Atmos Energy (ATO) 8-K 12 Apr 17 2016 FY Other Events Financial data

Document and Entity Information

Document and Entity Information	12 Months Ended
	Sep. 30, 2016
Document And Entity Information [Abstract]
Entity Registrant Name	Atmos Energy Corporation
Entity Central Index Key	731,802
Entity Filer Category	Large Accelerated Filer
Document Type	8-K
Document Period End Date	Sep. 30, 2016
Document Fiscal Year Focus	2,016
Document Fiscal Period Focus	FY
Amendment Flag	false

CONSOLIDATED BALANCE SHEETS

CONSOLIDATED BALANCE SHEETS - USD ($)		Sep. 30, 2016	Sep. 30, 2015
ASSETS
Property, plant and equipment		$ 9,958,627,000	$ 8,931,254,000
Construction in progress		183,879,000	280,421,000
Total property, plant and equipment and construction in progress		10,142,506,000	9,211,675,000
Less accumulated depreciation and amortization		1,873,900,000	1,794,975,000
Net property, plant and equipment	[1]	8,268,606,000	7,416,700,000
Current assets
Cash and cash equivalents		47,534,000	28,653,000
Accounts receivable, less allowance for doubtful accounts of $13,367 in 2016 and $15,283 in 2015		215,880,000	213,333,000
Gas stored underground		179,070,000	195,336,000
Current assets of disposal group classified as held for sale		151,117,000	139,055,000
Other current assets		88,085,000	49,929,000
Total current assets		681,686,000	626,306,000
Goodwill	[2]	726,962,000	726,257,000
Noncurrent assets of disposal group classified as held for sale		28,616,000	30,385,000
Deferred charges and other assets		305,019,000	275,424,000
Total assets		10,010,889,000	9,075,072,000
Shareholders' equity
Common stock, no par value (stated at $.005 per share); 200,000,000 shares authorized; issued and outstanding: 2016 — 103,930,560 shares, 2015 — 101,478,818 shares		520,000	507,000
Additional paid-in capital		2,388,027,000	2,230,591,000
Accumulated other comprehensive loss		(188,022,000)	(109,330,000)
Retained earnings		1,262,534,000	1,073,029,000
Shareholders' equity		3,463,059,000	3,194,797,000
Long-term debt		2,188,779,000	2,437,515,000
Total capitalization		5,651,838,000	5,632,312,000
Current liabilities
Accounts payable and accrued liabilities		196,485,000	174,646,000
Current liabilities of disposal group classified as held for sale		72,900,000	74,560,000
Other current liabilities		439,085,000	447,690,000
Short-term debt		829,811,000	457,927,000
Current maturities of long-term debt		250,000,000	0
Total current liabilities		1,788,281,000	1,154,823,000
Deferred income taxes		1,603,056,000	1,411,315,000
Regulatory cost of removal obligation		424,281,000	427,553,000
Pension and postretirement liabilities		297,743,000	287,373,000
Noncurrent liabilities of disposal group held for sale		316,000	347,000
Deferred credits and other liabilities		245,374,000	161,349,000
Total shareholders' equity and liabilities		$ 10,010,889,000	$ 9,075,072,000
[1]	Net property, plant and equipment includes plant acquisition adjustments of $(59.8) million and $(68.1) million at September 30, 2016 and 2015.
[2]	Natural gas marketing had goodwill of $16.4 million at September 30, 2016 and 2015 classified as assets held for sale on the consolidated balance sheet.

CONSOLIDATED BALANCE SHEETS (PA

CONSOLIDATED BALANCE SHEETS (PARENTHETICALS) - USD ($) $ in Thousands	Sep. 30, 2016	Sep. 30, 2015
Statement of Financial Position [Abstract]
Allowance for doubtful accounts	$ 11,056	$ 12,934
Common Stock, Stated Value Per Share	$ 0.005	$ 0.005
Common Stock, Shares Authorized	200,000,000	200,000,000
Common Stock, Shares, Issued	103,930,560	101,478,818

CONSOLIDATED STATEMENTS OF INCO

CONSOLIDATED STATEMENTS OF INCOME - USD ($) shares in Thousands, $ in Thousands	3 Months Ended								12 Months Ended
	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2014	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2014
Operating revenues
Operating revenues	$ 433,643	$ 456,212	$ 890,040	$ 674,753	$ 411,143	$ 455,505	$ 1,173,096	$ 887,241	$ 2,454,648	$ 2,926,985	$ 3,243,904
Purchased gas cost
Purchased gas cost									746,192	1,295,675	1,722,060
Gross profit	369,716	391,629	512,684	434,427	344,265	368,134	505,571	413,340	1,708,456	1,631,310	1,521,844
Operating expenses
Operation and maintenance									538,592	516,406	482,476
Depreciation and amortization									290,791	272,408	251,672
Taxes, other than income									221,843	230,264	210,474
Total operating expenses									1,051,226	1,019,078	944,622
Operating income	84,449	128,396	251,656	192,729	74,347	111,001	242,000	184,884	657,230	612,232	577,222
Miscellaneous income (expense), net									(234)	(819)	(3,003)
Interest charges									114,812	116,241	129,276
Income before income taxes									542,184	495,172	444,943
Income tax expense									196,642	189,549	174,612
Income from Continuing Operations, Net of Tax	34,850	66,143	143,003	101,546	23,908	52,487	133,142	96,086	345,542	305,623	270,331
Net income from discontinued operations, net of tax	(610)	5,050	(1,193)	1,315	(393)	3,794	4,542	1,509	4,562	9,452	19,486
Net income	$ 34,240	$ 71,193	$ 141,810	$ 102,861	$ 23,515	$ 56,281	$ 137,684	$ 97,595	$ 350,104	$ 315,075	$ 289,817
Income from Continuing Operations, Per Basic Share	$ 0.33	$ 0.64	$ 1.39	$ 0.99	$ 0.23	$ 0.51	$ 1.31	$ 0.94	$ 3.33	$ 3	$ 2.76
Income from Discontinued Operation, Net of Tax, Per Basic Share	0	0.05	(0.01)	0.01	0	0.04	0.04	0.02	$ 0.05	$ 0.09	$ 0.20
Discontinued Operation, Tax Effect of Discontinued Operation									$ 3,731	$ 6,141	$ 12,389
Earnings Per Share, Basic	0.33	0.69	1.38	1	0.23	0.55	1.35	0.96	$ 3.38	$ 3.09	$ 2.96
Income from Continuing Operations, Per Diluted Share	0.33	0.64	1.39	0.99	0.23	0.51	1.31	0.94	3.33	3	2.76
Income from Discontinued Operation, Net of Tax, Per Diluted Share	0	0.05	(0.01)	0.01	0	0.04	0.04	0.02	0.05	0.09	0.20
Diluted net income per share	$ 0.33	$ 0.69	$ 1.38	$ 1	$ 0.23	$ 0.55	$ 1.35	$ 0.96	$ 3.38	$ 3.09	$ 2.96000
Weighted average shares outstanding:
Basic (shares)									103,524	101,892	97,606
Diluted (shares)									103,524	101,892	97,608
Distribution Segment [Member]
Operating revenues
Operating revenues	$ 403,303	$ 424,905	$ 862,127	$ 649,443	$ 382,031	$ 429,482	$ 1,145,082	$ 864,767	$ 2,339,778	$ 2,821,362	$ 3,139,221
Purchased gas cost
Purchased gas cost									1,058,576	1,574,447	1,952,869
Gross profit									1,281,202	1,246,915	1,186,352
Operating expenses
Operation and maintenance									407,982	393,504	391,747
Depreciation and amortization									234,109	224,094	209,485
Taxes, other than income									197,227	206,625	196,503
Total operating expenses									839,318	824,223	797,735
Operating income									441,884	422,692	388,617
Miscellaneous income (expense), net									1,171	284	3
Interest charges									78,238	83,087	92,997
Income before income taxes									364,817	339,889	295,623
Income tax expense									130,987	134,069	121,165
Income from Continuing Operations, Net of Tax									233,830	205,820	174,458
Net income from discontinued operations, net of tax									0	0	0
Net income									233,830	205,820	174,458
Pipeline and Storage Segment [Member]
Operating revenues
Operating revenues	112,772	113,855	102,153	98,416	101,895	99,008	96,893	87,161	427,196	384,957	337,540
Purchased gas cost
Purchased gas cost									(58)	562	2,048
Gross profit									427,254	384,395	335,492
Operating expenses
Operation and maintenance									130,610	122,902	90,729
Depreciation and amortization									56,682	48,314	42,187
Taxes, other than income									24,616	23,639	13,971
Total operating expenses									211,908	194,855	146,887
Operating income									215,346	189,540	188,605
Miscellaneous income (expense), net									(1,405)	(1,103)	(3,006)
Interest charges									36,574	33,154	36,279
Income before income taxes									177,367	155,283	149,320
Income tax expense									65,655	55,480	53,447
Income from Continuing Operations, Net of Tax									111,712	99,803	95,873
Net income from discontinued operations, net of tax									0	0	0
Net income									111,712	99,803	95,873
Intersegment Elimination [Member]
Operating revenues
Operating revenues	$ (82,432)	$ (82,548)	$ (74,240)	$ (73,106)	$ (72,783)	$ (72,985)	$ (68,879)	$ (64,687)	(312,326)	(279,334)	(232,857)
Purchased gas cost
Purchased gas cost									(312,326)	(279,334)	(232,857)
Gross profit									0	0	0
Operating expenses
Operation and maintenance									0	0	0
Depreciation and amortization									0	0	0
Taxes, other than income									0	0	0
Total operating expenses									0	0	0
Operating income									0	0	0
Miscellaneous income (expense), net									0	0	0
Interest charges									0	0	0
Income before income taxes									0	0	0
Income tax expense									0	0	0
Income from Continuing Operations, Net of Tax									0	0	0
Net income from discontinued operations, net of tax									0	0	0
Net income									$ 0	$ 0	$ 0

CONSOLIDATED STATEMENTS OF COMP

CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME - USD ($) $ in Thousands		12 Months Ended
		Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2014
Statement of Comprehensive Income [Abstract]
Net income		$ 350,104	$ 315,075	$ 289,817
Other comprehensive income (loss), net of tax [Abstract]
Net unrealized holding gains (losses) on available-for-sale securities, net of tax of $(245), $(1,559) and $1,199		(465)	(2,713)	2,214
Schedule of Other Comprehensive Income (Loss), Cash Flow Hedges [Line Items]
Other Comprehensive Income (Loss), Derivatives Qualifying as Hedges, Net of Tax	[1]	(78,227)	(94,224)
Total other comprehensive income (loss)		(78,692)	(96,937)	(51,271)
Total comprehensive income		271,412	218,138	238,546
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		(98,682)	(70,461)	(56,287)
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		$ 20,455	$ (23,763)	$ 2,802
[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 COM6

CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME (PARENTHETICAL) - USD ($) $ in Thousands	12 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2014
Other Comprehensive Income (Loss), Tax, Portion Attributable to Parent, Parenthetical Disclosures [Abstract]
Unrealized holding gains (losses) on available-for-sale securities, tax	$ (476)	$ (442)	$ 1,199
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	52,429	2,749	(32,353)
Commodity Contract [Member]
Schedule of Other Comprehensive Income (Loss), Tax, Cash Flow Hedges [Line Items]
Other Comprehensive Income (Loss), Derivatives Qualifying as Hedges, Tax	$ 3,183	$ 1,505	$ 1,791

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, 2013		90,640,211
Shareholders' equity, beginning 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
Net income	350,104				350,104
Other comprehensive income (loss)	(78,692)			(78,692)
Cash dividends	(175,126)				(175,126)
Common stock issued:
Public offering, shares		1,360,756
Public offering, amount	98,574	$ 7	98,567
Direct stock purchase plan, shares		133,133
Direct stock purchase plan, amount	9,229	$ 1	9,228
Retirement savings plan, shares		359,414
Retirement savings plan, amount	25,049	$ 2	25,047
1998 Long-term incentive plan, shares		598,439
1998 Long-term incentive plan, amount	3,178	$ 3	3,175		0
Employee stock-based compensation	21,419		21,419
Common stock shares outstanding, ending balance at Sep. 30, 2016		103,930,560
Shareholders' equity, ending balance at Sep. 30, 2016	3,463,059	$ 520	$ 2,388,027	$ (188,022)	1,262,534
Cumulative Effect of New Accounting Principle in Period of Adoption	$ 14,527				$ 14,527

CONSOLIDATED STATEMENT OF SHAR8

CONSOLIDATED STATEMENT OF SHAREHOLDERS' EQUITY (PARENTHETICALS) - $ / shares	12 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2014
Statement of Stockholders' Equity [Abstract]
Cash dividends per share	$ 1.68	$ 1.56	$ 1.48

CONSOLIDATED STATEMENTS OF CASH

CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	12 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2014
CASH FLOWS FROM OPERATING ACTIVITIES
Net income	$ 350,104	$ 315,075	$ 289,817
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation, Depletion and Amortization	293,096	274,796	253,987
Deferred income taxes	193,556	192,886	189,952
Stock-based compensation	14,760	15,980	14,721
Debt financing costs	5,667	5,922	9,409
Other	1,019	359	541
Changes in assets and liabilities:
(Increase) decreased in accounts receivable	(4,847)	48,240	(41,408)
Decrease in gas stored underground	20,577	33,234	(31,996)
(Increase) decrease in other current assets	(18,739)	(11,951)	(24,411)
(Increase) decrease in deferred charges and other assets	(24,860)	51,614	28,875
Increase (decrease) in account payable and accrued liabilities	(5,195)	(59,112)	60,465
Increase (decrease) in other current liabilities	(44,482)	896	2,413
Increase (decrease) in deferred credits and other liabilities	14,334	(56,025)	(19,552)
Net cash provided by operating activities	794,990	811,914	732,813
CASH FLOWS USED IN INVESTING ACTIVITIES
Capital expenditures	(1,086,950)	(963,621)	(824,441)
Payments to Acquire Available-for-sale Securities	(32,551)	(29,527)	(32,734)
Proceeds from Sale of Available-for-sale Securities	27,019	24,889	24,872
Proceeds from Maturities, Prepayments and Calls of Available-for-sale Securities	6,290	6,235	5,215
Other, net	6,460	5,422	2,109
Net cash used in investing activities	(1,079,732)	(956,602)	(824,979)
CASH FLOWS FROM FINANCING ACTIVITIES
Net increase (decrease) in short-term debt	371,884	261,232	(171,289)
Proceeds from issuance of long-term debt	0	499,060	0
Net proceeds from equity offering	98,574	0	390,205
Issuance of common stock through stock purchase and employee retirement plans	34,278	30,952	4,274
Settlement of interest rate agreement	0	13,364	0
Interest rate agreements cash collateral	(25,670)	0	0
Repayment of long-term debt	0	(500,000)	0
Cash dividends paid	(175,126)	(160,018)	(146,248)
Repurchase of equity awards	0	(7,985)	(8,717)
Other	(317)	(5,522)	0
Net cash provided by (used in) financing activities	303,623	131,083	68,225
Net increase (decrease) in cash and cash equivalents	18,881	(13,605)	(23,941)
Cash and cash equivalents at beginning of period	28,653	42,258	66,199
Cash and cash equivalents at end of period	47,534	28,653	42,258
CASH PAID (RECEIVED) DURING THE PERIOD FOR:
Interest	154,748	151,334	156,606
Income taxes	$ 7,794	$ 1,802	$ (610)

Nature of Business

Nature of Business	12 Months Ended
	Sep. 30, 2016
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 and storage businesses. Through our 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 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 and manage our storage assets located in Kentucky and Tennessee, which are used solely to support our regulated natural gas distribution operations in those states. Our distribution business is subject to federal and state regulation and/or regulation by local authorities in each of the states in which our 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. Our pipeline and storage business, which is also subject to federal and state regulation, consists of the operations of our Atmos Pipeline–Texas (APT) Division and our Louisiana natural gas transmission business. The APT 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 natural gas transmission operations in Louisiana are comprised of a proprietary 21-mile pipeline located in New Orleans, Louisiana that is primarily used to aggregate gas supply for our distribution division in Louisiana under a long-term contract and on a more limited basis, to third parties. On October 29, 2016, we entered into a Membership Interest Purchase Agreement (the Agreement) with CenterPoint Energy Services, Inc., a subsidiary of CenterPoint Energy, Inc. (CES) to sell all of the equity interests of AEM. AEM’s historical financial results are reflected in the Company’s consolidated financial statements as discontinued operations, which required retrospective application to financial information for all periods presented. Refer to Note 15, "Discontinued Operations," of the notes to consolidated financial statements for further information. Our discontinued natural gas marketing segment is primarily engaged in a nonregulated natural gas marketing business, conducted by Atmos Energy Marketing (AEM). The natural gas marketing business operates primarily in the Midwest and Southeast and is based in Houston, Texas. This business provides natural gas management and transportation services to municipalities, regulated distribution companies, including certain divisions of Atmos Energy, and third parties. Additionally, as a result of the announced sale of AEM, we revised the information used by the chief operating decision maker to manage the Company, which led to a change in our reportable segments and required retrospective application to our financial information for all periods presented. Refer to Note 3, “Segment Information,” of the notes to consolidated financial statements for further information.

Significant Accounting Policies

Significant Accounting Policies	12 Months Ended
	Sep. 30, 2016
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 — As described under Recent Accounting Pronouncements below, we reclassified debt issuance costs from deferred charges and other assets to long-term debt. Additionally, we recorded immaterial corrections to the presentation of certain activities on our Consolidated Statement of Cash Flows for the years ended September 30, 2015 and 2014. 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 distribution and pipeline and storage 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, 2016 and 2015 included the following: September 30 2016 2015 (In thousands) Regulatory assets: Pension and postretirement benefit costs (1) $ 132,348 $ 121,183 Infrastructure mechanisms (2) 42,719 32,813 Deferred gas costs 45,184 9,715 Recoverable loss on reacquired debt 13,761 16,319 Deferred pipeline record collection costs 7,336 3,118 APT annual adjustment mechanism 7,171 1,002 Rate case costs 1,539 1,533 Other 13,565 6,656 $ 263,623 $ 192,339 Regulatory liabilities: Regulatory cost of removal obligation $ 476,891 $ 483,676 Deferred gas costs 20,180 28,100 Asset retirement obligation 13,404 9,063 Other 4,250 3,693 $ 514,725 $ 524,532 (1) Includes $12.4 million and $16.6 million of pension and postretirement expense deferred pursuant to regulatory authorization. (2) Infrastructure mechanisms in Texas and Louisiana allow for the deferral of all eligible expenses associated with capital expenditures incurred pursuant to these rules, including the recording of interest on the deferred expenses until the next rate proceeding (rate case or annual rate filing), at which time investment and costs would be recovered through base rates. Revenue recognition — Sales of natural gas to our 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 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 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 pipeline and storage and natural gas marketing segments are recognized in the period in which actual volumes are transported and storage services are provided. Operating revenues for our natural gas marketing 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 natural gas marketing 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 distribution operations and natural gas held by our natural gas marketing segment to conduct their operations. The average cost method is used for substantially all of our regulated operations. Our natural gas marketing 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 $2.8 million , $2.3 million and $1.5 million was capitalized in 2016 , 2015 and 2014 . 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 3.2 percent for the fiscal year ended September 30, 2016 , and 3.3 percent for each of the fiscal years ended September 30, 2015 and 2014 . 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, 2016 and 2015 , we had asset retirement obligations of $13.4 million and $11.1 million . Additionally, we had $8.1 million and $4.8 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, 2016 and 2015 , 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 distribution, pipeline and storage and natural gas marketing segments and interest rate risk. The objectives and strategies for using financial instruments have been tailored to our regulated and natural gas marketing businesses and are discussed in Note 13 . 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 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 distribution segment as a result of the use of financial instruments. In our natural gas marketing 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, which is reflected in income from discontinued operations 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, 2016 , 2015 and 2014 , we included unrealized gains (losses) on open contracts of $1.2 million , ($2.0) million and $9.5 million as a component of natural gas marketing purchased gas cost. These amounts are included in income from discontinued operations. Additionally, we have elected to treat fixed-price forward contracts used in our natural gas marketing 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 which is reflected in income from discontinued operations 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 reflected in income from discontinued operations for the years ended September 30, 2016 and 2015 . Our natural gas marketing 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, 2016 and 2015 , the Company netted $ 24.7 million and $ 43.5 million of cash held in margin accounts into its current and noncurrent risk management assets and liabilities, which are included in assets and liabilities held for sale. 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. As of September 30, 2016 , the Company netted $25.7 million of cash held in margin accounts into its current and noncurrent risk management liabilities. As of September 30, 2015 no cash was required to be held in margin accounts. 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 natural gas marketing 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, corporate bonds 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 currently do not have any Level 3 investments. 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 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 noted in Note 5 regarding the renewal of our revolving credit facility and the AEM uncommitted 364-day bilateral credit facility and Note 15 regarding the sale of AEM, 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. 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. As of September 30, 2016 , we were actively evaluating all of our sources of revenue to determine the potential effect of the new standard on our financial position, results of operations and cash flows and the transition approach we will utilize. We are also actively monitoring the deliberations of the FASB's Transition Resource Group as decisions made by this group will impact the final conclusions of this evaluation. In April 2015, the FASB issued guidance to simplify the presentation of debt issuance c

