cost									2,462,119	3,358,490	2,463,410
Gross profit	354,321	381,673	520,738	423,285	337,659	359,533	496,277	388,957	1,680,017	1,582,426	1,412,050
Operating expenses
Operation and maintenance									541,868	505,154	488,020
Depreciation and amortization									274,796	253,987	235,079
Taxes, other than income									231,958	211,936	187,072
Total operating expenses									1,048,622	971,077	910,171
Operating income	75,853	117,607	250,210	187,725	83,944	106,605	250,080	170,720	631,395	611,349	501,879
Miscellaneous income (expense), net									(4,389)	(5,235)	(197)
Interest charges									116,241	129,295	128,385
Income from continuing operations before income taxes									510,765	476,819	373,297
Income tax expense									195,690	187,002	142,599
Income from continuing operations									315,075	289,817	230,698
Income from discontinued operations, net of tax ($0, $0 and $3,986)									0	0	7,202
Gain on sale of discontinued operations, net of tax ($0, $0 and $2,909)									0	0	5,294
Net income	$ 23,515	$ 56,281	$ 137,684	$ 97,595	$ 23,713	$ 45,721	$ 133,367	$ 87,016	$ 315,075	$ 289,817	$ 243,194
Income per share from continuing operations - basic (usd per share)									$ 3.09	$ 2.96	$ 2.54
Income per share from discontinued operations - basic (usd per share)									0	0	0.14
Net income per share — basic (usd per share)	$ 0.23	$ 0.55	$ 1.35	$ 0.96	$ 0.23	$ 0.45	$ 1.38	$ 0.95	3.09	2.96	2.68
Income per share from continuing operations - diluted (usd per share)									3.09	2.96	2.50
Income per share from discontinued operations - diluted (usd per share)									0	0	0.14
Net income per share — diluted (usd per share)	$ 0.23	$ 0.55	$ 1.35	$ 0.96	$ 0.23	$ 0.45	$ 1.38	$ 0.95	$ 3.09	$ 2.96	$ 2.64
Weighted average shares outstanding:
Basic (shares)									101,892	97,606	90,533
Diluted (shares)									101,892	97,608	91,711
Intersegment Elimination [Member]
Operating revenues
Operating revenues									$ (464,020)	$ (506,381)	$ (380,847)
Purchased gas cost
Purchased gas cost									(463,488)	(505,878)	(379,430)
Regulated Distribution Segment [Member]
Operating revenues
Operating revenues	$ 369,656	$ 416,794	$ 1,130,613	$ 846,772	$ 409,014	$ 517,707	$ 1,290,960	$ 843,865	2,763,835	3,061,546	2,399,493
Purchased gas cost
Purchased gas cost									1,526,258	1,885,031	1,318,257
Gross profit									1,237,577	1,176,515	1,081,236
Operating expenses
Operation and maintenance									388,486	387,228	375,188
Depreciation and amortization									223,048	208,376	195,581
Taxes, other than income									205,894	196,343	167,374
Total operating expenses									817,428	791,947	738,143
Operating income									420,149	384,568	343,093
Miscellaneous income (expense), net									(377)	(381)	2,535
Interest charges									84,132	94,918	98,296
Income from continuing operations before income taxes									335,640	289,269	247,332
Income tax expense									130,827	117,684	96,476
Income from continuing operations											150,856
Income from discontinued operations, net of tax ($0, $0 and $3,986)											7,202
Gain on sale of discontinued operations, net of tax ($0, $0 and $2,909)											5,649
Net income									204,813	171,585	163,707
Regulated Pipeline Segment [Member]
Operating revenues
Operating revenues	97,807	97,008	91,730	83,567	86,314	87,189	73,615	71,341	370,112	318,459	268,900
Purchased gas cost
Purchased gas cost									0	0	0
Gross profit									370,112	318,459	268,900
Operating expenses
Operation and maintenance									118,866	91,466	76,686
Depreciation and amortization									47,236	41,031	35,302
Taxes, other than income									22,743	13,143	17,059
Total operating expenses									188,845	145,640	129,047
Operating income									181,267	172,819	139,853
Miscellaneous income (expense), net									(1,243)	(3,181)	(2,285)
Interest charges									33,151	36,280	30,678
Income from continuing operations before income taxes									146,873	133,358	106,890
Income tax expense									52,211	47,167	38,630
Income from continuing operations											68,260
Income from discontinued operations, net of tax ($0, $0 and $3,986)											0
Gain on sale of discontinued operations, net of tax ($0, $0 and $2,909)											0
Net income									94,662	86,191	68,260
Nonregulated Segment [Member]
Operating revenues
Operating revenues	$ 292,830	$ 278,769	$ 438,322	$ 462,288	$ 407,161	$ 465,485	$ 758,215	$ 436,431	1,472,209	2,067,292	1,587,914
Purchased gas cost
Purchased gas cost									1,399,349	1,979,337	1,524,583
Gross profit									72,860	87,955	63,331
Operating expenses
Operation and maintenance									35,048	26,963	37,569
Depreciation and amortization									4,512	4,580	4,196
Taxes, other than income									3,321	2,450	2,639
Total operating expenses									42,881	33,993	44,404
Operating income									29,979	53,962	18,927
Miscellaneous income (expense), net									(760)	2,216	2,316
Interest charges									967	1,986	2,168
Income from continuing operations before income taxes									28,252	54,192	19,075
Income tax expense									12,652	22,151	7,493
Income from continuing operations											11,582
Income from discontinued operations, net of tax ($0, $0 and $3,986)											0
Gain on sale of discontinued operations, net of tax ($0, $0 and $2,909)											(355)
Net income									$ 15,600	$ 32,041	$ 11,227

CONSOLIDATED STATEMENTS OF INC5

CONSOLIDATED STATEMENTS OF INCOME (PARENTHETICALS) - USD ($) $ in Thousands	12 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2013
Income Statement [Abstract]
Discontinued Operation Tax Effect Of Income Loss From Discontinued Operation During Phase Out Period	$ 0	$ 0	$ 3,986
Discontinued Operation, Tax Effect of Income (Loss) from Disposal of Discontinued Operation	$ 0	$ 0	$ 2,909

CONSOLIDATED STATEMENTS OF COMP

CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME - USD ($) $ in Thousands		12 Months Ended
		Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2013
Statement of Comprehensive Income [Abstract]
Net income		$ 315,075	$ 289,817	$ 243,194
Other comprehensive income (loss), net of tax [Abstract]
Net unrealized holding gains (losses) on available-for-sale securities, net of tax of $(1,559), $1,199 and $(186)		(2,713)	2,214	(213)
Schedule of Other Comprehensive Income (Loss), Cash Flow Hedges [Line Items]
Other Comprehensive Income (Loss), Derivatives Qualifying as Hedges, Net of Tax	[1]	(94,224)	(53,485)
Total other comprehensive income (loss)		(96,937)	(51,271)	86,485
Total comprehensive income		218,138	238,546	329,679
Interest Rate Contract [Member]
Schedule of Other Comprehensive Income (Loss), Cash Flow Hedges [Line Items]
Other Comprehensive Income (Loss), Derivatives Qualifying as Hedges, Net of Tax		(70,461)	(56,287)	82,179
Commodity Contract [Member]
Schedule of Other Comprehensive Income (Loss), Cash Flow Hedges [Line Items]
Other Comprehensive Income (Loss), Derivatives Qualifying as Hedges, Net of Tax		$ (23,763)	$ 2,802	$ 4,519
[1]	Utilizing an income tax rate ranging from approximately 37 percent to 39 percent based on the effective rates in each taxing jurisdiction.

CONSOLIDATED STATEMENTS OF COM7

CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME (PARENTHETICAL) - USD ($) $ in Thousands	12 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2013
Other Comprehensive Income (Loss), Tax, Portion Attributable to Parent, Parenthetical Disclosures [Abstract]
Unrealized holding gains (losses) on available-for-sale securities, tax	$ (1,559)	$ 1,199	$ (186)
Interest Rate Contract [Member]
Schedule of Other Comprehensive Income (Loss), Tax, Cash Flow Hedges [Line Items]
Other Comprehensive Income (Loss), Derivatives Qualifying as Hedges, Tax	(40,501)	(32,353)	47,236
Commodity Contract [Member]
Schedule of Other Comprehensive Income (Loss), Tax, Cash Flow Hedges [Line Items]
Other Comprehensive Income (Loss), Derivatives Qualifying as Hedges, Tax	$ (15,193)	$ 1,791	$ 2,889

CONSOLIDATED STATEMENT OF SHARE

CONSOLIDATED STATEMENT OF SHAREHOLDERS' EQUITY - USD ($) $ in Thousands	Total	Common Stock [Member]	Additional Paid In Capital [Member]	Accumulated Other Comprehensive Income [Member]	Retained Earnings [Member]
Common stock shares outstanding, balance at Sep. 30, 2012		90,239,900
Shareholders' equity, beginning balance at Sep. 30, 2012	$ 2,359,243	$ 451	$ 1,745,467	$ (47,607)	$ 660,932
Net income	243,194				243,194
Other comprehensive income (loss)	86,485			86,485
Repurchase of equity awards, shares		(133,449)
Repurchase of equity awards, amount	(5,150)	$ 0	(5,150)
Cash dividends	(128,115)				(128,115)
Common stock issued:
Direct stock purchase plan, shares		0
Direct stock purchase plan, amount	(50)	$ 0	(50)
1998 Long-term incentive plan, shares		531,672
1998 Long-term incentive plan, amount	8,788	$ 2	9,530		(744)
Employee stock-based compensation	15,934		15,934
Outside directors stock-for-fee plan, shares		2,088
Outside directors stock-for-fee-plan, amount	80		80
Common stock shares outstanding, ending balance at Sep. 30, 2013		90,640,211
Shareholders' equity, ending balance at Sep. 30, 2013	2,580,409	$ 453	1,765,811	38,878	775,267
Net income	289,817				289,817
Other comprehensive income (loss)	(51,271)			(51,271)
Repurchase of equity awards, shares		(190,134)
Repurchase of equity awards, amount	(8,717)	$ (1)	(8,716)
Cash dividends	(146,248)				(146,248)
Common stock issued:
Public offering, shares		9,200,000
Public offering, amount	390,205	$ 46	390,159
Direct stock purchase plan, shares		83,150
Direct stock purchase plan, amount	4,067	$ 1	4,066
1998 Long-term incentive plan, shares		653,130
1998 Long-term incentive plan, amount	4,353	$ 3	5,214		(864)
Employee stock-based compensation	23,536		23,536
Outside directors stock-for-fee plan, shares		1,735
Outside directors stock-for-fee-plan, amount	81		81
Common stock shares outstanding, ending balance at Sep. 30, 2014		100,388,092
Shareholders' equity, ending balance at Sep. 30, 2014	3,086,232	$ 502	2,180,151	(12,393)	917,972
Net income	315,075				315,075
Other comprehensive income (loss)	(96,937)			(96,937)
Repurchase of equity awards, shares		(148,464)
Repurchase of equity awards, amount	(7,985)	$ (1)	(7,984)
Cash dividends	(160,018)				(160,018)
Common stock issued:
Direct stock purchase plan, shares		176,391
Direct stock purchase plan, amount	10,626	$ 1	10,625
Retirement savings plan, shares		398,047
Retirement savings plan, amount	20,326	$ 2	20,324
1998 Long-term incentive plan, shares		664,752
1998 Long-term incentive plan, amount	2,266	$ 3	2,263		0
Employee stock-based compensation	25,212		25,212
Common stock shares outstanding, ending balance at Sep. 30, 2015		101,478,818
Shareholders' equity, ending balance at Sep. 30, 2015	$ 3,194,797	$ 507	$ 2,230,591	$ (109,330)	$ 1,073,029

CONSOLIDATED STATEMENT OF SHAR9

CONSOLIDATED STATEMENT OF SHAREHOLDERS' EQUITY (PARENTHETICALS) - $ / shares	12 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2013
Statement of Stockholders' Equity [Abstract]
Cash dividends per share	$ 1.56	$ 1.48	$ 1.40

CONSOLIDATED STATEMENTS OF CASH

CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	12 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2013
CASH FLOWS FROM OPERATING ACTIVITIES
Net income	$ 315,075	$ 289,817	$ 243,194
Adjustments to reconcile net income to net cash provided by operating activities:
Gain on sale of discontinued operations	0	0	(8,203)
Depreciation and amortization:
Charged to depreciation and amortization	274,796	253,987	236,928
Charged to other accounts	1,209	969	679
Deferred income taxes	192,886	189,952	141,336
Stock-based compensation	27,491	25,531	17,814
Debt financing costs	5,922	9,409	8,480
Other	(850)	(428)	(2,887)
Changes in assets and liabilities:
(Increase) decreased in accounts receivable	48,240	(41,408)	(73,669)
Decrease in gas stored underground	33,234	(31,996)	31,979
(Increase) decrease in other current assets	(11,951)	(24,411)	15,644
(Increase) decrease in deferred charges and other assets	58,256	30,662	111,069
Increase (decrease) in account payable and accrued liabilities	(52,660)	55,041	31,912
Increase (decrease) in other current liabilities	896	2,413	(44,491)
Increase (decrease) in deferred credits and other liabilities	(56,025)	(19,552)	(96,658)
Net cash provided by operating activities	836,519	739,986	613,127
CASH FLOWS USED IN INVESTING ACTIVITIES
Capital expenditures	(975,132)	(835,251)	(845,033)
Proceeds from the sale of discontinued operations	0	0	153,023
Other, net	377	(2,325)	(4,904)
Net cash used in investing activities	(974,755)	(837,576)	(696,914)
CASH FLOWS FROM FINANCING ACTIVITIES
Net increase (decrease) in short-term debt	254,780	(165,865)	(208,070)
Net proceeds from issuance of long-term debt	493,538	0	493,793
Net proceeds from equity offering	0	390,205	0
Settlement of Treasury lock agreement	13,364	0	(66,626)
Repayment of long-term debt	(500,000)	0	(131)
Cash dividends paid	(160,018)	(146,248)	(128,115)
Repurchase of equity awards	(7,985)	(8,717)	(5,150)
Issuance of common stock	30,952	4,274	46
Net cash provided by (used in) financing activities	124,631	73,649	85,747
Net increase (decrease) in cash and cash equivalents	(13,605)	(23,941)	1,960
Cash and cash equivalents at beginning of period	42,258	66,199	64,239
Cash and cash equivalents at end of period	28,653	42,258	66,199
CASH PAID (RECEIVED) DURING THE PERIOD FOR:
Interest	151,334	156,606	148,461
Income taxes	$ 1,802	$ (610)	$ 10,008

Nature of Business

Nature of Business	12 Months Ended
	Sep. 30, 2015
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 pipeline businesses as well as certain other nonregulated businesses. Through our regulated distribution business, we deliver natural gas through sales and transportation arrangements to over three million residential, commercial, public-authority and industrial customers through our six regulated distribution divisions in the service areas described below: Division Service Area Atmos Energy Colorado-Kansas Division Colorado, Kansas Atmos Energy Kentucky/Mid-States Division Kentucky, Tennessee, Virginia (1) Atmos Energy Louisiana Division Louisiana Atmos Energy Mid-Tex Division Texas, including the Dallas/Fort Worth metropolitan area Atmos Energy Mississippi Division Mississippi Atmos Energy West Texas Division West Texas (1) Denotes location where we have more limited service areas. In addition, we transport natural gas for others through our distribution system. Our distribution business is subject to federal and state regulation and/or regulation by local authorities in each of the states in which our regulated distribution divisions operate. Our corporate headquarters and shared-services function are located in Dallas, Texas, and our customer support centers are located in Amarillo and Waco, Texas. During fiscal 2013 and fiscal 2012, we sold our regulated distribution operations serving approximately 148,000 customers in Georgia, Illinois, Iowa and Missouri. Our regulated pipeline business, which is also subject to federal and state regulation, consists of the regulated operations of our Atmos Pipeline–Texas Division, a division of the Company. This division transports natural gas to our Mid-Tex Division, transports natural gas for third parties and manages five underground storage reservoirs in Texas. We also provide ancillary services customary to the pipeline industry including parking arrangements, lending and sales of inventory on hand. Our nonregulated businesses operate primarily in the Midwest and Southeast through various wholly-owned subsidiaries of Atmos Energy Holdings, Inc., (AEH). AEH is a wholly-owned subsidiary of the Company and based in Houston, Texas. Through AEH, we provide natural gas management and transportation services to municipalities, regulated distribution companies, including certain divisions of Atmos Energy and third parties.

Significant Accounting Policies

Significant Accounting Policies	12 Months Ended
	Sep. 30, 2015
Accounting Policies [Abstract]
Summary of Significant Accounting Policies	Summary of Significant Accounting Policies Principles of consolidation — The accompanying consolidated financial statements include the accounts of Atmos Energy Corporation and its wholly-owned subsidiaries. All material intercompany transactions have been eliminated; however, we have not eliminated intercompany profits when such amounts are probable of recovery under the affiliates’ rate regulation process. Basis of comparison — Certain prior-year amounts have been reclassified to conform with the current year presentation. Use of estimates — The preparation of financial statements in conformity with accounting principles generally accepted in the United States requires management to make estimates and assumptions that affect the reported amounts of assets, liabilities, revenues and expenses. The most significant estimates include the allowance for doubtful accounts, unbilled revenues, contingency accruals, pension and postretirement obligations, deferred income taxes, impairment of long-lived assets, risk management and trading activities, fair value measurements and the valuation of goodwill and other long-lived assets. Actual results could differ from those estimates. Regulation — Our regulated distribution and regulated pipeline operations are subject to regulation with respect to rates, service, maintenance of accounting records and various other matters by the respective regulatory authorities in the states in which we operate. Our accounting policies recognize the financial effects of the ratemaking and accounting practices and policies of the various regulatory commissions. 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 that would normally be expensed under accounting principles generally accepted in the United States are permitted to be capitalized or deferred on the balance sheet because it is probable they can be recovered through rates. Further, regulation may impact the period in which revenues or expenses are recognized. The amounts to be recovered or recognized are based upon historical experience and our understanding of the regulations. We record regulatory assets as a component of other current assets and deferred charges and other assets for costs that have been deferred for which future recovery through customer rates is considered probable. Regulatory liabilities are recorded either on the face of the balance sheet or as a component of current liabilities, deferred income taxes or deferred credits and other liabilities when it is probable that revenues will be reduced for amounts that will be credited to customers through the ratemaking process. Significant regulatory assets and liabilities as of September 30, 2015 and 2014 included the following: September 30 2015 2014 (In thousands) Regulatory assets: Pension and postretirement benefit costs (1) $ 121,183 $ 162,777 Infrastructure Mechanisms (2) 32,813 26,948 Deferred gas costs 9,715 20,069 Recoverable loss on reacquired debt 16,319 18,877 APT annual adjustment mechanism 1,002 8,479 Rate case costs 1,533 3,757 Other 9,774 9,402 $ 192,339 $ 250,309 Regulatory liabilities: Regulatory cost of removal obligation $ 483,676 $ 490,448 Deferred gas costs 28,100 35,063 Asset retirement obligation 9,063 10,508 Deferred franchise fees — 5,268 Other 3,693 4,472 $ 524,532 $ 545,759 (1) Includes $16.6 million and $18.8 million of pension and postretirement expense deferred pursuant to regulatory authorization. (2) Infrastructure mechanisms in Texas and Louisiana allow for the deferral of all expenses associated with capital expenditures incurred pursuant to these rules, which primarily consists of interest costs along with depreciation and other taxes, until the next rate proceeding (rate case or annual rate filing), at which time investment and costs would be recovered through base rates. Revenue recognition — Sales of natural gas to our regulated distribution customers are billed on a monthly basis; however, the billing cycle periods for certain classes of customers do not necessarily coincide with accounting periods used for financial reporting purposes. We follow the revenue accrual method of accounting for regulated distribution segment revenues whereby revenues applicable to gas delivered to customers, but not yet billed under the cycle billing method, are estimated and accrued and the related costs are charged to expense. On occasion, we are permitted to implement new rates that have not been formally approved by our state regulatory commissions, which are subject to refund. As permitted by accounting principles generally accepted in the United States, we recognize this revenue and establish a reserve for amounts that could be refunded based on our experience for the jurisdiction in which the rates were implemented. Rates established by regulatory authorities are adjusted for increases and decreases in our purchased gas costs through purchased gas cost adjustment mechanisms. Purchased gas cost adjustment mechanisms provide gas distribution companies a method of recovering purchased gas costs on an ongoing basis without filing a rate case to address all of their non-gas costs. There is no gross profit generated through purchased gas cost adjustments, but they provide a dollar-for-dollar offset to increases or decreases in our regulated distribution segment’s gas costs. The effects of these purchased gas cost adjustment mechanisms are recorded as deferred gas costs on our balance sheet. Operating revenues for our regulated pipeline and nonregulated segments are recognized in the period in which actual volumes are transported and storage services are provided. Operating revenues for our nonregulated segment and the associated carrying value of natural gas inventory (inclusive of storage costs) are recognized when we sell the gas and physically deliver it to our customers. Operating revenues include realized gains and losses arising from the settlement of financial instruments used in our nonregulated activities. Cash and cash equivalents — We consider all highly liquid investments with an original maturity of three months or less to be cash equivalents. Accounts receivable and allowance for doubtful accounts — Accounts receivable arise from natural gas sales to residential, commercial, industrial, municipal and other customers. We establish an allowance for doubtful accounts to reduce the net receivable balance to the amount we reasonably expect to collect based on our collection experience or where we are aware of a specific customer’s inability or reluctance to pay. However, if circumstances change, our estimate of the recoverability of accounts receivable could be affected. Circumstances which could affect our estimates include, but are not limited to, customer credit issues, the level of natural gas prices, customer deposits and general economic conditions. Accounts are written off once they are deemed to be uncollectible. Gas stored underground — Our gas stored underground is comprised of natural gas injected into storage to support the winter season withdrawals for our regulated distribution operations and natural gas held by our nonregulated segment to conduct their operations. The average cost method is used for substantially all of our regulated operations. Our nonregulated segment utilizes the average cost method; however, most of this inventory is hedged and is therefore reported at fair value at the end of each month. Gas in storage that is retained as cushion gas to maintain reservoir pressure is classified as property, plant and equipment and is valued at cost. Regulated property, plant and equipment — Regulated property, plant and equipment is stated at original cost, net of contributions in aid of construction. The cost of additions includes direct construction costs, payroll related costs (taxes, pensions and other fringe benefits), administrative and general costs and an allowance for funds used during construction. The allowance for funds used during construction represents the estimated cost of funds used to finance the construction of major projects and are capitalized in the rate base for ratemaking purposes when the completed projects are placed in service. Interest expense of $2.3 million , $1.5 million and $1.9 million was capitalized in 2015 , 2014 and 2013 . Major renewals, including replacement pipe, and betterments that are recoverable under our regulatory rate base are capitalized while the costs of maintenance and repairs that are not recoverable through rates are charged to expense as incurred. The costs of large projects are accumulated in construction in progress until the project is completed. When the project is completed, tested and placed in service, the balance is transferred to the regulated plant in service account included in the rate base and depreciation begins. Regulated property, plant and equipment is depreciated at various rates on a straight-line basis. These rates are approved by our regulatory commissions and are comprised of two components: one based on average service life and one based on cost of removal. Accordingly, we recognize our cost of removal expense as a component of depreciation expense. The related cost of removal accrual is reflected as a regulatory liability on the consolidated balance sheet. At the time property, plant and equipment is retired, removal expenses less salvage, are charged to the regulatory cost of removal accrual. The composite depreciation rate was 3.3 percent , for each of the fiscal years ended September 30, 2015 , 2014 and 2013 . Nonregulated property, plant and equipment — Nonregulated property, plant and equipment is stated at cost. Depreciation is generally computed on the straight-line method for financial reporting purposes based upon estimated useful lives ranging from three to 43 years. Asset retirement obligations — We record a liability at fair value for an asset retirement obligation when the legal obligation to retire the asset has been incurred with an offsetting increase to the carrying value of the related asset. Accretion of the asset retirement obligation due to the passage of time is recorded as an operating expense. As of September 30, 2015 and 2014 , we had asset retirement obligations of $11.1 million and $10.5 million . Additionally, we had $4.8 million and $5.9 million of asset retirement costs recorded as a component of property, plant and equipment that will be depreciated over the remaining life of the underlying associated assets. We believe we have a legal obligation to retire our natural gas storage facilities. However, we have not recognized an asset retirement obligation associated with our storage facilities because we are not able to determine the settlement date of this obligation as we do not anticipate taking our storage facilities out of service permanently. Therefore, we cannot reasonably estimate the fair value of this obligation. Impairment of long-lived assets — We periodically evaluate whether events or circumstances have occurred that indicate that other long-lived assets may not be recoverable or that the remaining useful life may warrant revision. When such events or circumstances are present, we assess the recoverability of long-lived assets by determining whether the carrying value will be recovered through the expected future cash flows. In the event the sum of the expected future cash flows resulting from the use of the asset is less than the carrying value of the asset, an impairment loss equal to the excess of the asset’s carrying value over its fair value is recorded. Goodwill — We annually evaluate our goodwill balances for impairment during our second fiscal quarter or more frequently as impairment indicators arise. We use a present value technique based on discounted cash flows to estimate the fair value of our reporting units. These calculations are dependent on several subjective factors including the timing of future cash flows, future growth rates and the discount rate. An impairment charge is recognized if the carrying value of a reporting unit’s goodwill exceeds its fair value. Marketable securities — As of September 30, 2015 and 2014 , all of our marketable securities were classified as available-for-sale. In accordance with the authoritative accounting standards, 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 an individual investment by investment 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 investment is written down to its estimated fair value. Financial instruments and hedging activities — We use financial instruments to mitigate commodity price risk in our regulated distribution and nonregulated segments and interest rate risk. The objectives and strategies for using financial instruments have been tailored to our regulated and nonregulated businesses and are discussed in Note 12. We record all of our financial instruments on the balance sheet at fair value , with changes in fair value ultimately recorded in the income statement. These financial instruments are reported as risk management assets and liabilities and are classified as current or noncurrent other assets or liabilities based upon the anticipated settlement date of the underlying financial instrument. We record the cash flow impact of our financial instruments in operating cash flows based upon their balance sheet classification. The timing of when changes in fair value of our financial instruments are recorded in the income statement depends on whether the financial instrument has been designated and qualifies as a part of a hedging relationship or if regulatory rulings require a different accounting treatment. Changes in fair value for financial instruments that do not meet one of these criteria are recognized in the income statement as they occur. Financial Instruments Associated with Commodity Price Risk In our regulated distribution segment, the costs associated with and 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 accounting principles generally accepted in the United States. Accordingly, there is no earnings impact on our regulated distribution segment as a result of the use of financial instruments. In our nonregulated segment, we have designated most of the natural gas inventory held by this operating segment as the hedged item in a fair-value hedge. This inventory is marked to market at the end of each month based on the Gas Daily index, with changes in fair value recognized as unrealized gains or losses in purchased gas cost in the period of change. The financial instruments associated with this natural gas inventory have been designated as fair-value hedges and are marked to market each month based upon the NYMEX price with changes in fair value recognized as unrealized gains or losses in purchased gas cost in the period of change. We have elected to exclude this spot/forward differential for purposes of assessing the effectiveness of these fair-value hedges. For the fiscal years ended September 30, 2015 , 2014 and 2013 , we included unrealized gains (losses) on open contracts of $(2.4) million , $9.6 million and $9.0 million as a component of nonregulated purchased gas cost. Additionally, we have elected to treat fixed-price forward contracts used in our nonregulated segment to deliver natural gas as normal purchases and normal sales. As such, these deliveries are recorded on an accrual basis in accordance with our revenue recognition policy. Financial instruments used to mitigate the commodity price risk associated with these contracts have been designated as cash flow hedges of anticipated purchases and sales at indexed prices. Accordingly, unrealized gains and losses on these open financial instruments are recorded as a component of accumulated other comprehensive income, and are recognized in earnings as a component of purchased gas cost when the hedged volumes are sold. Gains and losses from hedge ineffectiveness are recognized in the income statement. Fair value and cash flow hedge ineffectiveness arising from natural gas market price differences between the locations of the hedged inventory and the delivery location specified in the financial instruments is referred to as basis ineffectiveness. Ineffectiveness arising from changes in the fair value of the fair value hedges 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 is referred to as timing ineffectiveness. Hedge ineffectiveness, to the extent incurred, is reported as a component of purchased gas cost. Our nonregulated segment also utilizes master netting agreements with significant counterparties that allow us to offset gains and losses arising from financial instruments that may be settled in cash with gains and losses arising from financial instruments that may be settled with the physical commodity. Assets and liabilities from risk management activities, as well as accounts receivable and payable, reflect the master netting agreements in place. Additionally, the accounting guidance for master netting arrangements requires us to include the fair value of cash collateral or the obligation to return cash in the amounts that have been netted under master netting agreements used to offset gains and losses arising from financial instruments. As of September 30, 2015 and 2014 , the Company netted $ 43.5 million and $ 25.8 million of cash held in margin accounts into its current and noncurrent risk management assets and liabilities. Financial Instruments Associated with Interest Rate Risk We manage interest rate risk, primarily when we plan to issue new long-term debt or to refinance existing long-term debt. We currently manage this risk through the use of forward starting interest rate swaps to fix the Treasury yield component of the interest cost associated with anticipated financings. We designate these financial instruments as cash flow hedges at the time the agreements are executed. Unrealized gains and losses associated with the instruments are recorded as a component of accumulated other comprehensive income (loss). When the instruments settle, the realized gain or loss is 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. 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 primarily use quoted market prices and other observable market pricing information in valuing our financial assets and liabilities and minimize the use of unobservable pricing inputs in our measurements. Fair-value estimates also consider our own creditworthiness and the creditworthiness of the counterparties involved. Our counterparties consist primarily of financial institutions and major energy companies. This concentration of counterparties may materially impact our exposure to credit risk resulting from market, economic or regulatory conditions. We seek to minimize counterparty credit risk through an evaluation of their financial condition and credit ratings and the use of collateral requirements under certain circumstances. Amounts reported at fair value are subject to potentially significant volatility based upon changes in market prices, including, but not limited to, the valuation of the portfolio of our contracts, maturity and settlement of these contracts and newly originated transactions and interest rates, each of which directly affect the estimated fair value of our financial instruments. We believe the market prices and models used to value these financial instruments represent the best information available with respect to closing exchange and over-the-counter quotations, time value and volatility factors underlying the contracts. Values are adjusted to reflect the potential impact of an orderly liquidation of our positions over a reasonable period of time under then current market conditions. 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) and the lowest priority given to unobservable inputs (Level 3). The levels of the hierarchy are described below: Level 1 — Represents unadjusted quoted prices in active markets for identical assets or liabilities. An active market for the asset or liability is defined as a market in which transactions for the asset or liability occur with sufficient frequency and volume to provide pricing information on an ongoing basis. Prices actively quoted on national exchanges are used to determine the fair value of most of our assets and liabilities recorded on our balance sheet at fair value. Within our nonregulated operations, we utilize a mid-market pricing convention (the mid-point between the bid and ask prices), as permitted under current accounting standards. Values derived from these sources reflect the market in which transactions involving these financial instruments are executed. Our Level 1 measurements consist primarily of exchange-traded financial instruments, gas stored underground that has been designated as the hedged item in a fair value hedge and our available-for-sale securities. The Level 1 measurements for investments in the Atmos Energy Corporation Master Retirement Trust (the Master Trust), Supplemental Executive Benefit Plan and postretirement benefit plan consist primarily of exchange-traded financial instruments. Level 2 — Represents pricing inputs other than quoted prices included in Level 1 that are either directly or indirectly observable for the asset or liability as of the reporting date. These inputs are derived principally from, or corroborated by, observable market data. Our Level 2 measurements primarily consist of non-exchange-traded financial instruments, such as over-the-counter options and swaps and municipal and corporate bonds where market data for pricing is observable. The Level 2 measurements for investments in our Master Trust, Supplemental Executive Benefit Plan and postretirement benefit plan consist primarily of non-exchange traded financial instruments such as common collective trusts and investments in limited partnerships. Level 3 — Represents generally unobservable pricing inputs which are developed based on the best information available, including our own internal data, in situations where there is little if any market activity for the asset or liability at the measurement date. The pricing inputs utilized reflect what a market participant would use to determine fair value. We utilize models and other valuation methods to determine fair value when external sources are not available. We believe the market prices and models used to value these assets and liabilities represent the best information available with respect to closing exchange and over-the-counter quotations, time value and volatility factors underlying the assets and liabilities. Pension and other postretirement plans — Pension and other postretirement plan costs and liabilities are determined on an actuarial basis and are affected by numerous assumptions and estimates including the market value of plan assets, estimates of the expected return on plan assets, assumed discount rates and current demographic and actuarial mortality data. Our measurement date is September 30. The assumed discount rate and the expected return are the assumptions that generally have the most significant impact on our pension costs and liabilities. The assumed discount rate, the assumed health care cost trend rate and assumed rates of retirement generally have the most significant impact on our postretirement plan costs and liabilities. The discount rate is utilized principally in calculating the actuarial present value of our pension and postretirement obligation and net pension and postretirement cost. When establishing our discount rate, we consider high quality corporate bond rates based on bonds available in the marketplace that are suitable for settling the obligations, changes in those rates from the prior year and the implied discount rate that is derived from matching our projected benefit disbursements with currently available high quality corporate bonds. The expected long-term rate of return on assets is utilized in calculating the expected return on plan assets component of the annual pension and postretirement plan cost. We estimate the expected return on plan assets by evaluating expected bond returns, equity risk premiums, asset allocations, the effects of active plan management, the impact of periodic plan asset rebalancing and historical performance. We also consider the guidance from our investment advisors when making a final determination of our expected rate of return on assets. To the extent the actual rate of return on assets realized over the course of a year is greater than or less than the assumed rate, that year’s annual pension or postretirement plan cost is not affected. Rather, this gain or loss is amortized over the expected future working lifetime of the plan participants. The expected return on plan assets is then calculated by applying the expected long-term rate of return on plan assets to the market-related value of the plan assets. The market-related value of our plan assets represents the fair market value of the plan assets, adjusted to smooth out short-term market fluctuations over a five-year period. The use of this calculation will delay the impact of current market fluctuations on the pension expense for the period. We use a corridor approach to amortize actuarial gains and losses. Under this approach, net gains or losses in excess of ten percent of the larger of the pension benefit obligation or the market-related value of the assets are amortized on a straight-line basis. The period of amortization is the average remaining service of active participants who are expected to receive benefits under the plan. We estimate the assumed health care cost trend rate used in determining our annual postretirement net cost based upon our actual health care cost experience, the effects of recently enacted legislation and general economic conditions. Our assumed rate of retirement is estimated based upon the annual review of our participant census information as of the measurement date. Income taxes — Income taxes are determined based on the liability method, which results in income tax assets and liabilities arising from temporary differences. Temporary differences are differences between the tax bases of assets and liabilities and their reported amounts in the financial statements that will result in taxable or deductible amounts in future years. The liability method requires the effect of tax rate changes on current and accumulated deferred income taxes to be reflected in the period in which the rate change was enacted. The liability method also requires that deferred tax assets be reduced by a valuation allowance unless it is more likely than not that the assets will be realized. The Company may recognize the tax benefit from uncertain tax positions only if it is at least more likely than not that the tax position will be sustained on examination by the taxing authorities, based on the technical merits of the position. The tax benefits recognized in the financial statements from such a position should be measured based on the largest benefit that has a greater than fifty percent likelihood of being realized upon settlement with the taxing authorities. We recognize accrued interest related to unrecognized tax benefits as a component of interest expense. We recognize penalties related to unrecognized tax benefits as a component of miscellaneous income (expense) in accordance with regulatory requirements. Tax collections — We are allowed to recover from customers revenue-related taxes that are imposed upon us. We record such taxes as operating expenses and record the corresponding customer charges as operating revenues. However, we do collect and remit various other taxes on behalf of various governmental authorities, and we record these amounts in our consolidated balance sheets on a net basis. We do not collect income taxes from our customers on behalf of governmental authorities. Contingencies — In the normal course of business, we are confronted with issues or events that may result in a contingent liability. These generally relate to lawsuits, claims made by third parties or the action of various regulatory agencies. For such matters, we record liabilities when they are considered probable and reasonably estimable, based on currently available facts and our estimates of the ultimate outcome or resolution of the liability in the future. Actual results may differ from estimates, depending on actual outcomes or changes in the facts or expectations surrounding each potential exposure. Subsequent events — Except as disclosed in Note 6 regarding the new mortality tables adopted for our pension plans and the approval of the merger of the AEH 401(k) Plan with the Retirement Savings Plan, no events occurred subsequent to the balance sheet date that would require recognition or disclosure in the financial statements. Recent accounting pronouncements — In May 2014, the Financial Accounting Standards Board (FASB) issued a comprehensive new revenue recognition standard that will supersede virtually all existing revenue recognition guidance under generally accepted accounting principles in the United States. Under the new standard, a company will recognize revenue when it transfers promised goods or services to customers in an amount that reflects the consideration to which the company expects to be entitled in exchange for those goods or services. In doing so, companies will need to use more judgment and make more estimates than under current guidance. On July 9, 2015, the FASB voted to approve a deferral of the effective date of the new standard by one year. With the one-year extension, the new standard is currently scheduled to become effective for us beginning on October 1, 2018 and can be applied either retrospectively to each period presented or as a cumulative-effect adjustment as of the date of adoption. We are currently evaluating the impact this standard may have on our financial position, results of operations and cash flows. In April 2015, the FASB issued guidance to simplify the presentation of debt issuance costs, which requires that debt issuance costs related to a recognized debt liability be presented in the balance sheet as a direct deduction from the carrying amount of that debt liability, consistent with debt discounts. The new standard will be effective for us beginning on October 1, 2016, and will be applied retrospectively. We are currently evaluating the impact this standard may have on our financial position, results of operations and cash flows. In April 2015, the FASB issued guidance to simplify the accounting for fees paid in connection with arrangements with cloud-based software providers. Under the new guidance, unless a software arrangement includes specific elements enabling customers to possess and operate software on platforms other than t

Segment Information

Segment Information	12 Months Ended
	Sep. 30, 2015
Segment Reporting [Abstract]
Segment Information	Segment Information Atmos Energy Corporation and its subsidiaries are engaged primarily in the regulated natural gas distribution and pipeline business as well as other nonregulated businesses. We distribute natural gas through sales and transportation arrangements to over three million residential, commercial, public authority and industrial customers through our six regulated distribution divisions, which cover service areas located in eight states. In addition, we transport natural gas for others through our distribution system. Through our nonregulated business, we provide natural gas management and transportation services to municipalities, regulated distribution companies, including certain divisions of Atmos Energy and third parties. We operate the Company through the following three segments: • The regulated distribution segment , includes our regulated distribution and related sales operations. • The regulated pipeline segment , includes the regulated pipeline and storage operations of our Atmos Pipeline — Texas Division. • The nonregulated segment , 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 regulated distribution segment operations are geographically dispersed, they are reported as a single segment as each regulated 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. We evaluate performance based on net income or loss of the respective operating units. Interest expense is allocated pro rata to each segment based upon our net investment in each segment. Income taxes are allocated to each segment as if each segment’s taxes were calculated on a separate return basis. Summarized income statements and capital expenditures by segment are shown in the following tables. Year Ended September 30, 2015 Regulated Distribution Regulated Pipeline Nonregulated Eliminations Consolidated (In thousands) Operating revenues from external parties $ 2,757,585 $ 97,662 $ 1,286,889 $ — $ 4,142,136 Intersegment revenues 6,250 272,450 185,320 (464,020 ) — 2,763,835 370,112 1,472,209 (464,020 ) 4,142,136 Purchased gas cost 1,526,258 — 1,399,349 (463,488 ) 2,462,119 Gross profit 1,237,577 370,112 72,860 (532 ) 1,680,017 Operating expenses Operation and maintenance 388,486 118,866 35,048 (532 ) 541,868 Depreciation and amortization 223,048 47,236 4,512 — 274,796 Taxes, other than income 205,894 22,743 3,321 — 231,958 Total operating expenses 817,428 188,845 42,881 (532 ) 1,048,622 Operating income 420,149 181,267 29,979 — 631,395 Miscellaneous expense (377 ) (1,243 ) (760 ) (2,009 ) (4,389 ) Interest charges 84,132 33,151 967 (2,009 ) 116,241 Income before income taxes 335,640 146,873 28,252 — 510,765 Income tax expense 130,827 52,211 12,652 — 195,690 Net income $ 204,813 $ 94,662 $ 15,600 $ — $ 315,075 Capital expenditures $ 680,961 $ 292,728 $ 1,443 $ — $ 975,132 Year Ended September 30, 2014 Regulated Distribution Regulated Pipeline Nonregulated Eliminations Consolidated (In thousands) Operating revenues from external parties $ 3,056,212 $ 92,166 $ 1,792,538 $ — $ 4,940,916 Intersegment revenues 5,334 226,293 274,754 (506,381 ) — 3,061,546 318,459 2,067,292 (506,381 ) 4,940,916 Purchased gas cost 1,885,031 — 1,979,337 (505,878 ) 3,358,490 Gross profit 1,176,515 318,459 87,955 (503 ) 1,582,426 Operating expenses Operation and maintenance 387,228 91,466 26,963 (503 ) 505,154 Depreciation and amortization 208,376 41,031 4,580 — 253,987 Taxes, other than income 196,343 13,143 2,450 — 211,936 Total operating expenses 791,947 145,640 33,993 (503 ) 971,077 Operating income 384,568 172,819 53,962 — 611,349 Miscellaneous income (expense) (381 ) (3,181 ) 2,216 (3,889 ) (5,235 ) Interest charges 94,918 36,280 1,986 (3,889 ) 129,295 Income before income taxes 289,269 133,358 54,192 — 476,819 Income tax expense 117,684 47,167 22,151 — 187,002 Net income $ 171,585 $ 86,191 $ 32,041 $ — $ 289,817 Capital expenditures $ 584,065 $ 249,347 $ 1,839 $ — $ 835,251 Year Ended September 30, 2013 Regulated Distribution Regulated Pipeline Nonregulated Eliminations Consolidated (In thousands) Operating revenues from external parties $ 2,394,418 $ 89,011 $ 1,392,031 $ — $ 3,875,460 Intersegment revenues 5,075 179,889 195,883 (380,847 ) — 2,399,493 268,900 1,587,914 (380,847 ) 3,875,460 Purchased gas cost 1,318,257 — 1,524,583 (379,430 ) 2,463,410 Gross profit 1,081,236 268,900 63,331 (1,417 ) 1,412,050 Operating expenses Operation and maintenance 375,188 76,686 37,569 (1,423 ) 488,020 Depreciation and amortization 195,581 35,302 4,196 — 235,079 Taxes, other than income 167,374 17,059 2,639 — 187,072 Total operating expenses 738,143 129,047 44,404 (1,423 ) 910,171 Operating income 343,093 139,853 18,927 6 501,879 Miscellaneous income (expense) 2,535 (2,285 ) 2,316 (2,763 ) (197 ) Interest charges 98,296 30,678 2,168 (2,757 ) 128,385 Income from continuing operations before income taxes 247,332 106,890 19,075 — 373,297 Income tax expense 96,476 38,630 7,493 — 142,599 Income from continuing operations 150,856 68,260 11,582 — 230,698 Income from discontinued operations, net of tax 7,202 — — — 7,202 Gain (loss) on sale of discontinued operations, net of tax 5,649 — (355 ) — 5,294 Net income $ 163,707 $ 68,260 $ 11,227 $ — $ 243,194 Capital expenditures $ 528,599 $ 313,230 $ 3,204 $ — $ 845,033 The following table summarizes our revenues by products and services for the fiscal year ended September 30. 2015 2014 2013 (In thousands) Regulated distribution revenues: Gas sales revenues: Residential $ 1,761,689 $ 1,933,099 $ 1,512,495 Commercial 772,187 876,042 661,930 Industrial 74,981 90,536 81,155 Public authority and other 53,401 64,779 60,557 Total gas sales revenues 2,662,258 2,964,456 2,316,137 Transportation revenues 67,475 64,049 55,938 Other gas revenues 27,852 27,707 22,343 Total regulated distribution revenues 2,757,585 3,056,212 2,394,418 Regulated pipeline revenues 97,662 92,166 89,011 Nonregulated revenues 1,286,889 1,792,538 1,392,031 Total operating revenues $ 4,142,136 $ 4,940,916 $ 3,875,460 Balance sheet information at September 30, 2015 and 2014 by segment is presented in the following tables. September 30, 2015 Regulated Distribution Regulated Pipeline Nonregulated Eliminations Consolidated (In thousands) ASSETS Property, plant and equipment, net $ 5,670,306 $ 1,706,449 $ 53,825 $ — $ 7,430,580 Investment in subsidiaries 1,038,670 — (2,096 ) (1,036,574 ) — Current assets Cash and cash equivalents 23,863 — 4,790 — 28,653 Assets from risk management activities 378 — 8,854 — 9,232 Other current assets 426,270 24,628 480,503 (338,301 ) 593,100 Intercompany receivables 887,713 — — (887,713 ) — Total current assets 1,338,224 24,628 494,147 (1,226,014 ) 630,985 Goodwill 575,449 132,542 34,711 — 742,702 Noncurrent assets from risk management activities 368 — — — 368 Deferred charges and other assets 265,693 17,288 5,329 — 288,310 $ 8,888,710 $ 1,880,907 $ 585,916 $ (2,262,588 ) $ 9,092,945 CAPITALIZATION AND LIABILITIES Shareholders’ equity $ 3,194,797 $ 577,275 $ 461,395 $ (1,038,670 ) $ 3,194,797 Long-term debt 2,455,388 — — — 2,455,388 Total capitalization 5,650,185 577,275 461,395 (1,038,670 ) 5,650,185 Current liabilities Short-term debt 782,927 — — (325,000 ) 457,927 Liabilities from risk management activities 9,568 — — — 9,568 Other current liabilities 569,273 29,780 99,480 (11,205 ) 687,328 Intercompany payables — 867,409 20,304 (887,713 ) — Total current liabilities 1,361,768 897,189 119,784 (1,223,918 ) 1,154,823 Deferred income taxes 1,008,091 406,254 (3,030 ) — 1,411,315 Noncurrent liabilities from risk management activities 110,539 — — — 110,539 Regulatory cost of removal obligation 427,553 — — — 427,553 Pension and postretirement liabilities 287,373 — — — 287,373 Deferred credits and other liabilities 43,201 189 7,767 — 51,157 $ 8,888,710 $ 1,880,907 $ 585,916 $ (2,262,588 ) $ 9,092,945 September 30, 2014 Regulated Distribution Regulated Pipeline Nonregulated Eliminations Consolidated (In thousands) ASSETS Property, plant and equipment, net $ 5,202,761 $ 1,464,572 $ 58,573 $ — $ 6,725,906 Investment in subsidiaries 952,171 — (2,096 ) (950,075 ) — Current assets Cash and cash equivalents 33,303 — 8,955 — 42,258 Assets from risk management activities 23,102 — 22,725 — 45,827 Other current assets 490,408 14,009 526,161 (342,823 ) 687,755 Intercompany receivables 790,442 — — (790,442 ) — Total current assets 1,337,255 14,009 557,841 (1,133,265 ) 775,840 Goodwill 574,816 132,502 34,711 — 742,029 Noncurrent assets from risk management activities 13,038 — — — 13,038 Deferred charges and other assets 309,965 21,826 6,100 — 337,891 $ 8,390,006 $ 1,632,909 $ 655,129 $ (2,083,340 ) $ 8,594,704 CAPITALIZATION AND LIABILITIES Shareholders’ equity $ 3,086,232 $ 482,612 $ 469,559 $ (952,171 ) $ 3,086,232 Long-term debt 2,455,986 — — — 2,455,986 Total capitalization 5,542,218 482,612 469,559 (952,171 ) 5,542,218 Current liabilities Short-term debt 522,695 — — (326,000 ) 196,695 Liabilities from risk management activities 1,730 — — — 1,730 Other current liabilities 559,765 24,790 142,397 (14,727 ) 712,225 Intercompany payables — 763,635 26,807 (790,442 ) — Total current liabilities 1,084,190 788,425 169,204 (1,131,169 ) 910,650 Deferred income taxes 913,260 361,688 11,668 — 1,286,616 Noncurrent liabilities from risk management activities 20,126 — — — 20,126 Regulatory cost of removal obligation 445,387 — — — 445,387 Pension and postretirement liabilities 340,963 — — — 340,963 Deferred credits and other liabilities 43,862 184 4,698 — 48,744 $ 8,390,006 $ 1,632,909 $ 655,129 $ (2,083,340 ) $ 8,594,704

Earnings Per Share

Earnings Per Share	12 Months Ended
	Sep. 30, 2015
Earnings Per Share [Abstract]
Earnings Per Share	Earnings Per Share Since we have non-vested share-based payments with a nonforfeitable right to dividends or dividend equivalents (referred to as participating securities), we are required to use the two-class method of computing earnings per share. The Company’s non-vested restricted stock units, granted under the 1998 Long-Term Incentive Plan, for which vesting is predicated solely on the passage of time, are considered to be participating securities. 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 fiscal years ended September 30 are calculated as follows: 2015 2014 2013 (In thousands, except per share data) Basic Earnings Per Share from continuing operations Income from continuing operations $ 315,075 $ 289,817 $ 230,698 Less: Income from continuing operations allocated to participating securities 626 711 775 Income from continuing operations available to common shareholders $ 314,449 $ 289,106 $ 229,923 Basic weighted average shares outstanding 101,892 97,606 90,533 Income from continuing operations per share — Basic $ 3.09 $ 2.96 $ 2.54 Basic Earnings Per Share from discontinued operations Income from discontinued operations $ — $ — $ 12,496 Less: Income from discontinued operations allocated to participating securities — — 42 Income from discontinued operations available to common shareholders $ — $ — $ 12,454 Basic weighted average shares outstanding 101,892 97,606 90,533 Income from discontinued operations per share — Basic $ — $ — $ 0.14 Net income per share — Basic $ 3.09 $ 2.96 $ 2.68 Diluted Earnings Per Share from continuing operations Income from continuing operations available to common shareholders $ 314,449 $ 289,106 $ 229,923 Effect of dilutive stock options and other shares — — 5 Income from continuing operations available to common shareholders $ 314,449 $ 289,106 $ 229,928 Basic weighted average shares outstanding 101,892 97,606 90,533 Additional dilutive stock options and other shares — 2 1,178 Diluted weighted average shares outstanding 101,892 97,608 91,711 Income from continuing operations per share — Diluted $ 3.09 $ 2.96 $ 2.50 Diluted Earnings Per Share from discontinued operations Income from discontinued operations available to common shareholders $ — $ — $ 12,454 Effect of dilutive stock options and other shares — — — Income from discontinued operations available to common shareholders $ — $ — $ 12,454 Basic weighted average shares outstanding 101,892 97,606 90,533 Additional dilutive stock options and other shares — 2 1,178 Diluted weighted average shares outstanding 101,892 97,608 91,711 Income from discontinued operations per share — Diluted $ — $ — $ 0.14 Net income per share — Diluted $ 3.09 $ 2.96 $ 2.64 There were no out-of-the-money options excluded from the computation of diluted earnings per share for the fiscal year ended September 30, 2013. As of September 30, 2015 and 2014 there were no outstanding options. 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 per share and generated net proceeds of $390.2 million , which were used to repay short-term debt outstanding under our commercial paper program, to fund infrastructure spending primarily to enhance the safety and reliability of our system and for general corporate purposes. Share Repurchase Program On September 28, 2011 our Board of Directors approved a program authorizing the repurchase of up to five million shares of common stock over a 5-year period. The program is primarily intended to minimize the dilutive effect of equity grants under various benefit related incentive compensation plans of the Company. The program may be terminated or limited at any time. Shares may be repurchased in the open market or in privately negotiated transactions in amounts the Company deems appropriate. As of September 30, 2015 , a total of 387,991 shares had been repurchased for an aggregate value of $12.5 million , with no shares repurchased since the first quarter of fiscal 2012. The share repurchase program is scheduled to end on September 30, 2016.

Debt

Debt	12 Months Ended
	Sep. 30, 2015
Debt Disclosure [Abstract]
Debt	Debt Long-term debt Long-term debt at September 30, 2015 and 2014 consisted of the following: 2015 2014 (In thousands) Unsecured 4.95% Senior Notes, due October 2014 $ — $ 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 Unsecured 4.125% Senior Notes, due 2044 500,000 — Medium term Series A notes, 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 4,612 4,014 $ 2,455,388 $ 2,455,986 On October 15, 2014, we issued $500 million of 4.125% 30-year unsecured senior notes, which replaced, on a long-term basis, our $500 million unsecured 4.95% senior notes. The effective rate of these notes is 4.086% , after giving effect to the offering costs and the settlement of the associated forward starting interest rate swaps discussed in Note 12. The net proceeds of approximately $494 million were used to repay our $500 million 4.95% senior unsecured notes at maturity on October 15, 2014. 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 borrowings typically reach their highest levels in the winter months. We currently finance our short-term borrowing requirements through a combination of a $1.25 billion commercial paper program, four committed revolving credit facilities and one uncommitted revolving credit facility, with a total availability from third-party lenders of approximately $1.3 billion of working capital funding. At September 30, 2015 and 2014 , there was $457.9 million and $196.7 million outstanding under our commercial paper program with weighted average interest rates of 0.42% and 0.23% , with average maturities of less than one month. We also use intercompany credit facilities to supplement the funding provided by these third-party committed credit facilities. These facilities are described in greater detail below. 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 $1.3 billion of working capital funding. The first facility is a five-year $1.25 billion unsecured facility with an accordion feature, which, if utilized would increase the borrowing capacity to $ 1.5 billion . On September 25, 2015, we terminated our existing $1.25 billion credit facility and entered into a new five-year $1.25 billion credit facility with substantially the same terms. The new facility also retains the $250 million accordion feature, which allows for an increase in the total committed loan amount to $1.5 billion . The credit facility bears interest at a base rate or at a LIBOR-based rate for the applicable interest period, plus a spread ranging from zero percent to 1.25 percent, based on the Company’s credit ratings. This credit facility serves primarily as a backup liquidity facility for our commercial paper program. At September 30, 2015 , there were no borrowings under this facility, but we had $457.9 million of commercial paper outstanding leaving $792.1 million available. The second facility is a $25 million unsecured facility that bears interest at a daily negotiated rate, generally based on the Federal Funds rate plus a variable margin. This facility was renewed on April 1, 2015. At September 30, 2015 , there were no borrowings outstanding under this facility. The third facility which was renewed on September 30, 2015 for $10 million is a committed revolving credit facility, used primarily to issue letters of credit and bears interest at a LIBOR-based rate plus 1.5 percent . At September 30, 2015 , there were no borrowings outstanding under this credit facility; however, letters of credit totaling $5.9 million had been issued under the facility at September 30, 2015 , which reduced the amount available by a corresponding amount. The availability of funds under these 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 our five-year $1.25 billion unsecured facility to maintain, at the end of each fiscal quarter, a ratio of total debt to total capitalization of no greater than 70 percent . At September 30, 2015 , our total-debt-to-total-capitalization ratio, as defined, was 49 percent . In addition, both the interest margin over the Eurodollar rate and the fee that we pay on unused amounts under each of these facilities are subject to adjustment depending upon our credit ratings. In addition to these third-party facilities, our regulated operations have a $500 million intercompany revolving credit facility with AEH. This facility bears interest at the lower of (i) the Eurodollar rate under the five-year revolving credit facility or (ii) the lowest rate outstanding under the commercial paper program. Applicable state regulatory commissions have approved our use of this facility through December 31, 2015 . We intend to seek renewal of this facility during the first quarter of fiscal 2016. There was $325.0 million outstanding under this facility at September 30, 2015 . Nonregulated Operations Atmos Energy Marketing, LLC (AEM), which is wholly owned by AEH, has one uncommitted $25 million 364-day bilateral credit facility and one committed $15 million 364-day bilateral credit facility that expire in December 2015. 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 $ 36.1 million at September 30, 2015 . AEH has a $500 million intercompany demand credit facility with AEC. This facility bears interest at a rate equal to the greater of (i) the one-month LIBOR rate plus 3.00 percent . Applicable state regulatory commissions have approved our use of this facility through December 31, 2015. We intend to seek renewal of this facility during the first quarter of fiscal 2016. There were no borrowings outstanding under this facility at September 30, 2015 . 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 . After giving effect to this issuance and the aforementioned $500 million senior note issuance completed in October 2014, $845 million of securities remained available for issuance under the shelf registration statement until March 28, 2016. Debt Covenants In addition to the financial covenants described above, 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. We were in compliance with all of our debt covenants as of September 30, 2015. 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. Maturities of long-term debt at September 30, 2015 were as follows (in thousands): 2016 $ — 2017 250,000 2018 — 2019 450,000 2020 — Thereafter 1,760,000 $ 2,460,000

Retirement and Post-retirement

Retirement and Post-retirement Employee Benefit Plans	12 Months Ended
	Sep. 30, 2015
Compensation and Retirement Disclosure [Abstract]
Retirement and Post-Retirement Employee Benefit Plans	Retirement and Post-Retirement Employee Benefit Plans We have both funded and unfunded noncontributory defined benefit plans that together cover most of our employees. We also maintain post-retirement plans that provide health care benefits to retired employees. Finally, we sponsor defined contribution plans that cover substantially all employees. These plans are discussed in further detail below. As a rate regulated entity, we generally recover our pension costs in our rates over a period of up to 15 years. The amounts that have not yet been recognized in net periodic pension cost that have been recorded as regulatory assets are as follows: Defined Benefits Plans Supplemental Executive Retirement Plans Postretirement Plans Total (In thousands) September 30, 2015 Unrecognized transition obligation $ — $ — $ 82 $ 82 Unrecognized prior service credit (1,735 ) — (4,524 ) (6,259 ) Unrecognized actuarial loss 120,948 36,915 (47,149 ) 110,714 $ 119,213 $ 36,915 $ (51,591 ) $ 104,537 September 30, 2014 Unrecognized transition obligation $ — $ — $ 354 $ 354 Unrecognized prior service credit (1,927 ) — (6,168 ) (8,095 ) Unrecognized actuarial loss 109,767 34,447 7,531 151,745 $ 107,840 $ 34,447 $ 1,717 $ 144,004 Defined Benefit Plans Employee Pension Plans Prior to December 31, 2014, we maintained two defined benefit plans: the Atmos Energy Corporation Pension Account Plan (the Plan) and the Atmos Energy Corporation Retirement Plan for Mississippi Valley Gas Union Employees (the Union Plan) (collectively referred to as the Plans). The assets of the Plans were held within the Atmos Energy Corporation Master Retirement Trust (the Master Trust). In June 2014, active collectively bargained employees of Atmos Energy’s Mississippi Division voted to decertify the union. As a result of this vote, effective January 1, 2015, active participants of the Union Plan became participants in the Plan. Opening account balances were established at the time of transfer equal to the present value of their respective accrued benefits under the Union Plan at December 31, 2014. Additionally, effective January 1, 2015, current retirees in the Union Plan as well as those participants who terminated and were vested in the Union Plan were transferred to the Plan with the same provisions that were in place at the time of their retirement or termination. The Plan is a cash balance pension plan that was established effective January 1999 and covers most of the employees of Atmos Energy’s regulated operations. Opening account balances were established for participants as of January 1999 equal to the present value of their respective accrued benefits under the pension plans which were previously in effect as of December 31, 1998. The Plan credits an allocation to each participant’s account at the end of each year according to a formula based on the participant’s age, service and total pay (excluding incentive pay). The Plan also provides for an additional annual allocation based upon a participant’s age as of January 1, 1999 for those participants who were participants in the prior pension plans. The Plan credited this additional allocation each year through December 31, 2008. In addition, at the end of each year, a participant’s account is credited with interest on the employee’s prior year account balance. A special grandfathered benefit also applied through December 31, 2008, for participants who were at least age 50 as of January 1, 1999 and who were participants in one of the prior plans on December 31, 1998. Participants are fully vested in their account balances after three years of service and may choose to receive their account balances as a lump sum or an annuity. In August 2010, the Board of Directors of Atmos Energy approved a proposal to close the Plan to new participants effective October 1, 2010. Additionally, employees participating in the Plan as of October 1, 2010 were allowed to make a one-time election to migrate from the Plan into our defined contribution plan, which was enhanced, effective January 1, 2011. Generally, our funding policy is to contribute annually an amount in accordance with the requirements of the Employee Retirement Income Security Act of 1974, including the funding requirements under the Pension Protection Act of 2006 (PPA). However, additional voluntary contributions are made from time to time as considered necessary. Contributions are intended to provide not only for benefits attributed to service to date but also for those expected to be earned in the future. During fiscal 2015 and 2014 we contributed $38.0 million and $27.1 million in cash to the Plans to achieve a desired level of funding while maximizing the tax deductibility of this payment. Based upon market conditions at September 30, 2015 , the current funded position of the Plans and the funding requirements under the PPA, we do not anticipate a minimum required contribution for fiscal 2016 . However, we may consider whether a voluntary contribution is prudent to maintain certain funding levels. We make investment decisions and evaluate performance of the assets in the Master Trust on a medium-term horizon of at least three to five years. We also consider our current financial status when making recommendations and decisions regarding the Master Trust’s assets. Finally, we strive to ensure the Master Trust’s assets are appropriately invested to maintain an acceptable level of risk and meet the Master Trust’s long-term asset investment policy adopted by the Board of Directors. To achieve these objectives, we invest the Master Trust’s assets in equity securities, fixed income securities, interests in commingled pension trust funds, other investment assets and cash and cash equivalents. Investments in equity securities are diversified among the market’s various subsectors in an effort to diversify risk and maximize returns. Fixed income securities are invested in investment grade securities. Cash equivalents are invested in securities that either are short term (less than 180 days) or readily convertible to cash with modest risk. The following table presents asset allocation information for the Master Trust as of September 30, 2015 and 2014 . Targeted Allocation Range Actual Allocation September 30 Security Class 2015 2014 Domestic equities 35%-55% 41.3 % 44.9 % International equities 10%-20% 14.9 % 15.3 % Fixed income 5%-30% 11.0 % 9.7 % Company stock 0%-15% 15.2 % 12.9 % Other assets 0%-20% 17.6 % 17.2 % At September 30, 2015 and 2014 , the Plan held 1,169,700 shares of our common stock, which represented 15.2 percent of total Plan assets and 12.9 percent of total Master Trust assets. These shares generated dividend income for the Plan of approximately $1.8 million and $1.7 million during fiscal 2015 and 2014 . Our employee pension plan expenses and liabilities are determined on an actuarial basis and are affected by numerous assumptions and estimates including the market value of plan assets, estimates of the expected return on plan assets and assumed discount rates and demographic data. We review the estimates and assumptions underlying our employee pension plans annually based upon a September 30 measurement date. The development of our assumptions is fully described in our significant accounting policies in Note 2. The actuarial assumptions used to determine the pension liability for the Plans were determined as of September 30, 2015 and 2014 and the actuarial assumptions used to determine the net periodic pension cost for the Plans were determined as of September 30, 2014 , 2013 and 2012 . In October 2014, the Society of Actuaries released its final report on mortality tables and the mortality improvement scale to reflect increasing life expectancies in the United States. On October 8, 2015 , the Society of Actuaries issued an additional report related to mortality tables and the mortality improvement scale. As of September 30, 2015, we updated our assumed mortality rates to incorporate both new sets of mortality tables issued by the Society of Actuaries. Additional assumptions are presented in the following table: Pension Liability Pension Cost 2015 2014 2015 2014 2013 Discount rate 4.55 % 4.43 % 4.43 % 4.95 % 4.04 % Rate of compensation increase 3.50 % 3.50 % 3.50 % 3.50 % 3.50 % Expected return on plan assets 7.00 % 7.25 % 7.25 % 7.25 % 7.75 % The following table presents the Plans’ accumulated benefit obligation, projected benefit obligation and funded status as of September 30, 2015 and 2014 : 2015 2014 (In thousands) Accumulated benefit obligation $ 485,921 $ 466,182 Change in projected benefit obligation: Benefit obligation at beginning of year $ 493,594 $ 455,799 Service cost 16,231 15,345 Interest cost 21,850 22,330 Actuarial (gain) loss 7,420 26,611 Benefits paid (30,496 ) (24,519 ) Plan amendments — (1,972 ) Benefit obligation at end of year 508,599 493,594 Change in plan assets: Fair value of plan assets at beginning of year 434,767 396,887 Actual return on plan assets 8,661 35,289 Employer contributions 38,000 27,110 Benefits paid (30,496 ) (24,519 ) Fair value of plan assets at end of year 450,932 434,767 Reconciliation: Funded status (57,667 ) (58,827 ) Unrecognized prior service cost — — Unrecognized net loss — — Net amount recognized $ (57,667 ) $ (58,827 ) Net periodic pension cost for the Plans for fiscal 2015 , 2014 and 2013 is recorded as operating expense and included the following components: Fiscal Year Ended September 30 2015 2014 2013 (In thousands) Components of net periodic pension cost: Service cost $ 16,231 $ 15,345 $ 17,754 Interest cost 21,850 22,330 19,334 Expected return on assets (25,744 ) (23,601 ) (22,955 ) Amortization of prior service credit (192 ) (136 ) (141 ) Recognized actuarial loss 13,322 13,777 19,066 Net periodic pension cost $ 25,467 $ 27,715 $ 33,058 The following table sets forth by level, within the fair value hierarchy, the Master Trust's assets at fair value as of September 30, 2015 and 2014 . As required by authoritative accounting literature, assets are categorized in their entirety based on the lowest level of input that is significant to the fair value measurement. The methods used to determine fair value for the assets held by the Master Trust are fully described in Note 2. In addition to the assets shown below, the Master Trust had net accounts receivable of $2.4 million and $2.7 million at September 30, 2015 and 2014 which materially approximates fair value due to the short-term nature of these assets. Assets at Fair Value as of September 30, 2015 Level 1 Level 2 Level 3 Total (In thousands) Investments: Common stocks $ 159,304 $ — $ — $ 159,304 Money market funds — 11,787 — 11,787 Registered investment companies: Domestic funds 33,312 — — 33,312 International funds 48,648 — — 48,648 Common/collective trusts — domestic funds — 93,081 — 93,081 Government securities: Mortgage-backed securities — 14,359 — 14,359 U.S. treasuries 5,279 805 — 6,084 Corporate bonds — 28,973 — 28,973 Limited partnerships — 52,996 — 52,996 Total investments at fair value $ 246,543 $ 202,001 $ — $ 448,544 Assets at Fair Value as of September 30, 2014 Level 1 Level 2 Level 3 Total (In thousands) Investments: Common stocks $ 155,107 $ — $ — $ 155,107 Money market funds — 11,226 — 11,226 Registered investment companies: Domestic funds 33,266 — — 33,266 International funds 48,134 — — 48,134 Common/collective trusts — domestic funds — 91,792 — 91,792 Government securities: Mortgage-backed securities — 12,520 — 12,520 U.S. treasuries 3,117 562 — 3,679 Corporate bonds — 25,734 — 25,734 Limited partnerships — 50,496 — 50,496 Real estate — — 155 155 Total investments at fair value $ 239,624 $ 192,330 $ 155 $ 432,109 During 2015, the Company determined that a 2014 investment in the registered investment companies - domestic funds should have been classified as common/collective trusts - domestic funds. The amount has been recast in the above table. Supplemental Executive Retirement Plans We have three nonqualified supplemental plans which provide additional pension, disability and death benefits to our officers, division presidents and certain other employees of the Company. The first plan is referred to as the Supplemental Executive Benefits Plan (SEBP) and covers our officers, division presidents and certain other employees of the Company who were employed on or before August 12, 1998. The SEBP is a defined benefit arrangement which provides a benefit equal to 75 percent of covered compensation under which benefits paid from the underlying qualified defined benefit plan are an offset to the benefits under the SEBP. In August 1998, we adopted the Supplemental Executive Retirement Plan (SERP) (formerly known as the Performance-Based Supplemental Executive Benefits Plan), which covers all officers or division presidents selected to participate in the plan between August 12, 1998 and August 5, 2009, any corporate officer who may be appointed to the Management Committee after August 5, 2009 and any other employees selected by our Board of Directors at its discretion. The SERP is a defined benefit arrangement which provides a benefit equal to 60 percent of covered compensation under which benefits paid from the underlying qualified defined benefit plan are an offset to the benefits under the SERP. Effective August 5, 2009, we adopted a new defined benefit Supplemental Executive Retirement Plan (the 2009 SERP), for corporate officers (other than such officer who is appointed as a member of the Company’s Management Committee), division presidents or any other employees selected at the discretion of the Board. Under the 2009 SERP, a nominal account has been established for each participant, to which the Company contributes at the end of each calendar year an amount equal to ten percent of the total of each participant’s base salary and cash incentive compensation earned during each prior calendar year, beginning December 31, 2009. The benefits vest after three years of service and attainment of age 55 and earn interest credits at the same annual rate as the Company’s Pension Account Plan (currently 4.69% ). On October 2, 2013, due to the retirement of one of our executives, we recognized a settlement loss of $4.5 million associated with our SEBP and made a $16.8 million benefit payment. On April 1, 2013, due to the retirement of certain executives, we recognized a settlement loss of $3.2 million associated with the supplemental plans and revalued the net periodic pension cost for the remainder of fiscal 2013. The revaluation of the net periodic pension cost resulted in an increase in the discount rate, effective April 1, 2013, to 4.21 percent, which reduced our net periodic pension cost by approximately $0.1 million for the remainder of the fiscal year. Similar to our employee pension plans, we review the estimates and assumptions underlying our supplemental plans annually based upon a September 30 measurement date using the same techniques as our employee pension plans. The actuarial assumptions used to determine the pension liability for the supplemental plans were determined as of September 30, 2015 and 2014 and the actuarial assumptions used to determine the net periodic pension cost for the supplemental plans were determined as of September 30, 2014 , 2013 and 2012 . These assumptions are presented in the following table: Pension Liability Pension Cost 2015 2014 2015 2014 2013 Discount rate 4.55 % 4.43 % 4.43 % 4.95 % 4.04 % (1) Rate of compensation increase 3.50 % 3.50 % 3.50 % 3.50 % 3.50 % (1) The discount rate for the supplemental plans increased from 4.04% to 4.21% effective April 1, 2013 due to a settlement loss recorded in fiscal 2013. The following table presents the supplemental plans’ accumulated benefit obligation, projected benefit obligation and funded status as of September 30, 2015 and 2014 : 2015 2014 (In thousands) Accumulated benefit obligation $ 118,835 $ 106,276 Change in projected benefit obligation: Benefit obligation at beginning of year $ 113,219 $ 117,080 Service cost 3,971 3,607 Interest cost 4,943 4,966 Actuarial (gain) loss 4,811 9,468 Benefits paid (4,551 ) (5,085 ) Settlements — (16,817 ) Benefit obligation at end of year 122,393 113,219 Change in plan assets: Fair value of plan assets at beginning of year — — Employer contribution 4,551 21,902 Benefits paid (4,551 ) (5,085 ) Settlements — (16,817 ) Fair value of plan assets at end of year — — Reconciliation: Funded status (122,393 ) (113,219 ) Unrecognized prior service cost — — Unrecognized net loss — — Accrued pension cost $ (122,393 ) $ (113,219 ) Assets for the supplemental plans are held in separate rabbi trusts. At September 30, 2015 and 2014 , assets held in the rabbi trusts consisted of available-for-sale securities of $41.7 million and $46.2 million , which are included in our fair value disclosures in Note 14. Net periodic pension cost for the supplemental plans for fiscal 2015 , 2014 and 2013 is recorded as operating expense and included the following components: Fiscal Year Ended September 30 2015 2014 2013 (In thousands) Components of net periodic pension cost: Service cost $ 3,971 $ 3,607 $ 3,039 Interest cost 4,943 4,966 4,755 Amortization of transition asset — — — Amortization of prior service cost — — — Recognized actuarial loss 2,343 1,948 2,918 Settlements — 4,539 3,160 Net periodic pension cost $ 11,257 $ 15,060 $ 13,872 Estimated Future Benefit Payments The following benefit payments for our defined benefit plans, which reflect expected future service, as appropriate, are expected to be paid in the following fiscal years: Pension Plans Supplemental Plans (In thousands) 2016 $ 30,909 $ 21,857 2017 31,805 13,901 2018 33,086 12,807 2019 34,712 6,808 2020 36,128 4,454 2021-2025 201,857 47,047 Postretirement Benefits We sponsor the Retiree Medical Plan for Retirees and Disabled Employees of Atmos Energy Corporation (the Atmos Retiree Medical Plan). This plan provides medical and prescription drug protection to all qualified participants based on their date of retirement. The Atmos Retiree Medical Plan provides different levels of benefits depending on the level of coverage chosen by the participants and the terms of predecessor plans; however, we generally pay 80 percent of the projected net claims and administrative costs and participants pay the remaining 20 percent of this cost. As of September 30, 2009, the Board of Directors approved a change to the cost sharing methodology for employees who had not met the participation requirements by that date for the Atmos Retiree Medical Plan. Starting on January 1, 2015, the contribution rates that apply to all non-grandfathered participants are determined using a cost sharing methodology by which Atmos Energy will limit its contribution to a three percent cost increase in claims and administrative costs each year. If medical costs covered by the Atmos Retiree Medical Plan increase more than three percent annually, participants will be responsible for the additional costs. Generally, our funding policy is to contribute annually an amount in accordance with the requirements of ERISA. However, additional voluntary contributions are made annually as considered necessary. Contributions are intended to provide not only for benefits attributed to service to date but also for those expected to be earned in the future. We expect to contribute between $30 million and $40 million to our postretirement benefits plan during fiscal 2016 . We maintain a formal investment policy with respect to the assets in our postretirement benefits plan to ensure the assets funding the postretirement benefit plan are appropriately invested to maintain an acceptable level of risk. We also consider our current financial status when making recommendations and decisions regarding the postretirement benefits plan. We currently invest the assets funding our postretirement benefit plan in diversified investment funds which consist of common stocks, preferred stocks and fixed income securities. The diversified investment funds may invest up to 75 percent of assets in common stocks and convertible securities. The following table presents asset allocation information for the postretirement benefit plan assets as of September 30, 2015 and 2014 . Actual Allocation September 30 Security Class 2015 2014 Diversified investment funds 97.5 % 99.7 % Cash and cash equivalents 2.5 % 0.3 % Similar to our employee pension and supplemental plans, we review the estimates and assumptions underlying our postretirement benefit plan annually based upon a September 30 measurement date using the same techniques as our employee pension plans. The actuarial assumptions used to determine the pension liability for our postretirement plan were determined as of September 30, 2015 and 2014 and the actuarial assumptions used to determine the net periodic pension cost for the postretirement plan were determined as of September 30, 2014 , 2013 and 2012 . The assumptions are presented in the following table: Postretirement Liability Postretirement Cost 2015 2014 2015 2014 2013 Discount rate 4.55 % 4.43 % 4.43 % 4.95 % 4.04 % Expected return on plan assets 4.45 % 4.60 % 4.60 % 4.60 % 4.70 % Initial trend rate 7.50 % 7.50 % 7.50 % 8.00 % 8.00 % Ultimate trend rate 5.00 % 5.00 % 5.00 % 5.00 % 5.00 % Ultimate trend reached in 2021 2020 2020 2020 2019 The following table presents the postretirement plan’s benefit obligation and funded status as of September 30, 2015 and 2014 : 2015 2014 (In thousands) Change in benefit obligation: Benefit obligation at beginning of year $ 315,118 $ 312,148 Service cost 15,583 16,784 Interest cost 14,385 15,951 Plan participants’ contributions 4,563 4,435 Actuarial (gain) loss (69,962 ) (18,963 ) Benefits paid (12,508 ) (13,580 ) Plan amendments — (1,657 ) Benefit obligation at end of year 267,179 315,118 Change in plan assets: Fair value of plan assets at beginning of year 134,821 106,413 Actual return on plan assets (8,851 ) 14,003 Employer contributions 19,984 23,550 Plan participants’ contributions 4,563 4,435 Benefits paid (12,508 ) (13,580 ) Fair value of plan assets at end of year 138,009 134,821 Reconciliation: Funded status (129,170 ) (180,297 ) Unrecognized transition obligation — — Unrecognized prior service cost — — Unrecognized net loss — — Accrued postretirement cost $ (129,170 ) $ (180,297 ) Net periodic postretirement cost for fiscal 2015 , 2014 and 2013 is recorded as operating expense and included the components presented below. Fiscal Year Ended September 30 2015 2014 2013 (In thousands) Components of net periodic postretirement cost: Service cost $ 15,583 $ 16,784 $ 18,800 Interest cost 14,385 15,951 12,964 Expected return on assets (6,431 ) (5,167 ) (3,988 ) Amortization of transition obligation 272 274 1,081 Amortization of prior service credit (1,644 ) (1,450 ) (1,450 ) Recognized actuarial loss — 631 4,196 Net periodic postretirement cost $ 22,165 $ 27,023 $ 31,603 Assumed health care cost trend rates have a significant effect on the amounts reported for the plan. A one-percentage point change in assumed health care cost trend rates would have the following effects on the latest actuarial calculations: One-Percentage Point Increase One-Percentage Point Decrease (In thousands) Effect on total service and interest cost components $ 4,288 $ (3,426 ) Effect on postretirement benefit obligation $ 39,572 $ (32,440 ) We are currently recovering other postretirement benefits costs through our regulated rates under accrual accounting as prescribed by accounting principles generally accepted in the United States in substantially all of our service areas. Other postretirement benefits costs have been specifically addressed in rate orders in each jurisdiction served by our Kentucky/Mid-States, West Texas, Mid-Tex and Mississippi Divisions as well as our Kansas jurisdiction and Atmos Pipeline – Texas or have been included in a rate case and not disallowed. Management believes that this accounting method is appropriate and will continue to seek rate recovery of accrual-based expenses in its ratemaking jurisdictions that have not yet approved the recovery of these expenses. The following tables set forth by level, within the fair value hierarchy, the Retiree Medical Plan’s assets at fair value as of September 30, 2015 and 2014 . The methods used to determine fair value for the assets held by the Retiree Medical Plan are fully described in Note 2. Assets at Fair Value as of September 30, 2015 Level 1 Level 2 Level 3 Total (In thousands) Investments: Money market funds $ — $ 3,486 $ — $ 3,486 Registered investment companies: Domestic funds 123,921 — — 123,921 International funds 10,602 — — 10,602 Total investments at fair value $ 134,523 $ 3,486 $ — $ 138,009 Assets at Fair Value as of September 30, 2014 Level 1 Level 2 Level 3 Total (In thousands) Investments: Money market funds $ — $ 434 $ — $ 434 Registered investment companies: Domestic funds 124,006 — — 124,006 International funds 10,381 — — 10,381 Total investments at fair value $ 134,387 $ 434 $ — $ 134,821 During 2015, the Company determined that a 2014 investment in the registered investment companies - international funds should have been classified as registered investment companies - domestic funds. The amount has been recast in the above table. Estimated Future Benefit Payments The following benefit payments paid by us, retirees and prescription drug subsidy payments for our postretirement benefit plans, which reflect expected future service, as appropriate, are expected to be paid in the following fiscal years. Company payments for fiscal 2015 include contributions to our postretirement plan trusts. Company Payments Retiree Payments Subsidy Payments Total Postretirement Benefits (In thousands) 2016 $ 15,498 $ 2,382 $ — $ 17,880 2017 11,245 2,677 — 13,922 2018 12,185 2,980 — 15,165 2019 12,755 3,324 — 16,079 2020 13,995 3,766 — 17,761 2021-2025 86,519 26,363 — 112,882 Defined Contribution Plans As of September 30, 2015 , we maintained two defined contribution benefit plans: the Atmos Energy Corporation Retirement Savings Plan and Trust (the Retirement Savings Plan) and the Atmos Energy Holdings, LLC 401K Profit-Sharing Plan (the AEH 401K Profit-Sharing Plan). The Retirement Savings Plan covers substantially all employees in our regulated operations and is subject to the provisions of Section 401(k) of the Internal Revenue Code. Effective January 1, 2007, employees automatically become participants of the Retirement Savings Plan on the date of employment. Participants may elect a salary reduction up to a maximum of 65 percent of eligible compensation, as defined by the Plan, not to exceed the maximum allowed by the Internal Revenue Service. New participants are automatically enrolled in the Plan at a salary reduction amount of four percent of eligible compensation, from which they may opt out. We match 100 percent of a participant’s contributions, limited to four percent of the participant’s salary, in our common stock. However, participants have the option to immediately transfer this matching contribution into other funds held within the plan. Participants are eligible to receive matching contributions after completing one year of service. Participants are also permitted to take out loans against their accounts subject to certain restrictions. Employees hired on or after October 1, 2010 participate in the enhanced plan in which participants receive a fixed annual contribution of four percent of eligible earnings to their Retirement Savings Plan account. Participants will continue to be eligible for company matching contributions of up to four percent of their eligible earnings and will be fully vested in the fixed annual contribution after three years of service. Prior to December 31, 2014, we also maintained the Atmos Energy Corporation Savings Plan for MVG Union Employees (the Union 401K Plan). In June 2014, active collectively bargained employees of Atmos Energy’s Mississippi Division voted to decertify the Union. As a result, effective July 19, 2014, active participants of the Union 401K Plan were eligible to participate in the Retirement Savings Plan. Participants who did not actively elect to participate in the Retirement Savings Plan were automatically enrolled in the Retirement Savings Plan at a salary reduction level of four percent , which they had the choice to opt out of within 30 days. In addition, participants could have elected to transfer their funds from the Union 401K Plan to the Retirement Savings Plan. Effective January 1, 2015, all remaining participants became participants in the Retirement Savings Plan. Following this transfer, the Union 401K Plan was terminated. Matching contributions to the Retirement Savings Plan and the Union 401K Plan are expensed as incurred and amounted to $11.5 million , $10.9 million and $10.4 million for fiscal years 2015 , 2014 and 2013 . The Board of Directors may also approve discretionary contrib utions, subject to the provisions of the Internal Revenue Code and applicable Treasury regulations. No discretionary contributions were made for fiscal years 2015 , 2014 or 2013 . At September 30, 2015 and 2014 , the Retirement Savings Plan held 4.3 percent and 4.5 percent of our outstanding common stock. The AEH 401K Profit-Sharing Plan covers substantially all AEH employees and is subject to the provisions of Section 401(k) of the Internal Revenue Code. Participants may elect a salary reduction up to a maximum of 75 percent of eligible compensation, as defined by the Plan, not to exceed the maximum allowed by the Internal Revenue Service. The Company may elect to make safe harbor contributions up to four percent of the employee’s salary which vest immediately. The Company may also make discretionary profit sharing contributions to the AEH 401K Profit-Sharing Plan. Participants become fully vested in the discretionary profit-sharing contributions after three years of service. Participants are also permitted to take out loans against their accounts subject to certain restrictions. Discretionary contributions to the AEH 401K Profit-Sharing Plan are expensed as incurred and amounted to $1.1 million , $1.4 million and $1.1 million for fiscal years 2015 , 2014 and 2013 . On November 4, 2015 , the Atmos Energy Corporation Board of Directors voted to approve the merger of the assets and liabilities of the AEH 401K Profit-Sharing Plan with the Retirement Savings Plan, effective January 1, 2016 to improve administrative efficiency and reduce total costs.