Segment Information

Segment Information	12 Months Ended
	Sep. 30, 2016
Segment Reporting [Abstract]
Segment Information	Segment Information Atmos Energy Corporation and its subsidiaries are engaged primarily in the regulated natural gas distribution and pipeline and storage 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 distribution divisions, which cover service areas located in eight states. In addition, we transport natural gas for others through our distribution system. Prior to the sale of AEM, our consolidated operations were previously managed and reviewed through three segments: • The regulated distribution segment , which included our regulated natural gas distribution and related sales operations. • The regulated pipeline segment , which included the pipeline and storage operations of our Atmos Energy Pipeline-Texas division and, • The nonregulated segment , which included our nonregulated natural gas management, nonregulated natural gas transmission, storage and other services. As a result of the announced sale of Atmos Energy Marketing, we revised the information used by the chief operating decision maker to manage the Company. Accordingly, we now manage and review our consolidated operations through the following three reportable segments: • The distribution segment primarily comprised of our regulated natural gas distribution and related sales operations in eight states and storage assets located in Kentucky and Tennessee, which are used to solely support our natural gas distribution operations in those states. These storage assets were formerly included in our nonregulated segment. • The pipeline and storage segment is comprised primarily of the pipeline and storage operations of our Atmos Pipeline-Texas division and our natural gas transmission operations in Louisiana, which were formerly included in our nonregulated segment. • The natural gas marketing segment is comprised of our discontinued natural gas marketing business. 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 distribution segment operations are geographically dispersed, they are aggregated and reported as a single segment as each distribution division has similar economic characteristics. In addition, the pipeline and storage operations of our Atmos Pipeline-Texas division and our natural gas transmission operations in Louisiana have similar economic characteristics and have been aggregated and reported as a single segment. 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 between continuing operations and discontinued operations using an intraperiod tax allocation. Income taxes from continuing operations are allocated to each segment of continuing operations based on the separate return basis. Summarized income statements and capital expenditures by segment are shown in the following tables. Year Ended September 30, 2016 Distribution Pipeline and Storage Natural Gas Marketing Eliminations Consolidated (In thousands) Operating revenues from external parties $ 2,338,404 $ 116,244 $ — $ — $ 2,454,648 Intersegment revenues 1,374 310,952 — (312,326 ) — 2,339,778 427,196 — (312,326 ) 2,454,648 Purchased gas cost 1,058,576 (58 ) — (312,326 ) 746,192 Gross profit 1,281,202 427,254 — — 1,708,456 Operating expenses Operation and maintenance 407,982 130,610 — — 538,592 Depreciation and amortization 234,109 56,682 — — 290,791 Taxes, other than income 197,227 24,616 — — 221,843 Total operating expenses 839,318 211,908 — — 1,051,226 Operating income 441,884 215,346 — — 657,230 Miscellaneous income (expense) 1,171 (1,405 ) — — (234 ) Interest charges 78,238 36,574 — — 114,812 Income from continuing operations before income taxes 364,817 177,367 — — 542,184 Income tax expense 130,987 65,655 — — 196,642 Income from continuing operations 233,830 111,712 — — 345,542 Income from discontinued operations, net of tax — — 4,562 — 4,562 Net income $ 233,830 $ 111,712 $ 4,562 $ — $ 350,104 Capital expenditures $ 740,246 $ 346,383 $ 321 $ — $ 1,086,950 Year Ended September 30, 2015 Distribution Pipeline and Storage Natural Gas Marketing Eliminations Consolidated (In thousands) Operating revenues from external parties $ 2,819,977 $ 107,008 $ — $ — $ 2,926,985 Intersegment revenues 1,385 277,949 — (279,334 ) — 2,821,362 384,957 — (279,334 ) 2,926,985 Purchased gas cost 1,574,447 562 — (279,334 ) 1,295,675 Gross profit 1,246,915 384,395 — — 1,631,310 Operating expenses Operation and maintenance 393,504 122,902 — — 516,406 Depreciation and amortization 224,094 48,314 — — 272,408 Taxes, other than income 206,625 23,639 — — 230,264 Total operating expenses 824,223 194,855 — — 1,019,078 Operating income 422,692 189,540 — — 612,232 Miscellaneous income (expense) 284 (1,103 ) — — (819 ) Interest charges 83,087 33,154 — — 116,241 Income from continuing operations before income taxes 339,889 155,283 — — 495,172 Income tax expense 134,069 55,480 — — 189,549 Income from continuing operations 205,820 99,803 — — 305,623 Income from discontinued operations, net of tax — — 9,452 — 9,452 Net income $ 205,820 $ 99,803 $ 9,452 $ — $ 315,075 Capital expenditures $ 670,620 $ 292,775 $ 226 $ — $ 963,621 Year Ended September 30, 2014 Distribution Pipeline and Storage Natural Gas Marketing Eliminations Consolidated (In thousands) Operating revenues from external parties $ 3,137,858 $ 106,046 $ — $ — $ 3,243,904 Intersegment revenues 1,363 231,494 — (232,857 ) — 3,139,221 337,540 — (232,857 ) 3,243,904 Purchased gas cost 1,952,869 2,048 — (232,857 ) 1,722,060 Gross profit 1,186,352 335,492 — — 1,521,844 Operating expenses Operation and maintenance 391,747 90,729 — — 482,476 Depreciation and amortization 209,485 42,187 — — 251,672 Taxes, other than income 196,503 13,971 — — 210,474 Total operating expenses 797,735 146,887 — — 944,622 Operating income 388,617 188,605 — — 577,222 Miscellaneous income (expense) 3 (3,006 ) — — (3,003 ) Interest charges 92,997 36,279 — — 129,276 Income from continuing operations before income taxes 295,623 149,320 — — 444,943 Income tax expense 121,165 53,447 — — 174,612 Income from continuing operations 174,458 95,873 — — 270,331 Income from discontinued operations, net of tax — — 19,486 — 19,486 Net income $ 174,458 $ 95,873 $ 19,486 $ — $ 289,817 Capital expenditures $ 574,656 $ 248,226 $ 1,559 $ — $ 824,441 The following table summarizes our revenues from external parties by products and services for the fiscal year ended September 30. 2016 2015 2014 (In thousands) Distribution revenues: Gas sales revenues: Residential $ 1,477,049 $ 1,761,689 $ 1,933,099 Commercial 619,979 772,187 876,042 Industrial 98,439 131,034 166,736 Public authority and other 41,307 53,401 64,779 Total gas sales revenues 2,236,774 2,718,311 3,040,656 Transportation revenues 76,690 72,340 68,020 Other gas revenues 24,940 29,326 29,182 Total distribution revenues 2,338,404 2,819,977 3,137,858 Pipeline and storage revenues 116,244 107,008 106,046 Total operating revenues $ 2,454,648 $ 2,926,985 $ 3,243,904 Balance sheet information at September 30, 2016 and 2015 by segment is presented in the following tables. September 30, 2016 Distribution Pipeline and Storage Natural Gas Marketing Eliminations Consolidated (In thousands) ASSETS Property, plant and equipment, net $ 6,208,465 $ 2,060,141 $ — $ — $ 8,268,606 Investment in subsidiaries 768,415 13,854 — (782,269 ) — Current assets Cash and cash equivalents 22,117 — 25,417 — 47,534 Current assets of disposal group classified as held for sale — — 162,508 (11,391 ) 151,117 Other current assets 489,963 39,078 5 (46,011 ) 483,035 Intercompany receivables 971,665 — — (971,665 ) — Total current assets 1,483,745 39,078 187,930 (1,029,067 ) 681,686 Goodwill 583,950 143,012 — — 726,962 Noncurrent assets of disposal group classified as held for sale — — 28,785 (169 ) 28,616 Deferred charges and other assets 277,240 27,779 — — 305,019 $ 9,321,815 $ 2,283,864 $ 216,715 $ (1,811,505 ) $ 10,010,889 CAPITALIZATION AND LIABILITIES Shareholders’ equity $ 3,463,059 $ 715,672 $ 66,597 $ (782,269 ) $ 3,463,059 Long-term debt 2,188,779 — — — 2,188,779 Total capitalization 5,651,838 715,672 66,597 (782,269 ) 5,651,838 Current liabilities Current maturities of long-term debt 250,000 — — — 250,000 Short-term debt 829,811 — 35,000 (35,000 ) 829,811 Current liabilities of disposal group classified as held for sale — — 81,908 (9,008 ) 72,900 Other current liabilities 605,790 39,911 3,263 (13,394 ) 635,570 Intercompany payables — 957,526 14,139 (971,665 ) — Total current liabilities 1,685,601 997,437 134,310 (1,029,067 ) 1,788,281 Deferred income taxes 1,055,348 543,390 4,318 — 1,603,056 Regulatory cost of removal obligation 397,162 27,119 — — 424,281 Pension and postretirement liabilities 297,743 — — — 297,743 Noncurrent liabilities of disposal group classified as held for sale — — 316 — 316 Deferred credits and other liabilities 234,123 246 11,174 (169 ) 245,374 $ 9,321,815 $ 2,283,864 $ 216,715 $ (1,811,505 ) $ 10,010,889 September 30, 2015 Distribution Pipeline and Storage Natural Gas Marketing Eliminations Consolidated (In thousands) ASSETS Property, plant and equipment, net $ 5,656,788 $ 1,759,912 $ — $ — $ 7,416,700 Investment in subsidiaries 653,249 13,854 — (667,103 ) — Current assets Cash and cash equivalents 24,645 — 4,008 — 28,653 Current assets of disposal group classified as held for sale — — 148,904 (9,849 ) 139,055 Other current assets 478,054 50,309 (3,385 ) (66,380 ) 458,598 Intercompany receivables 863,088 — 2,960 (866,048 ) — Total current assets 1,365,787 50,309 152,487 (942,277 ) 626,306 Goodwill 583,285 142,972 — — 726,257 Noncurrent assets of disposal group classified as held for sale — — 30,385 — 30,385 Deferred charges and other assets 257,635 17,890 (101 ) — 275,424 $ 8,516,744 $ 1,984,937 $ 182,771 $ (1,609,380 ) $ 9,075,072 CAPITALIZATION AND LIABILITIES Shareholders’ equity $ 3,194,797 $ 629,820 $ 37,283 $ (667,103 ) $ 3,194,797 Long-term debt 2,437,515 — — — 2,437,515 Total capitalization 5,632,312 629,820 37,283 (667,103 ) 5,632,312 Current liabilities Short-term debt 457,927 — 50,000 (50,000 ) 457,927 Current liabilities of the disposal group classified as held for sale — — 89,471 (14,911 ) 74,560 Other current liabilities 578,439 49,352 5,863 (11,318 ) 622,336 Intercompany payables — 866,048 — (866,048 ) — Total current liabilities 1,036,366 915,400 145,334 (942,277 ) 1,154,823 Deferred income taxes 1,007,198 411,722 (7,605 ) — 1,411,315 Regulatory cost of removal obligation 399,747 27,806 — — 427,553 Pension and postretirement liabilities 287,373 — — — 287,373 Noncurrent liabilities of disposal group classified as held for sale — — 347 — 347 Deferred credits and other liabilities 153,748 189 7,412 — 161,349 $ 8,516,744 $ 1,984,937 $ 182,771 $ (1,609,380 ) $ 9,075,072

Earnings Per Share

Earnings Per Share	12 Months Ended
	Sep. 30, 2016
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: 2016 2015 2014 (In thousands, except per share data) Basic Earnings Per Share from continuing operations Income from continuing operations $ 345,542 $ 305,623 $ 270,331 Less: Income from continuing operations allocated to participating securities 538 607 663 Income from continuing operations available to common shareholders $ 345,004 $ 305,016 $ 269,668 Basic weighted average shares outstanding 103,524 101,892 97,606 Income from continuing operations per share — Basic $ 3.33 $ 3.00 $ 2.76 Basic Earnings Per Share from discontinued operations Income from discontinued operations $ 4,562 $ 9,452 $ 19,486 Less: Income from discontinued operations allocated to participating securities 8 19 48 Income from discontinued operations available to common shareholders $ 4,554 $ 9,433 $ 19,438 Basic weighted average shares outstanding 103,524 101,892 97,606 Income from discontinued operations per share - Basic $ 0.05 $ 0.09 $ 0.20 Net income per share - Basic $ 3.38 $ 3.09 $ 2.96 Diluted Earnings Per Share from continuing operations Income from continuing operations available to common shareholders $ 345,004 $ 305,016 $ 269,668 Effect of dilutive stock options and other shares — — — Income from continuing operations available to common shareholders $ 345,004 $ 305,016 $ 269,668 Basic weighted average shares outstanding 103,524 101,892 97,606 Additional dilutive stock options and other shares — — 2 Diluted weighted average shares outstanding 103,524 101,892 97,608 Income from continuing operations per share — Diluted $ 3.33 $ 3.00 $ 2.76 Diluted Earnings Per Share from discontinued operations Income from discontinued operations available to common shareholders $ 4,554 $ 9,433 $ 19,438 Effect of dilutive stock options and other shares — — — Income from discontinued operations available to common shareholders $ 4,554 $ 9,433 $ 19,438 Basic weighted average shares outstanding 103,524 101,892 97,606 Additional dilutive stock options and other shares — — 2 Diluted weighted average shares outstanding 103,524 101,892 97,608 Income from discontinued operations per share — Diluted $ 0.05 $ 0.09 $ 0.20 Net income per share - Diluted $ 3.38 $ 3.09 $ 2.96

Debt

Debt	12 Months Ended
	Sep. 30, 2016
Debt Disclosure [Abstract]
Debt	Debt Long-term debt at September 30, 2016 and 2015 consisted of the following: 2016 2015 (In thousands) Unsecured 6.35% Senior Notes, due June 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 500,000 500,000 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 4,270 4,612 Debt issuance cost 16,951 17,873 Current maturities 250,000 — $ 2,188,779 $ 2,437,515 On September 22, 2016, we entered into a three year, $200 million multi-draw term loan agreement with a syndicate of three lenders. Borrowings under the term loan may be made in increments of $1.0 million or higher, may be repaid at any time during the loan period and will bear interest at a rate dependent upon our credit ratings at the time of such borrowing and based, at our election, on a base rate or LIBOR for the applicable interest period. The term loan will be used to refinance existing indebtedness and for working capital, capital expenditures and other general corporate purposes. At September 30, 2016, there were no borrowings under the term loan. 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 13 . 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. We utilize short-term debt to fund ongoing working capital needs, such as our seasonal requirements for gas supply and general corporate liquidity. Our short-term borrowings typically reach their highest levels in the winter months. As of September 30, 2016, we financed 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. On October 5, 2016 , we amended our existing $1.25 billion unsecured credit facility (the five-year unsecured credit facility) which increased the committed loan to $1.5 billion and extended the facility through September 25, 2021. The 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. The amended facility also retains the $250 million accordion feature, which provides the opportunity to increase the total committed loan amount to $1.75 billion . After giving effect to the amended facility, we have total availability from third-party lenders of approximately $1.6 billion of working capital funding. At September 30, 2016 and 2015 , there was $829.8 million and $457.9 million outstanding under our commercial paper program with weighted average interest rates of 0.81% and 0.42% , 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. We have a $25 million unsecured facility and a $10 million committed revolving credit facility, which is used primarily to issue letters of credit and bears interest at a LIBOR-based rate plus 1.5 percent . At September 30, 2016 , there were no borrowings outstanding under either of these credit facilities; however, outstanding letters of credit reduced the total amount available to us under our $10 million revolving facility to $4.1 million . Atmos Energy Marketing, LLC (AEM), has one uncommitted $25 million 364-day bilateral credit facility that expires in December 2016 and one committed $15 million 364-day bilateral credit facility that was renewed on September 30, 2016. On October 25, 2016 , the uncommitted $25 million bilateral credit facility was renewed through July 31, 2017. 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 $ 32.8 million at September 30, 2016 . 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 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, 2016 , our total-debt-to-total-capitalization ratio, as defined, was 50 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, 2016 . We intend to seek renewal of this facility during the first quarter of fiscal 2017. There was $197.0 million outstanding under this facility at September 30, 2016 . AEH has a $500 million intercompany demand credit facility with AEC. This facility bears interest at a rate equal to the one-month LIBOR rate plus 3.00 percent . Applicable state regulatory commissions have approved our use of this facility through December 31, 2016. We intend to seek renewal of this facility during the first quarter of fiscal 2017. There were no borrowings outstanding under this facility at September 30, 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, 2016 . 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, 2016 were as follows (in thousands): 2017 $ 250,000 2018 — 2019 450,000 2020 — 2021 — Thereafter 1,760,000 $ 2,460,000

Shareholders' Equity

Shareholders' Equity	12 Months Ended
	Sep. 30, 2016
Equity [Abstract]
Shareholders' Equity	Shareholders' Equity Shelf Registration On March 28, 2016, we filed a registration statement with the Securities and Exchange Commission (SEC) that originally permitted us to issue, from time to time, up to $2.5 billion in common stock and/or debt securities, which replaced our registration statement that expired on March 28, 2016. At September 30, 2016 , $2.4 billion of securities remain available for issuance under the shelf registration statement. At-the-Market Equity Sales Program On March 28, 2016, we entered into an at-the-market (ATM) equity distribution agreement (the Agreement) with Goldman, Sachs & Co., Merrill Lynch, Pierce, Fenner & Smith Incorporated and Morgan Stanley & Co. LLC in their capacity as agents and/or as principals (Agents). Under the terms of the Agreement, we may issue and sell, through any of the Agents, shares of our common stock, up to an aggregate offering price of $200 million , through the period ended March 28, 2019. We may also sell shares from time to time to an Agent for its own account at a price to be agreed upon at the time of sale. We will pay each Agent a commission of 1.0% of the gross offering proceeds of the shares sold through it as a sales agent. We have no obligation to offer or sell any shares under the Agreement, and may at any time suspend offers and sales under the Agreement. The shares will be issued pursuant to our shelf registration statement filed with the SEC on March 28, 2016. During fiscal 2016, we sold 1,360,756 shares of common stock under the ATM program for $100.0 million and received net proceeds of $98.6 million . 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 our 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. In February 2016, our shareholders voted to increase the number of authorized LTIP shares by 2.5 million shares and to extend the term of the plan for an additional five years, through September 2021. On March 29, 2016, we filed with the SEC a registration statement on Form S-8 to register an additional 2.5 million shares; we also listed such shares with the New York Stock Exchange. As of September 30, 2016, we were authorized to grant awards for up to a maximum of 11.2 million shares of common stock under this plan subject to certain adjustment provisions. 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, the Board of Directors approved a program authorizing the repurchase of up to five million shares of common stock over a five-year period. The program expired on September 30, 2016 and will not be renewed. We did not repurchase any shares during fiscal 2016, 2015, or 2014 under the program. Accumulated Other Comprehensive Income (Loss) 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, 2015 $ 4,949 $ (88,842 ) $ (25,437 ) $ (109,330 ) Other comprehensive income (loss) before reclassifications (263 ) (99,029 ) (11,662 ) (110,954 ) Amounts reclassified from accumulated other comprehensive income (202 ) 347 32,117 32,262 Net current-period other comprehensive income (loss) (465 ) (98,682 ) 20,455 (78,692 ) September 30, 2016 $ 4,484 $ (187,524 ) $ (4,982 ) $ (188,022 ) 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 ) The following tables detail reclassifications out of AOCI for the fiscal years ended September 30, 2016 and 2015 . Amounts in parentheses below indicate decreases to net income in the statement of income. Fiscal Year Ended September 30, 2016 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 $ 318 Operation and maintenance expense 318 Total before tax (116 ) Tax expense $ 202 Net of tax Cash flow hedges Interest rate agreements $ (546 ) Interest charges Commodity contracts (52,651 ) Purchased gas cost (1) (53,197 ) Total before tax 20,733 Tax benefit $ (32,464 ) Net of tax Total reclassifications $ (32,262 ) Net of tax 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 (1) (42,569 ) Total before tax 16,579 Tax benefit $ (25,990 ) Net of tax Total reclassifications $ (25,450 ) Net of tax (1) Amounts are presented as part of income from discontinued operations on the consolidated statements of income.