Stock and Other Compensation Pl

Stock and Other Compensation Plans	12 Months Ended
	Sep. 30, 2015
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Stock and Other Compensation Plans	Stock and Other Compensation Plans Stock-Based Compensation Plans Total stock-based compensation expense was $27.5 million , $25.5 million and $17.8 million for the fiscal years ended September 30, 2015 , 2014 and 2013 , primarily related to restricted stock costs. 1998 Long-Term Incentive Plan In August 1998, the Board of Directors approved and adopted the 1998 Long-Term Incentive Plan (LTIP), which became effective in October 1998 after approval by our shareholders. The LTIP is a comprehensive, long-term incentive compensation plan providing for discretionary awards of incentive stock options, non-qualified stock options, stock appreciation rights, bonus stock, time-lapse restricted stock, time-lapse restricted stock units, performance-based restricted stock units and stock units to certain employees and non-employee directors of the Company and our subsidiaries. The objectives of this plan include attracting and retaining the best personnel, providing for additional performance incentives and promoting our success by providing employees with the opportunity to acquire common stock. As of September 30, 2015 , we were authorized to grant awards for up to a maximum of 8.7 million shares of common stock under this plan subject to certain adjustment provisions. As of September 30, 2015 , non-qualified stock options, bonus stock, time-lapse restricted stock, time-lapse restricted stock units, performance-based restricted stock units and stock units had been issued under this plan, and 308,582 shares were available for future issuance. Restricted Stock Unit Award Grants As noted above, the LTIP provides for discretionary awards of restricted stock units to help attract, retain and reward employees of Atmos Energy and its subsidiaries. Certain of these awards vest based upon the passage of time and other awards vest based upon the passage of time and the achievement of specified performance targets. The fair value of the awards granted is based on the market price of our stock at the date of grant. The associated expense is recognized ratably over the vesting period. Employees who are granted time-lapse restricted stock units under our LTIP have a nonforfeitable right to dividend equivalents that are paid at the same rate and at the same time at which they are paid on shares of stock without restrictions. Time-lapse restricted stock units contain only a service condition that the employee recipients render continuous services to the Company for a period of three years from the date of grant, except for accelerated vesting in the event of death, disability, change of control of the Company or termination without cause (with certain exceptions). There are no performance conditions required to be met for employees to be vested in time-lapse restricted stock units. Employees who are granted performance-based restricted stock units under our LTIP have a forfeitable right to dividend equivalents that accrue at the same rate at which they are paid on shares of stock without restrictions. Dividend equivalents on the performance-based restricted stock units are paid either in cash or in the form of shares upon the vesting of the award. Performance-based restricted stock units contain a service condition that the employee recipients render continuous services to the Company for a period of three years from the beginning of the applicable three-year performance period, except for accelerated vesting in the event of death, disability, change of control of the Company or termination without cause (with certain exceptions) and a performance condition based on a cumulative earnings per share target amount. The following summarizes information regarding the restricted stock units granted under the plan during the fiscal years ended September 30, 2015 , 2014 and 2013 : 2015 2014 2013 Number of Restricted Units Weighted Average Grant-Date Fair Value Number of Weighted Average Grant-Date Fair Value Number of Weighted Average Grant-Date Fair Value Nonvested at beginning of year 988,637 $ 42.22 1,052,844 $ 36.20 1,262,582 $ 32.46 Granted 444,543 50.50 464,438 45.05 473,775 40.48 Vested (551,688 ) 39.28 (524,532 ) 32.67 (657,795 ) 32.20 Forfeited (3,388 ) 48.55 (4,113 ) 39.00 (25,718 ) 33.42 Nonvested at end of year 878,104 $ 48.24 988,637 $ 42.22 1,052,844 $ 36.20 As of September 30, 2015 , there was $10.2 million of total unrecognized compensation cost related to nonvested restricted stock units granted under the LTIP. That cost is expected to be recognized over a weighted-average period of 1.5 years . The fair value of restricted stock vested during the fiscal years ended September 30, 2015 , 2014 and 2013 was $21.7 million , $17.1 million and $21.2 million . Other Plans Direct Stock Purchase Plan We maintain a Direct Stock Purchase Plan, open to all investors, which allows participants to have all or part of their cash dividends paid quarterly in additional shares of our common stock. The minimum initial investment required to join the plan is $1,250 . Direct Stock Purchase Plan participants may purchase additional shares of our common stock as often as weekly with voluntary cash payments of at least $25 , up to an annual maximum of $100,000 . Outside Directors Stock-For-Fee Plan In November 1994, the Board of Directors adopted the Outside Directors Stock-for-Fee Plan, which was approved by our shareholders in February 1995. The plan permits non-employee directors to receive all or part of their annual retainer and meeting fees in stock rather than in cash. This plan was terminated by the Board of Directors, effective September 1, 2014, when the LTIP was amended to incorporate substantially all of its provisions. Equity Incentive and Deferred Compensation Plan for Non-Employee Directors In November 1998, the Board of Directors adopted the Equity Incentive and Deferred Compensation Plan for Non-Employee Directors, which was approved by our shareholders in February 1999. This plan amended the Atmos Energy Corporation Deferred Compensation Plan for Outside Directors adopted by the Company in May 1990 and replaced the pension payable under our Retirement Plan for Non-Employee Directors. The plan provides non-employee directors of Atmos Energy with the opportunity to defer receipt, until retirement, of compensation for services rendered to the Company and invest deferred compensation into either a cash account or a stock account. Other Discretionary Compensation Plans We have an annual incentive program covering substantially all employees to give each employee an opportunity to share in our financial success based on the achievement of key performance measures considered critical to achieving business objectives for a given year with minimum and maximum thresholds. The Company must meet the minimum threshold for the plan to be funded and distributed to employees. These performance measures may include earnings growth objectives, improved cash flow objectives or crucial customer satisfaction and safety results. We monitor progress towards the achievement of the performance measures throughout the year and record accruals based upon the expected payout using the best estimates available at the time the accrual is recorded. During the last several fiscal years, we have used earnings per share as our sole performance measure.

Details of Selected Consolidate

Details of Selected Consolidated Balance Sheet Captions	12 Months Ended
	Sep. 30, 2015
Details Of Selected Consolidated Balance Sheet Captions Disclosure [Abstract]
Details of Selected Consolidated Balance Sheet Captions	Details of Selected Consolidated Balance Sheet Captions The following tables provide additional information regarding the composition of certain of our balance sheet captions. Accounts receivable Accounts receivable was comprised of the following at September 30, 2015 and 2014 : September 30 2015 2014 (In thousands) Billed accounts receivable $ 204,585 $ 262,937 Unbilled revenue 65,008 62,484 Other accounts receivable 40,850 41,971 Total accounts receivable 310,443 367,392 Less: allowance for doubtful accounts (15,283 ) (23,992 ) Net accounts receivable $ 295,160 $ 343,400 Other current assets Other current assets as of September 30, 2015 and 2014 were comprised of the following accounts. September 30 2015 2014 (In thousands) Assets from risk management activities $ 9,232 $ 45,827 Deferred gas costs 9,715 20,069 Taxes receivable 4,479 5,481 Prepaid expenses 27,734 25,039 Materials and supplies 12,587 5,704 Other 6,822 9,145 Total $ 70,569 $ 111,265 Property, plant and equipment Property, plant and equipment was comprised of the following as of September 30, 2015 and 2014 : September 30 2015 2014 (In thousands) Production plant $ 131 $ 4,821 Storage plant 286,011 275,579 Transmission plant 1,844,117 1,622,846 Distribution plant 6,019,001 5,522,794 General plant 769,311 735,223 Intangible plant 41,131 38,858 8,959,702 8,200,121 Construction in progress 280,398 247,579 9,240,100 8,447,700 Less: accumulated depreciation and amortization (1,809,520 ) (1,721,794 ) Net property, plant and equipment (1) $ 7,430,580 $ 6,725,906 (1) Net property, plant and equipment includes plant acquisition adjustments of $(68.1) million and $(76.4) million at September 30, 2015 and 2014 . Goodwill The following presents our goodwill balance allocated by segment and changes in the balance for the fiscal year ended September 30, 2015 : Regulated Distribution Regulated Pipeline Nonregulated Total (In thousands) Balance as of September 30, 2014 $ 574,816 $ 132,502 $ 34,711 $ 742,029 Deferred tax adjustments on prior acquisitions (1) 633 40 — 673 Balance as of September 30, 2015 $ 575,449 $ 132,542 $ 34,711 $ 742,702 (1) We annually adjust certain deferred taxes recorded in connection with acquisitions completed in fiscal 2001 and fiscal 2004, which resulted in an increase to goodwill and net deferred tax liabilities of $0.7 million for fiscal 2015 . Deferred charges and other assets Deferred charges and other assets as of September 30, 2015 and 2014 were comprised of the following accounts. September 30 2015 2014 (In thousands) Marketable securities $ 74,200 $ 79,613 Regulatory assets 182,573 230,240 Deferred financing costs 17,873 13,698 Assets from risk management activities 368 13,038 Other 13,664 14,340 Total $ 288,678 $ 350,929 Accounts payable and accrued liabilities Accounts payable and accrued liabilities as of September 30, 2015 and 2014 were comprised of the following accounts. September 30 2015 2014 (In thousands) Trade accounts payable $ 78,534 $ 77,860 Accrued gas payable 119,825 179,425 Accrued liabilities 40,583 50,801 Total $ 238,942 $ 308,086 Other current liabilities Other current liabilities as of September 30, 2015 and 2014 were comprised of the following accounts. September 30 2015 2014 (In thousands) Customer credit balances and deposits $ 100,232 $ 82,085 Accrued employee costs 47,602 46,445 Deferred gas costs 28,100 35,063 Accrued interest 34,914 36,768 Liabilities from risk management activities 9,568 1,730 Taxes payable 93,674 77,601 Pension and postretirement obligations 21,857 11,380 Current deferred tax liability 55,918 48,751 Regulatory cost of removal accrual 56,123 45,061 Other 9,966 20,985 Total $ 457,954 $ 405,869 Deferred credits and other liabilities Deferred credits and other liabilities as of September 30, 2015 and 2014 were comprised of the following accounts. September 30 2015 2014 (In thousands) Customer advances for construction $ 9,316 $ 9,883 Regulatory liabilities 3,693 4,472 Asset retirement obligation 9,063 10,508 Liabilities from risk management activities 110,539 20,126 Other 29,085 23,881 Total $ 161,696 $ 68,870

Leases

Leases	12 Months Ended
	Sep. 30, 2015
Leases [Abstract]
Leases	Leases We have entered into operating leases for office and warehouse space, vehicles and heavy equipment used in our operations. The remaining lease terms range from one to 19 years and generally provide for the payment of taxes, insurance and maintenance by the lessee. Renewal options exist for certain of these leases. The related future minimum lease payments at September 30, 2015 were as follows: Operating Leases (In thousands) 2016 $ 16,475 2017 16,639 2018 16,490 2019 15,207 2020 14,251 Thereafter 61,651 Total minimum lease payments $ 140,713 Consolidated lease and rental expense amounted to $32.5 million , $31.7 million and $32.4 million for fiscal 2015 , 2014 and 2013 .

Commitments and Contingencies

Commitments and Contingencies	12 Months Ended
	Sep. 30, 2015
Commitments and Contingencies Disclosure [Abstract]
Commitments and Contingencies	Commitments and Contingencies Litigation We are a party to various litigation that has arisen in the ordinary course of our business. While the results of such litigation cannot be predicted with certainty, we believe the final outcome of such litigation will not have a material adverse effect on our financial condition, results of operations or cash flows. Environmental Matters We are a party to environmental matters and claims that have arisen in the ordinary course of our business. While the ultimate results of response actions to these environmental matters and claims cannot be predicted with certainty, we believe the final outcome of such response actions will not have a material adverse effect on our financial condition, results of operations or cash flows because we believe that the expenditures related to such response actions will either be recovered through rates, shared with other parties or are adequately covered by insurance. Purchase Commitments Our regulated 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 Mid-Tex Division also maintains a limited number of long-term supply contracts to ensure a reliable source of gas for our customers in its service area which obligate it to purchase specified volumes at prices indexed to natural gas distribution hubs. At September 30, 2015 , we were committed to purchase 36.6 Bcf within one year and 26.8 Bcf within one to three years under indexed contracts. Purchases under these contracts totaled $ 113.3 million , $ 140.9 million and $ 89.0 million for 2015 , 2014 , 2013 . Our nonregulated segment has commitments to purchase physical quantities of natural gas under contracts indexed to the forward NYMEX strip or fixed price contracts. At September 30, 2015 , we were committed to purchase 101.9 Bcf within one year, 16.0 Bcf within one to three years and 0.5 Bcf after three years under indexed contracts. We are committed to purchase 3.0 Bcf within one year under fixed price contracts with prices ranging from $2.32 to $3.23 per Mcf. Purchases under these contracts totaled $1,141.3 million , $1,687.5 million and $1,246.1 million for 2015 , 2014 and 2013 . In addition, 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 as of September 30, 2015 are as follows (in thousands): 2016 $ 7,843 2017 3,522 2018 1,966 2019 426 2020 398 Thereafter 1,101 $ 15,256 Regulatory Matters In July 2010, the Dodd-Frank Act was enacted, representing an extensive overhaul of the framework for regulation of U.S. financial markets. The Dodd-Frank Act required various regulatory agencies, including the SEC and the Commodities Futures Trading Commission, to establish regulations for implementation of many of the provisions of the Dodd-Frank Act. A number of those regulations have been adopted; we have enacted new procedures and modified existing business practices and contractual arrangements to comply with such regulations. We expect additional regulations to be issued, which should provide additional clarity regarding the extent of the impact of this legislation on us. The costs of participating in financial markets for hedging certain risks inherent in our business may be further increased when these expected additional regulations are adopted. We also anticipate that the Commodities Futures Trading Commission will issue additional related reporting and disclosure obligations.

Income Taxes

Income Taxes	12 Months Ended
	Sep. 30, 2015
Income Tax Disclosure [Abstract]
Income Taxes	Income Taxes The components of income tax expense from continuing operations for 2015 , 2014 and 2013 were as follows: 2015 2014 2013 (In thousands) Current Federal $ — $ — $ — State 7,251 5,527 8,178 Deferred Federal 175,897 169,106 124,836 State 12,548 12,375 9,605 Investment tax credits (6 ) (6 ) (20 ) $ 195,690 $ 187,002 $ 142,599 Reconciliations of the provision for income taxes computed at the statutory rate to the reported provisions for income taxes from continuing operations for 2015 , 2014 and 2013 are set forth below: 2015 2014 2013 (In thousands) Tax at statutory rate of 35% $ 178,768 $ 166,887 $ 130,655 Common stock dividends deductible for tax reporting (2,413 ) (2,307 ) (2,153 ) State taxes (net of federal benefit) 12,869 11,636 11,559 Change in valuation allowance 4,998 6,969 1,085 Other, net 1,468 3,817 1,453 Income tax expense $ 195,690 $ 187,002 $ 142,599 Deferred income taxes reflect the tax effect of differences between the basis of assets and liabilities for book and tax purposes. The tax effect of temporary differences that gave rise to significant components of the deferred tax liabilities and deferred tax assets at September 30, 2015 and 2014 are presented below: 2015 2014 (In thousands) Deferred tax assets: Employee benefit plans $ 121,619 $ 116,157 Interest rate agreements 51,067 10,565 Net operating loss carryforwards 313,224 236,626 Charitable and other credit carryforwards 22,281 21,614 Other 36,695 28,849 Total deferred tax assets 544,886 413,811 Valuation allowance (10,872 ) (6,969 ) Net deferred tax assets 534,014 406,842 Deferred tax liabilities: Difference in net book value and net tax value of assets (1,890,886 ) (1,655,894 ) Pension funding (35,247 ) (17,890 ) Gas cost adjustments (43,634 ) (31,252 ) Other (31,480 ) (37,173 ) Total deferred tax liabilities (2,001,247 ) (1,742,209 ) Net deferred tax liabilities $ (1,467,233 ) $ (1,335,367 ) Deferred credits for rate regulated entities $ 412 $ (109 ) At September 30, 2015 , we had $307.3 million of federal net operating loss carryforwards, which includes the impact of stock based compensation. The federal net operating loss carryforwards are available to offset taxable income and will begin to expire in 2029 . The Company also has $10.1 million of federal alternative minimum tax credit carryforwards which do not expire. In addition, the Company has $11.4 million in charitable contribution carryforwards to offset taxable income. The Company’s charitable contribution carryforwards expire in 2015 - 2020 . We believe it is more likely than not that the benefit from certain charitable contribution carryforwards will not be realized. Due to the uncertainty of realizing a benefit from the deferred tax asset recorded for charitable contribution carryforwards, a valuation allowance of $4.4 million and $7.0 million was established for the years ended September 30, 2015 and 2014 . In addition, $1.1 million of deferred tax assets expired for which a valuation allowance had previously been recorded during the year ended September 30, 2015 . For state taxable income, the Company has $14.9 million of state net operating loss carryforwards (net of $8.0 million of federal effects) and $0.8 million of state tax credits carryforwards (net of federal effects). Depending on the jurisdiction in which the state net operating loss was generated, the carryforwards will begin to expire between 2016 and 2030 . We believe it is more likely than not that a portion of the benefit from certain state net operating loss carryfowards will not be realized. Due to the uncertainty of realizing a benefit from the deferred tax asset for these carryforwards, a valuation allowance of $0.6 million (net of federal effects) was established for the year ended September 30, 2015 . The state tax credits will begin to expire in 2018 . At September 30, 2015 , we had recorded liabilities associated with unrecognized tax benefits totaling $17.1 million . The following table reconciles the beginning and ending balance of our unrecognized tax benefits: 2015 2014 (In thousands) Unrecognized tax benefits - beginning balance $ 12,629 $ 4,158 Increase resulting from prior period tax positions 1,009 3,846 Increase resulting from current period tax positions 3,431 4,625 Unrecognized tax benefits - ending balance 17,069 12,629 Accrued interest and penalties 820 411 Gross unrecognized tax benefits 17,889 13,040 Less: deferred federal and state income tax benefits (6,261 ) (4,564 ) Total unrecognized tax benefits that, if recognized, would impact the effective income tax rate as of the end of the year $ 11,628 $ 8,476 We file income tax returns in the U.S. federal jurisdiction as well as in various states where we have operations. We have concluded substantially all U.S. federal income tax matters through fiscal year 2007.

Financial Instruments

Financial Instruments	12 Months Ended
	Sep. 30, 2015
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. Currently, we utilize financial instruments in our regulated distribution and nonregulated segments. We currently do not manage commodity price risk with financial instruments in our regulated pipeline segment. Our financial instruments do not contain any credit-risk-related or other contingent features that could cause accelerated payments when our financial instruments are in net liability positions. As discussed in Note 2, we report our financial instruments as risk management assets and liabilities, each of which is classified as current or noncurrent based upon the anticipated settlement date of the underlying financial instrument. The following table shows the fair values of our risk management assets and liabilities by segment at September 30, 2015 and 2014 : Regulated Distribution Nonregulated Total (In thousands) September 30, 2015 Assets from risk management activities, current (1) $ 378 $ 8,854 $ 9,232 Assets from risk management activities, noncurrent 368 — 368 Liabilities from risk management activities, current (1) (9,568 ) — (9,568 ) Liabilities from risk management activities, noncurrent (1) (110,539 ) — (110,539 ) Net assets (liabilities) $ (119,361 ) $ 8,854 $ (110,507 ) September 30, 2014 Assets from risk management activities, current (2) $ 23,102 $ 22,725 $ 45,827 Assets from risk management activities, noncurrent 13,038 — 13,038 Liabilities from risk management activities, current (2) (1,730 ) — (1,730 ) Liabilities from risk management activities, noncurrent (2) (20,126 ) — (20,126 ) Net assets $ 14,284 $ 22,725 $ 37,009 (1) Includes $43.5 million of cash held on deposit to collateralize certain financial instruments. Of this amount, $34.6 million was used to offset current and noncurent risk management liabilities under master netting arrangements and the remaining $8.9 million is classified as current risk management assets. (2) Includes $25.8 million of cash held on deposit to collateralize certain financial instruments. Of this amount, $3.1 million was used to offset current and noncurrent risk management liabilities under master netting arrangements and the remaining $22.7 million is classified as current risk management assets. Regulated Commodity Risk Management Activities Although our purchased gas cost adjustment mechanisms essentially insulate our regulated 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 regulated 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 2014 - 2015 heating season (generally October through March), in the jurisdictions where we are permitted to utilize financial instruments, we hedged approximately 37 percent , or approximately 28.2 Bcf of the winter flowing gas requirements at a weighted average cost of approximately $4.34 per Mcf. We have not designated these financial instruments as hedges. Nonregulated Commodity Risk Management Activities In our nonregulated operations, we buy, sell and deliver natural gas at competitive prices by aggregating and purchasing gas supply, arranging transportation and storage logistics and effectively managing commodity price risk. 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 to buy or sell the commodity at a fixed price in the future. 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. Specifically, these operations use financial instruments in the following ways: • Gas delivery and related services - We use financial instruments, designated as cash flow hedges of anticipated purchases and sales at index prices, to mitigate the commodity price risk associated with deliveries under fixed-priced forward contracts to either deliver gas to customers or purchase gas from suppliers. These financial instruments have maturity dates ranging from one to 49 months . • Transportation and storage services - Our nonregulated operations use storage and basis swaps, futures and various over-the-counter and exchange-traded options 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. • Aggregating and purchasing gas supply - Certain financial instruments, designated as fair value hedges, are used to hedge our natural gas inventory used in asset optimization activities. Our nonregulated risk management activities are controlled through various risk management policies and procedures. Our Audit Committee has oversight responsibility for our nonregulated risk management limits and policies. A risk committee, comprised of corporate and business unit officers, is responsible for establishing and enforcing our nonregulated risk management policies and procedures. Under our risk management policies, we seek to match our financial instrument positions to our physical storage positions as well as our expected current and future sales and purchase obligations in order to maintain no open positions at the end of each trading day. The determination of our net open position as of any day, however, requires us to make assumptions as to future circumstances, including the use of gas by our customers in relation to our anticipated storage and market positions. Because the price risk associated with any net open position at the end of each day may increase if the assumptions are not realized, we review these assumptions as part of our daily monitoring activities. Our operations can also be affected by intraday fluctuations of gas prices, since the price of natural gas purchased or sold for future delivery earlier in the day may not be hedged until later in the day. At times, limited net open positions related to our existing and anticipated commitments may occur. At the close of business on September 30, 2015 , our nonregulated segment had net open positions (including existing storage and related financial contracts) of 1.0 Bcf. Interest Rate Risk Management Activities We currently manage interest rate risk through the use of forward starting interest rate swaps to fix the Treasury yield component of the interest cost associated with anticipated financings. In October 2012, we entered into forward starting interest rate swaps to fix the Treasury yield component associated with the then anticipated issuance of $500 million senior notes in October 2014. These notes were issued as planned in October 2014 and we settled swaps with the receipt of $13.4 million . Because the swaps were effective, the realized gain was recorded as a component of accumulated other comprehensive income and is being recognized as a component of interest expense over the 30-year life of the senior notes. In October 2012, we entered into forward starting interest rate swaps to fix the Treasury yield component associated with the anticipated issuance of $250 million million unsecured senior notes in fiscal 2017. Additionally, in fiscal 2014 and 2015, we entered into forward starting interest rate swaps to effectively fix the Treasury yield component associated with $450 million of the anticipated issuance of $450 million unsecured senior notes in fiscal 2019. We designated all of these swaps as cash flow hedges at the time the agreements were executed. Accordingly, unrealized gains and losses associated with the forward starting interest rate swaps will be 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, will be reported as a component of interest expense. Prior to fiscal 2012, we entered into several Treasury lock agreements to fix the Treasury yield component of the interest cost of financing for 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. The remaining amortization periods for the settled Treasury locks extend through fiscal 2045. Quantitative Disclosures Related to Financial Instruments The following tables present detailed information concerning the impact of financial instruments on our consolidated balance sheet and income statements. As of September 30, 2015 , 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 September 30, 2015 , we had net long/(short) commodity contracts outstanding in the following quantities: Contract Type Hedge Designation Regulated Distribution Nonregulated Quantity (MMcf) Commodity contracts Fair Value — (18,378 ) Cash Flow — 56,368 Not designated 24,849 58,513 24,849 96,503 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 September 30, 2015 and 2014 . The gross amounts of recognized assets and liabilities are netted within our Consolidated Balance Sheets to the extent that we have netting arrangements with the counterparties. Regulated Distribution Nonregulated Balance Sheet Location Assets Liabilities Assets Liabilities (In thousands) September 30, 2015 Designated As Hedges: Commodity contracts Other current assets / Other current liabilities $ — $ — $ 11,680 $ (36,067 ) Commodity contracts Deferred charges and other assets / Deferred credits and other liabilities — — 126 (9,918 ) Interest rate contracts Deferred charges and other assets / Deferred credits and other liabilities — (110,539 ) — — Total — (110,539 ) 11,806 (45,985 ) Not Designated As Hedges: Commodity contracts Other current assets / Other current liabilities 378 (9,568 ) 65,239 (65,780 ) Commodity contracts Deferred charges and other assets / Deferred credits and other liabilities 368 — 14,318 (14,218 ) Total 746 (9,568 ) 79,557 (79,998 ) Gross Financial Instruments 746 (120,107 ) 91,363 (125,983 ) Gross Amounts Offset on Consolidated Balance Sheet: Contract netting — — (91,363 ) 91,363 Net Financial Instruments 746 (120,107 ) — (34,620 ) Cash collateral — — 8,854 34,620 Net Assets/Liabilities from Risk Management Activities $ 746 $ (120,107 ) $ 8,854 $ — Regulated Distribution Nonregulated Balance Sheet Location Assets Liabilities Assets Liabilities (In thousands) September 30, 2014 Designated As Hedges: Commodity contracts Other current assets / Other current liabilities $ — $ — $ 8,912 $ (7,082 ) Interest rate contracts Other current assets / 21,869 — — — Commodity contracts Deferred charges and other assets / Deferred credits and other liabilities — — 757 (2,459 ) Interest rate contracts Deferred charges and other assets / Deferred credits and other liabilities 12,608 (19,835 ) — — Total 34,477 (19,835 ) 9,669 (9,541 ) Not Designated As Hedges: Commodity contracts Other current assets / Other current liabilities 1,233 (1,730 ) 43,677 (47,729 ) Commodity contracts Deferred charges and other assets / Deferred credits and other liabilities 430 (291 ) 15,677 (14,786 ) Total 1,663 (2,021 ) 59,354 (62,515 ) Gross Financial Instruments 36,140 (21,856 ) 69,023 (72,056 ) Gross Amounts Offset on Consolidated Balance Sheet: Contract netting — — (69,023 ) 69,023 Net Financial Instruments 36,140 (21,856 ) — (3,033 ) Cash collateral — — 22,725 3,033 Net Assets/Liabilities from Risk Management Activities $ 36,140 $ (21,856 ) $ 22,725 $ — Impact of Financial Instruments on the Income Statement Hedge ineffectiveness for our nonregulated segment is recorded as a component of purchased gas cost 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 years ended September 30, 2015 , 2014 and 2013 , we recognized a gain arising from fair value and cash flow hedge ineffectiveness of $0.2 million , $1.9 million and $18.2 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 consolidated income statement for the years ended September 30, 2015 , 2014 and 2013 is presented below. Fiscal Year Ended September 30 2015 2014 2013 (In thousands) Commodity contracts $ 10,311 $ (792 ) $ 2,165 Fair value adjustment for natural gas inventory designated as the hedged item (9,768 ) 2,486 15,938 Total decrease in purchased gas cost $ 543 $ 1,694 $ 18,103 The decrease in purchased gas cost is comprised of the following: Basis ineffectiveness $ 811 $ (919 ) $ (208 ) Timing ineffectiveness (268 ) 2,613 18,311 $ 543 $ 1,694 $ 18,103 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 consolidated income statements for the years ended September 30, 2015 , 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. Fiscal Year Ended September 30, 2015 Regulated Distribution Nonregulated Consolidated (In thousands) Loss reclassified from AOCI for effective portion of commodity contracts $ — $ (41,716 ) $ (41,716 ) Loss arising from ineffective portion of commodity contracts — (325 ) (325 ) Total impact on purchased gas cost — (42,041 ) (42,041 ) Net loss on settled interest rate agreements reclassified from AOCI into interest expense (853 ) — (853 ) Total impact from cash flow hedges $ (853 ) $ (42,041 ) $ (42,894 ) Fiscal Year Ended September 30, 2014 Regulated Distribution Nonregulated Consolidated (In thousands) Gain reclassified from AOCI for effective portion of commodity contracts $ — $ 8,365 $ 8,365 Gain arising from ineffective portion of commodity contracts — 198 198 Total impact on purchased gas cost — 8,563 8,563 Net loss on settled interest rate agreements reclassified from AOCI into interest expense (4,230 ) — (4,230 ) Total impact from cash flow hedges $ (4,230 ) $ 8,563 $ 4,333 Fiscal Year Ended September 30, 2013 Regulated Distribution Nonregulated Consolidated (In thousands) Loss reclassified from AOCI for effective portion of commodity contracts $ — $ (10,778 ) $ (10,778 ) Gain arising from ineffective portion of commodity contracts — 97 97 Total impact on purchased gas cost — (10,681 ) (10,681 ) Net loss on settled interest rate agreements reclassified from AOCI into interest expense (3,489 ) — (3,489 ) Total impact from cash flow hedges $ (3,489 ) $ (10,681 ) $ (14,170 ) 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 years ended September 30, 2015 and 2014 . The amounts included in the table below exclude gains and losses arising from ineffectiveness because these amounts are immediately recognized in the income statement as incurred. Fiscal Year Ended September 30 2015 2014 (In thousands) Increase (decrease) in fair value: Interest rate agreements $ (71,003 ) $ (58,973 ) Forward commodity contracts (49,211 ) 7,904 Recognition of (gains) losses in earnings due to settlements: Interest rate agreements 542 2,686 Forward commodity contracts 25,448 (5,102 ) Total other comprehensive income (loss) from hedging, net of tax (1) $ (94,224 ) $ (53,485 ) (1) Utilizing an income tax rate ranging from approximately 37 percent to 39 percent based on the effective rates in each taxing jurisdiction. Deferred gains (losses) recorded in AOCI associated with our interest rate agreements are recognized in earnings as they are amortized, while deferred 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 September 30, 2015 . However, the table below does not include the expected recognition in earnings of the interest rate agreements entered into in October 2012 and fiscal 2014 as those financial instruments have not yet settled. Interest Rate Agreements Commodity Contracts Total (In thousands) 2016 $ (347 ) $ (19,484 ) $ (19,831 ) 2017 (447 ) (5,044 ) (5,491 ) 2018 (649 ) (819 ) (1,468 ) 2019 (673 ) (85 ) (758 ) 2020 (698 ) (5 ) (703 ) Thereafter (15,836 ) — (15,836 ) Total (1) $ (18,650 ) $ (25,437 ) $ (44,087 ) (1) Utilizing an income tax rate ranging from approximately 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 consolidated income statements for the years ended September 30, 2015 , 2014 and 2013 was an increase (decrease) in purchased gas cost of $15.5 million , $(5.0) million and $3.0 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 regulated distribution segment are not designated as hedges. However, there is no earnings impact on our regulated 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 Comprehensive

Accumulated Other Comprehensive Income	12 Months Ended
	Sep. 30, 2015
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- for-Sale Securities Interest Rate Agreement Cash Flow Hedges Commodity Contracts Cash Flow Hedges Total (In thousands) September 30, 2014 $ 7,662 $ (18,381 ) $ (1,674 ) $ (12,393 ) Other comprehensive income (loss) before reclassifications (2,173 ) (71,003 ) (49,211 ) (122,387 ) Amounts reclassified from accumulated other comprehensive income (540 ) 542 25,448 25,450 Net current-period other comprehensive income (loss) (2,713 ) (70,461 ) (23,763 ) (96,937 ) September 30, 2015 $ 4,949 $ (88,842 ) $ (25,437 ) $ (109,330 ) Available- for-Sale Securities Interest Rate Agreement Cash Flow Hedges Commodity Contracts Cash Flow Hedges Total (In thousands) September 30, 2013 $ 5,448 $ 37,906 $ (4,476 ) $ 38,878 Other comprehensive income (loss) before reclassifications 3,009 (58,973 ) 7,904 (48,060 ) Amounts reclassified from accumulated other comprehensive income (795 ) 2,686 (5,102 ) (3,211 ) Net current-period other comprehensive income (loss) 2,214 (56,287 ) 2,802 (51,271 ) September 30, 2014 $ 7,662 $ (18,381 ) $ (1,674 ) $ (12,393 ) The following tables detail reclassifications out of AOCI for the fiscal years ended September 30, 2015 and 2014 . Amounts in parentheses below indicate decreases to net income in the statement of income. Fiscal Year Ended September 30, 2015 Accumulated Other Comprehensive Income Components Amount Reclassified from Accumulated Other Comprehensive Income Affected Line Item in the Statement of Income (In thousands) Available-for-sale securities $ 850 Operation and maintenance expense 850 Total before tax (310 ) Tax expense $ 540 Net of tax Cash flow hedges Interest rate agreements $ (853 ) Interest charges Commodity contracts (41,716 ) Purchased gas cost (42,569 ) Total before tax 16,579 Tax benefit $ (25,990 ) Net of tax Total reclassifications $ (25,450 ) Net of tax Fiscal Year Ended September 30, 2014 Accumulated Other Comprehensive Income Components Amount Reclassified from Accumulated Other Comprehensive Income Affected Line Item in the Statement of Income (In thousands) Available-for-sale securities $ 1,252 Operation and maintenance expense 1,252 Total before tax (457 ) Tax expense $ 795 Net of tax Cash flow hedges Interest rate agreements $ (4,230 ) Interest charges Commodity contracts 8,365 Purchased gas cost 4,135 Total before tax (1,719 ) Tax expense $ 2,416 Net of tax Total reclassifications $ 3,211 Net of tax

Fair Value Measurements

Fair Value Measurements	12 Months Ended
	Sep. 30, 2015
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. Fair value measurements also apply to the valuation of our pension and post-retirement plan assets. The fair value of these assets is presented in Note 6. 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. 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 September 30, 2015 and 2014 . As required under authoritative accounting literature, assets and liabilities are categorized in their entirety based on the lowest level of input that is significant to the fair value measurement. Quoted Prices in Active Markets (Level 1) Significant Other Observable Inputs (Level 2) (1) Significant Other Unobservable Inputs (Level 3) Netting and Cash Collateral (2) September 30, 2015 (In thousands) Assets: Financial instruments Regulated distribution segment $ — $ 746 $ — $ — $ 746 Nonregulated segment — 91,363 — (82,509 ) 8,854 Total financial instruments — 92,109 — (82,509 ) 9,600 Hedged portion of gas stored underground 43,901 — — — 43,901 Available-for-sale securities Money market funds — 1,072 — — 1,072 Registered investment companies 40,619 — — — 40,619 Bonds — 32,509 — — 32,509 Total available-for-sale securities 40,619 33,581 — — 74,200 Total assets $ 84,520 $ 125,690 $ — $ (82,509 ) $ 127,701 Liabilities: Financial instruments Regulated distribution segment $ — $ 120,107 $ — $ — $ 120,107 Nonregulated segment — 125,983 — (125,983 ) — Total liabilities $ — $ 246,090 $ — $ (125,983 ) $ 120,107 Quoted Prices in Active Markets (Level 1) Significant Other Observable Inputs (Level 2) (1) Significant Other Unobservable Inputs (Level 3) Netting and Cash Collateral (3) September 30, 2014 (In thousands) Assets: Financial instruments Regulated distribution segment $ — $ 36,140 $ — $ — $ 36,140 Nonregulated segment 25 68,998 — (46,298 ) 22,725 Total financial instruments 25 105,138 — (46,298 ) 58,865 Hedged portion of gas stored underground 40,492 — — — 40,492 Available-for-sale securities Money market funds — 2,185 — — 2,185 Registered investment companies 44,014 — — — 44,014 Bonds — 33,414 — — 33,414 Total available-for-sale securities 44,014 35,599 — — 79,613 Total assets $ 84,531 $ 140,737 $ — $ (46,298 ) $ 178,970 Liabilities: Financial instruments Regulated distribution segment $ — $ 21,856 $ — $ — $ 21,856 Nonregulated segment 12 72,044 — (72,056 ) — Total liabilities $ 12 $ 93,900 $ — $ (72,056 ) $ 21,856 (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 September 30, 2015 we had $43.5 million of cash held in margin accounts to collateralize certain financial instruments. Of this amount, $34.6 million was used to offset current and noncurrent risk management liabilities under master netting agreements and the remaining $8.9 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, 2014 we had $25.8 million of cash held in margin accounts to collateralize certain financial instruments. Of this amount, $3.1 million was used to offset current and noncurrent risk management liabilities under master netting agreements and the remaining $22.7 million is classified as current risk management assets. Available-for-sale securities are comprised of the following: Amortized Cost Gross Unrealized Gain Gross Unrealized Loss Fair Value (In thousands) As of September 30, 2015 Domestic equity mutual funds $ 27,643 $ 7,332 $ (456 ) $ 34,519 Foreign equity mutual funds 5,261 905 (66 ) 6,100 Bonds 32,423 106 (20 ) 32,509 Money market funds 1,072 — — 1,072 $ 66,399 $ 8,343 $ (542 ) $ 74,200 As of September 30, 2014 Domestic equity mutual funds $ 26,633 $ 10,136 $ — $ 36,769 Foreign equity mutual funds 5,382 1,863 — 7,245 Bonds 33,266 161 (13 ) 33,414 Money market funds 2,185 — — 2,185 $ 67,466 $ 12,160 $ (13 ) $ 79,613 At September 30, 2015 and 2014 , our available-for-sale securities included $41.7 million and $46.2 million related to assets held in separate rabbi trusts for our supplemental executive retirement plans as discussed in Note 6. At September 30, 2015 we maintained investments in bonds that have contractual maturity dates ranging from October 2015 through September 2020. Other Fair Value Measures In addition to the financial instruments above, we have several financial and nonfinancial assets and liabilities subject to fair value measures. These financial assets and liabilities include cash and cash equivalents, accounts receivable, accounts payable and debt. The nonfinancial assets and liabilities include asset retirement obligations and pension and post-retirement plan assets. We record cash and cash equivalents, accounts receivable, accounts payable and debt at carrying value. For cash and cash equivalents, accounts receivable and accounts payable, we consider carrying value to materially approximate fair value due to the short-term nature of these assets and liabilities. 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 September 30, 2015 : September 30, 2015 (In thousands) Carrying Amount $ 2,460,000 Fair Value $ 2,669,323

Concentration of Credit Risk

Concentration of Credit Risk	12 Months Ended
	Sep. 30, 2015
Risks and Uncertainties [Abstract]
Concentration of Credit Risk	Concentration of Credit Risk Credit risk is the risk of financial loss to us if a customer fails to perform its contractual obligations. We engage in transactions for the purchase and sale of products and services with major companies in the energy industry and with industrial, commercial, residential and municipal energy consumers. These transactions principally occur in the southern and midwestern regions of the United States. We believe that this geographic concentration does not contribute significantly to our overall exposure to credit risk. Credit risk associated with trade accounts receivable for the regulated distribution segment is mitigated by the large number of individual customers and diversity in our customer base. The credit risk for our other segments is not significant.

Discontinued Operations

Discontinued Operations	12 Months Ended
	Sep. 30, 2015
Discontinued Operations and Disposal Groups [Abstract]
Discontinued Operations	Discontinued Operations On April 1, 2013, we completed the sale of substantially all of our regulated 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 , pursuant to an asset purchase agreement executed on August 8, 2012. In connection with the sale, we recognized a pre-tax gain of approximately $8.2 million . As required under generally accepted accounting principles, the operating results of our Georgia operations for the year ended September 30, 2013 have been aggregated and reported on the 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 following table presents statement of income data related to discontinued operations in our Georgia service area for the year ended September 30, 2013 . Year Ended September 30, 2013 (In thousands) Operating revenues $ 37,962 Purchased gas cost 21,464 Gross profit 16,498 Operating expenses 5,858 Operating income 10,640 Other nonoperating income 548 Income from discontinued operations before income taxes 11,188 Income tax expense 3,986 Income from discontinued operations 7,202 Gain on sale of discontinued operations, net of tax 5,294 Net income from discontinued operations $ 12,496

Selected Quarterly Financial Da

Selected Quarterly Financial Data	12 Months Ended
	Sep. 30, 2015
Quarterly Financial Information Disclosure [Abstract]
Selected Quarterly Financial Data (Unaudited)	Selected Quarterly Financial Data (Unaudited) Summarized unaudited quarterly financial data is presented below. The sum of net income per share by quarter may not equal the net income per share for the fiscal year due to variations in the weighted average shares outstanding used in computing such amounts. Our businesses are seasonal due to weather conditions in our service areas. For further information on its effects on quarterly results, see the “Results of Operations” discussion included in the “Management’s Discussion and Analysis of Financial Condition and Results of Operations” section herein. Quarter Ended December 31 March 31 June 30 September 30 (In thousands, except per share data) Fiscal year 2015: Operating revenues Regulated distribution $ 846,772 $ 1,130,613 $ 416,794 $ 369,656 Regulated pipeline 83,567 91,730 97,008 97,807 Nonregulated 462,288 438,322 278,769 292,830 Intersegment eliminations (133,862 ) (120,597 ) (106,170 ) (103,391 ) 1,258,765 1,540,068 686,401 656,902 Gross profit 423,285 520,738 381,673 354,321 Operating income 187,725 250,210 117,607 75,853 Net income 97,595 137,684 56,281 23,515 Net income per share — basic $ 0.96 $ 1.35 $ 0.55 $ 0.23 Net income per share — diluted $ 0.96 $ 1.35 $ 0.55 $ 0.23 Quarter Ended December 31 March 31 June 30 September 30 (In thousands, except per share data) Fiscal year 2014: Operating revenues Regulated distribution $ 843,865 $ 1,290,960 $ 517,707 $ 409,014 Regulated pipeline 71,341 73,615 87,189 86,314 Nonregulated 436,431 758,215 465,485 407,161 Intersegment eliminations (107,779 ) (157,936 ) (127,211 ) (113,455 ) 1,243,858 1,964,854 943,170 789,034 Gross profit 388,957 496,277 359,533 337,659 Operating income 170,720 250,080 106,605 83,944 Net income 87,016 133,367 45,721 23,713 Net income per share — basic $ 0.95 $ 1.38 $ 0.45 $ 0.23 Net income per share — diluted $ 0.95 $ 1.38 $ 0.45 $ 0.23

Schedule II - Valuation and Qua

Schedule II - Valuation and Qualifying Accounts	12 Months Ended
	Sep. 30, 2015
Valuation and Qualifying Accounts [Abstract]
Schedule II Valuation and Qualifying Accounts	ATMOS ENERGY CORPORATION Valuation and Qualifying Accounts Three Years Ended September 30, 2015 Additions Balance at beginning of period Charged to cost & expenses Charged to other accounts Deductions Balance at end of period (In thousands) 2015 Allowance for doubtful accounts $ 23,992 $ 15,082 $ — $ 23,791 (1) $ 15,283 2014 Allowance for doubtful accounts $ 20,624 $ 19,491 $ — $ 16,123 (1) $ 23,992 2013 Allowance for doubtful accounts $ 9,425 $ 14,484 $ — $ 3,285 (1) $ 20,624 (1) Uncollectible accounts written off.

Summary of Significant Accounti

Summary of Significant Accounting Policies (Policy)	12 Months Ended
	Sep. 30, 2015
Accounting Policies [Abstract]
Principles of consolidation	Principles of consolidation — The accompanying consolidated financial statements include the accounts of Atmos Energy Corporation and its wholly-owned subsidiaries. All material intercompany transactions have been eliminated; however, we have not eliminated intercompany profits when such amounts are probable of recovery under the affiliates’ rate regulation process.
Basis of comparison	Basis of comparison — Certain prior-year amounts have been reclassified to conform with the current year presentation.
Use of estimates	Use of estimates — The preparation of financial statements in conformity with accounting principles generally accepted in the United States requires management to make estimates and assumptions that affect the reported amounts of assets, liabilities, revenues and expenses. The most significant estimates include the allowance for doubtful accounts, unbilled revenues, contingency accruals, pension and postretirement obligations, deferred income taxes, impairment of long-lived assets, risk management and trading activities, fair value measurements and the valuation of goodwill and other long-lived assets. Actual results could differ from those estimates.
Regulation	Regulation — Our regulated distribution and regulated pipeline operations are subject to regulation with respect to rates, service, maintenance of accounting records and various other matters by the respective regulatory authorities in the states in which we operate. Our accounting policies recognize the financial effects of the ratemaking and accounting practices and policies of the various regulatory commissions. 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 that would normally be expensed under accounting principles generally accepted in the United States are permitted to be capitalized or deferred on the balance sheet because it is probable they can be recovered through rates. Further, regulation may impact the period in which revenues or expenses are recognized. The amounts to be recovered or recognized are based upon historical experience and our understanding of the regulations. We record regulatory assets as a component of other current assets and deferred charges and other assets for costs that have been deferred for which future recovery through customer rates is considered probable. Regulatory liabilities are recorded either on the face of the balance sheet or as a component of current liabilities, deferred income taxes or deferred credits and other liabilities when it is probable that revenues will be reduced for amounts that will be credited to customers through the ratemaking process.
Revenue recognition	Revenue recognition — Sales of natural gas to our regulated distribution customers are billed on a monthly basis; however, the billing cycle periods for certain classes of customers do not necessarily coincide with accounting periods used for financial reporting purposes. We follow the revenue accrual method of accounting for regulated distribution segment revenues whereby revenues applicable to gas delivered to customers, but not yet billed under the cycle billing method, are estimated and accrued and the related costs are charged to expense. On occasion, we are permitted to implement new rates that have not been formally approved by our state regulatory commissions, which are subject to refund. As permitted by accounting principles generally accepted in the United States, we recognize this revenue and establish a reserve for amounts that could be refunded based on our experience for the jurisdiction in which the rates were implemented. Rates established by regulatory authorities are adjusted for increases and decreases in our purchased gas costs through purchased gas cost adjustment mechanisms. Purchased gas cost adjustment mechanisms provide gas distribution companies a method of recovering purchased gas costs on an ongoing basis without filing a rate case to address all of their non-gas costs. There is no gross profit generated through purchased gas cost adjustments, but they provide a dollar-for-dollar offset to increases or decreases in our regulated distribution segment’s gas costs. The effects of these purchased gas cost adjustment mechanisms are recorded as deferred gas costs on our balance sheet. Operating revenues for our regulated pipeline and nonregulated segments are recognized in the period in which actual volumes are transported and storage services are provided. Operating revenues for our nonregulated segment and the associated carrying value of natural gas inventory (inclusive of storage costs) are recognized when we sell the gas and physically deliver it to our customers. Operating revenues include realized gains and losses arising from the settlement of financial instruments used in our nonregulated activities.
Cash and cash equivalents	Cash and cash equivalents — We consider all highly liquid investments with an original maturity of three months or less to be cash equivalents.
Accounts receivable and allowance for doubtful accounts	Accounts receivable and allowance for doubtful accounts — Accounts receivable arise from natural gas sales to residential, commercial, industrial, municipal and other customers. We establish an allowance for doubtful accounts to reduce the net receivable balance to the amount we reasonably expect to collect based on our collection experience or where we are aware of a specific customer’s inability or reluctance to pay. However, if circumstances change, our estimate of the recoverability of accounts receivable could be affected. Circumstances which could affect our estimates include, but are not limited to, customer credit issues, the level of natural gas prices, customer deposits and general economic conditions. Accounts are written off once they are deemed to be uncollectible.
Gas stored underground	Gas stored underground — Our gas stored underground is comprised of natural gas injected into storage to support the winter season withdrawals for our regulated distribution operations and natural gas held by our nonregulated segment to conduct their operations. The average cost method is used for substantially all of our regulated operations. Our nonregulated segment utilizes the average cost method; however, most of this inventory is hedged and is therefore reported at fair value at the end of each month. Gas in storage that is retained as cushion gas to maintain reservoir pressure is classified as property, plant and equipment and is valued at cost.
Property, plant and equipment	Regulated property, plant and equipment — Regulated property, plant and equipment is stated at original cost, net of contributions in aid of construction. The cost of additions includes direct construction costs, payroll related costs (taxes, pensions and other fringe benefits), administrative and general costs and an allowance for funds used during construction. The allowance for funds used during construction represents the estimated cost of funds used to finance the construction of major projects and are capitalized in the rate base for ratemaking purposes when the completed projects are placed in service. Interest expense of $2.3 million , $1.5 million and $1.9 million was capitalized in 2015 , 2014 and 2013 . Major renewals, including replacement pipe, and betterments that are recoverable under our regulatory rate base are capitalized while the costs of maintenance and repairs that are not recoverable through rates are charged to expense as incurred. The costs of large projects are accumulated in construction in progress until the project is completed. When the project is completed, tested and placed in service, the balance is transferred to the regulated plant in service account included in the rate base and depreciation begins. Regulated property, plant and equipment is depreciated at various rates on a straight-line basis. These rates are approved by our regulatory commissions and are comprised of two components: one based on average service life and one based on cost of removal. Accordingly, we recognize our cost of removal expense as a component of depreciation expense. The related cost of removal accrual is reflected as a regulatory liability on the consolidated balance sheet. At the time property, plant and equipment is retired, removal expenses less salvage, are charged to the regulatory cost of removal accrual. The composite depreciation rate was 3.3 percent , for each of the fiscal years ended September 30, 2015 , 2014 and 2013 . Nonregulated property, plant and equipment — Nonregulated property, plant and equipment is stated at cost. Depreciation is generally computed on the straight-line method for financial reporting purposes based upon estimated useful lives ranging from three to 43 years.
Asset retirement obligations	Asset retirement obligations — We record a liability at fair value for an asset retirement obligation when the legal obligation to retire the asset has been incurred with an offsetting increase to the carrying value of the related asset. Accretion of the asset retirement obligation due to the passage of time is recorded as an operating expense. As of September 30, 2015 and 2014 , we had asset retirement obligations of $11.1 million and $10.5 million . Additionally, we had $4.8 million and $5.9 million of asset retirement costs recorded as a component of property, plant and equipment that will be depreciated over the remaining life of the underlying associated assets. We believe we have a legal obligation to retire our natural gas storage facilities. However, we have not recognized an asset retirement obligation associated with our storage facilities because we are not able to determine the settlement date of this obligation as we do not anticipate taking our storage facilities out of service permanently. Therefore, we cannot reasonably estimate the fair value of this obligation.
Impairment of long-lived assets	Impairment of long-lived assets — We periodically evaluate whether events or circumstances have occurred that indicate that other long-lived assets may not be recoverable or that the remaining useful life may warrant revision. When such events or circumstances are present, we assess the recoverability of long-lived assets by determining whether the carrying value will be recovered through the expected future cash flows. In the event the sum of the expected future cash flows resulting from the use of the asset is less than the carrying value of the asset, an impairment loss equal to the excess of the asset’s carrying value over its fair value is recorded.
Goodwill	Goodwill — We annually evaluate our goodwill balances for impairment during our second fiscal quarter or more frequently as impairment indicators arise. We use a present value technique based on discounted cash flows to estimate the fair value of our reporting units. These calculations are dependent on several subjective factors including the timing of future cash flows, future growth rates and the discount rate. An impairment charge is recognized if the carrying value of a reporting unit’s goodwill exceeds its fair value.
Marketable securities	Marketable securities — As of September 30, 2015 and 2014 , all of our marketable securities were classified as available-for-sale. In accordance with the authoritative accounting standards, 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 an individual investment by investment 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 investment is written down to its estimated fair value.
Financial instruments and hedging activities	Financial instruments and hedging activities — We use financial instruments to mitigate commodity price risk in our regulated distribution and nonregulated segments and interest rate risk. The objectives and strategies for using financial instruments have been tailored to our regulated and nonregulated businesses and are discussed in Note 12. We record all of our financial instruments on the balance sheet at fair value , with changes in fair value ultimately recorded in the income statement. These financial instruments are reported as risk management assets and liabilities and are classified as current or noncurrent other assets or liabilities based upon the anticipated settlement date of the underlying financial instrument. We record the cash flow impact of our financial instruments in operating cash flows based upon their balance sheet classification. The timing of when changes in fair value of our financial instruments are recorded in the income statement depends on whether the financial instrument has been designated and qualifies as a part of a hedging relationship or if regulatory rulings require a different accounting treatment. Changes in fair value for financial instruments that do not meet one of these criteria are recognized in the income statement as they occur. Financial Instruments Associated with Commodity Price Risk In our regulated distribution segment, the costs associated with and 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 accounting principles generally accepted in the United States. Accordingly, there is no earnings impact on our regulated distribution segment as a result of the use of financial instruments. In our nonregulated segment, we have designated most of the natural gas inventory held by this operating segment as the hedged item in a fair-value hedge. This inventory is marked to market at the end of each month based on the Gas Daily index, with changes in fair value recognized as unrealized gains or losses in purchased gas cost in the period of change. The financial instruments associated with this natural gas inventory have been designated as fair-value hedges and are marked to market each month based upon the NYMEX price with changes in fair value recognized as unrealized gains or losses in purchased gas cost in the period of change. We have elected to exclude this spot/forward differential for purposes of assessing the effectiveness of these fair-value hedges. For the fiscal years ended September 30, 2015 , 2014 and 2013 , we included unrealized gains (losses) on open contracts of $(2.4) million , $9.6 million and $9.0 million as a component of nonregulated purchased gas cost. Additionally, we have elected to treat fixed-price forward contracts used in our nonregulated segment to deliver natural gas as normal purchases and normal sales. As such, these deliveries are recorded on an accrual basis in accordance with our revenue recognition policy. Financial instruments used to mitigate the commodity price risk associated with these contracts have been designated as cash flow hedges of anticipated purchases and sales at indexed prices. Accordingly, unrealized gains and losses on these open financial instruments are recorded as a component of accumulated other comprehensive income, and are recognized in earnings as a component of purchased gas cost when the hedged volumes are sold. Gains and losses from hedge ineffectiveness are recognized in the income statement. Fair value and cash flow hedge ineffectiveness arising from natural gas market price differences between the locations of the hedged inventory and the delivery location specified in the financial instruments is referred to as basis ineffectiveness. Ineffectiveness arising from changes in the fair value of the fair value hedges 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 is referred to as timing ineffectiveness. Hedge ineffectiveness, to the extent incurred, is reported as a component of purchased gas cost. Our nonregulated segment also utilizes master netting agreements with significant counterparties that allow us to offset gains and losses arising from financial instruments that may be settled in cash with gains and losses arising from financial instruments that may be settled with the physical commodity. Assets and liabilities from risk management activities, as well as accounts receivable and payable, reflect the master netting agreements in place. Additionally, the accounting guidance for master netting arrangements requires us to include the fair value of cash collateral or the obligation to return cash in the amounts that have been netted under master netting agreements used to offset gains and losses arising from financial instruments. As of September 30, 2015 and 2014 , the Company netted $ 43.5 million and $ 25.8 million of cash held in margin accounts into its current and noncurrent risk management assets and liabilities. Financial Instruments Associated with Interest Rate Risk We manage interest rate risk, primarily when we plan to issue new long-term debt or to refinance existing long-term debt. We currently manage this risk through the use of forward starting interest rate swaps to fix the Treasury yield component of the interest cost associated with anticipated financings. We designate these financial instruments as cash flow hedges at the time the agreements are executed. Unrealized gains and losses associated with the instruments are recorded as a component of accumulated other comprehensive income (loss). When the instruments settle, the realized gain or loss is 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.
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 primarily use quoted market prices and other observable market pricing information in valuing our financial assets and liabilities and minimize the use of unobservable pricing inputs in our measurements. Fair-value estimates also consider our own creditworthiness and the creditworthiness of the counterparties involved. Our counterparties consist primarily of financial institutions and major energy companies. This concentration of counterparties may materially impact our exposure to credit risk resulting from market, economic or regulatory conditions. We seek to minimize counterparty credit risk through an evaluation of their financial condition and credit ratings and the use of collateral requirements under certain circumstances. Amounts reported at fair value are subject to potentially significant volatility based upon changes in market prices, including, but not limited to, the valuation of the portfolio of our contracts, maturity and settlement of these contracts and newly originated transactions and interest rates, each of which directly affect the estimated fair value of our financial instruments. We believe the market prices and models used to value these financial instruments represent the best information available with respect to closing exchange and over-the-counter quotations, time value and volatility factors underlying the contracts. Values are adjusted to reflect the potential impact of an orderly liquidation of our positions over a reasonable period of time under then current market conditions. 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) and the lowest priority given to unobservable inputs (Level 3). The levels of the hierarchy are described below: Level 1 — Represents unadjusted quoted prices in active markets for identical assets or liabilities. An active market for the asset or liability is defined as a market in which transactions for the asset or liability occur with sufficient frequency and volume to provide pricing information on an ongoing basis. Prices actively quoted on national exchanges are used to determine the fair value of most of our assets and liabilities recorded on our balance sheet at fair value. Within our nonregulated operations, we utilize a mid-market pricing convention (the mid-point between the bid and ask prices), as permitted under current accounting standards. Values derived from these sources reflect the market in which transactions involving these financial instruments are executed. Our Level 1 measurements consist primarily of exchange-traded financial instruments, gas stored underground that has been designated as the hedged item in a fair value hedge and our available-for-sale securities. The Level 1 measurements for investments in the Atmos Energy Corporation Master Retirement Trust (the Master Trust), Supplemental Executive Benefit Plan and postretirement benefit plan consist primarily of exchange-traded financial instruments. Level 2 — Represents pricing inputs other than quoted prices included in Level 1 that are either directly or indirectly observable for the asset or liability as of the reporting date. These inputs are derived principally from, or corroborated by, observable market data. Our Level 2 measurements primarily consist of non-exchange-traded financial instruments, such as over-the-counter options and swaps and municipal and corporate bonds where market data for pricing is observable. The Level 2 measurements for investments in our Master Trust, Supplemental Executive Benefit Plan and postretirement benefit plan consist primarily of non-exchange traded financial instruments such as common collective trusts and investments in limited partnerships. Level 3 — Represents generally unobservable pricing inputs which are developed based on the best information available, including our own internal data, in situations where there is little if any market activity for the asset or liability at the measurement date. The pricing inputs utilized reflect what a market participant would use to determine fair value. We utilize models and other valuation methods to determine fair value when external sources are not available. We believe the market prices and models used to value these assets and liabilities represent the best information available with respect to closing exchange and over-the-counter quotations, time value and volatility factors underlying the assets and liabilities.
Pension and other postretirement plans	Pension and other postretirement plans — Pension and other postretirement plan costs and liabilities are determined on an actuarial basis and are affected by numerous assumptions and estimates including the market value of plan assets, estimates of the expected return on plan assets, assumed discount rates and current demographic and actuarial mortality data. Our measurement date is September 30. The assumed discount rate and the expected return are the assumptions that generally have the most significant impact on our pension costs and liabilities. The assumed discount rate, the assumed health care cost trend rate and assumed rates of retirement generally have the most significant impact on our postretirement plan costs and liabilities. The discount rate is utilized principally in calculating the actuarial present value of our pension and postretirement obligation and net pension and postretirement cost. When establishing our discount rate, we consider high quality corporate bond rates based on bonds available in the marketplace that are suitable for settling the obligations, changes in those rates from the prior year and the implied discount rate that is derived from matching our projected benefit disbursements with currently available high quality corporate bonds. The expected long-term rate of return on assets is utilized in calculating the expected return on plan assets component of the annual pension and postretirement plan cost. We estimate the expected return on plan assets by evaluating expected bond returns, equity risk premiums, asset allocations, the effects of active plan management, the impact of periodic plan asset rebalancing and historical performance. We also consider the guidance from our investment advisors when making a final determination of our expected rate of return on assets. To the extent the actual rate of return on assets realized over the course of a year is greater than or less than the assumed rate, that year’s annual pension or postretirement plan cost is not affected. Rather, this gain or loss is amortized over the expected future working lifetime of the plan participants. The expected return on plan assets is then calculated by applying the expected long-term rate of return on plan assets to the market-related value of the plan assets. The market-related value of our plan assets represents the fair market value of the plan assets, adjusted to smooth out short-term market fluctuations over a five-year period. The use of this calculation will delay the impact of current market fluctuations on the pension expense for the period. We use a corridor approach to amortize actuarial gains and losses. Under this approach, net gains or losses in excess of ten percent of the larger of the pension benefit obligation or the market-related value of the assets are amortized on a straight-line basis. The period of amortization is the average remaining service of active participants who are expected to receive benefits under the plan. We estimate the assumed health care cost trend rate used in determining our annual postretirement net cost based upon our actual health care cost experience, the effects of recently enacted legislation and general economic conditions. Our assumed rate of retirement is estimated based upon the annual review of our participant census information as of the measurement date.
Income taxes	Income taxes — Income taxes are determined based on the liability method, which results in income tax assets and liabilities arising from temporary differences. Temporary differences are differences between the tax bases of assets and liabilities and their reported amounts in the financial statements that will result in taxable or deductible amounts in future years. The liability method requires the effect of tax rate changes on current and accumulated deferred income taxes to be reflected in the period in which the rate change was enacted. The liability method also requires that deferred tax assets be reduced by a valuation allowance unless it is more likely than not that the assets will be realized. The Company may recognize the tax benefit from uncertain tax positions only if it is at least more likely than not that the tax position will be sustained on examination by the taxing authorities, based on the technical merits of the position. The tax benefits recognized in the financial statements from such a position should be measured based on the largest benefit that has a greater than fifty percent likelihood of being realized upon settlement with the taxing authorities. We recognize accrued interest related to unrecognized tax benefits as a component of interest expense. We recognize penalties related to unrecognized tax benefits as a component of miscellaneous income (expense) in accordance with regulatory requirements.
Contingencies	Contingencies — In the normal course of business, we are confronted with issues or events that may result in a contingent liability. These generally relate to lawsuits, claims made by third parties or the action of various regulatory agencies. For such matters, we record liabilities when they are considered probable and reasonably estimable, based on currently available facts and our estimates of the ultimate outcome or resolution of the liability in the future. Actual results may differ from estimates, depending on actual outcomes or changes in the facts or expectations surrounding each potential exposure.
Earnings per share	Since we have non-vested share-based payments with a nonforfeitable right to dividends or dividend equivalents (referred to as participating securities), we are required to use the two-class method of computing earnings per share. The Company’s non-vested restricted stock units, granted under the 1998 Long-Term Incentive Plan, for which vesting is predicated solely on the passage of time, are considered to be participating securities. 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.
Segment Reporting Policy	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 regulated distribution segment operations are geographically dispersed, they are reported as a single segment as each regulated 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. We evaluate performance based on net income or loss of the respective operating units. Interest expense is allocated pro rata to each segment based upon our net investment in each segment. Income taxes are allocated to each segment as if each segment’s taxes were calculated on a separate return basis.
Tax Collections	Tax collections — We are allowed to recover from customers revenue-related taxes that are imposed upon us. We record such taxes as operating expenses and record the corresponding customer charges as operating revenues. However, we do collect and remit various other taxes on behalf of various governmental authorities, and we record these amounts in our consolidated balance sheets on a net basis. We do not collect income taxes from our customers on behalf of governmental authorities.

Nature of Business (Table)

Nature of Business (Table)	12 Months Ended
	Sep. 30, 2015
Schedule of Divisions And Service Areas Table [Abstract]
Schedule of divisions and service areas	Through our regulated distribution business, we deliver natural gas through sales and transportation arrangements to over three million residential, commercial, public-authority and industrial customers through our six regulated distribution divisions in the service areas described below: Division Service Area Atmos Energy Colorado-Kansas Division Colorado, Kansas Atmos Energy Kentucky/Mid-States Division Kentucky, Tennessee, Virginia (1) Atmos Energy Louisiana Division Louisiana Atmos Energy Mid-Tex Division Texas, including the Dallas/Fort Worth metropolitan area Atmos Energy Mississippi Division Mississippi Atmos Energy West Texas Division West Texas (1) Denotes location where we have more limited service areas.

Summary of Significant Accoun31

Summary of Significant Accounting Policies (Table)	12 Months Ended
	Sep. 30, 2015
Accounting Policies [Abstract]
Schedule Of Regulatory Assets And Liabilities	Significant regulatory assets and liabilities as of September 30, 2015 and 2014 included the following: September 30 2015 2014 (In thousands) Regulatory assets: Pension and postretirement benefit costs (1) $ 121,183 $ 162,777 Infrastructure Mechanisms (2) 32,813 26,948 Deferred gas costs 9,715 20,069 Recoverable loss on reacquired debt 16,319 18,877 APT annual adjustment mechanism 1,002 8,479 Rate case costs 1,533 3,757 Other 9,774 9,402 $ 192,339 $ 250,309 Regulatory liabilities: Regulatory cost of removal obligation $ 483,676 $ 490,448 Deferred gas costs 28,100 35,063 Asset retirement obligation 9,063 10,508 Deferred franchise fees — 5,268 Other 3,693 4,472 $ 524,532 $ 545,759	[1],[2]
[1]	Includes $16.6 million and $18.8 million of pension and postretirement expense deferred pursuant to regulatory authorization.
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Segment Information (Table)

Segment Information (Table)	12 Months Ended
	Sep. 30, 2015
Segment Reporting [Abstract]
Schedule of segment reporting income statement, by segment	Summarized income statements and capital expenditures by segment are shown in the following tables. Year Ended September 30, 2015 Regulated Distribution Regulated Pipeline Nonregulated Eliminations Consolidated (In thousands) Operating revenues from external parties $ 2,757,585 $ 97,662 $ 1,286,889 $ — $ 4,142,136 Intersegment revenues 6,250 272,450 185,320 (464,020 ) — 2,763,835 370,112 1,472,209 (464,020 ) 4,142,136 Purchased gas cost 1,526,258 — 1,399,349 (463,488 ) 2,462,119 Gross profit 1,237,577 370,112 72,860 (532 ) 1,680,017 Operating expenses Operation and maintenance 388,486 118,866 35,048 (532 ) 541,868 Depreciation and amortization 223,048 47,236 4,512 — 274,796 Taxes, other than income 205,894 22,743 3,321 — 231,958 Total operating expenses 817,428 188,845 42,881 (532 ) 1,048,622 Operating income 420,149 181,267 29,979 — 631,395 Miscellaneous expense (377 ) (1,243 ) (760 ) (2,009 ) (4,389 ) Interest charges 84,132 33,151 967 (2,009 ) 116,241 Income before income taxes 335,640 146,873 28,252 — 510,765 Income tax expense 130,827 52,211 12,652 — 195,690 Net income $ 204,813 $ 94,662 $ 15,600 $ — $ 315,075 Capital expenditures $ 680,961 $ 292,728 $ 1,443 $ — $ 975,132 Year Ended September 30, 2014 Regulated Distribution Regulated Pipeline Nonregulated Eliminations Consolidated (In thousands) Operating revenues from external parties $ 3,056,212 $ 92,166 $ 1,792,538 $ — $ 4,940,916 Intersegment revenues 5,334 226,293 274,754 (506,381 ) — 3,061,546 318,459 2,067,292 (506,381 ) 4,940,916 Purchased gas cost 1,885,031 — 1,979,337 (505,878 ) 3,358,490 Gross profit 1,176,515 318,459 87,955 (503 ) 1,582,426 Operating expenses Operation and maintenance 387,228 91,466 26,963 (503 ) 505,154 Depreciation and amortization 208,376 41,031 4,580 — 253,987 Taxes, other than income 196,343 13,143 2,450 — 211,936 Total operating expenses 791,947 145,640 33,993 (503 ) 971,077 Operating income 384,568 172,819 53,962 — 611,349 Miscellaneous income (expense) (381 ) (3,181 ) 2,216 (3,889 ) (5,235 ) Interest charges 94,918 36,280 1,986 (3,889 ) 129,295 Income before income taxes 289,269 133,358 54,192 — 476,819 Income tax expense 117,684 47,167 22,151 — 187,002 Net income $ 171,585 $ 86,191 $ 32,041 $ — $ 289,817 Capital expenditures $ 584,065 $ 249,347 $ 1,839 $ — $ 835,251 Year Ended September 30, 2013 Regulated Distribution Regulated Pipeline Nonregulated Eliminations Consolidated (In thousands) Operating revenues from external parties $ 2,394,418 $ 89,011 $ 1,392,031 $ — $ 3,875,460 Intersegment revenues 5,075 179,889 195,883 (380,847 ) — 2,399,493 268,900 1,587,914 (380,847 ) 3,875,460 Purchased gas cost 1,318,257 — 1,524,583 (379,430 ) 2,463,410 Gross profit 1,081,236 268,900 63,331 (1,417 ) 1,412,050 Operating expenses Operation and maintenance 375,188 76,686 37,569 (1,423 ) 488,020 Depreciation and amortization 195,581 35,302 4,196 — 235,079 Taxes, other than income 167,374 17,059 2,639 — 187,072 Total operating expenses 738,143 129,047 44,404 (1,423 ) 910,171 Operating income 343,093 139,853 18,927 6 501,879 Miscellaneous income (expense) 2,535 (2,285 ) 2,316 (2,763 ) (197 ) Interest charges 98,296 30,678 2,168 (2,757 ) 128,385 Income from continuing operations before income taxes 247,332 106,890 19,075 — 373,297 Income tax expense 96,476 38,630 7,493 — 142,599 Income from continuing operations 150,856 68,260 11,582 — 230,698 Income from discontinued operations, net of tax 7,202 — — — 7,202 Gain (loss) on sale of discontinued operations, net of tax 5,649 — (355 ) — 5,294 Net income $ 163,707 $ 68,260 $ 11,227 $ — $ 243,194 Capital expenditures $ 528,599 $ 313,230 $ 3,204 $ — $ 845,033
Revenue from External Customers by Products and Services	The following table summarizes our revenues by products and services for the fiscal year ended September 30. 2015 2014 2013 (In thousands) Regulated distribution revenues: Gas sales revenues: Residential $ 1,761,689 $ 1,933,099 $ 1,512,495 Commercial 772,187 876,042 661,930 Industrial 74,981 90,536 81,155 Public authority and other 53,401 64,779 60,557 Total gas sales revenues 2,662,258 2,964,456 2,316,137 Transportation revenues 67,475 64,049 55,938 Other gas revenues 27,852 27,707 22,343 Total regulated distribution revenues 2,757,585 3,056,212 2,394,418 Regulated pipeline revenues 97,662 92,166 89,011 Nonregulated revenues 1,286,889 1,792,538 1,392,031 Total operating revenues $ 4,142,136 $ 4,940,916 $ 3,875,460
Schedule of segment reporting balance sheet information, by segment	Balance sheet information at September 30, 2015 and 2014 by segment is presented in the following tables. September 30, 2015 Regulated Distribution Regulated Pipeline Nonregulated Eliminations Consolidated (In thousands) ASSETS Property, plant and equipment, net $ 5,670,306 $ 1,706,449 $ 53,825 $ — $ 7,430,580 Investment in subsidiaries 1,038,670 — (2,096 ) (1,036,574 ) — Current assets Cash and cash equivalents 23,863 — 4,790 — 28,653 Assets from risk management activities 378 — 8,854 — 9,232 Other current assets 426,270 24,628 480,503 (338,301 ) 593,100 Intercompany receivables 887,713 — — (887,713 ) — Total current assets 1,338,224 24,628 494,147 (1,226,014 ) 630,985 Goodwill 575,449 132,542 34,711 — 742,702 Noncurrent assets from risk management activities 368 — — — 368 Deferred charges and other assets 265,693 17,288 5,329 — 288,310 $ 8,888,710 $ 1,880,907 $ 585,916 $ (2,262,588 ) $ 9,092,945 CAPITALIZATION AND LIABILITIES Shareholders’ equity $ 3,194,797 $ 577,275 $ 461,395 $ (1,038,670 ) $ 3,194,797 Long-term debt 2,455,388 — — — 2,455,388 Total capitalization 5,650,185 577,275 461,395 (1,038,670 ) 5,650,185 Current liabilities Short-term debt 782,927 — — (325,000 ) 457,927 Liabilities from risk management activities 9,568 — — — 9,568 Other current liabilities 569,273 29,780 99,480 (11,205 ) 687,328 Intercompany payables — 867,409 20,304 (887,713 ) — Total current liabilities 1,361,768 897,189 119,784 (1,223,918 ) 1,154,823 Deferred income taxes 1,008,091 406,254 (3,030 ) — 1,411,315 Noncurrent liabilities from risk management activities 110,539 — — — 110,539 Regulatory cost of removal obligation 427,553 — — — 427,553 Pension and postretirement liabilities 287,373 — — — 287,373 Deferred credits and other liabilities 43,201 189 7,767 — 51,157 $ 8,888,710 $ 1,880,907 $ 585,916 $ (2,262,588 ) $ 9,092,945 September 30, 2014 Regulated Distribution Regulated Pipeline Nonregulated Eliminations Consolidated (In thousands) ASSETS Property, plant and equipment, net $ 5,202,761 $ 1,464,572 $ 58,573 $ — $ 6,725,906 Investment in subsidiaries 952,171 — (2,096 ) (950,075 ) — Current assets Cash and cash equivalents 33,303 — 8,955 — 42,258 Assets from risk management activities 23,102 — 22,725 — 45,827 Other current assets 490,408 14,009 526,161 (342,823 ) 687,755 Intercompany receivables 790,442 — — (790,442 ) — Total current assets 1,337,255 14,009 557,841 (1,133,265 ) 775,840 Goodwill 574,816 132,502 34,711 — 742,029 Noncurrent assets from risk management activities 13,038 — — — 13,038 Deferred charges and other assets 309,965 21,826 6,100 — 337,891 $ 8,390,006 $ 1,632,909 $ 655,129 $ (2,083,340 ) $ 8,594,704 CAPITALIZATION AND LIABILITIES Shareholders’ equity $ 3,086,232 $ 482,612 $ 469,559 $ (952,171 ) $ 3,086,232 Long-term debt 2,455,986 — — — 2,455,986 Total capitalization 5,542,218 482,612 469,559 (952,171 ) 5,542,218 Current liabilities Short-term debt 522,695 — — (326,000 ) 196,695 Liabilities from risk management activities 1,730 — — — 1,730 Other current liabilities 559,765 24,790 142,397 (14,727 ) 712,225 Intercompany payables — 763,635 26,807 (790,442 ) — Total current liabilities 1,084,190 788,425 169,204 (1,131,169 ) 910,650 Deferred income taxes 913,260 361,688 11,668 — 1,286,616 Noncurrent liabilities from risk management activities 20,126 — — — 20,126 Regulatory cost of removal obligation 445,387 — — — 445,387 Pension and postretirement liabilities 340,963 — — — 340,963 Deferred credits and other liabilities 43,862 184 4,698 — 48,744 $ 8,390,006 $ 1,632,909 $ 655,129 $ (2,083,340 ) $ 8,594,704

Earnings Per Share (Table)

Earnings Per Share (Table)	12 Months Ended
	Sep. 30, 2015
Earnings Per Share [Abstract]
Earnings per share table	Basic and diluted earnings per share for the fiscal years ended September 30 are calculated as follows: 2015 2014 2013 (In thousands, except per share data) Basic Earnings Per Share from continuing operations Income from continuing operations $ 315,075 $ 289,817 $ 230,698 Less: Income from continuing operations allocated to participating securities 626 711 775 Income from continuing operations available to common shareholders $ 314,449 $ 289,106 $ 229,923 Basic weighted average shares outstanding 101,892 97,606 90,533 Income from continuing operations per share — Basic $ 3.09 $ 2.96 $ 2.54 Basic Earnings Per Share from discontinued operations Income from discontinued operations $ — $ — $ 12,496 Less: Income from discontinued operations allocated to participating securities — — 42 Income from discontinued operations available to common shareholders $ — $ — $ 12,454 Basic weighted average shares outstanding 101,892 97,606 90,533 Income from discontinued operations per share — Basic $ — $ — $ 0.14 Net income per share — Basic $ 3.09 $ 2.96 $ 2.68 Diluted Earnings Per Share from continuing operations Income from continuing operations available to common shareholders $ 314,449 $ 289,106 $ 229,923 Effect of dilutive stock options and other shares — — 5 Income from continuing operations available to common shareholders $ 314,449 $ 289,106 $ 229,928 Basic weighted average shares outstanding 101,892 97,606 90,533 Additional dilutive stock options and other shares — 2 1,178 Diluted weighted average shares outstanding 101,892 97,608 91,711 Income from continuing operations per share — Diluted $ 3.09 $ 2.96 $ 2.50 Diluted Earnings Per Share from discontinued operations Income from discontinued operations available to common shareholders $ — $ — $ 12,454 Effect of dilutive stock options and other shares — — — Income from discontinued operations available to common shareholders $ — $ — $ 12,454 Basic weighted average shares outstanding 101,892 97,606 90,533 Additional dilutive stock options and other shares — 2 1,178 Diluted weighted average shares outstanding 101,892 97,608 91,711 Income from discontinued operations per share — Diluted $ — $ — $ 0.14 Net income per share — Diluted $ 3.09 $ 2.96 $ 2.64

Debt (Table)

Debt (Table)	12 Months Ended
	Sep. 30, 2015
Debt Disclosure [Abstract]
Debt instrument table	Long-term debt at September 30, 2015 and 2014 consisted of the following: 2015 2014 (In thousands) Unsecured 4.95% Senior Notes, due October 2014 $ — $ 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 Unsecured 4.125% Senior Notes, due 2044 500,000 — Medium term Series A notes, 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 4,612 4,014 $ 2,455,388 $ 2,455,986
Debt maturity schedule	Maturities of long-term debt at September 30, 2015 were as follows (in thousands): 2016 $ — 2017 250,000 2018 — 2019 450,000 2020 — Thereafter 1,760,000 $ 2,460,000