Retirement and Post-retirement

Retirement and Post-retirement Employee Benefit Plans	12 Months Ended
	Sep. 30, 2016
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 a defined contribution plan 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 Plan Supplemental Executive Retirement Plans Postretirement Plans Total (In thousands) September 30, 2016 Unrecognized prior service credit $ (1,509 ) $ — $ (2,880 ) $ (4,389 ) Unrecognized actuarial (gain) loss 127,028 51,558 (54,298 ) 124,288 $ 125,519 $ 51,558 $ (57,178 ) $ 119,899 September 30, 2015 Unrecognized transition obligation $ — $ — $ 82 $ 82 Unrecognized prior service credit (1,735 ) — (4,524 ) (6,259 ) Unrecognized actuarial (gain) loss 120,948 36,915 (47,149 ) 110,714 $ 119,213 $ 36,915 $ (51,591 ) $ 104,537 Defined Benefit Plans Employee Pension Plan 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 that were hired before September 30, 2010. The plan was closed to new participants effective October 1, 2010. 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). In addition, at the end of each year, a participant’s account is credited with interest on the employee’s prior year account balance. 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. 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 2016 and 2015 we contributed $15.0 million and $38.0 million in cash to the Plan to achieve a desired level of funding while maximizing the tax deductibility of this payment. Based upon market conditions at September 30, 2016 , the current funded position of the Plan and the funding requirements under the PPA, we do not anticipate a minimum required contribution for fiscal 2017 . 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, 2016 and 2015 . Targeted Allocation Range Actual Allocation September 30 Security Class 2016 2015 Domestic equities 35%-55% 40.5 % 41.3 % International equities 10%-20% 15.5 % 14.9 % Fixed income 5%-30% 11.2 % 11.0 % Company stock 0%-15% 15.1 % 15.2 % Other assets 0%-20% 17.7 % 17.6 % At September 30, 2016 and 2015 , the Plan held 956,700 and 1,169,700 shares of our common stock which represented 15.1 percent and 15.2 percent of total Plan assets. These shares generated dividend income for the Plan of approximately $1.8 million during fiscal 2016 and 2015 . 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 Plan was determined as of September 30, 2016 and 2015 and the actuarial assumptions used to determine the net periodic pension cost for the Plan was determined as of September 30, 2015 , 2014 and 2013 . On October 20, 2016 , the Society of Actuaries released its annually-updated mortality improvement scale for pension plans incorporating new assumptions surrounding life expectancies in the United States. As of September 30, 2016, we updated our assumed mortality rates to incorporate the updated mortality table. Additional assumptions are presented in the following table: Pension Liability Pension Cost 2016 2015 2016 2015 2014 Discount rate 3.73 % 4.55 % 4.55 % 4.43 % 4.95 % Rate of compensation increase 3.50 % 3.50 % 3.50 % 3.50 % 3.50 % Expected return on plan assets 7.00 % 7.00 % 7.00 % 7.25 % 7.25 % The following table presents the Plan’s accumulated benefit obligation, projected benefit obligation and funded status as of September 30, 2016 and 2015 : 2016 2015 (In thousands) Accumulated benefit obligation $ 516,924 $ 485,921 Change in projected benefit obligation: Benefit obligation at beginning of year $ 508,599 $ 493,594 Service cost 16,419 16,231 Interest cost 23,193 21,850 Actuarial loss 41,847 7,420 Benefits paid (1) (44,578 ) (30,496 ) Benefit obligation at end of year 545,480 508,599 Change in plan assets: Fair value of plan assets at beginning of year 450,932 434,767 Actual return on plan assets 52,596 8,661 Employer contributions 15,000 38,000 Benefits paid (1) (44,578 ) (30,496 ) Fair value of plan assets at end of year 473,950 450,932 Reconciliation: Funded status (71,530 ) (57,667 ) Unrecognized prior service cost — — Unrecognized net loss — — Accrued pension cost $ (71,530 ) $ (57,667 ) (1) Includes $12.8 million of one-time payments to eligible deferred vested participants who elected to receive a lump-sum payout of their pension benefits during fiscal 2016. Net periodic pension cost for the Plan for fiscal 2016 , 2015 and 2014 is recorded as operating expense and included the following components: Fiscal Year Ended September 30 2016 2015 2014 (In thousands) Components of net periodic pension cost: Service cost $ 16,419 $ 16,231 $ 15,345 Interest cost 23,193 21,850 22,330 Expected return on assets (27,522 ) (25,744 ) (23,601 ) Amortization of prior service credit (226 ) (192 ) (136 ) Recognized actuarial loss 10,693 13,322 13,777 Net periodic pension cost $ 22,557 $ 25,467 $ 27,715 The following table sets forth by level, within the fair value hierarchy, the Plan's assets at fair value as of September 30, 2016 and 2015 . 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 Plan are fully described in Note 2 . In addition to the assets shown below, the Plan had net accounts receivable of $2.6 million and $2.4 million at September 30, 2016 and 2015 which materially approximates fair value due to the short-term nature of these assets. Assets at Fair Value as of September 30, 2016 Level 1 Level 2 Level 3 Total (In thousands) Investments: Common stocks $ 157,111 $ — $ — $ 157,111 Money market funds — 11,522 — 11,522 Registered investment companies 87,396 — — 87,396 Common/collective trusts — 105,124 — 105,124 Government securities: Mortgage-backed securities — 15,223 — 15,223 U.S. treasuries 4,704 863 — 5,567 Corporate bonds — 31,929 — 31,929 Limited partnerships — 57,438 — 57,438 Total investments at fair value $ 249,211 $ 222,099 $ — $ 471,310 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 81,960 — — 81,960 Common/collective trusts — 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 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. 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, 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. 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, 2016 and 2015 and the actuarial assumptions used to determine the net periodic pension cost for the supplemental plans were determined as of September 30, 2015 , 2014 and 2013 . These assumptions are presented in the following table: Pension Liability Pension Cost 2016 2015 2016 2015 2014 Discount rate 3.73 % 4.55 % 4.55 % 4.43 % 4.95 % Rate of compensation increase 3.50 % 3.50 % 3.50 % 3.50 % 3.50 % The following table presents the supplemental plans’ accumulated benefit obligation, projected benefit obligation and funded status as of September 30, 2016 and 2015 : 2016 2015 (In thousands) Accumulated benefit obligation $ 137,616 $ 118,835 Change in projected benefit obligation: Benefit obligation at beginning of year $ 122,393 $ 113,219 Service cost 2,371 3,971 Interest cost 5,185 4,943 Actuarial loss 17,229 4,811 Benefits paid (4,604 ) (4,551 ) Benefit obligation at end of year 142,574 122,393 Change in plan assets: Fair value of plan assets at beginning of year — — Employer contribution 4,604 4,551 Benefits paid (4,604 ) (4,551 ) Fair value of plan assets at end of year — — Reconciliation: Funded status (142,574 ) (122,393 ) Unrecognized prior service cost — — Unrecognized net loss — — Accrued pension cost $ (142,574 ) $ (122,393 ) Assets for the supplemental plans are held in separate rabbi trusts. At September 30, 2016 and 2015 , assets held in the rabbi trusts consisted of available-for-sale securities of $41.3 million and $41.7 million , which are included in our fair value disclosures in Note 14 . Net periodic pension cost for the supplemental plans for fiscal 2016 , 2015 and 2014 is recorded as operating expense and included the following components: Fiscal Year Ended September 30 2016 2015 2014 (In thousands) Components of net periodic pension cost: Service cost $ 2,371 $ 3,971 $ 3,607 Interest cost 5,185 4,943 4,966 Amortization of transition asset — — — Amortization of prior service cost — — — Recognized actuarial loss 2,586 2,343 1,948 Settlements — — 4,539 Net periodic pension cost $ 10,142 $ 11,257 $ 15,060 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 Plan Supplemental Plans (In thousands) 2017 $ 31,306 $ 36,604 2018 32,047 14,289 2019 33,674 7,181 2020 35,232 4,395 2021 37,279 4,306 2022-2026 202,442 60,658 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. Effective January 1, 2015 for employees who had not met the participation requirements by September 30, 2009, the contribution rates for the Company will be limited to a three percent cost increase in claims and administrative costs each year, with the participant 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 $10 million and $20 million to our postretirement benefits plan during fiscal 2017 . 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, 2016 and 2015 . Actual Allocation September 30 Security Class 2016 2015 Diversified investment funds 97.2 % 97.5 % Cash and cash equivalents 2.8 % 2.5 % 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, 2016 and 2015 and the actuarial assumptions used to determine the net periodic pension cost for the postretirement plan were determined as of September 30, 2015 , 2014 and 2013 . The assumptions are presented in the following table: Postretirement Liability Postretirement Cost 2016 2015 2016 2015 2014 Discount rate 3.73 % 4.55 % 4.55 % 4.43 % 4.95 % Expected return on plan assets 4.45 % 4.45 % 4.45 % 4.60 % 4.60 % Initial trend rate 7.50 % 7.50 % 7.50 % 7.50 % 8.00 % Ultimate trend rate 5.00 % 5.00 % 5.00 % 5.00 % 5.00 % Ultimate trend reached in 2022 2021 2021 2020 2020 The following table presents the postretirement plan’s benefit obligation and funded status as of September 30, 2016 and 2015 : 2016 2015 (In thousands) Change in benefit obligation: Benefit obligation at beginning of year $ 267,179 $ 315,118 Service cost 10,823 15,583 Interest cost 12,424 14,385 Plan participants’ contributions 4,289 4,563 Actuarial gain (1,052 ) (69,962 ) Benefits paid (14,441 ) (12,508 ) Benefit obligation at end of year 279,222 267,179 Change in plan assets: Fair value of plan assets at beginning of year 138,009 134,821 Actual return on plan assets 14,528 (8,851 ) Employer contributions 16,592 19,984 Plan participants’ contributions 4,289 4,563 Benefits paid (14,441 ) (12,508 ) Fair value of plan assets at end of year 158,977 138,009 Reconciliation: Funded status (120,245 ) (129,170 ) Unrecognized transition obligation — — Unrecognized prior service cost — — Unrecognized net loss — — Accrued postretirement cost $ (120,245 ) $ (129,170 ) Net periodic postretirement cost for fiscal 2016 , 2015 and 2014 is recorded as operating expense and included the components presented below. Fiscal Year Ended September 30 2016 2015 2014 (In thousands) Components of net periodic postretirement cost: Service cost $ 10,823 $ 15,583 $ 16,784 Interest cost 12,424 14,385 15,951 Expected return on assets (6,264 ) (6,431 ) (5,167 ) Amortization of transition obligation 82 272 274 Amortization of prior service credit (1,644 ) (1,644 ) (1,450 ) Recognized actuarial (gain) loss (2,167 ) — 631 Net periodic postretirement cost $ 13,254 $ 22,165 $ 27,023 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 $ 4,539 $ (3,596 ) Effect on postretirement benefit obligation $ 42,079 $ (34,531 ) 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, 2016 and 2015 . 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, 2016 Level 1 Level 2 Level 3 Total (In thousands) Investments: Money market funds $ — $ 4,470 $ — $ 4,470 Registered investment companies 154,507 — — 154,507 Total investments at fair value $ 154,507 $ 4,470 $ — $ 158,977 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 134,523 — — 134,523 Total investments at fair value $ 134,523 $ 3,486 $ — $ 138,009 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 2016 include contributions to our postretirement plan trusts. Company Payments Retiree Payments Subsidy Payments Total Postretirement Benefits (In thousands) 2017 $ 15,806 $ 3,679 $ — $ 19,485 2018 11,602 3,992 — 15,594 2019 12,165 4,036 — 16,201 2020 13,246 4,756 — 18,002 2021 14,210 5,420 — 19,630 2022-2026 84,642 36,837 — 121,479 Defined Contribution Plan The Atmos Energy Corporation Retirement Savings Plan and Trust (the Retirement Savings Plan) covers substantially all employees 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, 2015, we also maintained the Atmos Energy Holdings, LLC 401(k) Profit-Sharing Plan (the AEH 401(k) Profit-Sharing Plan), which covered substantially all AEH employees. On November 4, 2015, the Atmos Energy Corporation Board of Directors voted to approve the merger of the assets and liabilities of the AEH 401(k) Profit-Sharing Plan with the Retirement Savings Plan, effective January 1, 2016. On December 31, 2015, the AEH 401(k) Profit Sharing Plan was merged into the Retirement Savings Plan and all assets and loans of active and inactive participants were transferred to the Retirement Savings Plan. Prior to December 31, 2014, we maintained the Atmos Energy Corporation Savings Plan for MVG Union Employees (the Union 401(k) 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 401(k) Plan were eligible to participate in the Retirement Savings Plan. Effective January 1, 2015, all remaining participants became participants in the Retirement Savings Plan and the Union 401(k) Plan was terminated. Matching contributions to the Retirement Savings Plan (and prior to December 31, 2015, the AEH 401(k) Profit-Sharing Plan, and prior to December 31, 2014, the Union 401(k) Plan) are expensed as incurred and amounted to $12.6 million , $11.5 million and $10.9 million for fiscal years 2016 , 2015 and 2014 . The Board of Directors may also approve discretionary contributions, subject to the provisions of the Internal Revenue Code and applicable Treasury regulations. No discretionary contributions were made for fiscal years 2016 , 2015 or 2014 . At September 30, 2016 and 2015 , the Retirement Savings Plan held 4.2 percent and 4.3 percent of our outstanding common stock. Discretionary contributions to the AEH 401(k) Profit-Sharing Plan were expensed as incurred and amounted to $0.3 million , $1.1 million and $1.4 million for fiscal years 2016 , 2015 and 2014 .

Stock and Other Compensation Pl

Stock and Other Compensation Plans	12 Months Ended
	Sep. 30, 2016
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 cost was $24.6 million , $27.5 million and $25.5 million for the fiscal years ended September 30, 2016 , 2015 and 2014 . Of this amount, $9.8 million , $11.5 million and $10.8 million was capitalized. Tax benefits related to stock-based compensation were $5.0 million , $4.7 million and $3.1 million for the fiscal years ended September 30, 2016 , 2015 and 2014 . 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, 2016 , we were authorized to grant awards for up to a maximum of 11.2 million shares of common stock under this plan subject to certain adjustment provisions. As of September 30, 2016 , 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 2.4 million 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. We estimate forfeitures using our historical forfeiture rate. The associated expense is recognized ratably over the vesting period. We use authorized and unissued shares to meet share requirements for the vesting of restricted stock units. 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, 2016 , 2015 and 2014 : 2016 2015 2014 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 878,104 $ 48.24 988,637 $ 42.22 1,052,844 $ 36.20 Granted 357,323 65.98 444,543 50.50 464,438 45.05 Vested (448,136 ) 45.88 (551,688 ) 39.28 (524,532 ) 32.67 Forfeited (4,860 ) 53.52 (3,388 ) 48.55 (4,113 ) 39.00 Nonvested at end of year 782,431 $ 57.66 878,104 $ 48.24 988,637 $ 42.22 As of September 30, 2016 , there was $11.4 million of total unrecognized compensation cost related to nonvested time-lapse restricted stock units granted under the LTIP. That cost is expected to be recognized over a weighted-average period of 1.6 years . The fair value of restricted stock vested during the fiscal years ended September 30, 2016 , 2015 and 2014 was $20.6 million , $21.7 million and $17.1 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, 2016
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, 2016 and 2015 : September 30 2016 2015 (In thousands) Billed accounts receivable $ 120,128 $ 120,482 Unbilled revenue 67,396 65,008 Other accounts receivable 39,412 40,777 Total accounts receivable 226,936 226,267 Less: allowance for doubtful accounts (11,056 ) (12,934 ) Net accounts receivable $ 215,880 $ 213,333 Other current assets Other current assets as of September 30, 2016 and 2015 were comprised of the following accounts. September 30 2016 2015 (In thousands) Assets from risk management activities $ 3,029 $ 378 Deferred gas costs 45,184 9,715 Taxes receivable 5,456 4,479 Prepaid expenses 21,489 21,654 Materials and supplies 5,825 12,587 Other 7,102 1,116 Total $ 88,085 $ 49,929 Property, plant and equipment Property, plant and equipment was comprised of the following as of September 30, 2016 and 2015 : September 30 2016 2015 (In thousands) Production plant $ 66 $ 131 Storage plant 353,523 286,011 Transmission plant 2,232,927 1,844,117 Distribution plant 6,598,990 6,019,001 General plant 732,606 740,863 Intangible plant 40,515 41,131 9,958,627 8,931,254 Construction in progress 183,879 280,421 10,142,506 9,211,675 Less: accumulated depreciation and amortization (1,873,900 ) (1,794,975 ) Net property, plant and equipment (1) $ 8,268,606 $ 7,416,700 (1) Net property, plant and equipment includes plant acquisition adjustments of $(59.8) million and $(68.1) million at September 30, 2016 and 2015 . Goodwill The following presents our goodwill balance allocated by segment and changes in the balance for the fiscal year ended September 30, 2016 : Distribution Pipeline and Storage Total (In thousands) Balance as of September 30, 2015 (2) $ 583,285 $ 142,972 $ 726,257 Deferred tax adjustments on prior acquisitions (1) 665 40 705 Balance as of September 30, 2016 (2) $ 583,950 $ 143,012 $ 726,962 (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 2016 . (2) Natural gas marketing had goodwill of $16.4 million at September 30, 2016 and 2015 classified as assets held for sale on the consolidated balance sheet. Deferred charges and other assets Deferred charges and other assets as of September 30, 2016 and 2015 were comprised of the following accounts. September 30 2016 2015 (In thousands) Marketable securities $ 72,701 $ 74,200 Regulatory assets 214,890 182,573 Assets from risk management activities 1,822 368 Other 15,606 18,283 Total $ 305,019 $ 275,424 Accounts payable and accrued liabilities Accounts payable and accrued liabilities as of September 30, 2016 and 2015 were comprised of the following accounts. September 30 2016 2015 (In thousands) Trade accounts payable $ 114,361 $ 78,376 Accrued gas payable 47,107 56,468 Accrued liabilities 35,017 39,802 Total $ 196,485 $ 174,646 Other current liabilities Other current liabilities as of September 30, 2016 and 2015 were comprised of the following accounts. September 30 2016 2015 (In thousands) Customer credit balances and deposits $ 81,219 $ 99,043 Accrued employee costs 47,058 47,602 Deferred gas costs 20,180 28,100 Accrued interest 34,863 34,914 Liabilities from risk management activities 56,771 9,568 Taxes payable 104,145 92,912 Pension and postretirement obligations 36,606 21,857 Current deferred tax liability — 55,918 Regulatory cost of removal accrual 52,610 56,123 Other 5,633 1,653 Total $ 439,085 $ 447,690 Deferred credits and other liabilities Deferred credits and other liabilities as of September 30, 2016 and 2015 were comprised of the following accounts. September 30 2016 2015 (In thousands) Customer advances for construction $ 9,850 $ 9,316 Regulatory liabilities 4,152 3,693 Asset retirement obligation 13,404 9,063 Liabilities from risk management activities 184,048 110,539 Other 33,920 28,738 Total $ 245,374 $ 161,349

Leases

Leases	12 Months Ended
	Sep. 30, 2016
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 18 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, 2016 were as follows: Operating Leases (In thousands) 2017 $ 17,073 2018 16,824 2019 15,450 2020 14,479 2021 14,335 Thereafter 47,714 Total minimum lease payments $ 125,875 Consolidated lease and rental expense amounted to $32.6 million , $32.5 million and $31.7 million for fiscal 2016 , 2015 and 2014 .