Retirement and Post-Retiremen35

Retirement and Post-Retirement Employee Benefit Plans (Table)	12 Months Ended
	Sep. 30, 2015
Compensation and Retirement Disclosure [Abstract]
Schedule of Net Periodic Benefit Cost Not Yet Recognized And Recorded as Regulatory Assets	The amounts that have not yet been recognized in net periodic pension cost that have been recorded as regulatory assets are as follows: Defined Benefits Plans Supplemental Executive Retirement Plans Postretirement Plans Total (In thousands) September 30, 2015 Unrecognized transition obligation $ — $ — $ 82 $ 82 Unrecognized prior service credit (1,735 ) — (4,524 ) (6,259 ) Unrecognized actuarial loss 120,948 36,915 (47,149 ) 110,714 $ 119,213 $ 36,915 $ (51,591 ) $ 104,537 September 30, 2014 Unrecognized transition obligation $ — $ — $ 354 $ 354 Unrecognized prior service credit (1,927 ) — (6,168 ) (8,095 ) Unrecognized actuarial loss 109,767 34,447 7,531 151,745 $ 107,840 $ 34,447 $ 1,717 $ 144,004
Schedule of Allocation of Plan Assets	The following table presents asset allocation information for the Master Trust as of September 30, 2015 and 2014 . Targeted Allocation Range Actual Allocation September 30 Security Class 2015 2014 Domestic equities 35%-55% 41.3 % 44.9 % International equities 10%-20% 14.9 % 15.3 % Fixed income 5%-30% 11.0 % 9.7 % Company stock 0%-15% 15.2 % 12.9 % Other assets 0%-20% 17.6 % 17.2 % The following table presents asset allocation information for the postretirement benefit plan assets as of September 30, 2015 and 2014 . Actual Allocation September 30 Security Class 2015 2014 Diversified investment funds 97.5 % 99.7 % Cash and cash equivalents 2.5 % 0.3 %
Schedule of Employee Pension Plans Investments at Fair Value	In addition to the assets shown below, the Master Trust had net accounts receivable of $2.4 million and $2.7 million at September 30, 2015 and 2014 which materially approximates fair value due to the short-term nature of these assets. Assets at Fair Value as of September 30, 2015 Level 1 Level 2 Level 3 Total (In thousands) Investments: Common stocks $ 159,304 $ — $ — $ 159,304 Money market funds — 11,787 — 11,787 Registered investment companies: Domestic funds 33,312 — — 33,312 International funds 48,648 — — 48,648 Common/collective trusts — domestic funds — 93,081 — 93,081 Government securities: Mortgage-backed securities — 14,359 — 14,359 U.S. treasuries 5,279 805 — 6,084 Corporate bonds — 28,973 — 28,973 Limited partnerships — 52,996 — 52,996 Total investments at fair value $ 246,543 $ 202,001 $ — $ 448,544 Assets at Fair Value as of September 30, 2014 Level 1 Level 2 Level 3 Total (In thousands) Investments: Common stocks $ 155,107 $ — $ — $ 155,107 Money market funds — 11,226 — 11,226 Registered investment companies: Domestic funds 33,266 — — 33,266 International funds 48,134 — — 48,134 Common/collective trusts — domestic funds — 91,792 — 91,792 Government securities: Mortgage-backed securities — 12,520 — 12,520 U.S. treasuries 3,117 562 — 3,679 Corporate bonds — 25,734 — 25,734 Limited partnerships — 50,496 — 50,496 Real estate — — 155 155 Total investments at fair value $ 239,624 $ 192,330 $ 155 $ 432,109
Schedule of Expected Benefit Payments	The following benefit payments paid by us, retirees and prescription drug subsidy payments for our postretirement benefit plans, which reflect expected future service, as appropriate, are expected to be paid in the following fiscal years. Company payments for fiscal 2015 include contributions to our postretirement plan trusts. Company Payments Retiree Payments Subsidy Payments Total Postretirement Benefits (In thousands) 2016 $ 15,498 $ 2,382 $ — $ 17,880 2017 11,245 2,677 — 13,922 2018 12,185 2,980 — 15,165 2019 12,755 3,324 — 16,079 2020 13,995 3,766 — 17,761 2021-2025 86,519 26,363 — 112,882 The following benefit payments for our defined benefit plans, which reflect expected future service, as appropriate, are expected to be paid in the following fiscal years: Pension Plans Supplemental Plans (In thousands) 2016 $ 30,909 $ 21,857 2017 31,805 13,901 2018 33,086 12,807 2019 34,712 6,808 2020 36,128 4,454 2021-2025 201,857 47,047
Schedule of Postretirement Benefit Plans Investments at Fair Value	Assets at Fair Value as of September 30, 2015 Level 1 Level 2 Level 3 Total (In thousands) Investments: Money market funds $ — $ 3,486 $ — $ 3,486 Registered investment companies: Domestic funds 123,921 — — 123,921 International funds 10,602 — — 10,602 Total investments at fair value $ 134,523 $ 3,486 $ — $ 138,009 Assets at Fair Value as of September 30, 2014 Level 1 Level 2 Level 3 Total (In thousands) Investments: Money market funds $ — $ 434 $ — $ 434 Registered investment companies: Domestic funds 124,006 — — 124,006 International funds 10,381 — — 10,381 Total investments at fair value $ 134,387 $ 434 $ — $ 134,821
Schedule of Assumptions Used [Table Text Block]	Additional assumptions are presented in the following table: Pension Liability Pension Cost 2015 2014 2015 2014 2013 Discount rate 4.55 % 4.43 % 4.43 % 4.95 % 4.04 % Rate of compensation increase 3.50 % 3.50 % 3.50 % 3.50 % 3.50 % Expected return on plan assets 7.00 % 7.25 % 7.25 % 7.25 % 7.75 % The actuarial assumptions used to determine the pension liability for the supplemental plans were determined as of September 30, 2015 and 2014 and the actuarial assumptions used to determine the net periodic pension cost for the supplemental plans were determined as of September 30, 2014 , 2013 and 2012 . These assumptions are presented in the following table: Pension Liability Pension Cost 2015 2014 2015 2014 2013 Discount rate 4.55 % 4.43 % 4.43 % 4.95 % 4.04 % (1) Rate of compensation increase 3.50 % 3.50 % 3.50 % 3.50 % 3.50 % (1) The discount rate for the supplemental plans increased from 4.04% to 4.21% effective April 1, 2013 due to a settlement loss recorded in fiscal 2013. The actuarial assumptions used to determine the pension liability for our postretirement plan were determined as of September 30, 2015 and 2014 and the actuarial assumptions used to determine the net periodic pension cost for the postretirement plan were determined as of September 30, 2014 , 2013 and 2012 . The assumptions are presented in the following table: Postretirement Liability Postretirement Cost 2015 2014 2015 2014 2013 Discount rate 4.55 % 4.43 % 4.43 % 4.95 % 4.04 % Expected return on plan assets 4.45 % 4.60 % 4.60 % 4.60 % 4.70 % Initial trend rate 7.50 % 7.50 % 7.50 % 8.00 % 8.00 % Ultimate trend rate 5.00 % 5.00 % 5.00 % 5.00 % 5.00 % Ultimate trend reached in 2021 2020 2020 2020 2019
Changes in Projected Benefit Obligations, Fair Value of Plan Assets, and Funded Status of Plan [Table Text Block]	The following table presents the Plans’ accumulated benefit obligation, projected benefit obligation and funded status as of September 30, 2015 and 2014 : 2015 2014 (In thousands) Accumulated benefit obligation $ 485,921 $ 466,182 Change in projected benefit obligation: Benefit obligation at beginning of year $ 493,594 $ 455,799 Service cost 16,231 15,345 Interest cost 21,850 22,330 Actuarial (gain) loss 7,420 26,611 Benefits paid (30,496 ) (24,519 ) Plan amendments — (1,972 ) Benefit obligation at end of year 508,599 493,594 Change in plan assets: Fair value of plan assets at beginning of year 434,767 396,887 Actual return on plan assets 8,661 35,289 Employer contributions 38,000 27,110 Benefits paid (30,496 ) (24,519 ) Fair value of plan assets at end of year 450,932 434,767 Reconciliation: Funded status (57,667 ) (58,827 ) Unrecognized prior service cost — — Unrecognized net loss — — Net amount recognized $ (57,667 ) $ (58,827 ) The following table presents the supplemental plans’ accumulated benefit obligation, projected benefit obligation and funded status as of September 30, 2015 and 2014 : 2015 2014 (In thousands) Accumulated benefit obligation $ 118,835 $ 106,276 Change in projected benefit obligation: Benefit obligation at beginning of year $ 113,219 $ 117,080 Service cost 3,971 3,607 Interest cost 4,943 4,966 Actuarial (gain) loss 4,811 9,468 Benefits paid (4,551 ) (5,085 ) Settlements — (16,817 ) Benefit obligation at end of year 122,393 113,219 Change in plan assets: Fair value of plan assets at beginning of year — — Employer contribution 4,551 21,902 Benefits paid (4,551 ) (5,085 ) Settlements — (16,817 ) Fair value of plan assets at end of year — — Reconciliation: Funded status (122,393 ) (113,219 ) Unrecognized prior service cost — — Unrecognized net loss — — Accrued pension cost $ (122,393 ) $ (113,219 ) The following table presents the postretirement plan’s benefit obligation and funded status as of September 30, 2015 and 2014 : 2015 2014 (In thousands) Change in benefit obligation: Benefit obligation at beginning of year $ 315,118 $ 312,148 Service cost 15,583 16,784 Interest cost 14,385 15,951 Plan participants’ contributions 4,563 4,435 Actuarial (gain) loss (69,962 ) (18,963 ) Benefits paid (12,508 ) (13,580 ) Plan amendments — (1,657 ) Benefit obligation at end of year 267,179 315,118 Change in plan assets: Fair value of plan assets at beginning of year 134,821 106,413 Actual return on plan assets (8,851 ) 14,003 Employer contributions 19,984 23,550 Plan participants’ contributions 4,563 4,435 Benefits paid (12,508 ) (13,580 ) Fair value of plan assets at end of year 138,009 134,821 Reconciliation: Funded status (129,170 ) (180,297 ) Unrecognized transition obligation — — Unrecognized prior service cost — — Unrecognized net loss — — Accrued postretirement cost $ (129,170 ) $ (180,297 )
Schedule of Net Benefit Costs [Table Text Block]	Net periodic postretirement cost for fiscal 2015 , 2014 and 2013 is recorded as operating expense and included the components presented below. Fiscal Year Ended September 30 2015 2014 2013 (In thousands) Components of net periodic postretirement cost: Service cost $ 15,583 $ 16,784 $ 18,800 Interest cost 14,385 15,951 12,964 Expected return on assets (6,431 ) (5,167 ) (3,988 ) Amortization of transition obligation 272 274 1,081 Amortization of prior service credit (1,644 ) (1,450 ) (1,450 ) Recognized actuarial loss — 631 4,196 Net periodic postretirement cost $ 22,165 $ 27,023 $ 31,603 Net periodic pension cost for the Plans for fiscal 2015 , 2014 and 2013 is recorded as operating expense and included the following components: Fiscal Year Ended September 30 2015 2014 2013 (In thousands) Components of net periodic pension cost: Service cost $ 16,231 $ 15,345 $ 17,754 Interest cost 21,850 22,330 19,334 Expected return on assets (25,744 ) (23,601 ) (22,955 ) Amortization of prior service credit (192 ) (136 ) (141 ) Recognized actuarial loss 13,322 13,777 19,066 Net periodic pension cost $ 25,467 $ 27,715 $ 33,058 Net periodic pension cost for the supplemental plans for fiscal 2015 , 2014 and 2013 is recorded as operating expense and included the following components: Fiscal Year Ended September 30 2015 2014 2013 (In thousands) Components of net periodic pension cost: Service cost $ 3,971 $ 3,607 $ 3,039 Interest cost 4,943 4,966 4,755 Amortization of transition asset — — — Amortization of prior service cost — — — Recognized actuarial loss 2,343 1,948 2,918 Settlements — 4,539 3,160 Net periodic pension cost $ 11,257 $ 15,060 $ 13,872
Schedule of Effect of One-Percentage-Point Change in Assumed Health Care Cost Trend Rates [Table Text Block]	Assumed health care cost trend rates have a significant effect on the amounts reported for the plan. A one-percentage point change in assumed health care cost trend rates would have the following effects on the latest actuarial calculations: One-Percentage Point Increase One-Percentage Point Decrease (In thousands) Effect on total service and interest cost components $ 4,288 $ (3,426 ) Effect on postretirement benefit obligation $ 39,572 $ (32,440 )

Stock and Other Compensation 36

Stock and Other Compensation Plans (Table)	12 Months Ended
	Sep. 30, 2015
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Schedule of restricted stock activity	The following summarizes information regarding the restricted stock units granted under the plan during the fiscal years ended September 30, 2015 , 2014 and 2013 : 2015 2014 2013 Number of Restricted Units Weighted Average Grant-Date Fair Value Number of Weighted Average Grant-Date Fair Value Number of Weighted Average Grant-Date Fair Value Nonvested at beginning of year 988,637 $ 42.22 1,052,844 $ 36.20 1,262,582 $ 32.46 Granted 444,543 50.50 464,438 45.05 473,775 40.48 Vested (551,688 ) 39.28 (524,532 ) 32.67 (657,795 ) 32.20 Forfeited (3,388 ) 48.55 (4,113 ) 39.00 (25,718 ) 33.42 Nonvested at end of year 878,104 $ 48.24 988,637 $ 42.22 1,052,844 $ 36.20

Details of Selected Consolida37

Details of Selected Consolidated Balance Sheet Captions (Table)	12 Months Ended
	Sep. 30, 2015
Details Of Selected Consolidated Balance Sheet Captions Disclosure [Abstract]
Accounts Receivables Detail Table	Accounts receivable was comprised of the following at September 30, 2015 and 2014 : September 30 2015 2014 (In thousands) Billed accounts receivable $ 204,585 $ 262,937 Unbilled revenue 65,008 62,484 Other accounts receivable 40,850 41,971 Total accounts receivable 310,443 367,392 Less: allowance for doubtful accounts (15,283 ) (23,992 ) Net accounts receivable $ 295,160 $ 343,400
Other Current Assets Detail Table	Other current assets as of September 30, 2015 and 2014 were comprised of the following accounts. September 30 2015 2014 (In thousands) Assets from risk management activities $ 9,232 $ 45,827 Deferred gas costs 9,715 20,069 Taxes receivable 4,479 5,481 Prepaid expenses 27,734 25,039 Materials and supplies 12,587 5,704 Other 6,822 9,145 Total $ 70,569 $ 111,265
Property, Plant and Equipment Detail Table	Property, plant and equipment was comprised of the following as of September 30, 2015 and 2014 : September 30 2015 2014 (In thousands) Production plant $ 131 $ 4,821 Storage plant 286,011 275,579 Transmission plant 1,844,117 1,622,846 Distribution plant 6,019,001 5,522,794 General plant 769,311 735,223 Intangible plant 41,131 38,858 8,959,702 8,200,121 Construction in progress 280,398 247,579 9,240,100 8,447,700 Less: accumulated depreciation and amortization (1,809,520 ) (1,721,794 ) Net property, plant and equipment (1) $ 7,430,580 $ 6,725,906 (1) Net property, plant and equipment includes plant acquisition adjustments of $(68.1) million and $(76.4) million at September 30, 2015 and 2014 .
Goodwill Detail Table	The following presents our goodwill balance allocated by segment and changes in the balance for the fiscal year ended September 30, 2015 : Regulated Distribution Regulated Pipeline Nonregulated Total (In thousands) Balance as of September 30, 2014 $ 574,816 $ 132,502 $ 34,711 $ 742,029 Deferred tax adjustments on prior acquisitions (1) 633 40 — 673 Balance as of September 30, 2015 $ 575,449 $ 132,542 $ 34,711 $ 742,702 (1) We annually adjust certain deferred taxes recorded in connection with acquisitions completed in fiscal 2001 and fiscal 2004, which resulted in an increase to goodwill and net deferred tax liabilities of $0.7 million
Deferred Charges and Other Assets Detail Table	Deferred charges and other assets as of September 30, 2015 and 2014 were comprised of the following accounts. September 30 2015 2014 (In thousands) Marketable securities $ 74,200 $ 79,613 Regulatory assets 182,573 230,240 Deferred financing costs 17,873 13,698 Assets from risk management activities 368 13,038 Other 13,664 14,340 Total $ 288,678 $ 350,929
Accounts Payable and Accrued Liabilities	Accounts payable and accrued liabilities as of September 30, 2015 and 2014 were comprised of the following accounts. September 30 2015 2014 (In thousands) Trade accounts payable $ 78,534 $ 77,860 Accrued gas payable 119,825 179,425 Accrued liabilities 40,583 50,801 Total $ 238,942 $ 308,086
Other Current Liabilities Detail Table	Other current liabilities as of September 30, 2015 and 2014 were comprised of the following accounts. September 30 2015 2014 (In thousands) Customer credit balances and deposits $ 100,232 $ 82,085 Accrued employee costs 47,602 46,445 Deferred gas costs 28,100 35,063 Accrued interest 34,914 36,768 Liabilities from risk management activities 9,568 1,730 Taxes payable 93,674 77,601 Pension and postretirement obligations 21,857 11,380 Current deferred tax liability 55,918 48,751 Regulatory cost of removal accrual 56,123 45,061 Other 9,966 20,985 Total $ 457,954 $ 405,869
Deferred Credits and Other Liabilities Detail Table	Deferred credits and other liabilities as of September 30, 2015 and 2014 were comprised of the following accounts. September 30 2015 2014 (In thousands) Customer advances for construction $ 9,316 $ 9,883 Regulatory liabilities 3,693 4,472 Asset retirement obligation 9,063 10,508 Liabilities from risk management activities 110,539 20,126 Other 29,085 23,881 Total $ 161,696 $ 68,870

Leases (Table)

Leases (Table)	12 Months Ended
	Sep. 30, 2015
Leases [Abstract]
Schedule of Future Minimum Rental Payments for Operating Leases [Table Text Block]	The related future minimum lease payments at September 30, 2015 were as follows: Operating Leases (In thousands) 2016 $ 16,475 2017 16,639 2018 16,490 2019 15,207 2020 14,251 Thereafter 61,651 Total minimum lease payments $ 140,713

Commitments and Contingencies (

Commitments and Contingencies (Table)	12 Months Ended
	Sep. 30, 2015
Commitments and Contingencies Disclosure [Abstract]
Schedule of Estimated Contractual Demand Fees	The estimated contractual demand fees for contracted storage and transportation under these contracts as of September 30, 2015 are as follows (in thousands): 2016 $ 7,843 2017 3,522 2018 1,966 2019 426 2020 398 Thereafter 1,101 $ 15,256

Income Taxes (Table)

Income Taxes (Table)	12 Months Ended
	Sep. 30, 2015
Income Tax Disclosure [Abstract]
Schedule of Components of Income Tax Expense (Benefit)	The components of income tax expense from continuing operations for 2015 , 2014 and 2013 were as follows: 2015 2014 2013 (In thousands) Current Federal $ — $ — $ — State 7,251 5,527 8,178 Deferred Federal 175,897 169,106 124,836 State 12,548 12,375 9,605 Investment tax credits (6 ) (6 ) (20 ) $ 195,690 $ 187,002 $ 142,599
Schedule of Effective Income Tax Rate Reconciliation	Reconciliations of the provision for income taxes computed at the statutory rate to the reported provisions for income taxes from continuing operations for 2015 , 2014 and 2013 are set forth below: 2015 2014 2013 (In thousands) Tax at statutory rate of 35% $ 178,768 $ 166,887 $ 130,655 Common stock dividends deductible for tax reporting (2,413 ) (2,307 ) (2,153 ) State taxes (net of federal benefit) 12,869 11,636 11,559 Change in valuation allowance 4,998 6,969 1,085 Other, net 1,468 3,817 1,453 Income tax expense $ 195,690 $ 187,002 $ 142,599
Schedule of Deferred Tax Assets and Liabilities	The tax effect of temporary differences that gave rise to significant components of the deferred tax liabilities and deferred tax assets at September 30, 2015 and 2014 are presented below: 2015 2014 (In thousands) Deferred tax assets: Employee benefit plans $ 121,619 $ 116,157 Interest rate agreements 51,067 10,565 Net operating loss carryforwards 313,224 236,626 Charitable and other credit carryforwards 22,281 21,614 Other 36,695 28,849 Total deferred tax assets 544,886 413,811 Valuation allowance (10,872 ) (6,969 ) Net deferred tax assets 534,014 406,842 Deferred tax liabilities: Difference in net book value and net tax value of assets (1,890,886 ) (1,655,894 ) Pension funding (35,247 ) (17,890 ) Gas cost adjustments (43,634 ) (31,252 ) Other (31,480 ) (37,173 ) Total deferred tax liabilities (2,001,247 ) (1,742,209 ) Net deferred tax liabilities $ (1,467,233 ) $ (1,335,367 ) Deferred credits for rate regulated entities $ 412 $ (109 )
Schedule of Unrecognized Tax Benefits Roll Forward	The following table reconciles the beginning and ending balance of our unrecognized tax benefits: 2015 2014 (In thousands) Unrecognized tax benefits - beginning balance $ 12,629 $ 4,158 Increase resulting from prior period tax positions 1,009 3,846 Increase resulting from current period tax positions 3,431 4,625 Unrecognized tax benefits - ending balance 17,069 12,629 Accrued interest and penalties 820 411 Gross unrecognized tax benefits 17,889 13,040 Less: deferred federal and state income tax benefits (6,261 ) (4,564 ) Total unrecognized tax benefits that, if recognized, would impact the effective income tax rate as of the end of the year $ 11,628 $ 8,476

Financial Instruments (Table)

Financial Instruments (Table)	12 Months Ended
	Sep. 30, 2015
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Schedule of financial instrument assets and liabilities at fair value	The following table shows the fair values of our risk management assets and liabilities by segment at September 30, 2015 and 2014 : Regulated Distribution Nonregulated Total (In thousands) September 30, 2015 Assets from risk management activities, current (1) $ 378 $ 8,854 $ 9,232 Assets from risk management activities, noncurrent 368 — 368 Liabilities from risk management activities, current (1) (9,568 ) — (9,568 ) Liabilities from risk management activities, noncurrent (1) (110,539 ) — (110,539 ) Net assets (liabilities) $ (119,361 ) $ 8,854 $ (110,507 ) September 30, 2014 Assets from risk management activities, current (2) $ 23,102 $ 22,725 $ 45,827 Assets from risk management activities, noncurrent 13,038 — 13,038 Liabilities from risk management activities, current (2) (1,730 ) — (1,730 ) Liabilities from risk management activities, noncurrent (2) (20,126 ) — (20,126 ) Net assets $ 14,284 $ 22,725 $ 37,009 (1) Includes $43.5 million of cash held on deposit to collateralize certain financial instruments. Of this amount, $34.6 million was used to offset current and noncurent risk management liabilities under master netting arrangements and the remaining $8.9 million is classified as current risk management assets. (2) Includes $25.8 million of cash held on deposit to collateralize certain financial instruments. Of this amount, $3.1 million was used to offset current and noncurrent risk management liabilities under master netting arrangements and the remaining $22.7 million is classified as current risk management assets.
Outstanding commodity contracts volumes table	As of September 30, 2015 , we had net long/(short) commodity contracts outstanding in the following quantities: Contract Type Hedge Designation Regulated Distribution Nonregulated Quantity (MMcf) Commodity contracts Fair Value — (18,378 ) Cash Flow — 56,368 Not designated 24,849 58,513 24,849 96,503
Financial instruments on the balance sheet	Regulated Distribution Nonregulated Balance Sheet Location Assets Liabilities Assets Liabilities (In thousands) September 30, 2014 Designated As Hedges: Commodity contracts Other current assets / Other current liabilities $ — $ — $ 8,912 $ (7,082 ) Interest rate contracts Other current assets / 21,869 — — — Commodity contracts Deferred charges and other assets / Deferred credits and other liabilities — — 757 (2,459 ) Interest rate contracts Deferred charges and other assets / Deferred credits and other liabilities 12,608 (19,835 ) — — Total 34,477 (19,835 ) 9,669 (9,541 ) Not Designated As Hedges: Commodity contracts Other current assets / Other current liabilities 1,233 (1,730 ) 43,677 (47,729 ) Commodity contracts Deferred charges and other assets / Deferred credits and other liabilities 430 (291 ) 15,677 (14,786 ) Total 1,663 (2,021 ) 59,354 (62,515 ) Gross Financial Instruments 36,140 (21,856 ) 69,023 (72,056 ) Gross Amounts Offset on Consolidated Balance Sheet: Contract netting — — (69,023 ) 69,023 Net Financial Instruments 36,140 (21,856 ) — (3,033 ) Cash collateral — — 22,725 3,033 Net Assets/Liabilities from Risk Management Activities $ 36,140 $ (21,856 ) $ 22,725 $ — The following tables present the fair value and balance sheet classification of our financial instruments by operating segment as of September 30, 2015 and 2014 . The gross amounts of recognized assets and liabilities are netted within our Consolidated Balance Sheets to the extent that we have netting arrangements with the counterparties. Regulated Distribution Nonregulated Balance Sheet Location Assets Liabilities Assets Liabilities (In thousands) September 30, 2015 Designated As Hedges: Commodity contracts Other current assets / Other current liabilities $ — $ — $ 11,680 $ (36,067 ) Commodity contracts Deferred charges and other assets / Deferred credits and other liabilities — — 126 (9,918 ) Interest rate contracts Deferred charges and other assets / Deferred credits and other liabilities — (110,539 ) — — Total — (110,539 ) 11,806 (45,985 ) Not Designated As Hedges: Commodity contracts Other current assets / Other current liabilities 378 (9,568 ) 65,239 (65,780 ) Commodity contracts Deferred charges and other assets / Deferred credits and other liabilities 368 — 14,318 (14,218 ) Total 746 (9,568 ) 79,557 (79,998 ) Gross Financial Instruments 746 (120,107 ) 91,363 (125,983 ) Gross Amounts Offset on Consolidated Balance Sheet: Contract netting — — (91,363 ) 91,363 Net Financial Instruments 746 (120,107 ) — (34,620 ) Cash collateral — — 8,854 34,620 Net Assets/Liabilities from Risk Management Activities $ 746 $ (120,107 ) $ 8,854 $ —
Fair value hedges table	The impact of our nonregulated commodity contracts designated as fair value hedges and the related hedged item on our consolidated income statement for the years ended September 30, 2015 , 2014 and 2013 is presented below. Fiscal Year Ended September 30 2015 2014 2013 (In thousands) Commodity contracts $ 10,311 $ (792 ) $ 2,165 Fair value adjustment for natural gas inventory designated as the hedged item (9,768 ) 2,486 15,938 Total decrease in purchased gas cost $ 543 $ 1,694 $ 18,103 The decrease in purchased gas cost is comprised of the following: Basis ineffectiveness $ 811 $ (919 ) $ (208 ) Timing ineffectiveness (268 ) 2,613 18,311 $ 543 $ 1,694 $ 18,103
Cash flow hedges table	The impact of cash flow hedges on our consolidated income statements for the years ended September 30, 2015 , 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. Fiscal Year Ended September 30, 2015 Regulated Distribution Nonregulated Consolidated (In thousands) Loss reclassified from AOCI for effective portion of commodity contracts $ — $ (41,716 ) $ (41,716 ) Loss arising from ineffective portion of commodity contracts — (325 ) (325 ) Total impact on purchased gas cost — (42,041 ) (42,041 ) Net loss on settled interest rate agreements reclassified from AOCI into interest expense (853 ) — (853 ) Total impact from cash flow hedges $ (853 ) $ (42,041 ) $ (42,894 ) Fiscal Year Ended September 30, 2014 Regulated Distribution Nonregulated Consolidated (In thousands) Gain reclassified from AOCI for effective portion of commodity contracts $ — $ 8,365 $ 8,365 Gain arising from ineffective portion of commodity contracts — 198 198 Total impact on purchased gas cost — 8,563 8,563 Net loss on settled interest rate agreements reclassified from AOCI into interest expense (4,230 ) — (4,230 ) Total impact from cash flow hedges $ (4,230 ) $ 8,563 $ 4,333 Fiscal Year Ended September 30, 2013 Regulated Distribution Nonregulated Consolidated (In thousands) Loss reclassified from AOCI for effective portion of commodity contracts $ — $ (10,778 ) $ (10,778 ) Gain arising from ineffective portion of commodity contracts — 97 97 Total impact on purchased gas cost — (10,681 ) (10,681 ) Net loss on settled interest rate agreements reclassified from AOCI into interest expense (3,489 ) — (3,489 ) Total impact from cash flow hedges $ (3,489 ) $ (10,681 ) $ (14,170 )
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 years ended September 30, 2015 and 2014 . The amounts included in the table below exclude gains and losses arising from ineffectiveness because these amounts are immediately recognized in the income statement as incurred. Fiscal Year Ended September 30 2015 2014 (In thousands) Increase (decrease) in fair value: Interest rate agreements $ (71,003 ) $ (58,973 ) Forward commodity contracts (49,211 ) 7,904 Recognition of (gains) losses in earnings due to settlements: Interest rate agreements 542 2,686 Forward commodity contracts 25,448 (5,102 ) Total other comprehensive income (loss) from hedging, net of tax (1) $ (94,224 ) $ (53,485 ) (1) Utilizing an income tax rate ranging from approximately 37 percent to 39 percent based on the effective rates in each taxing jurisdiction.
Expected recognition in earnings of deferred 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 September 30, 2015 . However, the table below does not include the expected recognition in earnings of the interest rate agreements entered into in October 2012 and fiscal 2014 as those financial instruments have not yet settled. Interest Rate Agreements Commodity Contracts Total (In thousands) 2016 $ (347 ) $ (19,484 ) $ (19,831 ) 2017 (447 ) (5,044 ) (5,491 ) 2018 (649 ) (819 ) (1,468 ) 2019 (673 ) (85 ) (758 ) 2020 (698 ) (5 ) (703 ) Thereafter (15,836 ) — (15,836 ) Total (1) $ (18,650 ) $ (25,437 ) $ (44,087 ) (1) Utilizing an income tax rate ranging from approximately 37 percent to 39 percent based on the effective rates in each taxing jurisdiction.

Accumulated Other Comprehensi42

Accumulated Other Comprehensive Income (Table)	12 Months Ended
	Sep. 30, 2015
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- for-Sale Securities Interest Rate Agreement Cash Flow Hedges Commodity Contracts Cash Flow Hedges Total (In thousands) September 30, 2014 $ 7,662 $ (18,381 ) $ (1,674 ) $ (12,393 ) Other comprehensive income (loss) before reclassifications (2,173 ) (71,003 ) (49,211 ) (122,387 ) Amounts reclassified from accumulated other comprehensive income (540 ) 542 25,448 25,450 Net current-period other comprehensive income (loss) (2,713 ) (70,461 ) (23,763 ) (96,937 ) September 30, 2015 $ 4,949 $ (88,842 ) $ (25,437 ) $ (109,330 ) Available- for-Sale Securities Interest Rate Agreement Cash Flow Hedges Commodity Contracts Cash Flow Hedges Total (In thousands) September 30, 2013 $ 5,448 $ 37,906 $ (4,476 ) $ 38,878 Other comprehensive income (loss) before reclassifications 3,009 (58,973 ) 7,904 (48,060 ) Amounts reclassified from accumulated other comprehensive income (795 ) 2,686 (5,102 ) (3,211 ) Net current-period other comprehensive income (loss) 2,214 (56,287 ) 2,802 (51,271 ) September 30, 2014 $ 7,662 $ (18,381 ) $ (1,674 ) $ (12,393 )
Reclassification out of Accumulated Other Comprehensive Income	The following tables detail reclassifications out of AOCI for the fiscal years ended September 30, 2015 and 2014 . Amounts in parentheses below indicate decreases to net income in the statement of income. Fiscal Year Ended September 30, 2015 Accumulated Other Comprehensive Income Components Amount Reclassified from Accumulated Other Comprehensive Income Affected Line Item in the Statement of Income (In thousands) Available-for-sale securities $ 850 Operation and maintenance expense 850 Total before tax (310 ) Tax expense $ 540 Net of tax Cash flow hedges Interest rate agreements $ (853 ) Interest charges Commodity contracts (41,716 ) Purchased gas cost (42,569 ) Total before tax 16,579 Tax benefit $ (25,990 ) Net of tax Total reclassifications $ (25,450 ) Net of tax Fiscal Year Ended September 30, 2014 Accumulated Other Comprehensive Income Components Amount Reclassified from Accumulated Other Comprehensive Income Affected Line Item in the Statement of Income (In thousands) Available-for-sale securities $ 1,252 Operation and maintenance expense 1,252 Total before tax (457 ) Tax expense $ 795 Net of tax Cash flow hedges Interest rate agreements $ (4,230 ) Interest charges Commodity contracts 8,365 Purchased gas cost 4,135 Total before tax (1,719 ) Tax expense $ 2,416 Net of tax Total reclassifications $ 3,211 Net of tax

Fair Value Measurements (Table)

Fair Value Measurements (Table)	12 Months Ended
	Sep. 30, 2015
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 September 30, 2015 and 2014 . As required under authoritative accounting literature, assets and liabilities are categorized in their entirety based on the lowest level of input that is significant to the fair value measurement. Quoted Prices in Active Markets (Level 1) Significant Other Observable Inputs (Level 2) (1) Significant Other Unobservable Inputs (Level 3) Netting and Cash Collateral (2) September 30, 2015 (In thousands) Assets: Financial instruments Regulated distribution segment $ — $ 746 $ — $ — $ 746 Nonregulated segment — 91,363 — (82,509 ) 8,854 Total financial instruments — 92,109 — (82,509 ) 9,600 Hedged portion of gas stored underground 43,901 — — — 43,901 Available-for-sale securities Money market funds — 1,072 — — 1,072 Registered investment companies 40,619 — — — 40,619 Bonds — 32,509 — — 32,509 Total available-for-sale securities 40,619 33,581 — — 74,200 Total assets $ 84,520 $ 125,690 $ — $ (82,509 ) $ 127,701 Liabilities: Financial instruments Regulated distribution segment $ — $ 120,107 $ — $ — $ 120,107 Nonregulated segment — 125,983 — (125,983 ) — Total liabilities $ — $ 246,090 $ — $ (125,983 ) $ 120,107 Quoted Prices in Active Markets (Level 1) Significant Other Observable Inputs (Level 2) (1) Significant Other Unobservable Inputs (Level 3) Netting and Cash Collateral (3) September 30, 2014 (In thousands) Assets: Financial instruments Regulated distribution segment $ — $ 36,140 $ — $ — $ 36,140 Nonregulated segment 25 68,998 — (46,298 ) 22,725 Total financial instruments 25 105,138 — (46,298 ) 58,865 Hedged portion of gas stored underground 40,492 — — — 40,492 Available-for-sale securities Money market funds — 2,185 — — 2,185 Registered investment companies 44,014 — — — 44,014 Bonds — 33,414 — — 33,414 Total available-for-sale securities 44,014 35,599 — — 79,613 Total assets $ 84,531 $ 140,737 $ — $ (46,298 ) $ 178,970 Liabilities: Financial instruments Regulated distribution segment $ — $ 21,856 $ — $ — $ 21,856 Nonregulated segment 12 72,044 — (72,056 ) — Total liabilities $ 12 $ 93,900 $ — $ (72,056 ) $ 21,856 (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 September 30, 2015 we had $43.5 million of cash held in margin accounts to collateralize certain financial instruments. Of this amount, $34.6 million was used to offset current and noncurrent risk management liabilities under master netting agreements and the remaining $8.9 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, 2014 we had $25.8 million of cash held in margin accounts to collateralize certain financial instruments. Of this amount, $3.1 million was used to offset current and noncurrent risk management liabilities under master netting agreements and the remaining $22.7 million is classified as current risk management assets.
Available for sale securities	Available-for-sale securities are comprised of the following: Amortized Cost Gross Unrealized Gain Gross Unrealized Loss Fair Value (In thousands) As of September 30, 2015 Domestic equity mutual funds $ 27,643 $ 7,332 $ (456 ) $ 34,519 Foreign equity mutual funds 5,261 905 (66 ) 6,100 Bonds 32,423 106 (20 ) 32,509 Money market funds 1,072 — — 1,072 $ 66,399 $ 8,343 $ (542 ) $ 74,200 As of September 30, 2014 Domestic equity mutual funds $ 26,633 $ 10,136 $ — $ 36,769 Foreign equity mutual funds 5,382 1,863 — 7,245 Bonds 33,266 161 (13 ) 33,414 Money market funds 2,185 — — 2,185 $ 67,466 $ 12,160 $ (13 ) $ 79,613
Other fair value measurements table	The following table presents the carrying value and fair value of our debt as of September 30, 2015 : September 30, 2015 (In thousands) Carrying Amount $ 2,460,000 Fair Value $ 2,669,323

Discontinued Operations (Table)

Discontinued Operations (Table)	12 Months Ended
	Sep. 30, 2015
Discontinued Operations and Disposal Groups [Abstract]
Discontinued operations income statement detail table	The following table presents statement of income data related to discontinued operations in our Georgia service area for the year ended September 30, 2013 . Year Ended September 30, 2013 (In thousands) Operating revenues $ 37,962 Purchased gas cost 21,464 Gross profit 16,498 Operating expenses 5,858 Operating income 10,640 Other nonoperating income 548 Income from discontinued operations before income taxes 11,188 Income tax expense 3,986 Income from discontinued operations 7,202 Gain on sale of discontinued operations, net of tax 5,294 Net income from discontinued operations $ 12,496

Selected Quarterly Financial 45

Selected Quarterly Financial Data (Table)	12 Months Ended
	Sep. 30, 2015
Quarterly Financial Information Disclosure [Abstract]
Schedule of Quarterly Financial Information	Summarized unaudited quarterly financial data is presented below. The sum of net income per share by quarter may not equal the net income per share for the fiscal year due to variations in the weighted average shares outstanding used in computing such amounts. Our businesses are seasonal due to weather conditions in our service areas. For further information on its effects on quarterly results, see the “Results of Operations” discussion included in the “Management’s Discussion and Analysis of Financial Condition and Results of Operations” section herein. Quarter Ended December 31 March 31 June 30 September 30 (In thousands, except per share data) Fiscal year 2015: Operating revenues Regulated distribution $ 846,772 $ 1,130,613 $ 416,794 $ 369,656 Regulated pipeline 83,567 91,730 97,008 97,807 Nonregulated 462,288 438,322 278,769 292,830 Intersegment eliminations (133,862 ) (120,597 ) (106,170 ) (103,391 ) 1,258,765 1,540,068 686,401 656,902 Gross profit 423,285 520,738 381,673 354,321 Operating income 187,725 250,210 117,607 75,853 Net income 97,595 137,684 56,281 23,515 Net income per share — basic $ 0.96 $ 1.35 $ 0.55 $ 0.23 Net income per share — diluted $ 0.96 $ 1.35 $ 0.55 $ 0.23 Quarter Ended December 31 March 31 June 30 September 30 (In thousands, except per share data) Fiscal year 2014: Operating revenues Regulated distribution $ 843,865 $ 1,290,960 $ 517,707 $ 409,014 Regulated pipeline 71,341 73,615 87,189 86,314 Nonregulated 436,431 758,215 465,485 407,161 Intersegment eliminations (107,779 ) (157,936 ) (127,211 ) (113,455 ) 1,243,858 1,964,854 943,170 789,034 Gross profit 388,957 496,277 359,533 337,659 Operating income 170,720 250,080 106,605 83,944 Net income 87,016 133,367 45,721 23,713 Net income per share — basic $ 0.95 $ 1.38 $ 0.45 $ 0.23 Net income per share — diluted $ 0.95 $ 1.38 $ 0.45 $ 0.23

Nature of Business (Details)

Nature of Business (Details) customers in Thousands	Sep. 30, 2015customersregulated_gas_distributions_divisions	Sep. 30, 2013customers
Schedule of Number of Customers, Discontinued Operations [Line Items]
Number Of Customers, Regulated Distribution	3,000
Number Of Divisions, Regulated Distribution | regulated_gas_distributions_divisions	6
Georgia, Illinois, Iowa and Missouri [Member]
Schedule of Number of Customers, Discontinued Operations [Line Items]
Number Of Customers, Regulated Distribution		148