Commitments and Contingencies

Commitments and Contingencies	12 Months Ended
	Sep. 30, 2016
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 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 trading hubs. At September 30, 2016 , we were committed to purchase 28.5 Bcf within one year, 4.2 Bcf within two to three years and 0.6 Bcf beyond three years under indexed contracts. Purchases under these contracts totaled $85.3 million , $113.3 million and $140.9 million for 2016 , 2015 , 2014 . We also have commitments to purchase physical quantities of natural gas under contracts indexed to the forward NYMEX strip or fixed price contracts, primarily for our natural gas marketing segment. At September 30, 2016 , we were committed to purchase 93.5 Bcf within one year, 9.1 Bcf within two to three years and 0.2 Bcf after three years under indexed contracts. We are committed to purchase 11.9 Bcf within one year and 1.3 Bcf within one to three years under fixed price contracts with prices ranging from $0.25 to $3.16 per Mcf. Purchases under these contracts totaled $763.2 million , $1,141.3 million and $1,687.5 million for 2016 , 2015 and 2014 . In addition, we maintain long-term contracts related to storage and transportation in our pipeline and storage segment and in our natural gas marketing segment. The estimated contractual demand fees for contracted storage and transportation under these contracts as of September 30, 2016 are as follows (in thousands): 2017 $ 9,065 2018 2,336 2019 424 2020 400 2021 327 Thereafter 678 $ 13,230

Income Taxes

Income Taxes	12 Months Ended
	Sep. 30, 2016
Income Tax Disclosure [Abstract]
Income Taxes	Income Taxes The components of income tax expense from continuing operations for 2016 , 2015 and 2014 were as follows: 2016 2015 2014 (In thousands) Current Federal $ — $ — $ — State 5,667 6,513 5,192 Deferred Federal 178,630 170,649 158,362 State 12,350 12,393 11,064 Investment tax credits (5 ) (6 ) (6 ) $ 196,642 $ 189,549 $ 174,612 Reconciliations of the provision for income taxes computed at the statutory rate to the reported provisions for income taxes from continuing operations for 2016 , 2015 and 2014 are set forth below: 2016 2015 2014 (In thousands) Tax at statutory rate of 35% $ 189,764 $ 173,310 $ 155,730 Common stock dividends deductible for tax reporting (2,570 ) (2,413 ) (2,307 ) State taxes (net of federal benefit) 11,133 12,289 10,566 Change in valuation allowance 1,324 4,998 6,969 Other, net (3,009 ) 1,365 3,654 Income tax expense $ 196,642 $ 189,549 $ 174,612 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, 2016 and 2015 are presented below: 2016 2015 (In thousands) Deferred tax assets: Employee benefit plans $ 122,682 $ 121,619 Interest rate agreements 107,782 51,067 Net operating loss carryforwards 514,391 313,224 Charitable and other credit carryforwards 22,273 22,281 Other 23,648 36,695 Total deferred tax assets 790,776 544,886 Valuation allowance (10,481 ) (10,872 ) Net deferred tax assets 780,295 534,014 Deferred tax liabilities: Difference in net book value and net tax value of assets (2,259,278 ) (1,890,886 ) Pension funding (30,652 ) (35,247 ) Gas cost adjustments (54,725 ) (43,634 ) Other (38,696 ) (31,480 ) Total deferred tax liabilities (2,383,351 ) (2,001,247 ) Net deferred tax liabilities $ (1,603,056 ) $ (1,467,233 ) Deferred credits for rate regulated entities $ 861 $ 412 At September 30, 2016 , we had $494.0 million of federal net operating loss carryforwards. 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 $11.0 million in charitable contribution carryforwards to offset taxable income. The Company’s charitable contribution carryforwards expire in 2017 - 2021 . For state taxable income, the Company has $20.4 million of state net operating loss carryforwards (net of $11.0 million of federal effects) and $1.1 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 2017 and 2031 . We believe it is more likely than not that the benefit from certain charitable contribution carryforwards, state net operating loss carryforwards and state credit carryforwards will not be realized. Due to the uncertainty of realizing a benefit from the deferred tax asset recorded for the carryforwards, a valuation allowance of $1.1 million and $5.0 million was established for the years ended September 30, 2016 and 2015 . In addition, $1.4 million of deferred tax assets expired for which a valuation allowance had previously been recorded and $0.2 million of deferred tax assets expired for which a valuation allowance had not been previously recorded during the year ended September 30, 2016 . At September 30, 2016 , we had recorded liabilities associated with unrecognized tax benefits totaling $20.3 million . The following table reconciles the beginning and ending balance of our unrecognized tax benefits: 2016 2015 (In thousands) Unrecognized tax benefits - beginning balance $ 17,069 $ 12,629 Increase (decrease) resulting from prior period tax positions (290 ) 1,009 Increase resulting from current period tax positions 3,519 3,431 Unrecognized tax benefits - ending balance 20,298 17,069 Less: deferred federal and state income tax benefits (7,104 ) (5,974 ) Total unrecognized tax benefits that, if recognized, would impact the effective income tax rate as of the end of the year $ 13,194 $ 11,095 The Company recognizes interest accrued related to unrecognized tax benefits in interest expense and penalties in operating expense. During the years ended September 30, 2016 and 2015 , the Company recognized approximately $2.5 million and $0.5 million in interest and penalties. The Company had approximately $3.3 million and $0.8 million for the payment of interest and penalties accrued at September 30, 2016 and 2015 . 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 and concluded substantially all Texas income tax matters through fiscal year 2010.

Financial Instruments

Financial Instruments	12 Months Ended
	Sep. 30, 2016
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 natural gas marketing businesses. 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 distribution risk management assets and liabilities at September 30, 2016 and 2015 . Natural gas marketing's risk management assets and liabilities have been classified as held for sale at September 30, 2016 and 2015 related to the divestiture of our natural gas marketing business. These risk management assets and liabilities are detailed in Note 15. Distribution (In thousands) September 30, 2016 Assets from risk management activities, current $ 3,029 Assets from risk management activities, noncurrent 1,822 Liabilities from risk management activities, current (1) (56,771 ) Liabilities from risk management activities, noncurrent (1) (184,048 ) Net assets (liabilities) $ (235,968 ) September 30, 2015 Assets from risk management activities, current $ 378 Assets from risk management activities, noncurrent 368 Liabilities from risk management activities, current (9,568 ) Liabilities from risk management activities, noncurrent (110,539 ) Net assets (liabilities) $ (119,361 ) (1) Includes $25.7 million of cash held on deposit to collateralize certain distribution financial instruments, which were used to offset current and noncurrent risk management liabilities. Regulated Commodity Risk Management Activities Although our purchased gas cost adjustment mechanisms essentially insulate our 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 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 2015 - 2016 heating season (generally October through March), in the jurisdictions where we are permitted to utilize financial instruments, we hedged approximately 33 percent , or approximately 23.0 Bcf of the winter flowing gas requirements at a weighted average cost of approximately $3.14 per Mcf. We have not designated these financial instruments as hedges. Natural Gas Marketing Commodity Risk Management Activities In our natural gas marketing 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. Our natural gas marketing 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 63 months . • Transportation and storage services - Our natural gas marketing 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 natural gas marketing risk management activities are controlled through various risk management policies and procedures. Our Audit Committee has oversight responsibility for our natural gas marketing risk management limits and policies. A risk committee, comprised of corporate and business unit officers, is responsible for establishing and enforcing our natural gas marketing 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, 2016 , our natural gas marketing segment had net open positions (including existing storage and related financial contracts) of 0.1 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 $210 million of the anticipated issuance of $250 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 interest rate 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 interest rate agreements 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 interest rate agreements 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, 2016 , 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, 2016 , we had net long/(short) commodity contracts outstanding in the following quantities: Contract Type Hedge Designation Distribution Natural Gas Marketing Quantity (MMcf) Commodity contracts Fair Value — (19,395 ) Cash Flow — 39,278 Not designated 18,595 71,147 18,595 91,030 Financial Instruments on the Balance Sheet The following tables present the fair value and balance sheet classification of our financial instruments as of September 30, 2016 and 2015 . 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. Distribution Natural Gas Marketing Balance Sheet Location (1) Assets Liabilities Assets Liabilities (In thousands) September 30, 2016 Designated As Hedges: Commodity contracts Other current assets / Other current liabilities $ — $ — $ 6,612 $ (21,903 ) Interest rate contracts Other current assets / — (68,481 ) — — Commodity contracts Deferred charges and other assets / Deferred credits and other liabilities — — 2,178 (3,779 ) Interest rate contracts Deferred charges and other assets / Deferred credits and other liabilities — (198,008 ) — — Total — (266,489 ) 8,790 (25,682 ) Not Designated As Hedges: Commodity contracts Other current assets / Other current liabilities 3,029 — 18,157 (18,812 ) Commodity contracts Deferred charges and other assets / Deferred credits and other liabilities 1,822 — 12,343 (12,701 ) Total 4,851 — 30,500 (31,513 ) Gross Financial Instruments 4,851 (266,489 ) 39,290 (57,195 ) Gross Amounts Offset on Consolidated Balance Sheet: Contract netting — — (39,290 ) 39,290 Net Financial Instruments 4,851 (266,489 ) — (17,905 ) Cash collateral — 25,670 6,775 17,905 Net Assets/Liabilities from Risk Management Activities $ 4,851 $ (240,819 ) $ 6,775 $ — (1) Natural gas marketing's risk management assets and liabilities have been classified as held for sale at September 30, 2016 related to the divestiture of our natural gas marketing business. Distribution Natural Gas Marketing Balance Sheet Location (1) Assets Liabilities Assets Liabilities (In thousands) September 30, 2015 Designated As Hedges: Commodity contracts Other current assets / Other current liabilities $ — $ — $ 11,680 $ (36,067 ) Interest rate contracts Other current assets / — — — — 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 $ — (1) Natural gas marketing's risk management assets and liabilities have been classified as held for sale at September 30, 2015 related to the divestiture of our natural gas marketing business. Impact of Financial Instruments on the Income Statement Hedge ineffectiveness for our natural gas marketing segment is recorded as a component of purchased gas cost which is reflected in income from discontinued operations 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, 2016 , 2015 and 2014 , we recognized a gain arising from fair value and cash flow hedge ineffectiveness of $21.6 million , $0.2 million and $1.9 million . Additional information regarding ineffectiveness recognized in the income statement is included in the tables below. Fair Value Hedges The impact of our natural gas marketing commodity contracts designated as fair value hedges and the related hedged item on the results of discontinued operations on our consolidated income statement for the years ended September 30, 2016 , 2015 and 2014 is presented below. Fiscal Year Ended September 30 2016 2015 2014 (In thousands) Commodity contracts $ 3,516 $ 10,311 $ (792 ) Fair value adjustment for natural gas inventory designated as the hedged item 18,079 (9,768 ) 2,486 Total decrease in purchased gas cost reflected in income from discontinued operations $ 21,595 $ 543 $ 1,694 The decrease in purchased gas cost reflected in income from discontinued operations is comprised of the following: Basis ineffectiveness $ (1,390 ) $ 811 $ (919 ) Timing ineffectiveness 22,985 (268 ) 2,613 $ 21,595 $ 543 $ 1,694 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 AEM’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, 2016 , 2015 and 2014 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 2016 2015 2014 (In thousands) Gain (loss) reclassified from AOCI for effective portion of natural gas marketing commodity contracts $ (52,651 ) $ (41,716 ) $ 8,365 Gain (loss) arising from ineffective portion of natural gas marketing commodity contracts (19 ) (325 ) 198 Total impact on purchased gas cost reflected in income from discontinued operations (52,670 ) (42,041 ) 8,563 Net loss on settled distribution interest rate agreements reclassified from AOCI into interest expense (546 ) (853 ) (4,230 ) Total impact from cash flow hedges $ (53,216 ) $ (42,894 ) $ 4,333 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, 2016 and 2015 . 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 2016 2015 (In thousands) Decrease in fair value: Interest rate agreements $ (99,029 ) $ (71,003 ) Forward commodity contracts (11,662 ) (49,211 ) Recognition of losses in earnings due to settlements: Interest rate agreements 347 542 Forward commodity contracts 32,117 25,448 Total other comprehensive income (loss) from hedging, net of tax (1) $ (78,227 ) $ (94,224 ) (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, 2016 . However, the table below does not include the expected recognition in earnings of our outstanding interest rate agreements as those financial instruments have not yet settled. Interest Rate Agreements Commodity Contracts Total (In thousands) 2017 $ (447 ) $ (3,983 ) $ (4,430 ) 2018 (649 ) (561 ) (1,210 ) 2019 (673 ) (414 ) (1,087 ) 2020 (698 ) (26 ) (724 ) 2021 (698 ) 2 (696 ) Thereafter (15,139 ) — (15,139 ) Total (1) $ (18,304 ) $ (4,982 ) $ (23,286 ) (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 the natural gas marketing segment's financial instruments that have not been designated as hedges on our consolidated income statements for the years ended September 30, 2016 , 2015 and 2014 was an increase (decrease) in purchased gas cost reflected in income from discontinued operations of $(15.5) million , $15.5 million and $(5.0) 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 distribution segment are not designated as hedges. However, there is no earnings impact on our 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.

Fair Value Measurements

Fair Value Measurements	12 Months Ended
	Sep. 30, 2016
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 7 . 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, 2016 and 2015 . 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, 2016 (In thousands) Assets: Financial instruments Distribution segment $ — $ 4,851 $ — $ — $ 4,851 Natural gas marketing segment — 39,290 — (32,515 ) 6,775 Total financial instruments — 44,141 — (32,515 ) 11,626 Hedged portion of gas stored underground 52,578 — — — 52,578 Available-for-sale securities Money market funds — 2,630 — — 2,630 Registered investment companies 38,677 — — — 38,677 Bonds — 31,394 — — 31,394 Total available-for-sale securities 38,677 34,024 — — 72,701 Total assets $ 91,255 $ 78,165 $ — $ (32,515 ) $ 136,905 Liabilities: Financial instruments Distribution segment $ — $ 266,489 $ — $ (25,670 ) $ 240,819 Natural gas marketing segment — 57,195 — (57,195 ) — Total liabilities $ — $ 323,684 $ — $ (82,865 ) $ 240,819 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, 2015 (In thousands) Assets: Financial instruments Distribution segment $ — $ 746 $ — $ — $ 746 Natural gas marketing segment — 91,363 — (82,509 ) 8,854 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 Distribution segment $ — $ 120,107 $ — $ — $ 120,107 Natural gas marketing segment — 125,983 — (125,983 ) — Financial instruments $ — $ 246,090 $ — $ (125,983 ) $ 120,107 (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, 2016 , we had $25.7 million of cash held in margin accounts to collateralize certain distribution financial instruments, which were used to offset current and noncurrent risk management liabilities. As of September 30, 2016 we also had $24.7 million of cash held in margin accounts to collateralize certain natural gas marketing financial instruments. Of this amount, $17.9 million was used to offset current and noncurrent risk management liabilities under master netting agreements and the remaining $6.8 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, 2015 we had $43.5 million of cash held in margin accounts to collateralize certain natural gas marketing 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. 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, 2016 Domestic equity mutual funds $ 26,692 $ 6,419 $ (590 ) $ 32,521 Foreign equity mutual funds 4,954 1,202 — 6,156 Bonds 31,296 108 (10 ) 31,394 Money market funds 2,630 — — 2,630 $ 65,572 $ 7,729 $ (600 ) $ 72,701 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 At September 30, 2016 and 2015 , our available-for-sale securities included $41.3 million and $41.7 million related to assets held in separate rabbi trusts for our supplemental executive retirement plans as discussed in Note 7 . At September 30, 2016 we maintained investments in bonds that have contractual maturity dates ranging from October 2016 through May 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, 2016 : September 30, 2016 (In thousands) Carrying Amount $ 2,460,000 Fair Value $ 2,844,990

Discontinued Operations (Notes)

Discontinued Operations (Notes)	12 Months Ended
	Sep. 30, 2016
Discontinued Operations [Abstract]
Disposal Groups, Including Discontinued Operations, Disclosure [Text Block]	Discontinued Operations Divestiture of Atmos Energy Marketing (AEM) On October 29, 2016, we entered into a Membership Interest Purchase Agreement (the Agreement) with CenterPoint Energy Services, Inc., a subsidiary of CenterPoint Energy, Inc. (CES) to sell all of the equity interests of AEM. The transaction closed on January 3, 2017, with an effective date of January 1, 2017 . CES paid a cash purchase price of $38.3 million plus estimated working capital of $103.2 million for total cash consideration of $141.5 million . Of this amount, $7.0 million was placed into escrow and will be paid to the Company within 24 months, net of any indemnification claims agreed upon between the two companies. We expect to recognize a net gain of $0.03 per diluted share on the sale and complete the working capital true–up during the second quarter of fiscal 2017. The operating results of our natural gas marketing reportable segment have been reported on the consolidated statements of income as income from discontinued operations, net of income tax. Accordingly, expenses related to allocable general corporate overhead and interest expense are not included in these results. The decision to report this segment as a discontinued operation was predicated, in part, on the following qualitative and quantitative factors: 1) the disposal results in the company becoming a fully regulated entity; 2) the fact that an entire reportable segment will be disposed and 3) the fact the disposed segment represented in excess of 30 percent of consolidated revenues over the last five fiscal years. The tables below set forth selected financial and operational information related to assets, liabilities and operating results related to discontinued operations. Additionally, assets and liabilities related to our natural gas marketing operations are classified as “held for sale” on our consolidated balance sheets at September 30, 2016 and September 30, 2015 . Prior period revenues and expenses associated with these assets have been reclassified into discontinued operations. This reclassification had no impact on previously reported consolidated net income. The following table presents statement of income data related to discontinued operations. Year Ended September 30 2016 2015 2014 (In thousands) Operating revenues $ 1,005,090 $ 1,409,071 $ 1,984,829 Purchased gas cost 968,118 1,359,832 1,923,745 Gross profit 36,972 49,239 61,084 Operating expenses 26,184 30,076 26,957 Operating income 10,788 19,163 34,127 Other nonoperating expense (2,495 ) (3,570 ) $ (2,252 ) Income from discontinued operations before income taxes 8,293 15,593 31,875 Income tax expense 3,731 6,141 12,389 Net income from discontinued operations $ 4,562 $ 9,452 $ 19,486 The following table presents a reconciliation of the carrying amounts of major classes of assets and liabilities of our natural gas marketing's operations to total assets and liabilities classified as held for sale. September 30, 2016 September 30, 2015 (In thousands) Assets: Net property, plant and equipment $ 11,905 $ 13,878 Accounts receivable 93,551 91,675 Gas stored underground 54,246 41,267 Assets from risk management activities 8,743 8,854 Other current assets 5,968 7,108 Goodwill 16,445 16,445 Noncurrent assets from risk management activities 169 — Deferred charges and other assets 266 62 Total assets of the disposal group classified as held for sale in the statement of financial position 191,293 179,289 Cash 25,417 4,008 Intercompany receivable — 2,960 Other assets 5 (3,486 ) Total assets of disposal group in the statement of financial position $ 216,715 $ 182,771 Liabilities: Accounts payable and accrued liabilities $ 72,268 $ 76,170 Liabilities from risk management activities — 3,799 Other current liabilities 9,640 9,502 Deferred credits and other 316 347 Total liabilities of the disposal group classified as held for sale in the statement of financial position 82,224 89,818 Intercompany note payable 35,000 50,000 Tax liabilities 15,471 (200 ) Intercompany payables 14,139 — Other liabilities 3,284 5,870 Total liabilities of disposal group in the statement of financial position $ 150,118 $ 145,488 The following table presents statement of cash flow data related to discontinued operations. Year Ended September 30 2016 2015 2014 (In thousands) Depreciation and amortization $ 2,304 $ 2,388 $ 2,315 Capital expenditures $ 321 $ 226 $ 1,559 Noncash gain (loss) in commodity contract cash flow hedges $ (33,533 ) $ 38,956 $ (4,593 )

Concentration of Credit Risk

Concentration of Credit Risk	12 Months Ended
	Sep. 30, 2016
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 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.