Summary of Significant Accoun47

Summary of Significant Accounting Policies (Details) - USD ($) $ in Thousands		12 Months Ended
		Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2013
Regulatory Assets [Line Items]
Regulatory Assets		$ 192,339	$ 250,309
Regulatory Liabilities [Line Items]
Regulatory Liabilities		524,532	545,759
Regulatory Assets and Liabilities, Other Disclosures [Abstract]
Regulatory Asset - Future Recoverable Pension Costs		16,600	18,800
Property, Plant and Equipment [Line Items]
Interest Costs Capitalized		$ 2,300	$ 1,500	$ 1,900
Composite depreciation rate for regulated property, plant and equipment		3.30%	3.30%	3.30%
Other Information [Abstract]
Unrealized gain (loss) on open contracts		$ (2,400)	$ 9,600	$ 9,000
Asset Retirement Obligation		11,100	10,500
Asset Retirement Costs in Property, Plant and Equipment		4,800	5,900
Cash Held in Margin Accounts		43,500	25,800
Regulatory Cost Of Removal Liability [Member]
Regulatory Liabilities [Line Items]
Regulatory Liabilities		483,676	490,448
Deferred Gas Costs [Member]
Regulatory Liabilities [Line Items]
Regulatory Liabilities		28,100	35,063
Asset Retirement Obligation Costs [Member]
Regulatory Liabilities [Line Items]
Regulatory Liabilities		9,063	10,508
Deferred Franchise Fees Liability [Member]
Regulatory Liabilities [Line Items]
Regulatory Liabilities		0	5,268
Other [Member]
Regulatory Liabilities [Line Items]
Regulatory Liabilities		3,693	4,472
Pension And Postretirement Benefit Costs [Member]
Regulatory Assets [Line Items]
Regulatory Assets	[1]	121,183	162,777
Infrastructure Mechanisms [Member]
Regulatory Assets [Line Items]
Regulatory Assets	[2]	32,813	26,948
Deferred Gas Costs [Member]
Regulatory Assets [Line Items]
Regulatory Assets		9,715	20,069
Recoverable Loss On Reacquired Debt [Member]
Regulatory Assets [Line Items]
Regulatory Assets		16,319	18,877
APT Annual Adjustment Mechanism Asset [Member]
Regulatory Assets [Line Items]
Regulatory Assets		1,002	8,479
Rate Case Costs [Member]
Regulatory Assets [Line Items]
Regulatory Assets		1,533	3,757
Other [Member]
Regulatory Assets [Line Items]
Regulatory Assets		$ 9,774	$ 9,402
Minimum [Member]
Property, Plant and Equipment [Line Items]
Estimated useful lives for nonregulated property, plant and equipment		3 years
Maximum [Member]
Property, Plant and Equipment [Line Items]
Estimated useful lives for nonregulated property, plant and equipment		43 years
[1]	Includes $16.6 million and $18.8 million of pension and postretirement expense deferred pursuant to regulatory authorization.
[2]	{F|ahBzfndlYmZpbGluZ3MtaHJkcmoLEgZYTUxEb2MiXlhCUkxEb2NHZW5JbmZvOjY5MzVhMDg4NmFiZTQ4OWI4NGMwODRiNTY1ZWEzNjI5fFRleHRTZWxlY3Rpb246MkQxNzI1ODI3MDY5QTQ1MEUwNkM2NTMyQzUzODRCRTYM}

Segment Information (Details)

Segment Information (Details) $ in Thousands, customers in Millions		3 Months Ended										12 Months Ended
		Sep. 30, 2015USD ($)customersregulated_gas_distributions_divisionsstate		Jun. 30, 2015USD ($)	Mar. 31, 2015USD ($)	Dec. 31, 2014USD ($)	Sep. 30, 2014USD ($)		Jun. 30, 2014USD ($)	Mar. 31, 2014USD ($)	Dec. 31, 2013USD ($)	Sep. 30, 2015USD ($)customersregulated_gas_distributions_divisionsstatesegment		Sep. 30, 2014USD ($)		Sep. 30, 2013USD ($)	Sep. 30, 2012USD ($)
Segment Reporting Information Profit Loss [Abstract]
Operating revenues		$ 656,902		$ 686,401	$ 1,540,068	$ 1,258,765	$ 789,034		$ 943,170	$ 1,964,854	$ 1,243,858	$ 4,142,136		$ 4,940,916		$ 3,875,460
Purchased gas cost												2,462,119		3,358,490		2,463,410
Gross profit		354,321		381,673	520,738	423,285	337,659		359,533	496,277	388,957	1,680,017		1,582,426		1,412,050
Operating expenses
Operation and maintenance												541,868		505,154		488,020
Depreciation and amortization												274,796		253,987		235,079
Taxes, other than income												231,958		211,936		187,072
Total operating expenses												1,048,622		971,077		910,171
Operating income		75,853		117,607	250,210	187,725	83,944		106,605	250,080	170,720	631,395		611,349		501,879
Miscellaneous income (expense), net												(4,389)		(5,235)		(197)
Interest charges												116,241		129,295		128,385
Income (loss) before income taxes												510,765		476,819		373,297
Income tax expense												195,690		187,002		142,599
Income (loss) from continuing operations												315,075		289,817		230,698
Income from discontinued operations, net of tax												0		0		7,202
Gain (loss) on sale of discontinued operations, net of tax												0		0		5,294
Net income		23,515		56,281	137,684	97,595	23,713		45,721	133,367	87,016	315,075		289,817		243,194
Capital expenditures												975,132		835,251		845,033
Revenue from External Customers by Products and Services Table [Abstract]
Operating revenues		656,902		686,401	1,540,068	1,258,765	789,034		943,170	1,964,854	1,243,858	4,142,136		4,940,916		3,875,460
ASSETS
Net property, plant and equipment	[1]	7,430,580					6,725,906					7,430,580		6,725,906
Investment in subsidaries		0					0					0		0
Current assets
Cash and cash equivalents		28,653					42,258					28,653		42,258		66,199	$ 64,239
Assets from risk management activities current		9,232					45,827					9,232		45,827
Other current assets		593,100					687,755					593,100		687,755
Intercompany receivables		0					0					0		0
Total current assets		630,985					775,840					630,985		775,840
Goodwill		742,702					742,029					742,702		742,029
Assets from risk management activities noncurrent		368					13,038					368		13,038
Deferred charges and other assets		288,310					337,891					288,310		337,891
Total assets		9,092,945					8,594,704					9,092,945		8,594,704
CAPITALIZATION AND LIABILITIES
Shareholders' equity		3,194,797					3,086,232					3,194,797		3,086,232		2,580,409	$ 2,359,243
Long-term debt		2,455,388					2,455,986					2,455,388		2,455,986
Total capitalization		5,650,185					5,542,218					5,650,185		5,542,218
Current liabilities
Short-term debt		457,927					196,695					457,927		196,695
Liabilities from risk management activities current		9,568					1,730					9,568		1,730
Other current liabilities		687,328					712,225					687,328		712,225
Intercompany payables		0					0					0		0
Total current liabilities		1,154,823					910,650					1,154,823		910,650
Deferred income taxes		1,411,315					1,286,616					1,411,315		1,286,616
Liabilities from risk management activities noncurrent		110,539					20,126					110,539		20,126
Regulatory cost of removal obligation		427,553					445,387					427,553		445,387
Pension and postretirement liabilities		287,373					340,963					287,373		340,963
Deferred credits and other liabilities		51,157					48,744					51,157		48,744
Total shareholders' equity and liabilities		$ 9,092,945					8,594,704					$ 9,092,945		8,594,704
Number Of Customers, Regulated Distribution | customers		3										3
Number Of Divisions, Regulated Distribution | regulated_gas_distributions_divisions		6										6
Number of States in which Entity Operates | state		8										8
Number of Operating Segments | segment												3
Reportable Subsegments [Member]
Segment Reporting Information Profit Loss [Abstract]
Operating revenues from external parties												$ 4,142,136		4,940,916		3,875,460
Revenue from External Customers by Products and Services Table [Abstract]
Operating revenues from external parties												4,142,136		4,940,916		3,875,460
Intersubsegment Eliminations [Member]
Segment Reporting Information Profit Loss [Abstract]
Operating revenues from external parties												0		0		0
Revenue from External Customers by Products and Services Table [Abstract]
Operating revenues from external parties												0		0		0
Regulated Distribution Segment [Member]
Segment Reporting Information Profit Loss [Abstract]
Operating revenues from external parties												2,757,585		3,056,212		2,394,418
Operating revenues		$ 369,656		416,794	1,130,613	846,772	409,014		517,707	1,290,960	843,865	2,763,835		3,061,546		2,399,493
Purchased gas cost												1,526,258		1,885,031		1,318,257
Gross profit												1,237,577		1,176,515		1,081,236
Operating expenses
Operation and maintenance												388,486		387,228		375,188
Depreciation and amortization												223,048		208,376		195,581
Taxes, other than income												205,894		196,343		167,374
Total operating expenses												817,428		791,947		738,143
Operating income												420,149		384,568		343,093
Miscellaneous income (expense), net												(377)		(381)		2,535
Interest charges												84,132		94,918		98,296
Income (loss) before income taxes												335,640		289,269		247,332
Income tax expense												130,827		117,684		96,476
Income (loss) from continuing operations																150,856
Income from discontinued operations, net of tax																7,202
Gain (loss) on sale of discontinued operations, net of tax																5,649
Net income												204,813		171,585		163,707
Capital expenditures												680,961		584,065		528,599
Revenue from External Customers by Products and Services Table [Abstract]
Operating revenues from external parties												2,757,585		3,056,212		2,394,418
Operating revenues		369,656		416,794	1,130,613	846,772	409,014		517,707	1,290,960	843,865	2,763,835		3,061,546		2,399,493
ASSETS
Net property, plant and equipment		5,670,306					5,202,761					5,670,306		5,202,761
Investment in subsidaries		1,038,670					952,171					1,038,670		952,171
Current assets
Cash and cash equivalents		23,863					33,303					23,863		33,303
Assets from risk management activities current		378					23,102					378		23,102
Other current assets		426,270					490,408					426,270		490,408
Intercompany receivables		887,713					790,442					887,713		790,442
Total current assets		1,338,224					1,337,255					1,338,224		1,337,255
Goodwill		575,449					574,816					575,449		574,816
Assets from risk management activities noncurrent		368					13,038					368		13,038
Deferred charges and other assets		265,693					309,965					265,693		309,965
Total assets		8,888,710					8,390,006					8,888,710		8,390,006
CAPITALIZATION AND LIABILITIES
Shareholders' equity		3,194,797					3,086,232					3,194,797		3,086,232
Long-term debt		2,455,388					2,455,986					2,455,388		2,455,986
Total capitalization		5,650,185					5,542,218					5,650,185		5,542,218
Current liabilities
Short-term debt		782,927					522,695					782,927		522,695
Liabilities from risk management activities current		9,568					1,730					9,568		1,730
Other current liabilities		569,273					559,765					569,273		559,765
Intercompany payables		0					0					0		0
Total current liabilities		1,361,768					1,084,190					1,361,768		1,084,190
Deferred income taxes		1,008,091					913,260					1,008,091		913,260
Liabilities from risk management activities noncurrent		110,539					20,126					110,539		20,126
Regulatory cost of removal obligation		427,553					445,387					427,553		445,387
Pension and postretirement liabilities		287,373					340,963					287,373		340,963
Deferred credits and other liabilities		43,201					43,862					43,201		43,862
Total shareholders' equity and liabilities		8,888,710					8,390,006					8,888,710		8,390,006
Regulated Distribution Segment [Member] | Gas Sales Revenues [Member]
Segment Reporting Information Profit Loss [Abstract]
Operating revenues from external parties												2,662,258		2,964,456		2,316,137
Revenue from External Customers by Products and Services Table [Abstract]
Operating revenues from external parties												2,662,258		2,964,456		2,316,137
Regulated Distribution Segment [Member] | Gas Sales Revenues [Member] | Residential Customers [Member]
Segment Reporting Information Profit Loss [Abstract]
Operating revenues from external parties												1,761,689		1,933,099		1,512,495
Revenue from External Customers by Products and Services Table [Abstract]
Operating revenues from external parties												1,761,689		1,933,099		1,512,495
Regulated Distribution Segment [Member] | Gas Sales Revenues [Member] | Commercial Customers [Member]
Segment Reporting Information Profit Loss [Abstract]
Operating revenues from external parties												772,187		876,042		661,930
Revenue from External Customers by Products and Services Table [Abstract]
Operating revenues from external parties												772,187		876,042		661,930
Regulated Distribution Segment [Member] | Gas Sales Revenues [Member] | Industrial Customers [Member]
Segment Reporting Information Profit Loss [Abstract]
Operating revenues from external parties												74,981		90,536		81,155
Revenue from External Customers by Products and Services Table [Abstract]
Operating revenues from external parties												74,981		90,536		81,155
Regulated Distribution Segment [Member] | Gas Sales Revenues [Member] | Public Authority and Other Customers [Member]
Segment Reporting Information Profit Loss [Abstract]
Operating revenues from external parties												53,401		64,779		60,557
Revenue from External Customers by Products and Services Table [Abstract]
Operating revenues from external parties												53,401		64,779		60,557
Regulated Distribution Segment [Member] | Gas Transportation Revenues [Member]
Segment Reporting Information Profit Loss [Abstract]
Operating revenues from external parties												67,475		64,049		55,938
Revenue from External Customers by Products and Services Table [Abstract]
Operating revenues from external parties												67,475		64,049		55,938
Regulated Distribution Segment [Member] | Other Gas Revenues [Member]
Segment Reporting Information Profit Loss [Abstract]
Operating revenues from external parties												27,852		27,707		22,343
Revenue from External Customers by Products and Services Table [Abstract]
Operating revenues from external parties												27,852		27,707		22,343
Regulated Distribution Segment [Member] | Reportable Subsegments [Member]
Segment Reporting Information Profit Loss [Abstract]
Operating revenues from external parties												2,757,585		3,056,212		2,394,418
Revenue from External Customers by Products and Services Table [Abstract]
Operating revenues from external parties												2,757,585		3,056,212		2,394,418
Regulated Distribution Segment [Member] | Intersubsegment Eliminations [Member]
Segment Reporting Information Profit Loss [Abstract]
Operating revenues from external parties												6,250		5,334		5,075
Revenue from External Customers by Products and Services Table [Abstract]
Operating revenues from external parties												6,250		5,334		5,075
Regulated Pipeline Segment [Member]
Segment Reporting Information Profit Loss [Abstract]
Operating revenues from external parties												97,662		92,166		89,011
Operating revenues		97,807		97,008	91,730	83,567	86,314		87,189	73,615	71,341	370,112		318,459		268,900
Purchased gas cost												0		0		0
Gross profit												370,112		318,459		268,900
Operating expenses
Operation and maintenance												118,866		91,466		76,686
Depreciation and amortization												47,236		41,031		35,302
Taxes, other than income												22,743		13,143		17,059
Total operating expenses												188,845		145,640		129,047
Operating income												181,267		172,819		139,853
Miscellaneous income (expense), net												(1,243)		(3,181)		(2,285)
Interest charges												33,151		36,280		30,678
Income (loss) before income taxes												146,873		133,358		106,890
Income tax expense												52,211		47,167		38,630
Income (loss) from continuing operations																68,260
Income from discontinued operations, net of tax																0
Gain (loss) on sale of discontinued operations, net of tax																0
Net income												94,662		86,191		68,260
Capital expenditures												292,728		249,347		313,230
Revenue from External Customers by Products and Services Table [Abstract]
Operating revenues from external parties												97,662		92,166		89,011
Operating revenues		97,807		97,008	91,730	83,567	86,314		87,189	73,615	71,341	370,112		318,459		268,900
ASSETS
Net property, plant and equipment		1,706,449					1,464,572					1,706,449		1,464,572
Investment in subsidaries		0					0					0		0
Current assets
Cash and cash equivalents		0					0					0		0
Assets from risk management activities current		0					0					0		0
Other current assets		24,628					14,009					24,628		14,009
Intercompany receivables		0					0					0		0
Total current assets		24,628					14,009					24,628		14,009
Goodwill		132,542					132,502					132,542		132,502
Assets from risk management activities noncurrent		0					0					0		0
Deferred charges and other assets		17,288					21,826					17,288		21,826
Total assets		1,880,907					1,632,909					1,880,907		1,632,909
CAPITALIZATION AND LIABILITIES
Shareholders' equity		577,275					482,612					577,275		482,612
Long-term debt		0					0					0		0
Total capitalization		577,275					482,612					577,275		482,612
Current liabilities
Short-term debt		0					0					0		0
Liabilities from risk management activities current		0					0					0		0
Other current liabilities		29,780					24,790					29,780		24,790
Intercompany payables		867,409					763,635					867,409		763,635
Total current liabilities		897,189					788,425					897,189		788,425
Deferred income taxes		406,254					361,688					406,254		361,688
Liabilities from risk management activities noncurrent		0					0					0		0
Regulatory cost of removal obligation		0					0					0		0
Pension and postretirement liabilities		0					0					0		0
Deferred credits and other liabilities		189					184					189		184
Total shareholders' equity and liabilities		1,880,907					1,632,909					1,880,907		1,632,909
Regulated Pipeline Segment [Member] | Reportable Subsegments [Member]
Segment Reporting Information Profit Loss [Abstract]
Operating revenues from external parties												97,662		92,166		89,011
Revenue from External Customers by Products and Services Table [Abstract]
Operating revenues from external parties												97,662		92,166		89,011
Regulated Pipeline Segment [Member] | Intersubsegment Eliminations [Member]
Segment Reporting Information Profit Loss [Abstract]
Operating revenues from external parties												272,450		226,293		179,889
Revenue from External Customers by Products and Services Table [Abstract]
Operating revenues from external parties												272,450		226,293		179,889
Nonregulated Segment [Member]
Segment Reporting Information Profit Loss [Abstract]
Operating revenues from external parties												1,286,889		1,792,538		1,392,031
Operating revenues		292,830		278,769	438,322	462,288	407,161		465,485	758,215	436,431	1,472,209		2,067,292		1,587,914
Purchased gas cost												1,399,349		1,979,337		1,524,583
Gross profit												72,860		87,955		63,331
Operating expenses
Operation and maintenance												35,048		26,963		37,569
Depreciation and amortization												4,512		4,580		4,196
Taxes, other than income												3,321		2,450		2,639
Total operating expenses												42,881		33,993		44,404
Operating income												29,979		53,962		18,927
Miscellaneous income (expense), net												(760)		2,216		2,316
Interest charges												967		1,986		2,168
Income (loss) before income taxes												28,252		54,192		19,075
Income tax expense												12,652		22,151		7,493
Income (loss) from continuing operations																11,582
Income from discontinued operations, net of tax																0
Gain (loss) on sale of discontinued operations, net of tax																(355)
Net income												15,600		32,041		11,227
Capital expenditures												1,443		1,839		3,204
Revenue from External Customers by Products and Services Table [Abstract]
Operating revenues from external parties												1,286,889		1,792,538		1,392,031
Operating revenues		292,830		278,769	438,322	462,288	407,161		465,485	758,215	436,431	1,472,209		2,067,292		1,587,914
ASSETS
Net property, plant and equipment		53,825					58,573					53,825		58,573
Investment in subsidaries		(2,096)					(2,096)					(2,096)		(2,096)
Current assets
Cash and cash equivalents		4,790					8,955					4,790		8,955
Assets from risk management activities current		8,854	[2]				22,725	[3]				8,854	[2]	22,725	[3]
Other current assets		480,503					526,161					480,503		526,161
Intercompany receivables		0					0					0		0
Total current assets		494,147					557,841					494,147		557,841
Goodwill		34,711					34,711					34,711		34,711
Assets from risk management activities noncurrent		0					0					0		0
Deferred charges and other assets		5,329					6,100					5,329		6,100
Total assets		585,916					655,129					585,916		655,129
CAPITALIZATION AND LIABILITIES
Shareholders' equity		461,395					469,559					461,395		469,559
Long-term debt		0					0					0		0
Total capitalization		461,395					469,559					461,395		469,559
Current liabilities
Short-term debt		0					0					0		0
Liabilities from risk management activities current		0	[2]				0	[3]				0	[2]	0	[3]
Other current liabilities		99,480					142,397					99,480		142,397
Intercompany payables		20,304					26,807					20,304		26,807
Total current liabilities		119,784					169,204					119,784		169,204
Deferred income taxes		(3,030)					11,668					(3,030)		11,668
Liabilities from risk management activities noncurrent		0	[2]				0	[3]				0	[2]	0	[3]
Regulatory cost of removal obligation		0					0					0		0
Pension and postretirement liabilities		0					0					0		0
Deferred credits and other liabilities		7,767					4,698					7,767		4,698
Total shareholders' equity and liabilities		585,916					655,129					585,916		655,129
Nonregulated Segment [Member] | Reportable Subsegments [Member]
Segment Reporting Information Profit Loss [Abstract]
Operating revenues from external parties												1,286,889		1,792,538		1,392,031
Revenue from External Customers by Products and Services Table [Abstract]
Operating revenues from external parties												1,286,889		1,792,538		1,392,031
Nonregulated Segment [Member] | Intersubsegment Eliminations [Member]
Segment Reporting Information Profit Loss [Abstract]
Operating revenues from external parties												185,320		274,754		195,883
Revenue from External Customers by Products and Services Table [Abstract]
Operating revenues from external parties												185,320		274,754		195,883
Intersegment Elimination [Member]
Segment Reporting Information Profit Loss [Abstract]
Operating revenues		(103,391)		(106,170)	(120,597)	(133,862)	(113,455)		(127,211)	(157,936)	(107,779)	(464,020)		(506,381)		(380,847)
Purchased gas cost												(463,488)		(505,878)		(379,430)
Gross profit												(532)		(503)		(1,417)
Operating expenses
Operation and maintenance												(532)		(503)		(1,423)
Depreciation and amortization												0		0		0
Taxes, other than income												0		0		0
Total operating expenses												(532)		(503)		(1,423)
Operating income												0		0		6
Miscellaneous income (expense), net												(2,009)		(3,889)		(2,763)
Interest charges												(2,009)		(3,889)		(2,757)
Income (loss) before income taxes												0		0		0
Income tax expense												0		0		0
Income (loss) from continuing operations																0
Income from discontinued operations, net of tax																0
Gain (loss) on sale of discontinued operations, net of tax																0
Net income												0		0		0
Capital expenditures												0		0		0
Revenue from External Customers by Products and Services Table [Abstract]
Operating revenues		(103,391)		$ (106,170)	$ (120,597)	$ (133,862)	(113,455)		$ (127,211)	$ (157,936)	$ (107,779)	(464,020)		(506,381)		(380,847)
ASSETS
Net property, plant and equipment		0					0					0		0
Investment in subsidaries		(1,036,574)					(950,075)					(1,036,574)		(950,075)
Current assets
Cash and cash equivalents		0					0					0		0
Assets from risk management activities current		0					0					0		0
Other current assets		(338,301)					(342,823)					(338,301)		(342,823)
Intercompany receivables		(887,713)					(790,442)					(887,713)		(790,442)
Total current assets		(1,226,014)					(1,133,265)					(1,226,014)		(1,133,265)
Goodwill		0					0					0		0
Assets from risk management activities noncurrent		0					0					0		0
Deferred charges and other assets		0					0					0		0
Total assets		(2,262,588)					(2,083,340)					(2,262,588)		(2,083,340)
CAPITALIZATION AND LIABILITIES
Shareholders' equity		(1,038,670)					(952,171)					(1,038,670)		(952,171)
Long-term debt		0					0					0		0
Total capitalization		(1,038,670)					(952,171)					(1,038,670)		(952,171)
Current liabilities
Short-term debt		(325,000)					(326,000)					(325,000)		(326,000)
Liabilities from risk management activities current		0					0					0		0
Other current liabilities		(11,205)					(14,727)					(11,205)		(14,727)
Intercompany payables		(887,713)					(790,442)					(887,713)		(790,442)
Total current liabilities		(1,223,918)					(1,131,169)					(1,223,918)		(1,131,169)
Deferred income taxes		0					0					0		0
Liabilities from risk management activities noncurrent		0					0					0		0
Regulatory cost of removal obligation		0					0					0		0
Pension and postretirement liabilities		0					0					0		0
Deferred credits and other liabilities		0					0					0		0
Total shareholders' equity and liabilities		$ (2,262,588)					$ (2,083,340)					(2,262,588)		(2,083,340)
Intersegment Elimination [Member] | Reportable Subsegments [Member]
Segment Reporting Information Profit Loss [Abstract]
Operating revenues from external parties												0		0		0
Revenue from External Customers by Products and Services Table [Abstract]
Operating revenues from external parties												0		0		0
Intersegment Elimination [Member] | Intersubsegment Eliminations [Member]
Segment Reporting Information Profit Loss [Abstract]
Operating revenues from external parties												(464,020)		(506,381)		(380,847)
Revenue from External Customers by Products and Services Table [Abstract]
Operating revenues from external parties												$ (464,020)		$ (506,381)		$ (380,847)
[1]	Net property, plant and equipment includes plant acquisition adjustments of $(68.1) million and $(76.4) million at September 30, 2015 and 2014.
[2]	Includes $43.5 million of cash held on deposit to collateralize certain financial instruments. Of this amount, $34.6 million was used to offset current and noncurent risk management liabilities under master netting arrangements and the remaining $8.9 million is classified as current risk management assets.
[3]	Includes $25.8 million of cash held on deposit to collateralize certain financial instruments. Of this amount, $3.1 million was used to offset current and noncurrent risk management liabilities under master netting arrangements and the remaining $22.7 million is classified as current risk management assets.

Earnings Per Share (Details)

Earnings Per Share (Details) - USD ($) $ / shares in Units, $ in Thousands	Feb. 18, 2014	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2013	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2015
Basic Earnings per Share from Continuing Operations
Income from continuing operations										$ 315,075	$ 289,817	$ 230,698
Less: Income from continuing operations allocated to participating securities										626	711	775
Income from continuing operations available to common shareholders										$ 314,449	$ 289,106	$ 229,923
Basic weighted average shares outstanding (shares)										101,892,000	97,606,000	90,533,000
Income per share from continuing operations - basic (usd per share)										$ 3.09	$ 2.96	$ 2.54
Basic Earnings per Share from Discontinued Operations
Income from discontinued operations										$ 0	$ 0	$ 12,496
Less: Income from discontinued operations allocated to participating securities										0	0	42
Income from discontinued operations available to common shareholders										$ 0	$ 0	$ 12,454
Income (loss) from discontinued operations per share - Basic (usd per share)										$ 0	$ 0	$ 0.14
Net income per share — basic (usd per share)		$ 0.23	$ 0.55	$ 1.35	$ 0.96	$ 0.23	$ 0.45	$ 1.38	$ 0.95	$ 3.09	$ 2.96	$ 2.68
Diluted Earnings per Share from Continuing Operations
Effect of dilutive stock options and other shares										$ 0	$ 0	$ 5
Income (loss) from continuing operations available to common shareholders										$ 314,449	$ 289,106	$ 229,928
Additional dilutive stock options and other shares										0	2,000	1,178,000
Diluted weighted average shares outstanding (shares)										101,892,000	97,608,000	91,711,000
Income per share from continuing operations - diluted (usd per share)										$ 3.09	$ 2.96	$ 2.50
Diluted Earnings per Share from Discontinued Operations
Effect of dilutive stock options and other shares										$ 0	$ 0	$ 0
Income from discontinued operations available to common shareholders										$ 0	$ 0	$ 12,454
Additional dilutive stock options and other shares										0	2,000	1,178,000
Diluted weighted average shares outstanding										101,892,000	97,608,000	91,711,000
Income per share from discontinued operations - diluted (usd per share)										$ 0	$ 0	$ 0.14
Net income per share — diluted (usd per share)		$ 0.23	$ 0.55	$ 1.35	$ 0.96	$ 0.23	$ 0.45	$ 1.38	$ 0.95	$ 3.09	$ 2.96	$ 2.64
Earnings Per Share Diluted Other Disclosures Abstract
Anti-dilutive stock options excluded from computation of diluted earnings per share												0
Stock Issued During Period, Shares, New Issues	9,200,000
Shares Issued At Overallotment Option	1,200,000
Net proceeds from equity offering	$ 390,200									$ 0	$ 390,205	$ 0
Share Price	$ 44
Stock Repurchase Program [Abstract]
Stock Repurchased During Period, Shares													387,991
Stock Repurchased During Period, Value													$ 12,500
Summary Of Stock Option Activity [Abstract]
Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercisable, Number		0				0				0	0		0

Debt (Details)

Debt (Details) - USD ($)	Oct. 15, 2014	Feb. 18, 2014	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2013
Debt Instrument [Line Items]
Debt Instrument Carrying Amount			$ 2,460,000,000	$ 2,460,000,000
Debt Instrument Unamortized Discount			4,612,000	4,014,000
Long-term Debt, Excluding Current Maturities			2,455,388,000	2,455,986,000
Line Of Credit Facility [Line Items]
Line Of Credit Facility Maximum Borrowing Capacity			1,300,000,000
Long-term Debt, Other Disclosures [Abstract]
Commercial Paper			$ 457,900,000	$ 196,700,000
Commercial Paper Weighted Average Interest Rate			0.42%	0.23%
Debt and Equity Securities Authorized for Issuance			$ 1,750,000,000
Debt And Equity Securities Available For Issuance			845,000,000
Stock Issued During Period, Shares, New Issues		9,200,000
Net proceeds from equity offering		$ 390,200,000	0	$ 390,205,000	$ 0
Long-term Debt, Fiscal Year Maturity [Abstract]
2,016			0
2,017			250,000,000
2,018			0
2,019			450,000,000
2,020			0
Thereafter			1,760,000,000
Debt Instrument Carrying Amount			$ 2,460,000,000	$ 2,460,000,000
Required by Covenant [Member]
Line Of Credit Facility [Line Items]
Ratio of Total Debt to Total Capital			70.00%
Actual [Member]
Line Of Credit Facility [Line Items]
Ratio of Total Debt to Total Capital			49.00%
Regulated Operation [Member]
Line Of Credit Facility [Line Items]
Line Of Credit Facility Maximum Borrowing Capacity			$ 1,300,000,000
Regulated Operation [Member] | Five Year Unsecured Revolving Credit Agreement [Member]
Line Of Credit Facility [Line Items]
Line of Credit Facility, Maximum Borrowing Capacity with Accordion Feature			1,500,000,000
Unregulated Operation [Member]
Line Of Credit Facility [Line Items]
Line of Credit Facility, Remaining Borrowing Capacity			36,100,000
Minimum [Member] | Required by Covenant [Member]
Line Of Credit Facility [Line Items]
Excess of Debt			15,000,000
Maximum [Member] | Required by Covenant [Member]
Line Of Credit Facility [Line Items]
Excess of Debt			100,000,000
Unsecured Senior Notes Due 2014 [Member]
Debt Instrument [Line Items]
Debt Instrument Interest Rate Stated Percentage	4.95%			4.95%
Debt Instrument, Maturity Date				Oct. 15, 2014
Debt Instrument Carrying Amount	$ 500,000,000		0	$ 500,000,000
Extinguishment of Debt, Amount	500,000,000
Long-term Debt, Fiscal Year Maturity [Abstract]
Debt Instrument Carrying Amount	$ 500,000,000		$ 0	$ 500,000,000
Unsecured Senior Notes Due 2017 [Member]
Debt Instrument [Line Items]
Debt Instrument Interest Rate Stated Percentage			6.35%	6.35%
Debt Instrument, Maturity Date			Jun. 15, 2017	Jun. 15, 2017
Debt Instrument Carrying Amount			$ 250,000,000	$ 250,000,000
Long-term Debt, Fiscal Year Maturity [Abstract]
Debt Instrument Carrying Amount			$ 250,000,000	$ 250,000,000
Unsecured Senior Notes Due 2019 [Member]
Debt Instrument [Line Items]
Debt Instrument Interest Rate Stated Percentage			8.50%	8.50%
Debt Instrument, Maturity Date			Mar. 15, 2019	Mar. 15, 2019
Debt Instrument Carrying Amount			$ 450,000,000	$ 450,000,000
Long-term Debt, Fiscal Year Maturity [Abstract]
Debt Instrument Carrying Amount			$ 450,000,000	$ 450,000,000
Unsecured Senior Notes Due 2034 [Member]
Debt Instrument [Line Items]
Debt Instrument Interest Rate Stated Percentage			5.95%	5.95%
Debt Instrument, Maturity Date			Oct. 15, 2034	Oct. 15, 2034
Debt Instrument Carrying Amount			$ 200,000,000	$ 200,000,000
Long-term Debt, Fiscal Year Maturity [Abstract]
Debt Instrument Carrying Amount			$ 200,000,000	$ 200,000,000
Unsecured Senior Notes Due 2041 [Member]
Debt Instrument [Line Items]
Debt Instrument Interest Rate Stated Percentage			5.50%	5.50%
Debt Instrument, Maturity Date			Jun. 15, 2041	Jun. 15, 2041
Debt Instrument Carrying Amount			$ 400,000,000	$ 400,000,000
Long-term Debt, Fiscal Year Maturity [Abstract]
Debt Instrument Carrying Amount			$ 400,000,000	$ 400,000,000
Unsecured Senior Notes Due 2043 [Member]
Debt Instrument [Line Items]
Debt Instrument Interest Rate Stated Percentage			4.15%	4.15%
Debt Instrument, Maturity Date			Jan. 15, 2043	Jan. 15, 2043
Debt Instrument Carrying Amount			$ 500,000,000	$ 500,000,000
Long-term Debt, Fiscal Year Maturity [Abstract]
Debt Instrument Carrying Amount			$ 500,000,000	500,000,000
Unsecured Senior Notes Due 2044 [Member]
Debt Instrument [Line Items]
Debt Instrument Interest Rate Stated Percentage	4.125%		4.125%
Debt Instrument, Maturity Date			Oct. 15, 2044
Debt Instrument Carrying Amount	$ 500,000,000		$ 500,000,000	0
Debt Instrument Interest Rate Effective Percentage	4.086%
Net Proceeds From Issuance of Debt	$ 494,000,000
Long-term Debt, Fiscal Year Maturity [Abstract]
Debt Instrument Carrying Amount	$ 500,000,000		$ 500,000,000	$ 0
Medium Term Notes Due 2025 [Member]
Debt Instrument [Line Items]
Debt Instrument Interest Rate Stated Percentage			6.67%	6.67%
Debt Instrument, Maturity Date			Dec. 15, 2025	Dec. 15, 2025
Debt Instrument Carrying Amount			$ 10,000,000	$ 10,000,000
Long-term Debt, Fiscal Year Maturity [Abstract]
Debt Instrument Carrying Amount			$ 10,000,000	$ 10,000,000
Unsecured Debentures Due 2028 [Member]
Debt Instrument [Line Items]
Debt Instrument Interest Rate Stated Percentage			6.75%	6.75%
Debt Instrument, Maturity Date			Jul. 15, 2028	Jul. 15, 2028
Debt Instrument Carrying Amount			$ 150,000,000	$ 150,000,000
Long-term Debt, Fiscal Year Maturity [Abstract]
Debt Instrument Carrying Amount			150,000,000	$ 150,000,000
Commercial Paper [Member] | Regulated Operation [Member] | Five Year Unsecured Revolving Credit Agreement [Member]
Line Of Credit Facility [Line Items]
Line Of Credit Facility Maximum Borrowing Capacity			1,250,000,000
Uncommitted Revolving Credit Facility [Member] | Regulated Operation [Member] | Five Year Unsecured Revolving Credit Agreement [Member]
Line Of Credit Facility [Line Items]
Line Of Credit Facility Maximum Borrowing Capacity			1,250,000,000
Line Of Credit Facility Amount Outstanding			0
Line of Credit Facility, Remaining Borrowing Capacity			792,100,000
Line of Credit Facility, Accordion Feature			250,000,000
Uncommitted Revolving Credit Facility [Member] | Regulated Operation [Member] | Uncommitted Revolving Credit Facility and Promissory Note (AEH to AEC) [Member]
Line Of Credit Facility [Line Items]
Line Of Credit Facility Maximum Borrowing Capacity			500,000,000
Line Of Credit Facility Amount Outstanding			325,000,000
Uncommitted Revolving Credit Facility [Member] | Unregulated Operation [Member] | Uncommitted Revolving Credit Facility and Promissory Note (AEC to AEH) [Member]
Line Of Credit Facility [Line Items]
Line Of Credit Facility Maximum Borrowing Capacity			500,000,000
Line Of Credit Facility Amount Outstanding			$ 0
Debt Instrument, Basis Spread on Variable Rate			3.00%
Uncommitted Revolving Credit Facility [Member] | Unregulated Operation [Member] | $25 Million Uncommitted Facility [Member]
Line Of Credit Facility [Line Items]
Line Of Credit Facility Maximum Borrowing Capacity			$ 25,000,000
Uncommitted Revolving Credit Facility [Member] | Minimum [Member] | Regulated Operation [Member] | Five Year Unsecured Revolving Credit Agreement [Member]
Line Of Credit Facility [Line Items]
Debt Instrument, Basis Spread on Variable Rate			0.00%
Uncommitted Revolving Credit Facility [Member] | Maximum [Member] | Regulated Operation [Member] | Five Year Unsecured Revolving Credit Agreement [Member]
Line Of Credit Facility [Line Items]
Debt Instrument, Basis Spread on Variable Rate			1.25%
Unsecured Revolving Credit Note [Member] | Regulated Operation [Member] | $10 Million Revolving Credit Note [Member]
Line Of Credit Facility [Line Items]
Line Of Credit Facility Maximum Borrowing Capacity			$ 10,000,000
Line Of Credit Facility Amount Outstanding			$ 0
Debt Instrument, Basis Spread on Variable Rate			1.50%
Letters of Credit Outstanding, Amount			$ 5,900,000
Unsecured Revolving Credit Note [Member] | Unregulated Operation [Member] | $15 Million Revolving Credit Note [Member]
Line Of Credit Facility [Line Items]
Line Of Credit Facility Maximum Borrowing Capacity			15,000,000
Unsecured Loan Agreement [Member] | Regulated Operation [Member] | $25 Million Bank Loan Agreement [Member]
Line Of Credit Facility [Line Items]
Line Of Credit Facility Maximum Borrowing Capacity			25,000,000
Line Of Credit Facility Amount Outstanding			$ 0

Retirement and Post-Retiremen51

Retirement and Post-Retirement Employee Benefit Plans Defined Benefit Plans Disclosure (Details) - USD ($) $ in Thousands	Nov. 04, 2015	Oct. 08, 2015	Oct. 02, 2013	Apr. 02, 2013	Sep. 30, 2013	Mar. 31, 2013	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2013
Net Periodic Benefit Cost Not Yet Recognized, Recorded as Regulatory Assets [Abstract]
Unrecognized transition obligation							$ 82	$ 354
Unrecognized prior service cost							(6,259)	(8,095)
Unrecognized actuarial loss							110,714	151,745
Total unrecognized in net periodic cost							$ 104,537	144,004
Effect of One-Percentage Point Change in Assumed Health Care Cost Trend Rates
Remaining Recovery Period of Regulatory Assets for which No Return on Investment During Recovery Period is Provided							15 years
Subsequent Event, AEH 401K Merger [Member]
Subsequent Event [Line Items]
Subsequent Event, Date	Nov. 4, 2015
Subsequent Event, Description	the Atmos Energy Corporation Board of Directors voted to approve the merger of the assets and liabilities of the AEH 401K Profit-Sharing Plan with the Retirement Savings Plan, effective January 1, 2016 to improve administrative efficiency and reduce total costs.
Subsequent Event, Mortality Tables Update [Member]
Subsequent Event [Line Items]
Subsequent Event, Date		Oct. 8, 2015
Subsequent Event, Description		the Society of Actuaries issued an additional report related to mortality tables and the mortality improvement scale.  As of September 30, 2015, we updated our assumed mortality rates to incorporate both new sets of mortality tables issued by the Society of Actuaries.
Pension Plans, Defined Benefit [Member]
Net Periodic Benefit Cost Not Yet Recognized, Recorded as Regulatory Assets [Abstract]
Unrecognized transition obligation							$ 0	0
Unrecognized prior service cost							(1,735)	(1,927)
Unrecognized actuarial loss							120,948	109,767
Total unrecognized in net periodic cost							$ 119,213	$ 107,840
Defined Benefit Plan Weighted Average Assumptions Used In Calculating Net Periodic Benefit Cost Abstract
Discount rate							4.43%	4.95%	4.04%
Rate of compensation increase							3.50%	3.50%	3.50%
Expected return on plan assets							7.25%	7.25%	7.75%
Defined Benefit Plan Weighted Average Assumptions Used In Calculating Benefit Obligation Abstract
Discount rate							4.55%	4.43%
Rate of compensation increase							3.50%	3.50%
Expected return on plan assets							7.00%	7.25%
Accumulated benefit obligation							$ 485,921	$ 466,182
Defined Benefit Plan Change In Benefit Obligation Roll Forward
Benefit obligation at beginning of year			$ 455,799				493,594	455,799
Service cost							16,231	15,345	$ 17,754
Interest cost							21,850	22,330	19,334
Actuarial (gain) loss							7,420	26,611
Benefits paid							(30,496)	(24,519)
Plan amendments							0	(1,972)
Benefit obligation at end of year					$ 455,799		508,599	493,594	$ 455,799
Funded Status of Plan Reconciliation
Funded status							(57,667)	(58,827)
Unrecognized prior service cost							0	0
Unrecognized net loss							0	0
Net amount recognized							(57,667)	$ (58,827)
Estimated Future Benefits Payment, Total
Expected future benefit payments in year one, total							30,909
Expected future benefit payments in year two, total							31,805
Expected future benefit payments in year three, total							33,086
Expected future benefit payments in year four, total							34,712
Expected future benefit payments in year five, total							36,128
Expected future benefit payments in five fiscal years thereafter, total							$ 201,857
Pension Plans, Defined Benefit [Member] | Minimum [Member]
Effect of One-Percentage Point Change in Assumed Health Care Cost Trend Rates
Defined Benefit Plan, Investment Performance Review Period							3 years
Pension Plans, Defined Benefit [Member] | Maximum [Member]
Effect of One-Percentage Point Change in Assumed Health Care Cost Trend Rates
Defined Benefit Plan, Investment Performance Review Period							5 years
Pension Plans, Defined Benefit [Member] | Domestic Equity Securities [Member]
Defined Benefit Plan, Assets, Target Allocations [Abstract]
Defined Benefit Plan, Target Plan Asset Allocations Range Minimum							35.00%
Defined Benefit Plan, Target Plan Asset Allocations Range Maximum							55.00%
Defined Benefit Plan, Information about Plan Assets [Abstract]
Defined Benefit Plan, Actual Plan Asset Allocations							41.30%	44.90%
Pension Plans, Defined Benefit [Member] | International Equity Securities [Member]
Defined Benefit Plan, Assets, Target Allocations [Abstract]
Defined Benefit Plan, Target Plan Asset Allocations Range Minimum							10.00%
Defined Benefit Plan, Target Plan Asset Allocations Range Maximum							20.00%
Defined Benefit Plan, Information about Plan Assets [Abstract]
Defined Benefit Plan, Actual Plan Asset Allocations							14.90%	15.30%
Pension Plans, Defined Benefit [Member] | Fixed Income Securities [Member]
Defined Benefit Plan, Assets, Target Allocations [Abstract]
Defined Benefit Plan, Target Plan Asset Allocations Range Minimum							5.00%
Defined Benefit Plan, Target Plan Asset Allocations Range Maximum							30.00%
Defined Benefit Plan, Information about Plan Assets [Abstract]
Defined Benefit Plan, Actual Plan Asset Allocations							11.00%	9.70%
Pension Plans, Defined Benefit [Member] | Company Stock [Member]
Defined Benefit Plan, Assets, Target Allocations [Abstract]
Defined Benefit Plan, Target Plan Asset Allocations Range Minimum							0.00%
Defined Benefit Plan, Target Plan Asset Allocations Range Maximum							15.00%
Defined Benefit Plan, Information about Plan Assets [Abstract]
Defined Benefit Plan, Actual Plan Asset Allocations							15.20%	12.90%
Number of shares of Atmos Energy common stock in Master Trust							1,169,700	1,169,700
Amount of dividend income from Atmos Energy common stock in Master Trust							$ 1,800	$ 1,700
Pension Plans, Defined Benefit [Member] | Other Investment Assets [Member]
Defined Benefit Plan, Assets, Target Allocations [Abstract]
Defined Benefit Plan, Target Plan Asset Allocations Range Minimum							0.00%
Defined Benefit Plan, Target Plan Asset Allocations Range Maximum							20.00%
Defined Benefit Plan, Information about Plan Assets [Abstract]
Defined Benefit Plan, Actual Plan Asset Allocations							17.60%	17.20%
Pension Account Plan, Defined Benefit [Member]
Effect of One-Percentage Point Change in Assumed Health Care Cost Trend Rates
Defined Benefit Plan, Vesting Period							3 years
Supplemental Employee Retirement Plan [Member]
Net Periodic Benefit Cost Not Yet Recognized, Recorded as Regulatory Assets [Abstract]
Unrecognized transition obligation							$ 0	$ 0
Unrecognized prior service cost							0	0
Unrecognized actuarial loss							36,915	34,447
Total unrecognized in net periodic cost							$ 36,915	$ 34,447
Defined Benefit Plan Weighted Average Assumptions Used In Calculating Net Periodic Benefit Cost Abstract
Discount rate				4.21%	4.21%	4.04%	4.43%	4.95%	4.04%	[1]
Rate of compensation increase							3.50%	3.50%	3.50%
Defined Benefit Plan Weighted Average Assumptions Used In Calculating Benefit Obligation Abstract
Discount rate							4.55%	4.43%
Rate of compensation increase							3.50%	3.50%
Accumulated benefit obligation							$ 118,835	$ 106,276
Defined Benefit Plan Change In Benefit Obligation Roll Forward
Benefit obligation at beginning of year			117,080				113,219	117,080
Service cost							3,971	3,607	$ 3,039
Interest cost							4,943	4,966	4,755
Actuarial (gain) loss							4,811	9,468
Benefits paid							(4,551)	(5,085)
Settlements							0	(16,817)
Benefit obligation at end of year					$ 117,080		122,393	113,219	117,080
Funded Status of Plan Reconciliation
Funded status							(122,393)	(113,219)
Unrecognized prior service cost							0	0
Unrecognized net loss							0	0
Net amount recognized							(122,393)	$ (113,219)
Estimated Future Benefits Payment, Total
Expected future benefit payments in year one, total							21,857
Expected future benefit payments in year two, total							13,901
Expected future benefit payments in year three, total							12,807
Expected future benefit payments in year four, total							6,808
Expected future benefit payments in year five, total							4,454
Expected future benefit payments in five fiscal years thereafter, total							47,047
Effect of One-Percentage Point Change in Assumed Health Care Cost Trend Rates
Defined Benefit Plan, Description of Settlements and Curtailments								On April 1, 2013, due to the retirement of certain executives, we recognized a settlement loss of $3.2 million associated with the supplemental plans and revalued the net periodic pension cost for the remainder of fiscal 2013. The revaluation of the net periodic pension cost resulted in an increase in the discount rate, effective April 1, 2013, to 4.21 percent, which reduced our net periodic pension cost by approximately $0.1 million for the remainder of the fiscal year.
Settlements				$ 3,200			$ 0	$ 4,539	$ 3,160
Supplemental Executive Benefit Plan, Defined Benefit [Member]
Defined Benefit Plan Change In Benefit Obligation Roll Forward
Benefits paid			(16,800)
Effect of One-Percentage Point Change in Assumed Health Care Cost Trend Rates
Defined Benefit Plan, Percent of Covered Compensation							75.00%
Defined Benefit Plan, Description of Settlements and Curtailments							On October 2, 2013, due to the retirement of one of our executives, we recognized a settlement loss of $4.5 million associated with our SEBP and made a $16.8 million benefit payment.
Settlements			4,500
1998 Supplemental Executive Retirement Plan, Defined Benefit [Member]
Effect of One-Percentage Point Change in Assumed Health Care Cost Trend Rates
Defined Benefit Plan, Percent of Covered Compensation							60.00%
2009 Supplemental Executive Retirement Plan, Defined Benefit [Member]
Defined Benefit Plan Weighted Average Assumptions Used In Calculating Benefit Obligation Abstract
Interest crediting rate							4.69%
Effect of One-Percentage Point Change in Assumed Health Care Cost Trend Rates
Defined Benefit Plan, Vesting Period							3 years
Defined Benefit Plan, Age Attained							55 years
Defined Benefit Plan, Percent of Contributed Compensation							10.00%
Other Postretirement Benefit Plans, Defined Benefit [Member]
Net Periodic Benefit Cost Not Yet Recognized, Recorded as Regulatory Assets [Abstract]
Unrecognized transition obligation							$ 82	354
Unrecognized prior service cost							(4,524)	(6,168)
Unrecognized actuarial loss							(47,149)	7,531
Total unrecognized in net periodic cost							$ (51,591)	$ 1,717
Defined Benefit Plan Weighted Average Assumptions Used In Calculating Net Periodic Benefit Cost Abstract
Discount rate							4.43%	4.95%	4.04%
Expected return on plan assets							4.60%	4.60%	4.70%
Initial Trend							7.50%	8.00%	8.00%
Ultimate trend rate							5.00%	5.00%	5.00%
Ultimate trend rate reached in					2,019		2,020	2,020	2,019
Defined Benefit Plan Weighted Average Assumptions Used In Calculating Benefit Obligation Abstract
Discount rate							4.55%	4.43%
Expected return on plan assets							4.45%	4.60%
Initial trend rate							7.50%	7.50%
Ultimate trend rate							5.00%	5.00%
Ultimate trend reached in							2,021	2,020
Defined Benefit Plan Change In Benefit Obligation Roll Forward
Benefit obligation at beginning of year			$ 312,148				$ 315,118	$ 312,148
Service cost							15,583	16,784	$ 18,800
Interest cost							14,385	15,951	12,964
Plan participants' contributions							4,563	4,435
Actuarial (gain) loss							(69,962)	(18,963)
Benefits paid							(12,508)	(13,580)
Plan amendments							0	(1,657)
Benefit obligation at end of year					$ 312,148		267,179	315,118	$ 312,148
Funded Status of Plan Reconciliation
Funded status							(129,170)	(180,297)
Unrecognized prior service cost							0	0
Unrecognized transition obligation							0	0
Unrecognized net loss							0	0
Net amount recognized							(129,170)	$ (180,297)
Estimated company benefit payments
2,006							15,498
2,007							11,245
Estimated company benefit payments in year three							12,185
Estimated company benefit payments in year four							12,755
Estimated company benefit payments in year five							13,995
Estimated company benefit payments in five fiscal years thereafter							86,519
Estimated retiree benefit payments
Estimated retiree benefit payments in year one							2,382
Estimated retiree benefit payments in year two							2,677
Estimated retiree benefit payments in year three							2,980
Estimated retiree benefit payments in year four							3,324
Estimated retiree benefit payments in year five							3,766
Estimated retiree benefit payments in five fiscal years thereafter							26,363
Disclosure Of Expected Gross Prescription Drug Subsidy Receipts Abstract
Prescription drug subsidy receipts in year one							0
Prescription drug subsidy receipts in year two							0
Prescription drug subsidy receipts in year three							0
Prescription drug subsidy receipts in year four							0
Prescription drug subsidy receipts in year five							0
Prescription drug subsidy receipts in five fiscal years thereafter							0
Estimated Future Benefits Payment, Total
Expected future benefit payments in year one, total							17,880
Expected future benefit payments in year two, total							13,922
Expected future benefit payments in year three, total							15,165
Expected future benefit payments in year four, total							16,079
Expected future benefit payments in year five, total							17,761
Expected future benefit payments in five fiscal years thereafter, total							112,882
Effect of One-Percentage Point Change in Assumed Health Care Cost Trend Rates
Effect of One Percentage Point Increase on Service and Interest Cost Components							4,288
Effect of One Percentage Point Decrease on Service and Interest Cost Components							(3,426)
Effect of One Percentage Point Increase on Accumulated Postretirement Benefit Obligation							39,572
Effect of One Percentage Point Decrease on Accumulated Postretirement Benefit Obligation							$ (32,440)
Defined Benefit Plan, Employer Claims Paid							80.00%
Defined Benefit Plan, Employee Paid Claims							20.00%
Defined Benefit Plan, Percent Limit on Future Contributions							3.00%
Other Postretirement Benefit Plans, Defined Benefit [Member] | Minimum [Member]
Current Year Benefit Plan Contributions [Abstract]
Defined Benefit Plans, Estimated Future Employer Contributions in Next Fiscal Year							$ 30,000
Other Postretirement Benefit Plans, Defined Benefit [Member] | Maximum [Member]
Current Year Benefit Plan Contributions [Abstract]
Defined Benefit Plans, Estimated Future Employer Contributions in Next Fiscal Year							$ 40,000
Other Postretirement Benefit Plans, Defined Benefit [Member] | Diversified Investment Funds [Member]
Defined Benefit Plan, Information about Plan Assets [Abstract]
Defined Benefit Plan, Actual Plan Asset Allocations							97.50%	99.70%
Effect of One-Percentage Point Change in Assumed Health Care Cost Trend Rates
Defined Benefit Plan, Funds Available for Investment in Common Stock and Convertible Securities							75.00%
Other Postretirement Benefit Plans, Defined Benefit [Member] | Cash and Cash Equivalents [Member]
Defined Benefit Plan, Information about Plan Assets [Abstract]
Defined Benefit Plan, Actual Plan Asset Allocations							2.50%	0.30%
[1]	(1)The discount rate for the supplemental plans increased from 4.04% to 4.21% effective April 1, 2013 due to a settlement loss recorded in fiscal 2013.

Retirement and Post-Retiremen52

Retirement and Post-Retirement Employee Benefit Plans Fair Value Disclosures (Details) - USD ($) $ in Thousands		Sep. 30, 2015	Sep. 30, 2014
Schedule of Total Investments at Fair Value [Line Items]
Available-for-sale Securities		$ 74,200	$ 79,613
Fair Value Inputs Level 1 [Member]
Schedule of Total Investments at Fair Value [Line Items]
Available-for-sale Securities		40,619	44,014
Fair Value Inputs Level 2 [Member]
Schedule of Total Investments at Fair Value [Line Items]
Available-for-sale Securities	[1]	33,581	35,599
Fair Value Inputs Level 3 [Member]
Schedule of Total Investments at Fair Value [Line Items]
Available-for-sale Securities		0	0
Pension Plans, Defined Benefit [Member]
Schedule of Total Investments at Fair Value [Line Items]
Investments, Fair Value Disclosure		448,544	432,109
Fair value of accounts receivable		2,400	2,700
Pension Plans, Defined Benefit [Member] | Equity Securities [Member]
Schedule of Total Investments at Fair Value [Line Items]
Investments, Fair Value Disclosure		159,304	155,107
Pension Plans, Defined Benefit [Member] | Money Market Funds [Member]
Schedule of Total Investments at Fair Value [Line Items]
Investments, Fair Value Disclosure		11,787	11,226
Pension Plans, Defined Benefit [Member] | Registered Investment Companies, Domestic [Member]
Schedule of Total Investments at Fair Value [Line Items]
Investments, Fair Value Disclosure		33,312	33,266
Pension Plans, Defined Benefit [Member] | Registered Investment Companies, International [Member]
Schedule of Total Investments at Fair Value [Line Items]
Investments, Fair Value Disclosure		48,648	48,134
Pension Plans, Defined Benefit [Member] | Common Collective Trusts [Member]
Schedule of Total Investments at Fair Value [Line Items]
Investments, Fair Value Disclosure		93,081	91,792
Pension Plans, Defined Benefit [Member] | Mortgage-backed securities [Member]
Schedule of Total Investments at Fair Value [Line Items]
Investments, Fair Value Disclosure		14,359	12,520
Pension Plans, Defined Benefit [Member] | U.S. Treasuries [Member]
Schedule of Total Investments at Fair Value [Line Items]
Investments, Fair Value Disclosure		6,084	3,679
Pension Plans, Defined Benefit [Member] | Corporate Debt Securities [Member]
Schedule of Total Investments at Fair Value [Line Items]
Investments, Fair Value Disclosure		28,973	25,734
Pension Plans, Defined Benefit [Member] | Limited Partnership Interest [Member]
Schedule of Total Investments at Fair Value [Line Items]
Investments, Fair Value Disclosure		52,996	50,496
Pension Plans, Defined Benefit [Member] | Real Estate Investment [Member]
Schedule of Total Investments at Fair Value [Line Items]
Investments, Fair Value Disclosure			155
Pension Plans, Defined Benefit [Member] | Fair Value Inputs Level 1 [Member]
Schedule of Total Investments at Fair Value [Line Items]
Investments, Fair Value Disclosure		246,543	239,624
Pension Plans, Defined Benefit [Member] | Fair Value Inputs Level 1 [Member] | Equity Securities [Member]
Schedule of Total Investments at Fair Value [Line Items]
Investments, Fair Value Disclosure		159,304	155,107
Pension Plans, Defined Benefit [Member] | Fair Value Inputs Level 1 [Member] | Money Market Funds [Member]
Schedule of Total Investments at Fair Value [Line Items]
Investments, Fair Value Disclosure		0	0
Pension Plans, Defined Benefit [Member] | Fair Value Inputs Level 1 [Member] | Registered Investment Companies, Domestic [Member]
Schedule of Total Investments at Fair Value [Line Items]
Investments, Fair Value Disclosure		33,312	33,266
Pension Plans, Defined Benefit [Member] | Fair Value Inputs Level 1 [Member] | Registered Investment Companies, International [Member]
Schedule of Total Investments at Fair Value [Line Items]
Investments, Fair Value Disclosure		48,648	48,134
Pension Plans, Defined Benefit [Member] | Fair Value Inputs Level 1 [Member] | Common Collective Trusts [Member]
Schedule of Total Investments at Fair Value [Line Items]
Investments, Fair Value Disclosure		0	0
Pension Plans, Defined Benefit [Member] | Fair Value Inputs Level 1 [Member] | Mortgage-backed securities [Member]
Schedule of Total Investments at Fair Value [Line Items]
Investments, Fair Value Disclosure		0	0
Pension Plans, Defined Benefit [Member] | Fair Value Inputs Level 1 [Member] | U.S. Treasuries [Member]
Schedule of Total Investments at Fair Value [Line Items]
Investments, Fair Value Disclosure		5,279	3,117
Pension Plans, Defined Benefit [Member] | Fair Value Inputs Level 1 [Member] | Corporate Debt Securities [Member]
Schedule of Total Investments at Fair Value [Line Items]
Investments, Fair Value Disclosure		0	0
Pension Plans, Defined Benefit [Member] | Fair Value Inputs Level 1 [Member] | Limited Partnership Interest [Member]
Schedule of Total Investments at Fair Value [Line Items]
Investments, Fair Value Disclosure		0	0
Pension Plans, Defined Benefit [Member] | Fair Value Inputs Level 1 [Member] | Real Estate Investment [Member]
Schedule of Total Investments at Fair Value [Line Items]
Investments, Fair Value Disclosure			0
Pension Plans, Defined Benefit [Member] | Fair Value Inputs Level 2 [Member]
Schedule of Total Investments at Fair Value [Line Items]
Investments, Fair Value Disclosure		202,001	192,330
Pension Plans, Defined Benefit [Member] | Fair Value Inputs Level 2 [Member] | Equity Securities [Member]
Schedule of Total Investments at Fair Value [Line Items]
Investments, Fair Value Disclosure		0	0
Pension Plans, Defined Benefit [Member] | Fair Value Inputs Level 2 [Member] | Money Market Funds [Member]
Schedule of Total Investments at Fair Value [Line Items]
Investments, Fair Value Disclosure		11,787	11,226
Pension Plans, Defined Benefit [Member] | Fair Value Inputs Level 2 [Member] | Registered Investment Companies, Domestic [Member]
Schedule of Total Investments at Fair Value [Line Items]
Investments, Fair Value Disclosure		0	0
Pension Plans, Defined Benefit [Member] | Fair Value Inputs Level 2 [Member] | Registered Investment Companies, International [Member]
Schedule of Total Investments at Fair Value [Line Items]
Investments, Fair Value Disclosure		0	0
Pension Plans, Defined Benefit [Member] | Fair Value Inputs Level 2 [Member] | Common Collective Trusts [Member]
Schedule of Total Investments at Fair Value [Line Items]
Investments, Fair Value Disclosure		93,081	91,792
Pension Plans, Defined Benefit [Member] | Fair Value Inputs Level 2 [Member] | Mortgage-backed securities [Member]
Schedule of Total Investments at Fair Value [Line Items]
Investments, Fair Value Disclosure		14,359	12,520
Pension Plans, Defined Benefit [Member] | Fair Value Inputs Level 2 [Member] | U.S. Treasuries [Member]
Schedule of Total Investments at Fair Value [Line Items]
Investments, Fair Value Disclosure		805	562
Pension Plans, Defined Benefit [Member] | Fair Value Inputs Level 2 [Member] | Corporate Debt Securities [Member]
Schedule of Total Investments at Fair Value [Line Items]
Investments, Fair Value Disclosure		28,973	25,734
Pension Plans, Defined Benefit [Member] | Fair Value Inputs Level 2 [Member] | Limited Partnership Interest [Member]
Schedule of Total Investments at Fair Value [Line Items]
Investments, Fair Value Disclosure		52,996	50,496
Pension Plans, Defined Benefit [Member] | Fair Value Inputs Level 2 [Member] | Real Estate Investment [Member]
Schedule of Total Investments at Fair Value [Line Items]
Investments, Fair Value Disclosure			0
Pension Plans, Defined Benefit [Member] | Fair Value Inputs Level 3 [Member]
Schedule of Total Investments at Fair Value [Line Items]
Investments, Fair Value Disclosure		0	155
Pension Plans, Defined Benefit [Member] | Fair Value Inputs Level 3 [Member] | Equity Securities [Member]
Schedule of Total Investments at Fair Value [Line Items]
Investments, Fair Value Disclosure		0	0
Pension Plans, Defined Benefit [Member] | Fair Value Inputs Level 3 [Member] | Money Market Funds [Member]
Schedule of Total Investments at Fair Value [Line Items]
Investments, Fair Value Disclosure		0	0
Pension Plans, Defined Benefit [Member] | Fair Value Inputs Level 3 [Member] | Registered Investment Companies, Domestic [Member]
Schedule of Total Investments at Fair Value [Line Items]
Investments, Fair Value Disclosure		0	0
Pension Plans, Defined Benefit [Member] | Fair Value Inputs Level 3 [Member] | Registered Investment Companies, International [Member]
Schedule of Total Investments at Fair Value [Line Items]
Investments, Fair Value Disclosure		0	0
Pension Plans, Defined Benefit [Member] | Fair Value Inputs Level 3 [Member] | Common Collective Trusts [Member]
Schedule of Total Investments at Fair Value [Line Items]
Investments, Fair Value Disclosure		0	0
Pension Plans, Defined Benefit [Member] | Fair Value Inputs Level 3 [Member] | Mortgage-backed securities [Member]
Schedule of Total Investments at Fair Value [Line Items]
Investments, Fair Value Disclosure		0	0
Pension Plans, Defined Benefit [Member] | Fair Value Inputs Level 3 [Member] | U.S. Treasuries [Member]
Schedule of Total Investments at Fair Value [Line Items]
Investments, Fair Value Disclosure		0	0
Pension Plans, Defined Benefit [Member] | Fair Value Inputs Level 3 [Member] | Corporate Debt Securities [Member]
Schedule of Total Investments at Fair Value [Line Items]
Investments, Fair Value Disclosure		0	0
Pension Plans, Defined Benefit [Member] | Fair Value Inputs Level 3 [Member] | Limited Partnership Interest [Member]
Schedule of Total Investments at Fair Value [Line Items]
Investments, Fair Value Disclosure		0	0
Pension Plans, Defined Benefit [Member] | Fair Value Inputs Level 3 [Member] | Real Estate Investment [Member]
Schedule of Total Investments at Fair Value [Line Items]
Investments, Fair Value Disclosure			155
Supplemental Employee Retirement Plan [Member]
Schedule of Total Investments at Fair Value [Line Items]
Available-for-sale Securities		41,700	46,200
Other Postretirement Benefit Plans, Defined Benefit [Member]
Schedule of Total Investments at Fair Value [Line Items]
Investments, Fair Value Disclosure		138,009	134,821
Other Postretirement Benefit Plans, Defined Benefit [Member] | Money Market Funds [Member]
Schedule of Total Investments at Fair Value [Line Items]
Investments, Fair Value Disclosure		3,486	434
Other Postretirement Benefit Plans, Defined Benefit [Member] | Registered Investment Companies, Domestic [Member]
Schedule of Total Investments at Fair Value [Line Items]
Investments, Fair Value Disclosure		123,921	124,006
Other Postretirement Benefit Plans, Defined Benefit [Member] | Registered Investment Companies, International [Member]
Schedule of Total Investments at Fair Value [Line Items]
Investments, Fair Value Disclosure		10,602	10,381
Other Postretirement Benefit Plans, Defined Benefit [Member] | Fair Value Inputs Level 1 [Member]
Schedule of Total Investments at Fair Value [Line Items]
Investments, Fair Value Disclosure		134,523	134,387
Other Postretirement Benefit Plans, Defined Benefit [Member] | Fair Value Inputs Level 1 [Member] | Money Market Funds [Member]
Schedule of Total Investments at Fair Value [Line Items]
Investments, Fair Value Disclosure		0	0
Other Postretirement Benefit Plans, Defined Benefit [Member] | Fair Value Inputs Level 1 [Member] | Registered Investment Companies, Domestic [Member]
Schedule of Total Investments at Fair Value [Line Items]
Investments, Fair Value Disclosure		123,921	124,006
Other Postretirement Benefit Plans, Defined Benefit [Member] | Fair Value Inputs Level 1 [Member] | Registered Investment Companies, International [Member]
Schedule of Total Investments at Fair Value [Line Items]
Investments, Fair Value Disclosure		10,602	10,381
Other Postretirement Benefit Plans, Defined Benefit [Member] | Fair Value Inputs Level 2 [Member]
Schedule of Total Investments at Fair Value [Line Items]
Investments, Fair Value Disclosure		3,486	434
Other Postretirement Benefit Plans, Defined Benefit [Member] | Fair Value Inputs Level 2 [Member] | Money Market Funds [Member]
Schedule of Total Investments at Fair Value [Line Items]
Investments, Fair Value Disclosure		3,486	434
Other Postretirement Benefit Plans, Defined Benefit [Member] | Fair Value Inputs Level 2 [Member] | Registered Investment Companies, Domestic [Member]
Schedule of Total Investments at Fair Value [Line Items]
Investments, Fair Value Disclosure		0	0
Other Postretirement Benefit Plans, Defined Benefit [Member] | Fair Value Inputs Level 2 [Member] | Registered Investment Companies, International [Member]
Schedule of Total Investments at Fair Value [Line Items]
Investments, Fair Value Disclosure		0	0
Other Postretirement Benefit Plans, Defined Benefit [Member] | Fair Value Inputs Level 3 [Member]
Schedule of Total Investments at Fair Value [Line Items]
Investments, Fair Value Disclosure		0	0
Other Postretirement Benefit Plans, Defined Benefit [Member] | Fair Value Inputs Level 3 [Member] | Money Market Funds [Member]
Schedule of Total Investments at Fair Value [Line Items]
Investments, Fair Value Disclosure		0	0
Other Postretirement Benefit Plans, Defined Benefit [Member] | Fair Value Inputs Level 3 [Member] | Registered Investment Companies, Domestic [Member]
Schedule of Total Investments at Fair Value [Line Items]
Investments, Fair Value Disclosure		0	0
Other Postretirement Benefit Plans, Defined Benefit [Member] | Fair Value Inputs Level 3 [Member] | Registered Investment Companies, International [Member]
Schedule of Total Investments at Fair Value [Line Items]
Investments, Fair Value Disclosure		$ 0	$ 0
[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.

Retirement and Post-Retiremen53

Retirement and Post-Retirement Employee Benefit Plans Fair Value of Plan Assets (Details) - USD ($) $ in Thousands	12 Months Ended
	Sep. 30, 2015	Sep. 30, 2014
Pension Plans, Defined Benefit [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets at beginning of year	$ 434,767	$ 396,887
Actual return on plan assets	8,661	35,289
Employer contributions	38,000	27,110
Benefits paid	(30,496)	(24,519)
Fair value of plan assets at end of year	450,932	434,767
Supplemental Employee Retirement Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets at beginning of year	0	0
Employer contributions	4,551	21,902
Benefits paid	(4,551)	(5,085)
Settlements	0	(16,817)
Fair value of plan assets at end of year	0	0
Other Postretirement Benefit Plans, Defined Benefit [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets at beginning of year	134,821	106,413
Actual return on plan assets	(8,851)	14,003
Employer contributions	19,984	23,550
Plan participants' contributions	4,563	4,435
Benefits paid	(12,508)	(13,580)
Fair value of plan assets at end of year	$ 138,009	$ 134,821

Retirement and Post-Retiremen54

Retirement and Post-Retirement Employee Benefit Plans Net Periodic Cost (Details) - USD ($) $ in Thousands	Apr. 02, 2013	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2013
Pension Plans, Defined Benefit [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost		$ 16,231	$ 15,345	$ 17,754
Interest cost		21,850	22,330	19,334
Expected return on assets		(25,744)	(23,601)	(22,955)
Amortization of prior service cost		(192)	(136)	(141)
Recognized actuarial loss		13,322	13,777	19,066
Net periodic pension cost		25,467	27,715	33,058
Supplemental Employee Retirement Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost		3,971	3,607	3,039
Interest cost		4,943	4,966	4,755
Amortization of transition asset		0	0	0
Amortization of prior service cost		0	0	0
Recognized actuarial loss		2,343	1,948	2,918
Settlements	$ 3,200	0	4,539	3,160
Net periodic pension cost		11,257	15,060	13,872
Effect on Net Periodic Cost Due To Discount Rate Change, Remaining Fiscal Year	$ (100)
Other Postretirement Benefit Plans, Defined Benefit [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost		15,583	16,784	18,800
Interest cost		14,385	15,951	12,964
Expected return on assets		(6,431)	(5,167)	(3,988)
Amortization of transition asset		272	274	1,081
Amortization of prior service cost		(1,644)	(1,450)	(1,450)
Recognized actuarial loss		0	631	4,196
Net periodic pension cost		$ 22,165	$ 27,023	$ 31,603

Retirement and Post-Retiremen55

Retirement and Post-Retirement Employee Benefit Plans Defined Contribution Plans (Details) - USD ($) $ in Millions	12 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2013
Retirement Savings Plan [Member]
Defined Contribution Plan Disclosure [Line Items]
Defined Contribution Plan, Maximum Annual Contributions Per Employee, Percent	65.00%
Defined Contribution Plan, Deferral Rate	4.00%
Defined Contribution Plan, Employer Matching Contribution, Percent of Employees' Gross Pay	4.00%
Defined Contribution Plan, Employer Contribution Service Period Until Eligibility	1 year
Defined Contribution Plan, Employer Matching Contribution, Percent of Match	100.00%
Defined Contribution Plan, Employer Discretionary Contribution Percent	4.00%
Defined Contribution Plan, Percent of Equity Securities Issued by Employer and Related Parties Included in Plan Assets	4.30%	4.50%
Defined Contribution Plan, Vesting Period	3 years
AEH 401K Profit-Sharing Plan [Member]
Defined Contribution Plan Disclosure [Line Items]
Defined Contribution Plan, Maximum Annual Contributions Per Employee, Percent	75.00%
Defined Contribution Plan, Employer Discretionary Contribution Amount	$ 1.1	$ 1.4	$ 1.1
Defined Contribution Plan, Vesting Period	3 years
Defined Contribution Plan, Employer Safe Harbor Contribution, Percent	4.00%
Retirement Savings Plan and Union 401K Plan [Member]
Defined Contribution Plan Disclosure [Line Items]
Defined Contribution Plan, Cost Recognized	$ 11.5	$ 10.9	$ 10.4

Stock and Other Compensation 56

Stock and Other Compensation Plans (Details) - USD ($)	12 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2013
Share-based Compensation, Allocation and Classification in Financial Statements [Abstract]
Stock Based Compensation Expense	$ 27,500,000	$ 25,500,000	$ 17,800,000
Authorized Shares	8,700,000
Share-based Compensation Arrangement by Share-based Payment Award, Number of Shares Available	308,582
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Additional Disclosures [Abstract]
Nonvested at beginning of year-Shares	988,637	1,052,844	1,262,582
Nonvested at beginning of year-Weighted Average	$ 42.22	$ 36.20	$ 32.46
Granted-Shares	444,543	464,438	473,775
Granted-Weighted Average	$ 50.50	$ 45.05	$ 40.48
Vested-Shares	(551,688)	(524,532)	(657,795)
Vested-Weighted Average	$ 39.28	$ 32.67	$ 32.20
Forfeited-Shares	(3,388)	(4,113)	(25,718)
Forfeited-Weighted Average	$ 48.55	$ 39	$ 33.42
Nonvested at end of year-Shares	878,104	988,637	1,052,844
Nonvested at end of year-Weighted Average	$ 48.24	$ 42.22	$ 36.20
Unrecognized Compensation Cost	$ 10,200,000
Weighted Average Recognized Period	1 year 6 months
Fair Value Restricted Stock Vested	$ 21,700,000	$ 17,100,000	$ 21,200,000
Direct Stock Purchse Plan [Abstract]
Minimum Initial Investment for Direct Stock Purchase Plan	1,250
Minimum Continuing Investment for Direct Stock Purchase Plan	25
Annual Maximum Investment for Direct Stock Purchase Plan	$ 100,000

Details of Selected Consolida57

Details of Selected Consolidated Balance Sheet Captions (Details) - USD ($) $ in Thousands		12 Months Ended
		Sep. 30, 2015		Sep. 30, 2014
Accounts, Notes, Loans and Financing Receivable [Line Items]
Accounts Receivable, Gross, Current		$ 310,443		$ 367,392
Less: allowance for doubtful accounts		(15,283)		(23,992)
Net accounts receivable		295,160		343,400
Schedule of Other Current Assets [Abstract]
Assets from risk management activities current		9,232		45,827
Deferred gas cost		9,715		20,069
Taxes receivable		4,479		5,481
Prepaid expenses		27,734		25,039
Materials and supplies		12,587		5,704
Other		6,822		9,145
Total other current assets		70,569		111,265
Public Utilities, Property, Plant and Equipment [Abstract]
Production plant		131		4,821
Storage plant		286,011		275,579
Transmission plant		1,844,117		1,622,846
Distribution plant		6,019,001		5,522,794
General plant		769,311		735,223
Intangible plant		41,131		38,858
Property, plant and equipment		8,959,702		8,200,121
Construction in progress		280,398		247,579
Total property, plant and equipment and construction in progress		9,240,100		8,447,700
Less accumulated depreciation and amortization		(1,809,520)		(1,721,794)
Net property, plant and equipment	[1]	7,430,580		6,725,906
Plant acquisition adjustments		(68,100)		(76,400)
Goodwill [Line Items]
Goodwill, Beginning Balance		742,029
Goodwill, Other Changes	[2]	673
Goodwill, Ending Balance		742,702
Schedule of Other Noncurrent Assets [Abstract]
Marketable securities		74,200		79,613
Regulatory assets		182,573		230,240
Deferred financing costs		17,873		13,698
Assets from risk management activities noncurrent		368		13,038
Other		13,664		14,340
Total		288,678		350,929
Schedule of Accounts Payable and Accrued Liabilities [Abstract]
Trade accounts payable		78,534		77,860
Accrued gas payable		119,825		179,425
Accrued liabilities		40,583		50,801
Total		238,942		308,086
Schedule of Other Current Liabilities [Abstract]
Customer deposits		100,232		82,085
Accrued employee costs		47,602		46,445
Deferred gas costs		28,100		35,063
Accrued interest		34,914		36,768
Liabilities from risk management activities current		9,568		1,730
Taxes payable		93,674		77,601
Pension and postretirement obligations		21,857		11,380
Regulatory cost of removal accrual		56,123		45,061
Current deferred tax liability		55,918		48,751
Other		9,966		20,985
Total		457,954		405,869
Schedule of Other Noncurrent Liabilities [Abstract]
Customer advances for construction		9,316		9,883
Regulatory liabilities		3,693		4,472
Asset retirement obligation		9,063		10,508
Liabilities from risk management activities noncurrent		110,539		20,126
Other		29,085		23,881
Total		161,696		68,870
Regulated Distribution Segment [Member]
Schedule of Other Current Assets [Abstract]
Assets from risk management activities current		378		23,102
Public Utilities, Property, Plant and Equipment [Abstract]
Net property, plant and equipment		5,670,306		5,202,761
Goodwill [Line Items]
Goodwill, Beginning Balance		574,816
Goodwill, Other Changes	[2]	633
Goodwill, Ending Balance		575,449
Schedule of Other Noncurrent Assets [Abstract]
Assets from risk management activities noncurrent		368		13,038
Schedule of Other Current Liabilities [Abstract]
Liabilities from risk management activities current		9,568		1,730
Schedule of Other Noncurrent Liabilities [Abstract]
Liabilities from risk management activities noncurrent		110,539		20,126
Regulated Pipeline Segment [Member]
Schedule of Other Current Assets [Abstract]
Assets from risk management activities current		0		0
Public Utilities, Property, Plant and Equipment [Abstract]
Net property, plant and equipment		1,706,449		1,464,572
Goodwill [Line Items]
Goodwill, Beginning Balance		132,502
Goodwill, Other Changes	[2]	40
Goodwill, Ending Balance		132,542
Schedule of Other Noncurrent Assets [Abstract]
Assets from risk management activities noncurrent		0		0
Schedule of Other Current Liabilities [Abstract]
Liabilities from risk management activities current		0		0
Schedule of Other Noncurrent Liabilities [Abstract]
Liabilities from risk management activities noncurrent		0		0
Nonregulated Segment [Member]
Schedule of Other Current Assets [Abstract]
Assets from risk management activities current		8,854	[3]	22,725	[4]
Public Utilities, Property, Plant and Equipment [Abstract]
Net property, plant and equipment		53,825		58,573
Goodwill [Line Items]
Goodwill, Beginning Balance		34,711
Goodwill, Other Changes	[2]	0
Goodwill, Ending Balance		34,711
Schedule of Other Noncurrent Assets [Abstract]
Assets from risk management activities noncurrent		0		0
Schedule of Other Current Liabilities [Abstract]
Liabilities from risk management activities current		0	[3]	0	[4]
Schedule of Other Noncurrent Liabilities [Abstract]
Liabilities from risk management activities noncurrent		0	[3]	0	[4]
Trade Accounts Receivable [Member] | Billed Revenues [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Accounts Receivable, Gross, Current		204,585		262,937
Trade Accounts Receivable [Member] | Unbilled Revenues [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Accounts Receivable, Gross, Current		65,008		62,484
Other Accounts Receivable [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Accounts Receivable, Gross, Current		$ 40,850		$ 41,971
[1]	Net property, plant and equipment includes plant acquisition adjustments of $(68.1) million and $(76.4) million at September 30, 2015 and 2014.
[2]	We annually adjust certain deferred taxes recorded in connection with acquisitions completed in fiscal 2001 and fiscal 2004, which resulted in an increase to goodwill and net deferred tax liabilities of $0.7 million for fiscal 2015.
[3]	Includes $43.5 million of cash held on deposit to collateralize certain financial instruments. Of this amount, $34.6 million was used to offset current and noncurent risk management liabilities under master netting arrangements and the remaining $8.9 million is classified as current risk management assets.
[4]	Includes $25.8 million of cash held on deposit to collateralize certain financial instruments. Of this amount, $3.1 million was used to offset current and noncurrent risk management liabilities under master netting arrangements and the remaining $22.7 million is classified as current risk management assets.