Selected Quarterly Financial Da

Selected Quarterly Financial Data	12 Months Ended
	Sep. 30, 2016
Quarterly Financial Information Disclosure [Abstract]
Selected Quarterly Financial Data (Unaudited)	Selected Quarterly Financial Data (Unaudited) Summarized unaudited quarterly financial data is presented below. Operating revenues, gross profit, operating income and net income are now presented on a continuing and discontinued basis, which were not previously reported. 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 2016: Operating revenues Distribution $ 649,443 $ 862,127 $ 424,905 $ 403,303 Pipeline and storage 98,416 102,153 113,855 112,772 Intersegment eliminations (73,106 ) (74,240 ) (82,548 ) (82,432 ) Operating revenues from continuing operations 674,753 890,040 456,212 433,643 Operating revenues from discontinued operations (1) 231,468 242,253 176,704 244,876 Gross profit from continuing operations 434,427 512,684 391,629 369,716 Gross profit from discontinued operations 9,469 5,260 15,815 6,428 Operating income from continuing operations 192,729 251,656 128,396 84,449 Operating income (loss) from discontinued operations 3,476 (1,640 ) 8,768 184 Income from continuing operations 101,546 143,003 66,143 34,850 Income (loss) from discontinued operations 1,315 (1,193 ) 5,050 (610 ) Net income 102,861 141,810 71,193 34,240 Basic earnings per share Income per share from continuing operations $ 0.99 $ 1.39 $ 0.64 $ 0.33 Income (loss) per share from discontinued operations 0.01 (0.01 ) 0.05 — Net income per share — basic $ 1.00 $ 1.38 $ 0.69 $ 0.33 Diluted earnings per share Income per share from continuing operations $ 0.99 $ 1.39 $ 0.64 $ 0.33 Income (loss) per share from discontinued operations 0.01 (0.01 ) 0.05 — Net income per share — diluted $ 1.00 $ 1.38 $ 0.69 $ 0.33 (1) Operating revenues from discontinued operations are shown net of intersegment eliminations. Quarter Ended December 31 March 31 June 30 September 30 (In thousands, except per share data) Fiscal year 2015: Operating revenues Distribution $ 864,767 $ 1,145,082 $ 429,482 $ 382,031 Pipeline and storage 87,161 96,893 99,008 101,895 Intersegment eliminations (64,687 ) (68,879 ) (72,985 ) (72,783 ) Operating revenues from continuing operations 887,241 1,173,096 455,505 411,143 Operating revenues from discontinued operations (1) 371,524 366,972 230,896 245,759 Gross profit from continuing operations 413,340 505,571 368,134 344,265 Gross profit from discontinued operations 10,078 15,300 13,672 10,189 Operating income from continuing operations 184,884 242,000 111,001 74,347 Operating income from discontinued operations 2,841 8,210 6,606 1,506 Income from continuing operations 96,086 133,142 52,487 23,908 Income (loss) from discontinued operations 1,509 4,542 3,794 (393 ) Net income 97,595 137,684 56,281 23,515 Basic earnings per share Income per share from continuing operations $ 0.94 $ 1.31 $ 0.51 $ 0.23 Income per share from discontinued operations 0.02 0.04 0.04 — Net income per share — basic $ 0.96 $ 1.35 $ 0.55 $ 0.23 Diluted earnings per share Income per share from continuing operations $ 0.94 $ 1.31 $ 0.51 $ 0.23 Income per share from discontinued operations 0.02 0.04 0.04 — Net income per share — diluted $ 0.96 $ 1.35 $ 0.55 $ 0.23 (1) Operating revenues from discontinued operations are shown net of intersegment eliminations.

Schedule II - Valuation and Qua

Schedule II - Valuation and Qualifying Accounts	12 Months Ended
	Sep. 30, 2016
Valuation and Qualifying Accounts [Abstract]
Schedule II Valuation and Qualifying Accounts	ATMOS ENERGY CORPORATION Valuation and Qualifying Accounts Three Years Ended September 30, 2016 Additions Balance at beginning of period Charged to cost & expenses Charged to other accounts Deductions Balance at end of period (In thousands) 2016 Allowance for doubtful accounts $ 12,934 $ 10,414 $ — $ 12,292 (1) $ 11,056 2015 Allowance for doubtful accounts $ 20,659 $ 15,923 $ — $ 23,648 (1) $ 12,934 2014 Allowance for doubtful accounts $ 18,462 $ 18,183 $ — $ 15,986 (1) $ 20,659 (1) Uncollectible accounts written off.

Summary of Significant Accounti

Summary of Significant Accounting Policies (Policy)	12 Months Ended
	Sep. 30, 2016
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 — As described under Recent Accounting Pronouncements below, we reclassified debt issuance costs from deferred charges and other assets to long-term debt. Additionally, we recorded immaterial corrections to the presentation of certain activities on our Consolidated Statement of Cash Flows for the years ended September 30, 2015 and 2014.
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 distribution and pipeline and storage 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 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 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 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 pipeline and storage and natural gas marketing segments are recognized in the period in which actual volumes are transported and storage services are provided. Operating revenues for our natural gas marketing 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 natural gas marketing 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 distribution operations and natural gas held by our natural gas marketing segment to conduct their operations. The average cost method is used for substantially all of our regulated operations. Our natural gas marketing 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 $2.8 million , $2.3 million and $1.5 million was capitalized in 2016 , 2015 and 2014 . 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 3.2 percent for the fiscal year ended September 30, 2016 , and 3.3 percent for each of the fiscal years ended September 30, 2015 and 2014 . 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, 2016 and 2015 , we had asset retirement obligations of $13.4 million and $11.1 million . Additionally, we had $8.1 million and $4.8 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, 2016 and 2015 , 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 distribution, pipeline and storage and natural gas marketing segments and interest rate risk. The objectives and strategies for using financial instruments have been tailored to our regulated and natural gas marketing businesses and are discussed in Note 13 . 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 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 distribution segment as a result of the use of financial instruments. In our natural gas marketing 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, which is reflected in income from discontinued operations 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, 2016 , 2015 and 2014 , we included unrealized gains (losses) on open contracts of $1.2 million , ($2.0) million and $9.5 million as a component of natural gas marketing purchased gas cost. These amounts are included in income from discontinued operations. Additionally, we have elected to treat fixed-price forward contracts used in our natural gas marketing 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 which is reflected in income from discontinued operations 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 reflected in income from discontinued operations for the years ended September 30, 2016 and 2015 . Our natural gas marketing 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, 2016 and 2015 , the Company netted $ 24.7 million and $ 43.5 million of cash held in margin accounts into its current and noncurrent risk management assets and liabilities, which are included in assets and liabilities held for sale. 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. As of September 30, 2016 , the Company netted $25.7 million of cash held in margin accounts into its current and noncurrent risk management liabilities. As of September 30, 2015 no cash was required to be held in margin accounts.
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 natural gas marketing 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, corporate bonds 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 currently do not have any Level 3 investments.
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 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 distribution segment operations are geographically dispersed, they are aggregated and reported as a single segment as each distribution division has similar economic characteristics. In addition, the pipeline and storage operations of our Atmos Pipeline-Texas division and our natural gas transmission operations in Louisiana have similar economic characteristics and have been aggregated and reported as a single segment. 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.
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, 2016
Schedule of Divisions And Service Areas Table [Abstract]
Schedule of divisions and service areas	Through our 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 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 Accoun30

Summary of Significant Accounting Policies (Table)	12 Months Ended
	Sep. 30, 2016
Accounting Policies [Abstract]
Schedule Of Regulatory Assets And Liabilities	Significant regulatory assets and liabilities as of September 30, 2016 and 2015 included the following: September 30 2016 2015 (In thousands) Regulatory assets: Pension and postretirement benefit costs (1) $ 132,348 $ 121,183 Infrastructure mechanisms (2) 42,719 32,813 Deferred gas costs 45,184 9,715 Recoverable loss on reacquired debt 13,761 16,319 Deferred pipeline record collection costs 7,336 3,118 APT annual adjustment mechanism 7,171 1,002 Rate case costs 1,539 1,533 Other 13,565 6,656 $ 263,623 $ 192,339 Regulatory liabilities: Regulatory cost of removal obligation $ 476,891 $ 483,676 Deferred gas costs 20,180 28,100 Asset retirement obligation 13,404 9,063 Other 4,250 3,693 $ 514,725 $ 524,532	[1],[2]
[1]	Includes $12.4 million and $16.6 million of pension and postretirement expense deferred pursuant to regulatory authorization.
[2]	Infrastructure mechanisms in Texas and Louisiana allow for the deferral of all eligible expenses associated with capital expenditures incurred pursuant to these rules, including the recording of interest on the deferred expenses until the next rate proceeding (rate case or annual rate filing), at which time investment and costs would be recovered through base rates.

Segment Information (Table)

Segment Information (Table)	12 Months Ended
	Sep. 30, 2016
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, 2016 Distribution Pipeline and Storage Natural Gas Marketing Eliminations Consolidated (In thousands) Operating revenues from external parties $ 2,338,404 $ 116,244 $ — $ — $ 2,454,648 Intersegment revenues 1,374 310,952 — (312,326 ) — 2,339,778 427,196 — (312,326 ) 2,454,648 Purchased gas cost 1,058,576 (58 ) — (312,326 ) 746,192 Gross profit 1,281,202 427,254 — — 1,708,456 Operating expenses Operation and maintenance 407,982 130,610 — — 538,592 Depreciation and amortization 234,109 56,682 — — 290,791 Taxes, other than income 197,227 24,616 — — 221,843 Total operating expenses 839,318 211,908 — — 1,051,226 Operating income 441,884 215,346 — — 657,230 Miscellaneous income (expense) 1,171 (1,405 ) — — (234 ) Interest charges 78,238 36,574 — — 114,812 Income from continuing operations before income taxes 364,817 177,367 — — 542,184 Income tax expense 130,987 65,655 — — 196,642 Income from continuing operations 233,830 111,712 — — 345,542 Income from discontinued operations, net of tax — — 4,562 — 4,562 Net income $ 233,830 $ 111,712 $ 4,562 $ — $ 350,104 Capital expenditures $ 740,246 $ 346,383 $ 321 $ — $ 1,086,950 Year Ended September 30, 2015 Distribution Pipeline and Storage Natural Gas Marketing Eliminations Consolidated (In thousands) Operating revenues from external parties $ 2,819,977 $ 107,008 $ — $ — $ 2,926,985 Intersegment revenues 1,385 277,949 — (279,334 ) — 2,821,362 384,957 — (279,334 ) 2,926,985 Purchased gas cost 1,574,447 562 — (279,334 ) 1,295,675 Gross profit 1,246,915 384,395 — — 1,631,310 Operating expenses Operation and maintenance 393,504 122,902 — — 516,406 Depreciation and amortization 224,094 48,314 — — 272,408 Taxes, other than income 206,625 23,639 — — 230,264 Total operating expenses 824,223 194,855 — — 1,019,078 Operating income 422,692 189,540 — — 612,232 Miscellaneous income (expense) 284 (1,103 ) — — (819 ) Interest charges 83,087 33,154 — — 116,241 Income from continuing operations before income taxes 339,889 155,283 — — 495,172 Income tax expense 134,069 55,480 — — 189,549 Income from continuing operations 205,820 99,803 — — 305,623 Income from discontinued operations, net of tax — — 9,452 — 9,452 Net income $ 205,820 $ 99,803 $ 9,452 $ — $ 315,075 Capital expenditures $ 670,620 $ 292,775 $ 226 $ — $ 963,621 Year Ended September 30, 2014 Distribution Pipeline and Storage Natural Gas Marketing Eliminations Consolidated (In thousands) Operating revenues from external parties $ 3,137,858 $ 106,046 $ — $ — $ 3,243,904 Intersegment revenues 1,363 231,494 — (232,857 ) — 3,139,221 337,540 — (232,857 ) 3,243,904 Purchased gas cost 1,952,869 2,048 — (232,857 ) 1,722,060 Gross profit 1,186,352 335,492 — — 1,521,844 Operating expenses Operation and maintenance 391,747 90,729 — — 482,476 Depreciation and amortization 209,485 42,187 — — 251,672 Taxes, other than income 196,503 13,971 — — 210,474 Total operating expenses 797,735 146,887 — — 944,622 Operating income 388,617 188,605 — — 577,222 Miscellaneous income (expense) 3 (3,006 ) — — (3,003 ) Interest charges 92,997 36,279 — — 129,276 Income from continuing operations before income taxes 295,623 149,320 — — 444,943 Income tax expense 121,165 53,447 — — 174,612 Income from continuing operations 174,458 95,873 — — 270,331 Income from discontinued operations, net of tax — — 19,486 — 19,486 Net income $ 174,458 $ 95,873 $ 19,486 $ — $ 289,817 Capital expenditures $ 574,656 $ 248,226 $ 1,559 $ — $ 824,441
Revenue from External Customers by Products and Services	The following table summarizes our revenues from external parties by products and services for the fiscal year ended September 30. 2016 2015 2014 (In thousands) Distribution revenues: Gas sales revenues: Residential $ 1,477,049 $ 1,761,689 $ 1,933,099 Commercial 619,979 772,187 876,042 Industrial 98,439 131,034 166,736 Public authority and other 41,307 53,401 64,779 Total gas sales revenues 2,236,774 2,718,311 3,040,656 Transportation revenues 76,690 72,340 68,020 Other gas revenues 24,940 29,326 29,182 Total distribution revenues 2,338,404 2,819,977 3,137,858 Pipeline and storage revenues 116,244 107,008 106,046 Total operating revenues $ 2,454,648 $ 2,926,985 $ 3,243,904
Schedule of segment reporting balance sheet information, by segment	Balance sheet information at September 30, 2016 and 2015 by segment is presented in the following tables. September 30, 2016 Distribution Pipeline and Storage Natural Gas Marketing Eliminations Consolidated (In thousands) ASSETS Property, plant and equipment, net $ 6,208,465 $ 2,060,141 $ — $ — $ 8,268,606 Investment in subsidiaries 768,415 13,854 — (782,269 ) — Current assets Cash and cash equivalents 22,117 — 25,417 — 47,534 Current assets of disposal group classified as held for sale — — 162,508 (11,391 ) 151,117 Other current assets 489,963 39,078 5 (46,011 ) 483,035 Intercompany receivables 971,665 — — (971,665 ) — Total current assets 1,483,745 39,078 187,930 (1,029,067 ) 681,686 Goodwill 583,950 143,012 — — 726,962 Noncurrent assets of disposal group classified as held for sale — — 28,785 (169 ) 28,616 Deferred charges and other assets 277,240 27,779 — — 305,019 $ 9,321,815 $ 2,283,864 $ 216,715 $ (1,811,505 ) $ 10,010,889 CAPITALIZATION AND LIABILITIES Shareholders’ equity $ 3,463,059 $ 715,672 $ 66,597 $ (782,269 ) $ 3,463,059 Long-term debt 2,188,779 — — — 2,188,779 Total capitalization 5,651,838 715,672 66,597 (782,269 ) 5,651,838 Current liabilities Current maturities of long-term debt 250,000 — — — 250,000 Short-term debt 829,811 — 35,000 (35,000 ) 829,811 Current liabilities of disposal group classified as held for sale — — 81,908 (9,008 ) 72,900 Other current liabilities 605,790 39,911 3,263 (13,394 ) 635,570 Intercompany payables — 957,526 14,139 (971,665 ) — Total current liabilities 1,685,601 997,437 134,310 (1,029,067 ) 1,788,281 Deferred income taxes 1,055,348 543,390 4,318 — 1,603,056 Regulatory cost of removal obligation 397,162 27,119 — — 424,281 Pension and postretirement liabilities 297,743 — — — 297,743 Noncurrent liabilities of disposal group classified as held for sale — — 316 — 316 Deferred credits and other liabilities 234,123 246 11,174 (169 ) 245,374 $ 9,321,815 $ 2,283,864 $ 216,715 $ (1,811,505 ) $ 10,010,889 September 30, 2015 Distribution Pipeline and Storage Natural Gas Marketing Eliminations Consolidated (In thousands) ASSETS Property, plant and equipment, net $ 5,656,788 $ 1,759,912 $ — $ — $ 7,416,700 Investment in subsidiaries 653,249 13,854 — (667,103 ) — Current assets Cash and cash equivalents 24,645 — 4,008 — 28,653 Current assets of disposal group classified as held for sale — — 148,904 (9,849 ) 139,055 Other current assets 478,054 50,309 (3,385 ) (66,380 ) 458,598 Intercompany receivables 863,088 — 2,960 (866,048 ) — Total current assets 1,365,787 50,309 152,487 (942,277 ) 626,306 Goodwill 583,285 142,972 — — 726,257 Noncurrent assets of disposal group classified as held for sale — — 30,385 — 30,385 Deferred charges and other assets 257,635 17,890 (101 ) — 275,424 $ 8,516,744 $ 1,984,937 $ 182,771 $ (1,609,380 ) $ 9,075,072 CAPITALIZATION AND LIABILITIES Shareholders’ equity $ 3,194,797 $ 629,820 $ 37,283 $ (667,103 ) $ 3,194,797 Long-term debt 2,437,515 — — — 2,437,515 Total capitalization 5,632,312 629,820 37,283 (667,103 ) 5,632,312 Current liabilities Short-term debt 457,927 — 50,000 (50,000 ) 457,927 Current liabilities of the disposal group classified as held for sale — — 89,471 (14,911 ) 74,560 Other current liabilities 578,439 49,352 5,863 (11,318 ) 622,336 Intercompany payables — 866,048 — (866,048 ) — Total current liabilities 1,036,366 915,400 145,334 (942,277 ) 1,154,823 Deferred income taxes 1,007,198 411,722 (7,605 ) — 1,411,315 Regulatory cost of removal obligation 399,747 27,806 — — 427,553 Pension and postretirement liabilities 287,373 — — — 287,373 Noncurrent liabilities of disposal group classified as held for sale — — 347 — 347 Deferred credits and other liabilities 153,748 189 7,412 — 161,349 $ 8,516,744 $ 1,984,937 $ 182,771 $ (1,609,380 ) $ 9,075,072

Earnings Per Share (Table)

Earnings Per Share (Table)	12 Months Ended
	Sep. 30, 2016
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: 2016 2015 2014 (In thousands, except per share data) Basic Earnings Per Share from continuing operations Income from continuing operations $ 345,542 $ 305,623 $ 270,331 Less: Income from continuing operations allocated to participating securities 538 607 663 Income from continuing operations available to common shareholders $ 345,004 $ 305,016 $ 269,668 Basic weighted average shares outstanding 103,524 101,892 97,606 Income from continuing operations per share — Basic $ 3.33 $ 3.00 $ 2.76 Basic Earnings Per Share from discontinued operations Income from discontinued operations $ 4,562 $ 9,452 $ 19,486 Less: Income from discontinued operations allocated to participating securities 8 19 48 Income from discontinued operations available to common shareholders $ 4,554 $ 9,433 $ 19,438 Basic weighted average shares outstanding 103,524 101,892 97,606 Income from discontinued operations per share - Basic $ 0.05 $ 0.09 $ 0.20 Net income per share - Basic $ 3.38 $ 3.09 $ 2.96 Diluted Earnings Per Share from continuing operations Income from continuing operations available to common shareholders $ 345,004 $ 305,016 $ 269,668 Effect of dilutive stock options and other shares — — — Income from continuing operations available to common shareholders $ 345,004 $ 305,016 $ 269,668 Basic weighted average shares outstanding 103,524 101,892 97,606 Additional dilutive stock options and other shares — — 2 Diluted weighted average shares outstanding 103,524 101,892 97,608 Income from continuing operations per share — Diluted $ 3.33 $ 3.00 $ 2.76 Diluted Earnings Per Share from discontinued operations Income from discontinued operations available to common shareholders $ 4,554 $ 9,433 $ 19,438 Effect of dilutive stock options and other shares — — — Income from discontinued operations available to common shareholders $ 4,554 $ 9,433 $ 19,438 Basic weighted average shares outstanding 103,524 101,892 97,606 Additional dilutive stock options and other shares — — 2 Diluted weighted average shares outstanding 103,524 101,892 97,608 Income from discontinued operations per share — Diluted $ 0.05 $ 0.09 $ 0.20 Net income per share - Diluted $ 3.38 $ 3.09 $ 2.96

Debt (Table)

Debt (Table)	12 Months Ended
	Sep. 30, 2016
Debt Disclosure [Abstract]
Debt instrument table	Long-term debt at September 30, 2016 and 2015 consisted of the following: 2016 2015 (In thousands) Unsecured 6.35% Senior Notes, due June 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 500,000 500,000 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 4,270 4,612 Debt issuance cost 16,951 17,873 Current maturities 250,000 — $ 2,188,779 $ 2,437,515
Debt maturity schedule	Maturities of long-term debt at September 30, 2016 were as follows (in thousands): 2017 $ 250,000 2018 — 2019 450,000 2020 — 2021 — Thereafter 1,760,000 $ 2,460,000

Shareholders' Equity (Table)

Shareholders' Equity (Table)	12 Months Ended
	Sep. 30, 2016
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, 2015 $ 4,949 $ (88,842 ) $ (25,437 ) $ (109,330 ) Other comprehensive income (loss) before reclassifications (263 ) (99,029 ) (11,662 ) (110,954 ) Amounts reclassified from accumulated other comprehensive income (202 ) 347 32,117 32,262 Net current-period other comprehensive income (loss) (465 ) (98,682 ) 20,455 (78,692 ) September 30, 2016 $ 4,484 $ (187,524 ) $ (4,982 ) $ (188,022 ) 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 )
Reclassification out of Accumulated Other Comprehensive Income	The following tables detail reclassifications out of AOCI for the fiscal years ended September 30, 2016 and 2015 . Amounts in parentheses below indicate decreases to net income in the statement of income. Fiscal Year Ended September 30, 2016 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 $ 318 Operation and maintenance expense 318 Total before tax (116 ) Tax expense $ 202 Net of tax Cash flow hedges Interest rate agreements $ (546 ) Interest charges Commodity contracts (52,651 ) Purchased gas cost (1) (53,197 ) Total before tax 20,733 Tax benefit $ (32,464 ) Net of tax Total reclassifications $ (32,262 ) Net of tax 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 (1) (42,569 ) Total before tax 16,579 Tax benefit $ (25,990 ) Net of tax Total reclassifications $ (25,450 ) Net of tax (1) Amounts are presented as part of income from discontinued operations on the consolidated statements of income.

Retirement and Post-Retiremen35

Retirement and Post-Retirement Employee Benefit Plans (Table)	12 Months Ended
	Sep. 30, 2016
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 Plan Supplemental Executive Retirement Plans Postretirement Plans Total (In thousands) September 30, 2016 Unrecognized prior service credit $ (1,509 ) $ — $ (2,880 ) $ (4,389 ) Unrecognized actuarial (gain) loss 127,028 51,558 (54,298 ) 124,288 $ 125,519 $ 51,558 $ (57,178 ) $ 119,899 September 30, 2015 Unrecognized transition obligation $ — $ — $ 82 $ 82 Unrecognized prior service credit (1,735 ) — (4,524 ) (6,259 ) Unrecognized actuarial (gain) loss 120,948 36,915 (47,149 ) 110,714 $ 119,213 $ 36,915 $ (51,591 ) $ 104,537
Schedule of Allocation of Plan Assets	The following table presents asset allocation information for the postretirement benefit plan assets as of September 30, 2016 and 2015 . Actual Allocation September 30 Security Class 2016 2015 Diversified investment funds 97.2 % 97.5 % Cash and cash equivalents 2.8 % 2.5 % The following table presents asset allocation information for the Master Trust as of September 30, 2016 and 2015 . Targeted Allocation Range Actual Allocation September 30 Security Class 2016 2015 Domestic equities 35%-55% 40.5 % 41.3 % International equities 10%-20% 15.5 % 14.9 % Fixed income 5%-30% 11.2 % 11.0 % Company stock 0%-15% 15.1 % 15.2 % Other assets 0%-20% 17.7 % 17.6 %
Schedule of Employee Pension Plans Investments at Fair Value	In addition to the assets shown below, the Plan had net accounts receivable of $2.6 million and $2.4 million at September 30, 2016 and 2015 which materially approximates fair value due to the short-term nature of these assets. Assets at Fair Value as of September 30, 2016 Level 1 Level 2 Level 3 Total (In thousands) Investments: Common stocks $ 157,111 $ — $ — $ 157,111 Money market funds — 11,522 — 11,522 Registered investment companies 87,396 — — 87,396 Common/collective trusts — 105,124 — 105,124 Government securities: Mortgage-backed securities — 15,223 — 15,223 U.S. treasuries 4,704 863 — 5,567 Corporate bonds — 31,929 — 31,929 Limited partnerships — 57,438 — 57,438 Total investments at fair value $ 249,211 $ 222,099 $ — $ 471,310 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 81,960 — — 81,960 Common/collective trusts — 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
Schedule of Expected 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 Plan Supplemental Plans (In thousands) 2017 $ 31,306 $ 36,604 2018 32,047 14,289 2019 33,674 7,181 2020 35,232 4,395 2021 37,279 4,306 2022-2026 202,442 60,658 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 2016 include contributions to our postretirement plan trusts. Company Payments Retiree Payments Subsidy Payments Total Postretirement Benefits (In thousands) 2017 $ 15,806 $ 3,679 $ — $ 19,485 2018 11,602 3,992 — 15,594 2019 12,165 4,036 — 16,201 2020 13,246 4,756 — 18,002 2021 14,210 5,420 — 19,630 2022-2026 84,642 36,837 — 121,479
Schedule of Postretirement Benefit Plans Investments at Fair Value	Assets at Fair Value as of September 30, 2016 Level 1 Level 2 Level 3 Total (In thousands) Investments: Money market funds $ — $ 4,470 $ — $ 4,470 Registered investment companies 154,507 — — 154,507 Total investments at fair value $ 154,507 $ 4,470 $ — $ 158,977 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 134,523 — — 134,523 Total investments at fair value $ 134,523 $ 3,486 $ — $ 138,009
Schedule of Assumptions Used [Table Text Block]	The actuarial assumptions used to determine the pension liability for our postretirement plan were determined as of September 30, 2016 and 2015 and the actuarial assumptions used to determine the net periodic pension cost for the postretirement plan were determined as of September 30, 2015 , 2014 and 2013 . The assumptions are presented in the following table: Postretirement Liability Postretirement Cost 2016 2015 2016 2015 2014 Discount rate 3.73 % 4.55 % 4.55 % 4.43 % 4.95 % Expected return on plan assets 4.45 % 4.45 % 4.45 % 4.60 % 4.60 % Initial trend rate 7.50 % 7.50 % 7.50 % 7.50 % 8.00 % Ultimate trend rate 5.00 % 5.00 % 5.00 % 5.00 % 5.00 % Ultimate trend reached in 2022 2021 2021 2020 2020 Additional assumptions are presented in the following table: Pension Liability Pension Cost 2016 2015 2016 2015 2014 Discount rate 3.73 % 4.55 % 4.55 % 4.43 % 4.95 % Rate of compensation increase 3.50 % 3.50 % 3.50 % 3.50 % 3.50 % Expected return on plan assets 7.00 % 7.00 % 7.00 % 7.25 % 7.25 % The actuarial assumptions used to determine the pension liability for the supplemental plans were determined as of September 30, 2016 and 2015 and the actuarial assumptions used to determine the net periodic pension cost for the supplemental plans were determined as of September 30, 2015 , 2014 and 2013 . These assumptions are presented in the following table: Pension Liability Pension Cost 2016 2015 2016 2015 2014 Discount rate 3.73 % 4.55 % 4.55 % 4.43 % 4.95 % Rate of compensation increase 3.50 % 3.50 % 3.50 % 3.50 % 3.50 %
Changes in Projected Benefit Obligations, Fair Value of Plan Assets, and Funded Status of Plan [Table Text Block]	The following table presents the supplemental plans’ accumulated benefit obligation, projected benefit obligation and funded status as of September 30, 2016 and 2015 : 2016 2015 (In thousands) Accumulated benefit obligation $ 137,616 $ 118,835 Change in projected benefit obligation: Benefit obligation at beginning of year $ 122,393 $ 113,219 Service cost 2,371 3,971 Interest cost 5,185 4,943 Actuarial loss 17,229 4,811 Benefits paid (4,604 ) (4,551 ) Benefit obligation at end of year 142,574 122,393 Change in plan assets: Fair value of plan assets at beginning of year — — Employer contribution 4,604 4,551 Benefits paid (4,604 ) (4,551 ) Fair value of plan assets at end of year — — Reconciliation: Funded status (142,574 ) (122,393 ) Unrecognized prior service cost — — Unrecognized net loss — — Accrued pension cost $ (142,574 ) $ (122,393 ) The following table presents the Plan’s accumulated benefit obligation, projected benefit obligation and funded status as of September 30, 2016 and 2015 : 2016 2015 (In thousands) Accumulated benefit obligation $ 516,924 $ 485,921 Change in projected benefit obligation: Benefit obligation at beginning of year $ 508,599 $ 493,594 Service cost 16,419 16,231 Interest cost 23,193 21,850 Actuarial loss 41,847 7,420 Benefits paid (1) (44,578 ) (30,496 ) Benefit obligation at end of year 545,480 508,599 Change in plan assets: Fair value of plan assets at beginning of year 450,932 434,767 Actual return on plan assets 52,596 8,661 Employer contributions 15,000 38,000 Benefits paid (1) (44,578 ) (30,496 ) Fair value of plan assets at end of year 473,950 450,932 Reconciliation: Funded status (71,530 ) (57,667 ) Unrecognized prior service cost — — Unrecognized net loss — — Accrued pension cost $ (71,530 ) $ (57,667 ) The following table presents the postretirement plan’s benefit obligation and funded status as of September 30, 2016 and 2015 : 2016 2015 (In thousands) Change in benefit obligation: Benefit obligation at beginning of year $ 267,179 $ 315,118 Service cost 10,823 15,583 Interest cost 12,424 14,385 Plan participants’ contributions 4,289 4,563 Actuarial gain (1,052 ) (69,962 ) Benefits paid (14,441 ) (12,508 ) Benefit obligation at end of year 279,222 267,179 Change in plan assets: Fair value of plan assets at beginning of year 138,009 134,821 Actual return on plan assets 14,528 (8,851 ) Employer contributions 16,592 19,984 Plan participants’ contributions 4,289 4,563 Benefits paid (14,441 ) (12,508 ) Fair value of plan assets at end of year 158,977 138,009 Reconciliation: Funded status (120,245 ) (129,170 ) Unrecognized transition obligation — — Unrecognized prior service cost — — Unrecognized net loss — — Accrued postretirement cost $ (120,245 ) $ (129,170 )
Schedule of Net Benefit Costs [Table Text Block]	Net periodic pension cost for the Plan for fiscal 2016 , 2015 and 2014 is recorded as operating expense and included the following components: Fiscal Year Ended September 30 2016 2015 2014 (In thousands) Components of net periodic pension cost: Service cost $ 16,419 $ 16,231 $ 15,345 Interest cost 23,193 21,850 22,330 Expected return on assets (27,522 ) (25,744 ) (23,601 ) Amortization of prior service credit (226 ) (192 ) (136 ) Recognized actuarial loss 10,693 13,322 13,777 Net periodic pension cost $ 22,557 $ 25,467 $ 27,715 Net periodic postretirement cost for fiscal 2016 , 2015 and 2014 is recorded as operating expense and included the components presented below. Fiscal Year Ended September 30 2016 2015 2014 (In thousands) Components of net periodic postretirement cost: Service cost $ 10,823 $ 15,583 $ 16,784 Interest cost 12,424 14,385 15,951 Expected return on assets (6,264 ) (6,431 ) (5,167 ) Amortization of transition obligation 82 272 274 Amortization of prior service credit (1,644 ) (1,644 ) (1,450 ) Recognized actuarial (gain) loss (2,167 ) — 631 Net periodic postretirement cost $ 13,254 $ 22,165 $ 27,023 Net periodic pension cost for the supplemental plans for fiscal 2016 , 2015 and 2014 is recorded as operating expense and included the following components: Fiscal Year Ended September 30 2016 2015 2014 (In thousands) Components of net periodic pension cost: Service cost $ 2,371 $ 3,971 $ 3,607 Interest cost 5,185 4,943 4,966 Amortization of transition asset — — — Amortization of prior service cost — — — Recognized actuarial loss 2,586 2,343 1,948 Settlements — — 4,539 Net periodic pension cost $ 10,142 $ 11,257 $ 15,060
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 $ 4,539 $ (3,596 ) Effect on postretirement benefit obligation $ 42,079 $ (34,531 )

Stock and Other Compensation 36

Stock and Other Compensation Plans (Table)	12 Months Ended
	Sep. 30, 2016
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, 2016 , 2015 and 2014 : 2016 2015 2014 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 878,104 $ 48.24 988,637 $ 42.22 1,052,844 $ 36.20 Granted 357,323 65.98 444,543 50.50 464,438 45.05 Vested (448,136 ) 45.88 (551,688 ) 39.28 (524,532 ) 32.67 Forfeited (4,860 ) 53.52 (3,388 ) 48.55 (4,113 ) 39.00 Nonvested at end of year 782,431 $ 57.66 878,104 $ 48.24 988,637 $ 42.22

Details of Selected Consolida37

Details of Selected Consolidated Balance Sheet Captions (Table)	12 Months Ended
	Sep. 30, 2016
Details Of Selected Consolidated Balance Sheet Captions Disclosure [Abstract]
Accounts Receivables Detail Table	Accounts receivable was comprised of the following at September 30, 2016 and 2015 : September 30 2016 2015 (In thousands) Billed accounts receivable $ 120,128 $ 120,482 Unbilled revenue 67,396 65,008 Other accounts receivable 39,412 40,777 Total accounts receivable 226,936 226,267 Less: allowance for doubtful accounts (11,056 ) (12,934 ) Net accounts receivable $ 215,880 $ 213,333
Other Current Assets Detail Table	Other current assets as of September 30, 2016 and 2015 were comprised of the following accounts. September 30 2016 2015 (In thousands) Assets from risk management activities $ 3,029 $ 378 Deferred gas costs 45,184 9,715 Taxes receivable 5,456 4,479 Prepaid expenses 21,489 21,654 Materials and supplies 5,825 12,587 Other 7,102 1,116 Total $ 88,085 $ 49,929
Property, Plant and Equipment Detail Table	Property, plant and equipment was comprised of the following as of September 30, 2016 and 2015 : September 30 2016 2015 (In thousands) Production plant $ 66 $ 131 Storage plant 353,523 286,011 Transmission plant 2,232,927 1,844,117 Distribution plant 6,598,990 6,019,001 General plant 732,606 740,863 Intangible plant 40,515 41,131 9,958,627 8,931,254 Construction in progress 183,879 280,421 10,142,506 9,211,675 Less: accumulated depreciation and amortization (1,873,900 ) (1,794,975 ) Net property, plant and equipment (1) $ 8,268,606 $ 7,416,700 (1) Net property, plant and equipment includes plant acquisition adjustments of $(59.8) million and $(68.1) million at September 30, 2016 and 2015 .
Goodwill Detail Table	The following presents our goodwill balance allocated by segment and changes in the balance for the fiscal year ended September 30, 2016 : Distribution Pipeline and Storage Total (In thousands) Balance as of September 30, 2015 (2) $ 583,285 $ 142,972 $ 726,257 Deferred tax adjustments on prior acquisitions (1) 665 40 705 Balance as of September 30, 2016 (2) $ 583,950 $ 143,012 $ 726,962 (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, 2016 and 2015 were comprised of the following accounts. September 30 2016 2015 (In thousands) Marketable securities $ 72,701 $ 74,200 Regulatory assets 214,890 182,573 Assets from risk management activities 1,822 368 Other 15,606 18,283 Total $ 305,019 $ 275,424
Accounts Payable and Accrued Liabilities	Accounts payable and accrued liabilities as of September 30, 2016 and 2015 were comprised of the following accounts. September 30 2016 2015 (In thousands) Trade accounts payable $ 114,361 $ 78,376 Accrued gas payable 47,107 56,468 Accrued liabilities 35,017 39,802 Total $ 196,485 $ 174,646
Other Current Liabilities Detail Table	Other current liabilities as of September 30, 2016 and 2015 were comprised of the following accounts. September 30 2016 2015 (In thousands) Customer credit balances and deposits $ 81,219 $ 99,043 Accrued employee costs 47,058 47,602 Deferred gas costs 20,180 28,100 Accrued interest 34,863 34,914 Liabilities from risk management activities 56,771 9,568 Taxes payable 104,145 92,912 Pension and postretirement obligations 36,606 21,857 Current deferred tax liability — 55,918 Regulatory cost of removal accrual 52,610 56,123 Other 5,633 1,653 Total $ 439,085 $ 447,690
Deferred Credits and Other Liabilities Detail Table	Deferred credits and other liabilities as of September 30, 2016 and 2015 were comprised of the following accounts. September 30 2016 2015 (In thousands) Customer advances for construction $ 9,850 $ 9,316 Regulatory liabilities 4,152 3,693 Asset retirement obligation 13,404 9,063 Liabilities from risk management activities 184,048 110,539 Other 33,920 28,738 Total $ 245,374 $ 161,349

Leases (Table)

Leases (Table)	12 Months Ended
	Sep. 30, 2016
Leases [Abstract]
Schedule of Future Minimum Lease Payments	The related future minimum lease payments at September 30, 2016 were as follows: Operating Leases (In thousands) 2017 $ 17,073 2018 16,824 2019 15,450 2020 14,479 2021 14,335 Thereafter 47,714 Total minimum lease payments $ 125,875

Commitments and Contingencies (

Commitments and Contingencies (Table)	12 Months Ended
	Sep. 30, 2016
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, 2016 are as follows (in thousands): 2017 $ 9,065 2018 2,336 2019 424 2020 400 2021 327 Thereafter 678 $ 13,230

Income Taxes (Table)

Income Taxes (Table)	12 Months Ended
	Sep. 30, 2016
Income Tax Disclosure [Abstract]
Schedule of Components of Income Tax Expense (Benefit)	The components of income tax expense from continuing operations for 2016 , 2015 and 2014 were as follows: 2016 2015 2014 (In thousands) Current Federal $ — $ — $ — State 5,667 6,513 5,192 Deferred Federal 178,630 170,649 158,362 State 12,350 12,393 11,064 Investment tax credits (5 ) (6 ) (6 ) $ 196,642 $ 189,549 $ 174,612
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 2016 , 2015 and 2014 are set forth below: 2016 2015 2014 (In thousands) Tax at statutory rate of 35% $ 189,764 $ 173,310 $ 155,730 Common stock dividends deductible for tax reporting (2,570 ) (2,413 ) (2,307 ) State taxes (net of federal benefit) 11,133 12,289 10,566 Change in valuation allowance 1,324 4,998 6,969 Other, net (3,009 ) 1,365 3,654 Income tax expense $ 196,642 $ 189,549 $ 174,612
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, 2016 and 2015 are presented below: 2016 2015 (In thousands) Deferred tax assets: Employee benefit plans $ 122,682 $ 121,619 Interest rate agreements 107,782 51,067 Net operating loss carryforwards 514,391 313,224 Charitable and other credit carryforwards 22,273 22,281 Other 23,648 36,695 Total deferred tax assets 790,776 544,886 Valuation allowance (10,481 ) (10,872 ) Net deferred tax assets 780,295 534,014 Deferred tax liabilities: Difference in net book value and net tax value of assets (2,259,278 ) (1,890,886 ) Pension funding (30,652 ) (35,247 ) Gas cost adjustments (54,725 ) (43,634 ) Other (38,696 ) (31,480 ) Total deferred tax liabilities (2,383,351 ) (2,001,247 ) Net deferred tax liabilities $ (1,603,056 ) $ (1,467,233 ) Deferred credits for rate regulated entities $ 861 $ 412
Schedule of Unrecognized Tax Benefits Roll Forward	The following table reconciles the beginning and ending balance of our unrecognized tax benefits: 2016 2015 (In thousands) Unrecognized tax benefits - beginning balance $ 17,069 $ 12,629 Increase (decrease) resulting from prior period tax positions (290 ) 1,009 Increase resulting from current period tax positions 3,519 3,431 Unrecognized tax benefits - ending balance 20,298 17,069 Less: deferred federal and state income tax benefits (7,104 ) (5,974 ) Total unrecognized tax benefits that, if recognized, would impact the effective income tax rate as of the end of the year $ 13,194 $ 11,095

Financial Instruments (Table)