Leases (Details)

Leases (Details) - USD ($) $ in Thousands	12 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2013
Operating Leases, Future Minimum Payments Due, Fiscal Year Maturity [Abstract]
2,016	$ 16,475
2,017	16,639
2,018	16,490
2,019	15,207
2,020	14,251
Operating Leases, Thereafter	61,651
Total Operating Lease Payments	140,713
Lease and Rental Expense	$ 32,500	$ 31,700	$ 32,400
Minimum [Member]
Operating Leased Assets [Line Items]
Lessee Leasing Arrangements, Operating Leases, Term of Contract	1 year
Maximum [Member]
Operating Leased Assets [Line Items]
Lessee Leasing Arrangements, Operating Leases, Term of Contract	19 years

Commitments and Contingencies59

Commitments and Contingencies (Details) $ in Thousands	12 Months Ended
	Sep. 30, 2015USD ($)$ / McfMMcf	Sep. 30, 2014USD ($)	Sep. 30, 2013USD ($)
Estimated Contractual Demand Fees [Abstract]
2,016	$ 7,843
2,017	3,522
2,018	1,966
2,019	426
2,020	398
Thereafter	1,101
Total Estimated Contractual Demand Fees	15,256
Mid-Tex Division [Member]
Long Term Purchase Commitment [Line Items]
Significant Purchase Commitment, Amount	113,300	$ 140,900	$ 89,000
Nonregulated Segment [Member]
Long Term Purchase Commitment [Line Items]
Significant Purchase Commitment, Amount	$ 1,141,300	$ 1,687,500	$ 1,246,100
Inventories Under Indexed Contracts [Member] | Mid-Tex Division [Member]
Long Term Purchase Commitment [Line Items]
Long Term Purchase Commitment Minimum Quantity Required Within One Year | MMcf	36,600
Long Term Purchase Commitment Minimum Quantity Required One To Three Years | MMcf	26,800
Inventories Under Indexed Contracts [Member] | Nonregulated Segment [Member]
Long Term Purchase Commitment [Line Items]
Long Term Purchase Commitment Minimum Quantity Required Within One Year | MMcf	101,900
Long Term Purchase Commitment Minimum Quantity Required One To Three Years | MMcf	16,000
Long Term Purchase Commitment Minimum Quantity Required After Three Years | MMcf	500
Inventories Under Fixed Price Contracts [Member] | Nonregulated Segment [Member]
Long Term Purchase Commitment [Line Items]
Long Term Purchase Commitment Minimum Quantity Required Within One Year | MMcf	3,000
Purchase Commitment Amount Minimum | $ / Mcf	2.32
Purchase Commitment Amount Maximum | $ / Mcf	3.23

Income Taxes (Details)

Income Taxes (Details) - USD ($) $ in Thousands	12 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2013
Current income taxes
Federal	$ 0	$ 0	$ 0
State	7,251	5,527	8,178
Deferred income taxes
Federal	175,897	169,106	124,836
State	12,548	12,375	9,605
Investment tax credits	(6)	(6)	(20)
Income tax expense	195,690	187,002	142,599
Deferred tax assets
Employee benefit plans	121,619	116,157
Interest rate agreements	51,067	10,565
Tax net operating loss carryforwards	313,224	236,626
Tax credit carryforward	22,281	21,614
Other	36,695	28,849
Total deferred tax assets	544,886	413,811
Valuation allowance	(10,872)	(6,969)
Net deferred tax assets	534,014	406,842
Deferred tax liabilities
Difference in net book value and net tax value of assets	(1,890,886)	(1,655,894)
Pension funding	(35,247)	(17,890)
Gas Cost Adjustments	(43,634)	(31,252)
Other	(31,480)	(37,173)
Total deferred tax liabilities	(2,001,247)	(1,742,209)
Net deferred tax liabilities	(1,467,233)	(1,335,367)
Deferred credits for rate regulated entities	412	(109)
Deferred Tax Assets, Charitable Contribution Carryforwards [Abstract]
Deferred Tax Assets, Charitable Contribution Carryforwards	$ 11,400
Charitable Contribution Carryforwards, Expiration Date, Minimum	Dec. 31, 2015
Charitable Contribution Carryforwards, Expiration Date, Maximum	Dec. 31, 2020
Reconciliation of Unrecognized Tax Benefits [Roll Forward]
Unrecognized Tax Benefits, Beginning Balance	$ 12,629	4,158
Unrecognized Tax Benefits, Increase Resulting from Prior Period Tax Positions	1,009	3,846
Unrecognized Tax Benefits, Increase Resulting from Current Period Tax Positions	3,431	4,625
Unrecognized Tax Benefits, Ending Balance	17,069	12,629	$ 4,158
Unrecognized Tax Benefits, Income Tax Penalties and Interest Accrued	820	411
Unrecognized Tax Benefits, Gross	17,889	13,040
Unrecognized Tax Benefits, Deferred Federal and State Income Tax Benefits	(6,261)	(4,564)
Unrecognized Tax Benefits that Would Impact Effective Tax Rate	11,628	8,476
Valuation Allowance, Tax Credit Carryforward [Member]
Valuation and Qualifying Accounts Disclosure [Line Items]
Valuation Allowances and Reserves, Charged to Cost and Expense	4,400	$ 7,000
Valuation Allowances and Reserves, Deductions	1,100
Valuation Allowance, Operating Loss Carryforwards [Member]
Valuation and Qualifying Accounts Disclosure [Line Items]
Valuation Allowances and Reserves, Charged to Cost and Expense	600
State and Local Jurisdiction [Member]
Operating Loss Carryforwards [Line Items]
Operating Loss Carryforwards	14,900
Operating Loss Carryforwards, Federal Tax Effects	$ 8,000
State and Local Jurisdiction [Member] | Minimum [Member]
Operating Loss Carryforwards [Line Items]
Operating Loss Carryforwards, Expiration Date	Dec. 31, 2016
State and Local Jurisdiction [Member] | Maximum [Member]
Operating Loss Carryforwards [Line Items]
Operating Loss Carryforwards, Expiration Date	Dec. 31, 2030
Domestic Tax Authority [Member]
Operating Loss Carryforwards [Line Items]
Operating Loss Carryforwards	$ 307,300
Domestic Tax Authority [Member] | Minimum [Member]
Operating Loss Carryforwards [Line Items]
Operating Loss Carryforwards, Expiration Date	Dec. 31, 2029

Income Taxes Tax Credit Carryfo

Income Taxes Tax Credit Carryforwards (Details) $ in Millions	12 Months Ended
	Sep. 30, 2015USD ($)
State and Local Jurisdiction [Member]
Tax Credit Carryforward [Line Items]
Tax Credit Carryforward, Amount	$ 0.8
State and Local Jurisdiction [Member] | Minimum [Member]
Tax Credit Carryforward [Line Items]
Tax Credit Carryforward, Expiration Date	Dec. 31, 2018
Domestic Tax Authority [Member]
Tax Credit Carryforward [Line Items]
Tax Credit Carryforward, Amount	$ 10.1

Income Taxes Rate Reconciliatio

Income Taxes Rate Reconciliation (Details) - USD ($) $ in Thousands	12 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2013
Effective Income Tax Rate Reconciliation, Amount [Abstract]
Tax at statutory rate of 35%	$ 178,768	$ 166,887	$ 130,655
Common stock dividends deductible for tax reporting	(2,413)	(2,307)	(2,153)
State taxes (net of federal benefit)	12,869	11,636	11,559
Change in valuation allowance	4,998	6,969	1,085
Other, net	1,468	3,817	1,453
Income tax expense (benefit)	$ 195,690	$ 187,002	$ 142,599

Financial Instruments Financial

Financial Instruments Financial Instruments at Fair Value (Details) - USD ($) $ in Thousands	Sep. 30, 2015		Sep. 30, 2014
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Derivative Asset, Current	$ 9,232		$ 45,827
Derivative Asset, Noncurrent	368		13,038
Derivative Liability, Current	(9,568)		(1,730)
Derivative Liability, Noncurrent	(110,539)		(20,126)
Derivative Assets (Liabilities), at Fair Value, Net	(110,507)		37,009
Cash Held in Margin Accounts	43,500		25,800
Cash Held In Margin Accounts Used to Offset Risk Management Liabilities	34,600		3,100
Cash Held In Margin Accounts Classified Current Risk Management Asset	8,900		22,700
Regulated Distribution Segment [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Derivative Asset, Current	378		23,102
Derivative Asset, Noncurrent	368		13,038
Derivative Liability, Current	(9,568)		(1,730)
Derivative Liability, Noncurrent	(110,539)		(20,126)
Derivative Assets (Liabilities), at Fair Value, Net	(119,361)		14,284
Cash Held In Margin Accounts Used to Offset Risk Management Liabilities	0		0
Cash Held In Margin Accounts Classified Current Risk Management Asset	0		0
Nonregulated Segment [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Derivative Asset, Current	8,854	[1]	22,725	[2]
Derivative Asset, Noncurrent	0		0
Derivative Liability, Current	0	[1]	0	[2]
Derivative Liability, Noncurrent	0	[1]	0	[2]
Derivative Assets (Liabilities), at Fair Value, Net	8,854		22,725
Cash Held In Margin Accounts Used to Offset Risk Management Liabilities	34,620		3,033
Cash Held In Margin Accounts Classified Current Risk Management Asset	$ 8,854		$ 22,725
[1]	Includes $43.5 million of cash held on deposit to collateralize certain financial instruments. Of this amount, $34.6 million was used to offset current and noncurent risk management liabilities under master netting arrangements and the remaining $8.9 million is classified as current risk management assets.
[2]	Includes $25.8 million of cash held on deposit to collateralize certain financial instruments. Of this amount, $3.1 million was used to offset current and noncurrent risk management liabilities under master netting arrangements and the remaining $22.7 million is classified as current risk management assets.

Financial Instruments Balance S

Financial Instruments Balance Sheet Location (Details) - USD ($) $ in Thousands	Sep. 30, 2015	Sep. 30, 2014
Derivatives, Fair Value [Line Items]
Derivative, Collateral, Right to Reclaim Cash	$ 8,900	$ 22,700
Derivative Asset	9,600	58,865
Derivative Liability, Collateral, Right to Reclaim Cash, Offset	34,600	3,100
Derivative Liability	(120,107)	(21,856)
Regulated Distribution Segment [Member]
Derivatives, Fair Value [Line Items]
Derivative Asset, Fair Value, Gross Asset	746	36,140
Derivative Asset, Contract Netting	0	0
Derivative Asset, Net of Contract Netting	746	36,140
Derivative, Collateral, Right to Reclaim Cash	0	0
Derivative Asset	746	36,140
Derivative Liability, Fair Value, Gross Liability	(120,107)	(21,856)
Derivative Liability, Contract Netting	0	0
Derivative Liability, Net of Contract Netting	(120,107)	(21,856)
Derivative Liability, Collateral, Right to Reclaim Cash, Offset	0	0
Derivative Liability	(120,107)	(21,856)
Regulated Distribution Segment [Member] | Designated as Hedging Instrument [Member]
Derivatives, Fair Value [Line Items]
Derivative Asset, Fair Value, Gross Asset	0	34,477
Derivative Liability, Fair Value, Gross Liability	(110,539)	(19,835)
Regulated Distribution Segment [Member] | Designated as Hedging Instrument [Member] | Other Current Assets [Member] | Commodity Contract [Member]
Derivatives, Fair Value [Line Items]
Derivative Asset, Fair Value, Gross Asset	0	0
Regulated Distribution Segment [Member] | Designated as Hedging Instrument [Member] | Other Current Assets [Member] | Interest Rate Contract [Member]
Derivatives, Fair Value [Line Items]
Derivative Asset, Fair Value, Gross Asset		21,869
Regulated Distribution Segment [Member] | Designated as Hedging Instrument [Member] | Deferred Charges And Other Assets [Member] | Commodity Contract [Member]
Derivatives, Fair Value [Line Items]
Derivative Asset, Fair Value, Gross Asset	0	0
Regulated Distribution Segment [Member] | Designated as Hedging Instrument [Member] | Deferred Charges And Other Assets [Member] | Interest Rate Contract [Member]
Derivatives, Fair Value [Line Items]
Derivative Asset, Fair Value, Gross Asset	0	12,608
Regulated Distribution Segment [Member] | Designated as Hedging Instrument [Member] | Other Current Liabilities [Member] | Commodity Contract [Member]
Derivatives, Fair Value [Line Items]
Derivative Liability, Fair Value, Gross Liability	0	0
Regulated Distribution Segment [Member] | Designated as Hedging Instrument [Member] | Other Current Liabilities [Member] | Interest Rate Contract [Member]
Derivatives, Fair Value [Line Items]
Derivative Liability, Fair Value, Gross Liability		0
Regulated Distribution Segment [Member] | Designated as Hedging Instrument [Member] | Deferred Credits And Other Liabilities [Member] | Commodity Contract [Member]
Derivatives, Fair Value [Line Items]
Derivative Liability, Fair Value, Gross Liability	0	0
Regulated Distribution Segment [Member] | Designated as Hedging Instrument [Member] | Deferred Credits And Other Liabilities [Member] | Interest Rate Contract [Member]
Derivatives, Fair Value [Line Items]
Derivative Liability, Fair Value, Gross Liability	(110,539)	(19,835)
Regulated Distribution Segment [Member] | Not Designated as Hedging Instrument [Member]
Derivatives, Fair Value [Line Items]
Derivative Asset, Fair Value, Gross Asset	746	1,663
Derivative Liability, Fair Value, Gross Liability	(9,568)	(2,021)
Regulated Distribution Segment [Member] | Not Designated as Hedging Instrument [Member] | Other Current Assets [Member] | Commodity Contract [Member]
Derivatives, Fair Value [Line Items]
Derivative Asset, Fair Value, Gross Asset	378	1,233
Regulated Distribution Segment [Member] | Not Designated as Hedging Instrument [Member] | Deferred Charges And Other Assets [Member] | Commodity Contract [Member]
Derivatives, Fair Value [Line Items]
Derivative Asset, Fair Value, Gross Asset	368	430
Regulated Distribution Segment [Member] | Not Designated as Hedging Instrument [Member] | Other Current Liabilities [Member] | Commodity Contract [Member]
Derivatives, Fair Value [Line Items]
Derivative Liability, Fair Value, Gross Liability	(9,568)	(1,730)
Regulated Distribution Segment [Member] | Not Designated as Hedging Instrument [Member] | Deferred Credits And Other Liabilities [Member] | Commodity Contract [Member]
Derivatives, Fair Value [Line Items]
Derivative Liability, Fair Value, Gross Liability	0	(291)
Nonregulated Segment [Member]
Derivatives, Fair Value [Line Items]
Derivative Asset, Fair Value, Gross Asset	91,363	69,023
Derivative Asset, Contract Netting	(91,363)	(69,023)
Derivative Asset, Net of Contract Netting	0	0
Derivative, Collateral, Right to Reclaim Cash	8,854	22,725
Derivative Asset	8,854	22,725
Derivative Liability, Fair Value, Gross Liability	(125,983)	(72,056)
Derivative Liability, Contract Netting	91,363	69,023
Derivative Liability, Net of Contract Netting	(34,620)	(3,033)
Derivative Liability, Collateral, Right to Reclaim Cash, Offset	34,620	3,033
Derivative Liability	0	0
Nonregulated Segment [Member] | Designated as Hedging Instrument [Member]
Derivatives, Fair Value [Line Items]
Derivative Asset, Fair Value, Gross Asset	11,806	9,669
Derivative Liability, Fair Value, Gross Liability	(45,985)	(9,541)
Nonregulated Segment [Member] | Designated as Hedging Instrument [Member] | Other Current Assets [Member] | Commodity Contract [Member]
Derivatives, Fair Value [Line Items]
Derivative Asset, Fair Value, Gross Asset	11,680	8,912
Nonregulated Segment [Member] | Designated as Hedging Instrument [Member] | Other Current Assets [Member] | Interest Rate Contract [Member]
Derivatives, Fair Value [Line Items]
Derivative Asset, Fair Value, Gross Asset		0
Nonregulated Segment [Member] | Designated as Hedging Instrument [Member] | Deferred Charges And Other Assets [Member] | Commodity Contract [Member]
Derivatives, Fair Value [Line Items]
Derivative Asset, Fair Value, Gross Asset	126	757
Nonregulated Segment [Member] | Designated as Hedging Instrument [Member] | Deferred Charges And Other Assets [Member] | Interest Rate Contract [Member]
Derivatives, Fair Value [Line Items]
Derivative Asset, Fair Value, Gross Asset	0	0
Nonregulated Segment [Member] | Designated as Hedging Instrument [Member] | Other Current Liabilities [Member] | Commodity Contract [Member]
Derivatives, Fair Value [Line Items]
Derivative Liability, Fair Value, Gross Liability	(36,067)	(7,082)
Nonregulated Segment [Member] | Designated as Hedging Instrument [Member] | Other Current Liabilities [Member] | Interest Rate Contract [Member]
Derivatives, Fair Value [Line Items]
Derivative Liability, Fair Value, Gross Liability		0
Nonregulated Segment [Member] | Designated as Hedging Instrument [Member] | Deferred Credits And Other Liabilities [Member] | Commodity Contract [Member]
Derivatives, Fair Value [Line Items]
Derivative Liability, Fair Value, Gross Liability	(9,918)	(2,459)
Nonregulated Segment [Member] | Designated as Hedging Instrument [Member] | Deferred Credits And Other Liabilities [Member] | Interest Rate Contract [Member]
Derivatives, Fair Value [Line Items]
Derivative Liability, Fair Value, Gross Liability	0	0
Nonregulated Segment [Member] | Not Designated as Hedging Instrument [Member]
Derivatives, Fair Value [Line Items]
Derivative Asset, Fair Value, Gross Asset	79,557	59,354
Derivative Liability, Fair Value, Gross Liability	(79,998)	(62,515)
Nonregulated Segment [Member] | Not Designated as Hedging Instrument [Member] | Other Current Assets [Member] | Commodity Contract [Member]
Derivatives, Fair Value [Line Items]
Derivative Asset, Fair Value, Gross Asset	65,239	43,677
Nonregulated Segment [Member] | Not Designated as Hedging Instrument [Member] | Deferred Charges And Other Assets [Member] | Commodity Contract [Member]
Derivatives, Fair Value [Line Items]
Derivative Asset, Fair Value, Gross Asset	14,318	15,677
Nonregulated Segment [Member] | Not Designated as Hedging Instrument [Member] | Other Current Liabilities [Member] | Commodity Contract [Member]
Derivatives, Fair Value [Line Items]
Derivative Liability, Fair Value, Gross Liability	(65,780)	(47,729)
Nonregulated Segment [Member] | Not Designated as Hedging Instrument [Member] | Deferred Credits And Other Liabilities [Member] | Commodity Contract [Member]
Derivatives, Fair Value [Line Items]
Derivative Liability, Fair Value, Gross Liability	$ (14,218)	$ (14,786)

Financial Instruments Descripti

Financial Instruments Descriptions (Details) $ in Millions	1 Months Ended	12 Months Ended
	Oct. 31, 2014USD ($)	Sep. 30, 2015USD ($)$ / McfMMcf	Sep. 30, 2014USD ($)	Sep. 30, 2013USD ($)
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		37.00%
Hedge Volume Of Actual Heating Season Gas | MMcf		28,200
Weighted Average Cost Of Actual Heating Season Gas | $ / Mcf		4.34
Minimum Length Of Time Hedged In Cash Flow Hedge		1 month
Maximum Length of Time Hedged in Cash Flow Hedge		49 months
Net Open Positions | MMcf		1,000
Gain (Loss) On Hedge Ineffectiveness		$ 0.2	$ 1.9	$ 18.2
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		$ 15.5	$ (5)	$ 3
Interest Rate Hedges, Senior Notes 2015 Issuance [Member]
Derivative [Line Items]
Derivative, Notional Amount		500
Derivative, Cash Received on Hedge	$ 13.4
Interest Rate Hedges, Senior Notes 2017 Issuance [Member]
Derivative [Line Items]
Derivative, Notional Amount		250
Interest Rate Hedges, Senior Notes 2019 Issuance [Member]
Derivative [Line Items]
Derivative, Notional Amount		450
Anticipated Debt Issuance, Amount		$ 450

Financial Instruments Commodity

Financial Instruments Commodity Contract Volumes (Details)	Sep. 30, 2015MMcf
Regulated Distribution Segment [Member]
Commodity Contract Outstanding Volumes [Line Items]
Investment Contract Volume	24,849
Regulated Distribution Segment [Member] | Not Designated as Hedging Instrument [Member]
Commodity Contract Outstanding Volumes [Line Items]
Investment Contract Volume	24,849
Regulated Distribution Segment [Member] | Fair Value Hedging [Member]
Commodity Contract Outstanding Volumes [Line Items]
Investment Contract Volume	0
Regulated 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	96,503
Nonregulated Segment [Member] | Not Designated as Hedging Instrument [Member]
Commodity Contract Outstanding Volumes [Line Items]
Investment Contract Volume	58,513
Nonregulated Segment [Member] | Fair Value Hedging [Member]
Commodity Contract Outstanding Volumes [Line Items]
Investment Contract Volume	(18,378)
Nonregulated Segment [Member] | Cash Flow Hedging [Member]
Commodity Contract Outstanding Volumes [Line Items]
Investment Contract Volume	56,368

Financial Instruments Fair Valu

Financial Instruments Fair Value Hedges and Cash Flow Hedges (Details) - USD ($) $ in Thousands	12 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2013
Effect of Fair Value Hedges on Results of Operations [Abstract]
Commodity contracts	$ 10,311	$ (792)	$ 2,165
Fair value adjustment for natural gas inventory designated as the hedged item	(9,768)	2,486	15,938
Total (increase) decrease in purchased gas cost	543	1,694	18,103
Fair Value Hedge Basis Ineffectiveness	811	(919)	(208)
Fair Value Hedge Timing Ineffectiveness	(268)	2,613	18,311
Cash Flow Hedge [Line Items]
Gain (loss) reclassified from AOCI into purchased gas cost for effective portion of commodity contracts	(41,716)	8,365	(10,778)
Gain (loss) arising from ineffective portion of commodity contracts	(325)	198	97
Total impact on purchased gas cost	(42,041)	8,563	(10,681)
Net loss on settled Treasury lock agreements reclassified from AOCI into interest expense	(853)	(4,230)	(3,489)
Total Impact from Cash Flow Hedges	(42,894)	4,333	(14,170)
Regulated 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
Gain (loss) arising from ineffective portion of commodity contracts	0	0	0
Total impact on purchased gas cost	0	0	0
Net loss on settled Treasury lock agreements reclassified from AOCI into interest expense	(853)	(4,230)	(3,489)
Total Impact from Cash Flow Hedges	(853)	(4,230)	(3,489)
Nonregulated Segment [Member]
Cash Flow Hedge [Line Items]
Gain (loss) reclassified from AOCI into purchased gas cost for effective portion of commodity contracts	(41,716)	8,365	(10,778)
Gain (loss) arising from ineffective portion of commodity contracts	(325)	198	97
Total impact on purchased gas cost	(42,041)	8,563	(10,681)
Net loss on settled Treasury lock agreements reclassified from AOCI into interest expense	0	0	0
Total Impact from Cash Flow Hedges	$ (42,041)	$ 8,563	$ (10,681)

Financial Instruments Other Com

Financial Instruments Other Comprehensive Income (Details) - USD ($) $ in Thousands		12 Months Ended
		Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2013
Other Comprehensive Income [Abstract]
Interest rate agreements fair value		$ (71,003)	$ (58,973)
Forward commodity contracts fair value		(49,211)	7,904
Interest rate agreements		542	2,686
Forward commodity contracts		25,448	(5,102)
Total other comprehensive income (loss) from hedging, net of tax	[1]	(94,224)	(53,485)
Expected Earnings [Line Items]
2,016		(19,831)
2,017		(5,491)
2,018		(1,468)
2,019		(758)
2,020		(703)
Thereafter		(15,836)
Cash Flow Hedge Gain (Loss) To Be Reclassiflied, Total	[2]	(44,087)
Interest Rate Contract [Member]
Other Comprehensive Income [Abstract]
Total other comprehensive income (loss) from hedging, net of tax		(70,461)	(56,287)	$ 82,179
Expected Earnings [Line Items]
2,016		(347)
2,017		(447)
2,018		(649)
2,019		(673)
2,020		(698)
Thereafter		(15,836)
Cash Flow Hedge Gain (Loss) To Be Reclassiflied, Total	[2]	(18,650)
Commodity Contract [Member]
Other Comprehensive Income [Abstract]
Total other comprehensive income (loss) from hedging, net of tax		(23,763)	$ 2,802	$ 4,519
Expected Earnings [Line Items]
2,016		(19,484)
2,017		(5,044)
2,018		(819)
2,019		(85)
2,020		(5)
Thereafter		0
Cash Flow Hedge Gain (Loss) To Be Reclassiflied, Total	[2]	$ (25,437)
[1]	Utilizing an income tax rate ranging from approximately 37 percent to 39 percent based on the effective rates in each taxing jurisdiction.
[2]	Utilizing an income tax rate ranging from approximately 37 percent to 39 percent based on the effective rates in each taxing jurisdiction.

Accumulated Other Comprehensi69

Accumulated Other Comprehensive Income Components (Details) - USD ($) $ in Thousands	12 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2013
Accumulated Other Comprehensive Income (Loss) [Line Items]
Shareholders' equity, beginning balance	$ 3,086,232	$ 2,580,409	$ 2,359,243
Net current-period other comprehensive income (loss)	(96,937)	(51,271)	86,485
Shareholders' equity, ending balance	3,194,797	3,086,232	2,580,409
Accumulated Net Unrealized Investment Gain (Loss) [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Shareholders' equity, beginning balance	7,662	5,448
Other comprehensive income before reclassifications	(2,173)	3,009
Amounts reclassified from accumulated other comprehensive income	(540)	(795)
Net current-period other comprehensive income (loss)	(2,713)	2,214
Shareholders' equity, ending balance	4,949	7,662	5,448
Accumulated Net Gain (Loss) from Cash Flow Hedges Attributable to Parent [Member] | Interest Rate Contract [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Shareholders' equity, beginning balance	(18,381)	37,906
Other comprehensive income before reclassifications	(71,003)	(58,973)
Amounts reclassified from accumulated other comprehensive income	542	2,686
Net current-period other comprehensive income (loss)	(70,461)	(56,287)
Shareholders' equity, ending balance	(88,842)	(18,381)	37,906
Accumulated Net Gain (Loss) from Cash Flow Hedges Attributable to Parent [Member] | Commodity Contract [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Shareholders' equity, beginning balance	(1,674)	(4,476)
Other comprehensive income before reclassifications	(49,211)	7,904
Amounts reclassified from accumulated other comprehensive income	25,448	(5,102)
Net current-period other comprehensive income (loss)	(23,763)	2,802
Shareholders' equity, ending balance	(25,437)	(1,674)	(4,476)
Accumulated Other Comprehensive Income [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Shareholders' equity, beginning balance	(12,393)	38,878	(47,607)
Other comprehensive income before reclassifications	(122,387)	(48,060)
Amounts reclassified from accumulated other comprehensive income	25,450	(3,211)
Net current-period other comprehensive income (loss)	(96,937)	(51,271)	86,485
Shareholders' equity, ending balance	$ (109,330)	$ (12,393)	$ 38,878

Accumulated Other Comprehensi70

Accumulated Other Comprehensive Income Affected Line Item in the Statement of Income (Details) - USD ($) $ in Thousands	12 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2013
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Operation and maintenance	$ (541,868)	$ (505,154)	$ (488,020)
Interest charges	(116,241)	(129,295)	(128,385)
Purchased gas cost	(2,462,119)	(3,358,490)	(2,463,410)
Income (loss) before income taxes	510,765	476,819	373,297
Income Tax Expense (Benefit)	(195,690)	(187,002)	(142,599)
Income (loss) from continuing operations	315,075	289,817	$ 230,698
Reclassification out of Accumulated Other Comprehensive Income [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Income (loss) from continuing operations	(25,450)	3,211
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	850	1,252
Income (loss) before income taxes	850	1,252
Income Tax Expense (Benefit)	(310)	(457)
Income (loss) from continuing operations	540	795
Reclassification out of Accumulated Other Comprehensive Income [Member] | Accumulated Net Gain (Loss) from Cash Flow Hedges Attributable to Parent [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Income (loss) before income taxes	(42,569)	4,135
Income Tax Expense (Benefit)	16,579	(1,719)
Income (loss) from continuing operations	(25,990)	2,416
Reclassification out of Accumulated Other Comprehensive Income [Member] | Accumulated Net Gain (Loss) from Cash Flow Hedges Attributable to Parent [Member] | Interest Rate Contract [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Interest charges	(853)	(4,230)
Reclassification out of Accumulated Other Comprehensive Income [Member] | Accumulated Net Gain (Loss) from Cash Flow Hedges Attributable to Parent [Member] | Commodity Contract [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Purchased gas cost	$ (41,716)	$ 8,365

Fair Value Measurements (Detail

Fair Value Measurements (Details) - USD ($) $ in Thousands		Sep. 30, 2015		Sep. 30, 2014
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Derivative Asset, Fair Value, Gross Liability and Obligation to Return Cash, Offset		$ (82,509)	[1]	$ (46,298)	[2]
Derivative Asset		9,600		58,865
Hedged portion of gas stored underground		43,901		40,492
Available-for-sale Securities		74,200		79,613
Total assets		127,701		178,970
Derivative Liability, Fair Value, Gross Asset and Right to Reclaim Cash, Offset		(125,983)	[1]	(72,056)	[2]
Derivative Liability		120,107		21,856
Additional Fair Value Elements [Abstract]
Cash Held in Margin Accounts		43,500		25,800
Cash Held In Margin Accounts Used to Offset Risk Management Liabilities		34,600		3,100
Cash Held In Margin Accounts Classified Current Risk Management Asset		8,900		22,700
Debt Instrument Carrying Amount		2,460,000		2,460,000
Debt Instrument Fair Value		2,669,323
Money Market Funds [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Available-for-sale Securities		1,072		2,185
Equity Securities [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Available-for-sale Securities		40,619		44,014
Debt Securities [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Available-for-sale Securities		32,509		33,414
Regulated Distribution Segment [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Derivative Asset, Fair Value, Gross Liability and Obligation to Return Cash, Offset		0	[1]	0	[2]
Derivative Asset		746		36,140
Derivative Liability, Fair Value, Gross Asset and Right to Reclaim Cash, Offset		0	[1]	0	[2]
Derivative Liability		120,107		21,856
Additional Fair Value Elements [Abstract]
Cash Held In Margin Accounts Used to Offset Risk Management Liabilities		0		0
Cash Held In Margin Accounts Classified Current Risk Management Asset		0		0
Nonregulated Segment [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Derivative Asset, Fair Value, Gross Liability and Obligation to Return Cash, Offset		(82,509)	[1]	(46,298)	[2]
Derivative Asset		8,854		22,725
Derivative Liability, Fair Value, Gross Asset and Right to Reclaim Cash, Offset		(125,983)	[1]	(72,056)	[2]
Derivative Liability		0		0
Additional Fair Value Elements [Abstract]
Cash Held In Margin Accounts Used to Offset Risk Management Liabilities		34,620		3,033
Cash Held In Margin Accounts Classified Current Risk Management Asset		8,854		22,725
Fair Value Inputs Level 1 [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Derivative Asset, Fair Value, Gross Asset Including Not Subject to Master Netting Arrangement		0		25
Hedged portion of gas stored underground		43,901		40,492
Available-for-sale Securities		40,619		44,014
Total assets		84,520		84,531
Derivative Liability, Fair Value, Gross Liability Including Not Subject to Master Netting Arrangement		0		12
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		40,619		44,014
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] | Regulated Distribution Segment [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Derivative Asset, Fair Value, Gross Asset Including Not Subject to Master Netting Arrangement		0		0
Derivative Liability, Fair Value, Gross Liability Including Not Subject to Master Netting Arrangement		0		0
Fair Value Inputs Level 1 [Member] | Nonregulated Segment [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Derivative Asset, Fair Value, Gross Asset Including Not Subject to Master Netting Arrangement		0		25
Derivative Liability, Fair Value, Gross Liability Including Not Subject to Master Netting Arrangement		0		12
Fair Value Inputs Level 2 [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Derivative Asset, Fair Value, Gross Asset Including Not Subject to Master Netting Arrangement	[3]	92,109		105,138
Hedged portion of gas stored underground	[3]	0		0
Available-for-sale Securities	[3]	33,581		35,599
Total assets	[3]	125,690		140,737
Derivative Liability, Fair Value, Gross Liability Including Not Subject to Master Netting Arrangement	[3]	246,090		93,900
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	[3]	1,072		2,185
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	[3]	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	[3]	32,509		33,414
Fair Value Inputs Level 2 [Member] | Regulated Distribution Segment [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Derivative Asset, Fair Value, Gross Asset Including Not Subject to Master Netting Arrangement	[3]	746		36,140
Derivative Liability, Fair Value, Gross Liability Including Not Subject to Master Netting Arrangement	[3]	120,107		21,856
Fair Value Inputs Level 2 [Member] | Nonregulated Segment [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Derivative Asset, Fair Value, Gross Asset Including Not Subject to Master Netting Arrangement	[3]	91,363		68,998
Derivative Liability, Fair Value, Gross Liability Including Not Subject to Master Netting Arrangement	[3]	125,983		72,044
Fair Value Inputs Level 3 [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Derivative Asset, Fair Value, Gross Asset Including Not Subject to Master Netting Arrangement		0		0
Hedged portion of gas stored underground		0		0
Available-for-sale Securities		0		0
Total assets		0		0
Derivative Liability, Fair Value, Gross Liability Including Not Subject to Master Netting Arrangement		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] | Regulated Distribution Segment [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Derivative Asset, Fair Value, Gross Asset Including Not Subject to Master Netting Arrangement		0		0
Derivative Liability, Fair Value, Gross Liability Including Not Subject to Master Netting Arrangement		0		0
Fair Value Inputs Level 3 [Member] | Nonregulated Segment [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Derivative Asset, Fair Value, Gross Asset Including Not Subject to Master Netting Arrangement		0		0
Derivative Liability, Fair Value, Gross Liability Including Not Subject to Master Netting Arrangement		$ 0		$ 0
[1]	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, 2015 we had $43.5 million of cash held in margin accounts to collateralize certain financial instruments. Of this amount, $34.6 million was used to offset current and noncurrent risk management liabilities under master netting agreements and the remaining $8.9 million is classified as current risk management assets.
[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 September 30, 2014 we had $25.8 million of cash held in margin accounts to collateralize certain financial instruments. Of this amount, $3.1 million was used to offset current and noncurrent risk management liabilities under master netting agreements and the remaining $22.7 million is classified as current risk management assets.
[3]	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.

Fair Value Measurements Availab

Fair Value Measurements Available-For-Sale Securities (Details) - USD ($) $ in Thousands	Sep. 30, 2015	Sep. 30, 2014
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	$ 66,399	$ 67,466
Gross Unrealized Gain	8,343	12,160
Gross Unrealized Loss	(542)	(13)
Fair value	74,200	79,613
Available-for-sale Securities, Other Disclosure Items [Abstract]
Available-for-sale Securities, Supplemental Executive Benefit Plans	41,700	46,200
Equity Funds Domestic [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	27,643	26,633
Gross Unrealized Gain	7,332	10,136
Gross Unrealized Loss	(456)	0
Fair value	34,519	36,769
Equity Funds Foreign [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	5,261	5,382
Gross Unrealized Gain	905	1,863
Gross Unrealized Loss	(66)	0
Fair value	6,100	7,245
Debt Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	32,423	33,266
Gross Unrealized Gain	106	161
Gross Unrealized Loss	(20)	(13)
Fair value	32,509	33,414
Money Market Funds [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	1,072	2,185
Gross Unrealized Gain	0	0
Gross Unrealized Loss	0	0
Fair value	$ 1,072	$ 2,185

Discontinued Operations (Detail

Discontinued Operations (Details) - USD ($) $ in Thousands	12 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2013
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Discontinued Operation, Gain (Loss) from Disposal of Discontinued Operation, before Income Tax	$ 0	$ 0	$ 8,203
Discontinued Operation Income Loss From Discontinued Operation Disclosures Abstract
Operating revenues			37,962
Purchased gas cost			21,464
Gross profit			16,498
Operating expenses			5,858
Operating income			10,640
Discontinued Operations Miscellaneous Income Expense			548
Income from discontinued operations before income taxes			11,188
Income tax expense	0	0	3,986
Income (loss) from discontinued operations	0	0	7,202
Gain (loss) on sale of discontinued operations, net of tax	0	0	5,294
Net income (loss) from discontinued operations	$ 0	$ 0	12,496
Georgia [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Discontinued Operation, Cash Price Received from Disposal of Discontinued Operation			153,000
Discontinued Operation, Gain (Loss) from Disposal of Discontinued Operation, before Income Tax			$ 8,200

Selected Quarterly Financial 74

Selected Quarterly Financial Data (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended								12 Months Ended
	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2013	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2013
Operating Revenues by Segment [Line Items]
Operating revenues	$ 656,902	$ 686,401	$ 1,540,068	$ 1,258,765	$ 789,034	$ 943,170	$ 1,964,854	$ 1,243,858	$ 4,142,136	$ 4,940,916	$ 3,875,460
Selected Quarterly Financial Information [Abstract]
Gross profit	354,321	381,673	520,738	423,285	337,659	359,533	496,277	388,957	1,680,017	1,582,426	1,412,050
Operating income	75,853	117,607	250,210	187,725	83,944	106,605	250,080	170,720	631,395	611,349	501,879
Income (loss) from continuing operations									315,075	289,817	230,698
Income from discontinued operations, net of tax									0	0	7,202
Gain (loss) on sale of discontinued operations, net of tax									0	0	5,294
Net income	$ 23,515	$ 56,281	$ 137,684	$ 97,595	$ 23,713	$ 45,721	$ 133,367	$ 87,016	$ 315,075	$ 289,817	$ 243,194
Income per share from continuing operations - basic (usd per share)									$ 3.09	$ 2.96	$ 2.54
Income per share from discontinued operations - basic (usd per share)									0	0	0.14
Net income per share — basic (usd per share)	$ 0.23	$ 0.55	$ 1.35	$ 0.96	$ 0.23	$ 0.45	$ 1.38	$ 0.95	3.09	2.96	2.68
Income per share from continuing operations - diluted (usd per share)									3.09	2.96	2.50
Income per share from discontinued operations - diluted (usd per share)									0	0	0.14
Net income per share — diluted (usd per share)	$ 0.23	$ 0.55	$ 1.35	$ 0.96	$ 0.23	$ 0.45	$ 1.38	$ 0.95	$ 3.09	$ 2.96	$ 2.64
Regulated Distribution Segment [Member]
Operating Revenues by Segment [Line Items]
Operating revenues	$ 369,656	$ 416,794	$ 1,130,613	$ 846,772	$ 409,014	$ 517,707	$ 1,290,960	$ 843,865	$ 2,763,835	$ 3,061,546	$ 2,399,493
Selected Quarterly Financial Information [Abstract]
Gross profit									1,237,577	1,176,515	1,081,236
Operating income									420,149	384,568	343,093
Income (loss) from continuing operations											150,856
Income from discontinued operations, net of tax											7,202
Gain (loss) on sale of discontinued operations, net of tax											5,649
Net income									204,813	171,585	163,707
Regulated Pipeline Segment [Member]
Operating Revenues by Segment [Line Items]
Operating revenues	97,807	97,008	91,730	83,567	86,314	87,189	73,615	71,341	370,112	318,459	268,900
Selected Quarterly Financial Information [Abstract]
Gross profit									370,112	318,459	268,900
Operating income									181,267	172,819	139,853
Income (loss) from continuing operations											68,260
Income from discontinued operations, net of tax											0
Gain (loss) on sale of discontinued operations, net of tax											0
Net income									94,662	86,191	68,260
Nonregulated Segment [Member]
Operating Revenues by Segment [Line Items]
Operating revenues	292,830	278,769	438,322	462,288	407,161	465,485	758,215	436,431	1,472,209	2,067,292	1,587,914
Selected Quarterly Financial Information [Abstract]
Gross profit									72,860	87,955	63,331
Operating income									29,979	53,962	18,927
Income (loss) from continuing operations											11,582
Income from discontinued operations, net of tax											0
Gain (loss) on sale of discontinued operations, net of tax											(355)
Net income									15,600	32,041	11,227
Intersegment Elimination [Member]
Operating Revenues by Segment [Line Items]
Operating revenues	$ (103,391)	$ (106,170)	$ (120,597)	$ (133,862)	$ (113,455)	$ (127,211)	$ (157,936)	$ (107,779)	(464,020)	(506,381)	(380,847)
Selected Quarterly Financial Information [Abstract]
Gross profit									(532)	(503)	(1,417)
Operating income									0	0	6
Income (loss) from continuing operations											0
Income from discontinued operations, net of tax											0
Gain (loss) on sale of discontinued operations, net of tax											0
Net income									$ 0	$ 0	$ 0

Valuation and Qualifying Accoun

Valuation and Qualifying Accounts (Details) - Allowance For Doubtful Accounts Member - USD ($) $ in Thousands		12 Months Ended
		Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2013
Valuation and Qualifying Accounts Disclosure [Line Items]
Balance at beginning of period		$ 23,992	$ 20,624	$ 9,425
Charged to costs & expenses		15,082	19,491	14,484
Charged to other accounts		0	0	0
Valuation Allowances and Reserves, Deductions	[1]	23,791	16,123	3,285
Balance at end of period		$ 15,283	$ 23,992	$ 20,624
[1]	Uncollectible accounts written off.