Financial Instruments (Table)	12 Months Ended
	Sep. 30, 2016
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 distribution risk management assets and liabilities at September 30, 2016 and 2015 . Natural gas marketing's risk management assets and liabilities have been classified as held for sale at September 30, 2016 and 2015 related to the divestiture of our natural gas marketing business. These risk management assets and liabilities are detailed in Note 15. Distribution (In thousands) September 30, 2016 Assets from risk management activities, current $ 3,029 Assets from risk management activities, noncurrent 1,822 Liabilities from risk management activities, current (1) (56,771 ) Liabilities from risk management activities, noncurrent (1) (184,048 ) Net assets (liabilities) $ (235,968 ) September 30, 2015 Assets from risk management activities, current $ 378 Assets from risk management activities, noncurrent 368 Liabilities from risk management activities, current (9,568 ) Liabilities from risk management activities, noncurrent (110,539 ) Net assets (liabilities) $ (119,361 ) (1) Includes $25.7 million of cash held on deposit to collateralize certain distribution financial instruments, which were used to offset current and noncurrent risk management liabilities.
Outstanding commodity contracts volumes table	As of September 30, 2016 , we had net long/(short) commodity contracts outstanding in the following quantities: Contract Type Hedge Designation Distribution Natural Gas Marketing Quantity (MMcf) Commodity contracts Fair Value — (19,395 ) Cash Flow — 39,278 Not designated 18,595 71,147 18,595 91,030
Financial instruments on the balance sheet	The following tables present the fair value and balance sheet classification of our financial instruments as of September 30, 2016 and 2015 . 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. Distribution Natural Gas Marketing Balance Sheet Location (1) Assets Liabilities Assets Liabilities (In thousands) September 30, 2016 Designated As Hedges: Commodity contracts Other current assets / Other current liabilities $ — $ — $ 6,612 $ (21,903 ) Interest rate contracts Other current assets / — (68,481 ) — — Commodity contracts Deferred charges and other assets / Deferred credits and other liabilities — — 2,178 (3,779 ) Interest rate contracts Deferred charges and other assets / Deferred credits and other liabilities — (198,008 ) — — Total — (266,489 ) 8,790 (25,682 ) Not Designated As Hedges: Commodity contracts Other current assets / Other current liabilities 3,029 — 18,157 (18,812 ) Commodity contracts Deferred charges and other assets / Deferred credits and other liabilities 1,822 — 12,343 (12,701 ) Total 4,851 — 30,500 (31,513 ) Gross Financial Instruments 4,851 (266,489 ) 39,290 (57,195 ) Gross Amounts Offset on Consolidated Balance Sheet: Contract netting — — (39,290 ) 39,290 Net Financial Instruments 4,851 (266,489 ) — (17,905 ) Cash collateral — 25,670 6,775 17,905 Net Assets/Liabilities from Risk Management Activities $ 4,851 $ (240,819 ) $ 6,775 $ — (1) Natural gas marketing's risk management assets and liabilities have been classified as held for sale at September 30, 2016 related to the divestiture of our natural gas marketing business. Distribution Natural Gas Marketing Balance Sheet Location (1) Assets Liabilities Assets Liabilities (In thousands) September 30, 2015 Designated As Hedges: Commodity contracts Other current assets / Other current liabilities $ — $ — $ 11,680 $ (36,067 ) Interest rate contracts Other current assets / — — — — 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 $ — (1) Natural gas marketing's risk management assets and liabilities have been classified as held for sale at September 30, 2015 related to the divestiture of our natural gas marketing business.
Fair value hedges table	The impact of our natural gas marketing commodity contracts designated as fair value hedges and the related hedged item on the results of discontinued operations on our consolidated income statement for the years ended September 30, 2016 , 2015 and 2014 is presented below. Fiscal Year Ended September 30 2016 2015 2014 (In thousands) Commodity contracts $ 3,516 $ 10,311 $ (792 ) Fair value adjustment for natural gas inventory designated as the hedged item 18,079 (9,768 ) 2,486 Total decrease in purchased gas cost reflected in income from discontinued operations $ 21,595 $ 543 $ 1,694 The decrease in purchased gas cost reflected in income from discontinued operations is comprised of the following: Basis ineffectiveness $ (1,390 ) $ 811 $ (919 ) Timing ineffectiveness 22,985 (268 ) 2,613 $ 21,595 $ 543 $ 1,694
Cash flow hedges table	The impact of cash flow hedges on our consolidated income statements for the years ended September 30, 2016 , 2015 and 2014 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 2016 2015 2014 (In thousands) Gain (loss) reclassified from AOCI for effective portion of natural gas marketing commodity contracts $ (52,651 ) $ (41,716 ) $ 8,365 Gain (loss) arising from ineffective portion of natural gas marketing commodity contracts (19 ) (325 ) 198 Total impact on purchased gas cost reflected in income from discontinued operations (52,670 ) (42,041 ) 8,563 Net loss on settled distribution interest rate agreements reclassified from AOCI into interest expense (546 ) (853 ) (4,230 ) Total impact from cash flow hedges $ (53,216 ) $ (42,894 ) $ 4,333
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, 2016 and 2015 . 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 2016 2015 (In thousands) Decrease in fair value: Interest rate agreements $ (99,029 ) $ (71,003 ) Forward commodity contracts (11,662 ) (49,211 ) Recognition of losses in earnings due to settlements: Interest rate agreements 347 542 Forward commodity contracts 32,117 25,448 Total other comprehensive income (loss) from hedging, net of tax (1) $ (78,227 ) $ (94,224 ) (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, 2016 . However, the table below does not include the expected recognition in earnings of our outstanding interest rate agreements as those financial instruments have not yet settled. Interest Rate Agreements Commodity Contracts Total (In thousands) 2017 $ (447 ) $ (3,983 ) $ (4,430 ) 2018 (649 ) (561 ) (1,210 ) 2019 (673 ) (414 ) (1,087 ) 2020 (698 ) (26 ) (724 ) 2021 (698 ) 2 (696 ) Thereafter (15,139 ) — (15,139 ) Total (1) $ (18,304 ) $ (4,982 ) $ (23,286 ) (1) Utilizing an income tax rate ranging from approximately 37 percent to 39 percent based on the effective rates in each taxing jurisdiction.

Fair Value Measurements (Table)

Fair Value Measurements (Table)	12 Months Ended
	Sep. 30, 2016
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, 2016 and 2015 . 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, 2016 (In thousands) Assets: Financial instruments Distribution segment $ — $ 4,851 $ — $ — $ 4,851 Natural gas marketing segment — 39,290 — (32,515 ) 6,775 Total financial instruments — 44,141 — (32,515 ) 11,626 Hedged portion of gas stored underground 52,578 — — — 52,578 Available-for-sale securities Money market funds — 2,630 — — 2,630 Registered investment companies 38,677 — — — 38,677 Bonds — 31,394 — — 31,394 Total available-for-sale securities 38,677 34,024 — — 72,701 Total assets $ 91,255 $ 78,165 $ — $ (32,515 ) $ 136,905 Liabilities: Financial instruments Distribution segment $ — $ 266,489 $ — $ (25,670 ) $ 240,819 Natural gas marketing segment — 57,195 — (57,195 ) — Total liabilities $ — $ 323,684 $ — $ (82,865 ) $ 240,819 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, 2015 (In thousands) Assets: Financial instruments Distribution segment $ — $ 746 $ — $ — $ 746 Natural gas marketing segment — 91,363 — (82,509 ) 8,854 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 Distribution segment $ — $ 120,107 $ — $ — $ 120,107 Natural gas marketing segment — 125,983 — (125,983 ) — Financial instruments $ — $ 246,090 $ — $ (125,983 ) $ 120,107 (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, 2016 , we had $25.7 million of cash held in margin accounts to collateralize certain distribution financial instruments, which were used to offset current and noncurrent risk management liabilities. As of September 30, 2016 we also had $24.7 million of cash held in margin accounts to collateralize certain natural gas marketing financial instruments. Of this amount, $17.9 million was used to offset current and noncurrent risk management liabilities under master netting agreements and the remaining $6.8 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, 2015 we had $43.5 million of cash held in margin accounts to collateralize certain natural gas marketing 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.
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, 2016 Domestic equity mutual funds $ 26,692 $ 6,419 $ (590 ) $ 32,521 Foreign equity mutual funds 4,954 1,202 — 6,156 Bonds 31,296 108 (10 ) 31,394 Money market funds 2,630 — — 2,630 $ 65,572 $ 7,729 $ (600 ) $ 72,701 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
Other fair value measurements table	The following table presents the carrying value and fair value of our debt as of September 30, 2016 : September 30, 2016 (In thousands) Carrying Amount $ 2,460,000 Fair Value $ 2,844,990

Discontinued Operations (Tables

Discontinued Operations (Tables)	12 Months Ended
	Sep. 30, 2016
Discontinued Operations [Abstract]
Disposal Groups, Including Discontinued Operations [Table Text Block]	The following table presents statement of income data related to discontinued operations. Year Ended September 30 2016 2015 2014 (In thousands) Operating revenues $ 1,005,090 $ 1,409,071 $ 1,984,829 Purchased gas cost 968,118 1,359,832 1,923,745 Gross profit 36,972 49,239 61,084 Operating expenses 26,184 30,076 26,957 Operating income 10,788 19,163 34,127 Other nonoperating expense (2,495 ) (3,570 ) $ (2,252 ) Income from discontinued operations before income taxes 8,293 15,593 31,875 Income tax expense 3,731 6,141 12,389 Net income from discontinued operations $ 4,562 $ 9,452 $ 19,486 The following table presents a reconciliation of the carrying amounts of major classes of assets and liabilities of our natural gas marketing's operations to total assets and liabilities classified as held for sale. September 30, 2016 September 30, 2015 (In thousands) Assets: Net property, plant and equipment $ 11,905 $ 13,878 Accounts receivable 93,551 91,675 Gas stored underground 54,246 41,267 Assets from risk management activities 8,743 8,854 Other current assets 5,968 7,108 Goodwill 16,445 16,445 Noncurrent assets from risk management activities 169 — Deferred charges and other assets 266 62 Total assets of the disposal group classified as held for sale in the statement of financial position 191,293 179,289 Cash 25,417 4,008 Intercompany receivable — 2,960 Other assets 5 (3,486 ) Total assets of disposal group in the statement of financial position $ 216,715 $ 182,771 Liabilities: Accounts payable and accrued liabilities $ 72,268 $ 76,170 Liabilities from risk management activities — 3,799 Other current liabilities 9,640 9,502 Deferred credits and other 316 347 Total liabilities of the disposal group classified as held for sale in the statement of financial position 82,224 89,818 Intercompany note payable 35,000 50,000 Tax liabilities 15,471 (200 ) Intercompany payables 14,139 — Other liabilities 3,284 5,870 Total liabilities of disposal group in the statement of financial position $ 150,118 $ 145,488 The following table presents statement of cash flow data related to discontinued operations. Year Ended September 30 2016 2015 2014 (In thousands) Depreciation and amortization $ 2,304 $ 2,388 $ 2,315 Capital expenditures $ 321 $ 226 $ 1,559 Noncash gain (loss) in commodity contract cash flow hedges $ (33,533 ) $ 38,956 $ (4,593 )

Selected Quarterly Financial 44

Selected Quarterly Financial Data (Table)	12 Months Ended
	Sep. 30, 2016
Quarterly Financial Information Disclosure [Abstract]
Schedule of Quarterly Financial Information	Summarized unaudited quarterly financial data is presented below. Operating revenues, gross profit, operating income and net income are now presented on a continuing and discontinued basis, which were not previously reported. 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 2016: Operating revenues Distribution $ 649,443 $ 862,127 $ 424,905 $ 403,303 Pipeline and storage 98,416 102,153 113,855 112,772 Intersegment eliminations (73,106 ) (74,240 ) (82,548 ) (82,432 ) Operating revenues from continuing operations 674,753 890,040 456,212 433,643 Operating revenues from discontinued operations (1) 231,468 242,253 176,704 244,876 Gross profit from continuing operations 434,427 512,684 391,629 369,716 Gross profit from discontinued operations 9,469 5,260 15,815 6,428 Operating income from continuing operations 192,729 251,656 128,396 84,449 Operating income (loss) from discontinued operations 3,476 (1,640 ) 8,768 184 Income from continuing operations 101,546 143,003 66,143 34,850 Income (loss) from discontinued operations 1,315 (1,193 ) 5,050 (610 ) Net income 102,861 141,810 71,193 34,240 Basic earnings per share Income per share from continuing operations $ 0.99 $ 1.39 $ 0.64 $ 0.33 Income (loss) per share from discontinued operations 0.01 (0.01 ) 0.05 — Net income per share — basic $ 1.00 $ 1.38 $ 0.69 $ 0.33 Diluted earnings per share Income per share from continuing operations $ 0.99 $ 1.39 $ 0.64 $ 0.33 Income (loss) per share from discontinued operations 0.01 (0.01 ) 0.05 — Net income per share — diluted $ 1.00 $ 1.38 $ 0.69 $ 0.33 (1) Operating revenues from discontinued operations are shown net of intersegment eliminations. Quarter Ended December 31 March 31 June 30 September 30 (In thousands, except per share data) Fiscal year 2015: Operating revenues Distribution $ 864,767 $ 1,145,082 $ 429,482 $ 382,031 Pipeline and storage 87,161 96,893 99,008 101,895 Intersegment eliminations (64,687 ) (68,879 ) (72,985 ) (72,783 ) Operating revenues from continuing operations 887,241 1,173,096 455,505 411,143 Operating revenues from discontinued operations (1) 371,524 366,972 230,896 245,759 Gross profit from continuing operations 413,340 505,571 368,134 344,265 Gross profit from discontinued operations 10,078 15,300 13,672 10,189 Operating income from continuing operations 184,884 242,000 111,001 74,347 Operating income from discontinued operations 2,841 8,210 6,606 1,506 Income from continuing operations 96,086 133,142 52,487 23,908 Income (loss) from discontinued operations 1,509 4,542 3,794 (393 ) Net income 97,595 137,684 56,281 23,515 Basic earnings per share Income per share from continuing operations $ 0.94 $ 1.31 $ 0.51 $ 0.23 Income per share from discontinued operations 0.02 0.04 0.04 — Net income per share — basic $ 0.96 $ 1.35 $ 0.55 $ 0.23 Diluted earnings per share Income per share from continuing operations $ 0.94 $ 1.31 $ 0.51 $ 0.23 Income per share from discontinued operations 0.02 0.04 0.04 — Net income per share — diluted $ 0.96 $ 1.35 $ 0.55 $ 0.23 (1) Operating revenues from discontinued operations are shown net of intersegment eliminations.

Nature of Business (Details)

Nature of Business (Details) customers in Millions	Sep. 30, 2016customersregulated_gas_distributions_divisions
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Number Of Divisions, Regulated Distribution | regulated_gas_distributions_divisions	6
Number Of Customers, Regulated Distribution | customers	3

Summary of Significant Accoun46

Summary of Significant Accounting Policies (Details) - USD ($)		12 Months Ended
		Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2014	Mar. 31, 2016
Regulatory Assets [Line Items]
Regulatory Assets		$ 263,623,000	$ 192,339,000
Regulatory Liabilities [Line Items]
Regulatory Liabilities		514,725,000	524,532,000
Regulatory Assets and Liabilities, Other Disclosures [Abstract]
Regulatory Asset - Future Recoverable Pension Costs		12,400,000	16,600,000
Property, Plant and Equipment [Line Items]
Interest Costs Capitalized		$ 2,800,000	$ 2,300,000	$ 1,500,000
Composite depreciation rate for regulated property, plant and equipment		3.20%	3.30%	3.30%
Derivative [Line Items]
Asset Retirement Costs in Property, Plant and Equipment		$ 8,100,000	$ 4,800,000
Asset Retirement Obligation		13,400,000	11,100,000
New Accounting Pronouncement, Early Adoption [Line Items]
Deferred charges and other assets		305,019,000	275,424,000
Deferred Tax Assets, Operating Loss Carryforwards		514,391,000	313,224,000
Retained earnings		1,262,534,000	1,073,029,000
Long-term debt		(2,188,779,000)	(2,437,515,000)
Income tax expense		196,642,000	189,549,000	$ 174,612,000
Regulated Distribution Segment [Member]
New Accounting Pronouncement, Early Adoption [Line Items]
Derivative Liability, Collateral, Right to Reclaim Cash, Offset		25,700,000	0
Nonregulated Segment [Member]
Derivative [Line Items]
Cash Held in Margin Accounts		24,700,000	43,500,000
Regulatory Cost Of Removal Liability [Member]
Regulatory Liabilities [Line Items]
Regulatory Liabilities		476,891,000	483,676,000
Deferred Gas Costs [Member]
Regulatory Liabilities [Line Items]
Regulatory Liabilities		20,180,000	28,100,000
Asset Retirement Obligation Costs [Member]
Regulatory Liabilities [Line Items]
Regulatory Liabilities		13,404,000	9,063,000
Other [Member]
Regulatory Liabilities [Line Items]
Regulatory Liabilities		4,250,000	3,693,000
Pension And Postretirement Benefit Costs [Member]
Regulatory Assets [Line Items]
Regulatory Assets	[1]	132,348,000	121,183,000
Infrastructure Mechanisms [Member]
Regulatory Assets [Line Items]
Regulatory Assets	[2]	42,719,000	32,813,000
Deferred Gas Costs [Member]
Regulatory Assets [Line Items]
Regulatory Assets		45,184,000	9,715,000
Recoverable Loss On Reacquired Debt [Member]
Regulatory Assets [Line Items]
Regulatory Assets		13,761,000	16,319,000
Deferred Pipeline Record Collection Costs [Member]
Regulatory Assets [Line Items]
Regulatory Assets		7,336,000	3,118,000
APT Annual Adjustment Mechanism Asset [Member]
Regulatory Assets [Line Items]
Regulatory Assets		7,171,000	1,002,000
Rate Case Costs [Member]
Regulatory Assets [Line Items]
Regulatory Assets		1,539,000	1,533,000
Other [Member]
Regulatory Assets [Line Items]
Regulatory Assets		$ 13,565,000	6,656,000
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
New Accounting Pronouncement, Early Adoption, Effect [Member] | Accounting Standards Update 2016-09 [Member]
New Accounting Pronouncement, Early Adoption [Line Items]
Deferred Tax Assets, Operating Loss Carryforwards		$ 5,000,000
Income tax expense		(5,000,000)
New Accounting Pronouncement, Early Adoption, Effect [Member] | Accounting Standards Update 2015-03 [Member]
New Accounting Pronouncement, Early Adoption [Line Items]
Deferred charges and other assets		(17,000,000)	(17,900,000)
Long-term debt		$ (17,000,000)	$ (17,900,000)
Adjustments for New Accounting Principle, Early Adoption [Member] | Accounting Standards Update 2016-09 [Member]
New Accounting Pronouncement, Early Adoption [Line Items]
Deferred Tax Assets, Operating Loss Carryforwards					$ 14,500,000
Retained earnings					$ 14,500,000
[1]	Includes $12.4 million and $16.6 million of pension and postretirement expense deferred pursuant to regulatory authorization.
[2]	Infrastructure mechanisms in Texas and Louisiana allow for the deferral of all eligible expenses associated with capital expenditures incurred pursuant to these rules, including the recording of interest on the deferred expenses until the next rate proceeding (rate case or annual rate filing), at which time investment and costs would be recovered through base rates.

Segment Information (Details)

Segment Information (Details) customers in Millions		3 Months Ended								12 Months Ended
		Sep. 30, 2016USD ($)statecustomersregulated_gas_distributions_divisions	Jun. 30, 2016USD ($)	Mar. 31, 2016USD ($)	Dec. 31, 2015USD ($)	Sep. 30, 2015USD ($)	Jun. 30, 2015USD ($)	Mar. 31, 2015USD ($)	Dec. 31, 2014USD ($)	Sep. 30, 2016USD ($)segmentstatecustomersregulated_gas_distributions_divisions	Sep. 30, 2015USD ($)	Sep. 30, 2014USD ($)	Sep. 30, 2013USD ($)
Segment Reporting Information Profit Loss [Abstract]
Operating revenues		$ 433,643,000	$ 456,212,000	$ 890,040,000	$ 674,753,000	$ 411,143,000	$ 455,505,000	$ 1,173,096,000	$ 887,241,000	$ 2,454,648,000	$ 2,926,985,000	$ 3,243,904,000
Purchased gas cost										746,192,000	1,295,675,000	1,722,060,000
Gross profit		369,716,000	391,629,000	512,684,000	434,427,000	344,265,000	368,134,000	505,571,000	413,340,000	1,708,456,000	1,631,310,000	1,521,844,000
Operating expenses
Operation and maintenance										538,592,000	516,406,000	482,476,000
Depreciation and amortization										290,791,000	272,408,000	251,672,000
Taxes, other than income										221,843,000	230,264,000	210,474,000
Total operating expenses										1,051,226,000	1,019,078,000	944,622,000
Operating income		84,449,000	128,396,000	251,656,000	192,729,000	74,347,000	111,001,000	242,000,000	184,884,000	657,230,000	612,232,000	577,222,000
Miscellaneous income (expense), net										(234,000)	(819,000)	(3,003,000)
Interest charges										114,812,000	116,241,000	129,276,000
Income (loss) before income taxes										542,184,000	495,172,000	444,943,000
Income tax expense										196,642,000	189,549,000	174,612,000
Income from Continuing Operations, Net of Tax		34,850,000	66,143,000	143,003,000	101,546,000	23,908,000	52,487,000	133,142,000	96,086,000	345,542,000	305,623,000	270,331,000
Net income from discontinued operations, net of tax		(610,000)	5,050,000	(1,193,000)	1,315,000	(393,000)	3,794,000	4,542,000	1,509,000	4,562,000	9,452,000	19,486,000
Net income		34,240,000	71,193,000	141,810,000	102,861,000	23,515,000	56,281,000	137,684,000	97,595,000	350,104,000	315,075,000	289,817,000
Capital expenditures										1,086,950,000	963,621,000	824,441,000
ASSETS
Net property, plant and equipment	[1]	8,268,606,000				7,416,700,000				8,268,606,000	7,416,700,000
Investment in subsidaries		0				0				0	0
Current assets
Cash and cash equivalents		47,534,000				28,653,000				47,534,000	28,653,000	42,258,000	$ 66,199,000
Assets from risk management activities current		3,029,000				378,000				3,029,000	378,000
Current assets of disposal group classified as held for sale		151,117,000				139,055,000				151,117,000	139,055,000
Other current assets		483,035,000				458,598,000				483,035,000	458,598,000
Intercompany receivables		0				0				0	0
Total current assets		681,686,000				626,306,000				681,686,000	626,306,000
Goodwill	[2]	726,962,000				726,257,000				726,962,000	726,257,000
Assets from risk management activities noncurrent		1,822,000				368,000				1,822,000	368,000
Noncurrent assets of disposal group classified as held for sale		28,616,000				30,385,000				28,616,000	30,385,000
Deferred charges and other assets		305,019,000				275,424,000				305,019,000	275,424,000
Total assets		10,010,889,000				9,075,072,000				10,010,889,000	9,075,072,000
CAPITALIZATION AND LIABILITIES
Shareholders' equity		3,463,059,000				3,194,797,000				3,463,059,000	3,194,797,000	3,086,232,000	$ 2,580,409,000
Long-term debt		2,188,779,000				2,437,515,000				2,188,779,000	2,437,515,000
Total capitalization		5,651,838,000				5,632,312,000				5,651,838,000	5,632,312,000
Current liabilities
Current maturities of long-term debt		250,000,000				0				250,000,000	0
Short-term debt		829,811,000				457,927,000				829,811,000	457,927,000
Liabilities from risk management activities current		56,771,000				9,568,000				56,771,000	9,568,000
Current liabilities of disposal group classified as held for sale		72,900,000				74,560,000				72,900,000	74,560,000
Other current liabilities		635,570,000				622,336,000				635,570,000	622,336,000
Intercompany payables		0				0				0	0
Total current liabilities		1,788,281,000				1,154,823,000				1,788,281,000	1,154,823,000
Deferred income taxes		1,603,056,000				1,411,315,000				1,603,056,000	1,411,315,000
Liabilities from risk management activities noncurrent		184,048,000				110,539,000				184,048,000	110,539,000
Regulatory cost of removal obligation		424,281,000				427,553,000				424,281,000	427,553,000
Pension and postretirement liabilities		297,743,000				287,373,000				297,743,000	287,373,000
Noncurrent liabilities of disposal group held for sale		316,000				347,000				316,000	347,000
Deferred credits and other liabilities		245,374,000				161,349,000				245,374,000	161,349,000
Total shareholders' equity and liabilities		$ 10,010,889,000				9,075,072,000				$ 10,010,889,000	9,075,072,000
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										$ 2,454,648,000	2,926,985,000	3,243,904,000
Revenue from External Customers by Products and Services Table [Abstract]
Operating revenues from external parties										2,454,648,000	2,926,985,000	3,243,904,000
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
Distribution Segment [Member]
Segment Reporting Information Profit Loss [Abstract]
Operating revenues		$ 403,303,000	424,905,000	862,127,000	649,443,000	382,031,000	429,482,000	1,145,082,000	864,767,000	2,339,778,000	2,821,362,000	3,139,221,000
Purchased gas cost										1,058,576,000	1,574,447,000	1,952,869,000
Gross profit										1,281,202,000	1,246,915,000	1,186,352,000
Operating expenses
Operation and maintenance										407,982,000	393,504,000	391,747,000
Depreciation and amortization										234,109,000	224,094,000	209,485,000
Taxes, other than income										197,227,000	206,625,000	196,503,000
Total operating expenses										839,318,000	824,223,000	797,735,000
Operating income										441,884,000	422,692,000	388,617,000
Miscellaneous income (expense), net										1,171,000	284,000	3,000
Interest charges										78,238,000	83,087,000	92,997,000
Income (loss) before income taxes										364,817,000	339,889,000	295,623,000
Income tax expense										130,987,000	134,069,000	121,165,000
Income from Continuing Operations, Net of Tax										233,830,000	205,820,000	174,458,000
Net income from discontinued operations, net of tax										0	0	0
Net income										233,830,000	205,820,000	174,458,000
Capital expenditures										740,246,000	670,620,000	574,656,000
ASSETS
Net property, plant and equipment		6,208,465,000				5,656,788,000				6,208,465,000	5,656,788,000
Investment in subsidaries		768,415,000				653,249,000				768,415,000	653,249,000
Current assets
Cash and cash equivalents		22,117,000				24,645,000				22,117,000	24,645,000
Current assets of disposal group classified as held for sale		0				0				0	0
Other current assets		489,963,000				478,054,000				489,963,000	478,054,000
Intercompany receivables		971,665,000				863,088,000				971,665,000	863,088,000
Total current assets		1,483,745,000				1,365,787,000				1,483,745,000	1,365,787,000
Goodwill		583,950,000				583,285,000				583,950,000	583,285,000
Noncurrent assets of disposal group classified as held for sale		0				0				0	0
Deferred charges and other assets		277,240,000				257,635,000				277,240,000	257,635,000
Total assets		9,321,815,000				8,516,744,000				9,321,815,000	8,516,744,000
CAPITALIZATION AND LIABILITIES
Shareholders' equity		3,463,059,000				3,194,797,000				3,463,059,000	3,194,797,000
Long-term debt		2,188,779,000				2,437,515,000				2,188,779,000	2,437,515,000
Total capitalization		5,651,838,000				5,632,312,000				5,651,838,000	5,632,312,000
Current liabilities
Current maturities of long-term debt		250,000,000								250,000,000
Short-term debt		829,811,000				457,927,000				829,811,000	457,927,000
Current liabilities of disposal group classified as held for sale		0				0				0	0
Other current liabilities		605,790,000				578,439,000				605,790,000	578,439,000
Intercompany payables		0				0				0	0
Total current liabilities		1,685,601,000				1,036,366,000				1,685,601,000	1,036,366,000
Deferred income taxes		1,055,348,000				1,007,198,000				1,055,348,000	1,007,198,000
Regulatory cost of removal obligation		397,162,000				399,747,000				397,162,000	399,747,000
Pension and postretirement liabilities		297,743,000				287,373,000				297,743,000	287,373,000
Noncurrent liabilities of disposal group held for sale		0				0				0	0
Deferred credits and other liabilities		234,123,000				153,748,000				234,123,000	153,748,000
Total shareholders' equity and liabilities		9,321,815,000				8,516,744,000				9,321,815,000	8,516,744,000
Distribution Segment [Member] | Reportable Subsegments [Member]
Segment Reporting Information Profit Loss [Abstract]
Operating revenues from external parties										2,338,404,000	2,819,977,000	3,137,858,000
Revenue from External Customers by Products and Services Table [Abstract]
Operating revenues from external parties										2,338,404,000	2,819,977,000	3,137,858,000
Distribution Segment [Member] | Reportable Subsegments [Member] | Gas Sales Revenues [Member]
Segment Reporting Information Profit Loss [Abstract]
Operating revenues from external parties										2,236,774,000	2,718,311,000	3,040,656,000
Revenue from External Customers by Products and Services Table [Abstract]
Operating revenues from external parties										2,236,774,000	2,718,311,000	3,040,656,000
Distribution Segment [Member] | Reportable Subsegments [Member] | Gas Sales Revenues [Member] | Residential Customers [Member]
Segment Reporting Information Profit Loss [Abstract]
Operating revenues from external parties										1,477,049,000	1,761,689,000	1,933,099,000
Revenue from External Customers by Products and Services Table [Abstract]
Operating revenues from external parties										1,477,049,000	1,761,689,000	1,933,099,000
Distribution Segment [Member] | Reportable Subsegments [Member] | Gas Sales Revenues [Member] | Commercial Customers [Member]
Segment Reporting Information Profit Loss [Abstract]
Operating revenues from external parties										619,979,000	772,187,000	876,042,000
Revenue from External Customers by Products and Services Table [Abstract]
Operating revenues from external parties										619,979,000	772,187,000	876,042,000
Distribution Segment [Member] | Reportable Subsegments [Member] | Gas Sales Revenues [Member] | Industrial Customers [Member]
Segment Reporting Information Profit Loss [Abstract]
Operating revenues from external parties										98,439,000	131,034,000	166,736,000
Revenue from External Customers by Products and Services Table [Abstract]
Operating revenues from external parties										98,439,000	131,034,000	166,736,000
Distribution Segment [Member] | Reportable Subsegments [Member] | Gas Sales Revenues [Member] | Public Authority and Other Customers [Member]
Segment Reporting Information Profit Loss [Abstract]
Operating revenues from external parties										41,307,000	53,401,000	64,779,000
Revenue from External Customers by Products and Services Table [Abstract]
Operating revenues from external parties										41,307,000	53,401,000	64,779,000
Distribution Segment [Member] | Reportable Subsegments [Member] | Gas Transportation Revenues [Member]
Segment Reporting Information Profit Loss [Abstract]
Operating revenues from external parties										76,690,000	72,340,000	68,020,000
Revenue from External Customers by Products and Services Table [Abstract]
Operating revenues from external parties										76,690,000	72,340,000	68,020,000
Distribution Segment [Member] | Reportable Subsegments [Member] | Other Gas Revenues [Member]
Segment Reporting Information Profit Loss [Abstract]
Operating revenues from external parties										24,940,000	29,326,000	29,182,000
Revenue from External Customers by Products and Services Table [Abstract]
Operating revenues from external parties										24,940,000	29,326,000	29,182,000
Distribution Segment [Member] | Intersubsegment Eliminations [Member]
Segment Reporting Information Profit Loss [Abstract]
Operating revenues from external parties										1,374,000	1,385,000	1,363,000
Revenue from External Customers by Products and Services Table [Abstract]
Operating revenues from external parties										1,374,000	1,385,000	1,363,000
Pipeline and Storage Segment [Member]
Segment Reporting Information Profit Loss [Abstract]
Operating revenues		112,772,000	113,855,000	102,153,000	98,416,000	101,895,000	99,008,000	96,893,000	87,161,000	427,196,000	384,957,000	337,540,000
Purchased gas cost										(58,000)	562,000	2,048,000
Gross profit										427,254,000	384,395,000	335,492,000
Operating expenses
Operation and maintenance										130,610,000	122,902,000	90,729,000
Depreciation and amortization										56,682,000	48,314,000	42,187,000
Taxes, other than income										24,616,000	23,639,000	13,971,000
Total operating expenses										211,908,000	194,855,000	146,887,000
Operating income										215,346,000	189,540,000	188,605,000
Miscellaneous income (expense), net										(1,405,000)	(1,103,000)	(3,006,000)
Interest charges										36,574,000	33,154,000	36,279,000
Income (loss) before income taxes										177,367,000	155,283,000	149,320,000
Income tax expense										65,655,000	55,480,000	53,447,000
Income from Continuing Operations, Net of Tax										111,712,000	99,803,000	95,873,000
Net income from discontinued operations, net of tax										0	0	0
Net income										111,712,000	99,803,000	95,873,000
Capital expenditures										346,383,000	292,775,000	248,226,000
ASSETS
Net property, plant and equipment		2,060,141,000				1,759,912,000				2,060,141,000	1,759,912,000
Investment in subsidaries		13,854,000				13,854,000				13,854,000	13,854,000
Current assets
Cash and cash equivalents		0				0				0	0
Current assets of disposal group classified as held for sale		0				0				0	0
Other current assets		39,078,000				50,309,000				39,078,000	50,309,000
Intercompany receivables		0				0				0	0
Total current assets		39,078,000				50,309,000				39,078,000	50,309,000
Goodwill		143,012,000				142,972,000				143,012,000	142,972,000
Noncurrent assets of disposal group classified as held for sale		0				0				0	0
Deferred charges and other assets		27,779,000				17,890,000				27,779,000	17,890,000
Total assets		2,283,864,000				1,984,937,000				2,283,864,000	1,984,937,000
CAPITALIZATION AND LIABILITIES
Shareholders' equity		715,672,000				629,820,000				715,672,000	629,820,000
Long-term debt		0				0				0	0
Total capitalization		715,672,000				629,820,000				715,672,000	629,820,000
Current liabilities
Current maturities of long-term debt		0								0
Short-term debt		0				0				0	0
Current liabilities of disposal group classified as held for sale		0				0				0	0
Other current liabilities		39,911,000				49,352,000				39,911,000	49,352,000
Intercompany payables		957,526,000				866,048,000				957,526,000	866,048,000
Total current liabilities		997,437,000				915,400,000				997,437,000	915,400,000
Deferred income taxes		543,390,000				411,722,000				543,390,000	411,722,000
Regulatory cost of removal obligation		27,119,000				27,806,000				27,119,000	27,806,000
Pension and postretirement liabilities		0				0				0	0
Noncurrent liabilities of disposal group held for sale		0				0				0	0
Deferred credits and other liabilities		246,000				189,000				246,000	189,000
Total shareholders' equity and liabilities		2,283,864,000				1,984,937,000				2,283,864,000	1,984,937,000
Pipeline and Storage Segment [Member] | Reportable Subsegments [Member]
Segment Reporting Information Profit Loss [Abstract]
Operating revenues from external parties										116,244,000	107,008,000	106,046,000
Revenue from External Customers by Products and Services Table [Abstract]
Operating revenues from external parties										116,244,000	107,008,000	106,046,000
Pipeline and Storage Segment [Member] | Intersubsegment Eliminations [Member]
Segment Reporting Information Profit Loss [Abstract]
Operating revenues from external parties										310,952,000	277,949,000	231,494,000
Revenue from External Customers by Products and Services Table [Abstract]
Operating revenues from external parties										310,952,000	277,949,000	231,494,000
Natural Gas Marketing Segment [Member]
Segment Reporting Information Profit Loss [Abstract]
Operating revenues										0	0	0
Purchased gas cost										0	0	0
Gross profit										0	0	0
Operating expenses
Operation and maintenance										0	0	0
Depreciation and amortization										0	0	0
Taxes, other than income										0	0	0
Total operating expenses										0	0	0
Operating income										0	0	0
Miscellaneous income (expense), net										0	0	0
Interest charges										0	0	0
Income (loss) before income taxes										0	0	0
Income tax expense										0	0	0
Income from Continuing Operations, Net of Tax										0	0	0
Net income from discontinued operations, net of tax										4,562,000	9,452,000	19,486,000
Net income										4,562,000	9,452,000	19,486,000
Capital expenditures										321,000	226,000	1,559,000
ASSETS
Net property, plant and equipment		0				0				0	0
Investment in subsidaries		0				0				0	0
Current assets
Cash and cash equivalents		25,417,000				4,008,000				25,417,000	4,008,000
Current assets of disposal group classified as held for sale		162,508,000				148,904,000				162,508,000	148,904,000
Other current assets		5,000				(3,385,000)				5,000	(3,385,000)
Intercompany receivables		0				2,960,000				0	2,960,000
Total current assets		187,930,000				152,487,000				187,930,000	152,487,000
Goodwill		0				0				0	0
Noncurrent assets of disposal group classified as held for sale		28,785,000				30,385,000				28,785,000	30,385,000
Deferred charges and other assets		0				(101,000)				0	(101,000)
Total assets		216,715,000				182,771,000				216,715,000	182,771,000
CAPITALIZATION AND LIABILITIES
Shareholders' equity		66,597,000				37,283,000				66,597,000	37,283,000
Long-term debt		0				0				0	0
Total capitalization		66,597,000				37,283,000				66,597,000	37,283,000
Current liabilities
Current maturities of long-term debt		0								0
Short-term debt		35,000,000				50,000,000				35,000,000	50,000,000
Current liabilities of disposal group classified as held for sale		81,908,000				89,471,000				81,908,000	89,471,000
Other current liabilities		3,263,000				5,863,000				3,263,000	5,863,000
Intercompany payables		14,139,000				0				14,139,000	0
Total current liabilities		134,310,000				145,334,000				134,310,000	145,334,000
Deferred income taxes		4,318,000				(7,605,000)				4,318,000	(7,605,000)
Regulatory cost of removal obligation		0				0				0	0
Pension and postretirement liabilities		0				0				0	0
Noncurrent liabilities of disposal group held for sale		316,000				347,000				316,000	347,000
Deferred credits and other liabilities		11,174,000				7,412,000				11,174,000	7,412,000
Total shareholders' equity and liabilities		216,715,000				182,771,000				216,715,000	182,771,000
Natural Gas Marketing Segment [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
Natural Gas Marketing Segment [Member] | 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
Intersegment Elimination [Member]
Segment Reporting Information Profit Loss [Abstract]
Operating revenues		(82,432,000)	$ (82,548,000)	$ (74,240,000)	$ (73,106,000)	(72,783,000)	$ (72,985,000)	$ (68,879,000)	$ (64,687,000)	(312,326,000)	(279,334,000)	(232,857,000)
Purchased gas cost										(312,326,000)	(279,334,000)	(232,857,000)
Gross profit										0	0	0
Operating expenses
Operation and maintenance										0	0	0
Depreciation and amortization										0	0	0
Taxes, other than income										0	0	0
Total operating expenses										0	0	0
Operating income										0	0	0
Miscellaneous income (expense), net										0	0	0
Interest charges										0	0	0
Income (loss) before income taxes										0	0	0
Income tax expense										0	0	0
Income from Continuing Operations, Net of Tax										0	0	0
Net income from discontinued operations, net of tax										0	0	0
Net income										0	0	0
Capital expenditures										0	0	0
ASSETS
Net property, plant and equipment		0				0				0	0
Investment in subsidaries		(782,269,000)				(667,103,000)				(782,269,000)	(667,103,000)
Current assets
Cash and cash equivalents		0				0				0	0
Current assets of disposal group classified as held for sale		(11,391,000)				(9,849,000)				(11,391,000)	(9,849,000)
Other current assets		(46,011,000)				(66,380,000)				(46,011,000)	(66,380,000)
Intercompany receivables		(971,665,000)				(866,048,000)				(971,665,000)	(866,048,000)
Total current assets		(1,029,067,000)				(942,277,000)				(1,029,067,000)	(942,277,000)
Goodwill		0				0				0	0
Noncurrent assets of disposal group classified as held for sale		(169,000)				0				(169,000)	0
Deferred charges and other assets		0				0				0	0
Total assets		(1,811,505,000)				(1,609,380,000)				(1,811,505,000)	(1,609,380,000)
CAPITALIZATION AND LIABILITIES
Shareholders' equity		(782,269,000)				(667,103,000)				(782,269,000)	(667,103,000)
Long-term debt		0				0				0	0
Total capitalization		(782,269,000)				(667,103,000)				(782,269,000)	(667,103,000)
Current liabilities
Current maturities of long-term debt		0								0
Short-term debt		(35,000,000)				(50,000,000)				(35,000,000)	(50,000,000)
Current liabilities of disposal group classified as held for sale		(9,008,000)				(14,911,000)				(9,008,000)	(14,911,000)
Other current liabilities		(13,394,000)				(11,318,000)				(13,394,000)	(11,318,000)
Intercompany payables		(971,665,000)				(866,048,000)				(971,665,000)	(866,048,000)
Total current liabilities		(1,029,067,000)				(942,277,000)				(1,029,067,000)	(942,277,000)
Deferred income taxes		0				0				0	0
Regulatory cost of removal obligation		0				0				0	0
Pension and postretirement liabilities		0				0				0	0
Noncurrent liabilities of disposal group held for sale		0				0				0	0
Deferred credits and other liabilities		(169,000)				0				(169,000)	0
Total shareholders' equity and liabilities		$ (1,811,505,000)				$ (1,609,380,000)				(1,811,505,000)	(1,609,380,000)
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										(312,326,000)	(279,334,000)	(232,857,000)
Revenue from External Customers by Products and Services Table [Abstract]
Operating revenues from external parties										$ (312,326,000)	$ (279,334,000)	$ (232,857,000)
[1]	Net property, plant and equipment includes plant acquisition adjustments of $(59.8) million and $(68.1) million at September 30, 2016 and 2015.
[2]	Natural gas marketing had goodwill of $16.4 million at September 30, 2016 and 2015 classified as assets held for sale on the consolidated balance sheet.

Earnings Per Share (Details)

Earnings Per Share (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended								12 Months Ended
	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2014	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2014
Basic Earnings per Share
Income from Continuing Operations, Net of Tax	$ 34,850	$ 66,143	$ 143,003	$ 101,546	$ 23,908	$ 52,487	$ 133,142	$ 96,086	$ 345,542	$ 305,623	$ 270,331
Less: Income from continuing operations allocated to participating securities									$ 538	$ 607	$ 663
Basic weighted average shares outstanding (shares)									103,524	101,892	97,606
Income from Continuing Operations, Per Basic Share	$ 0.33	$ 0.64	$ 1.39	$ 0.99	$ 0.23	$ 0.51	$ 1.31	$ 0.94	$ 3.33	$ 3	$ 2.76
Net income from discontinued operations, net of tax	$ (610)	$ 5,050	$ (1,193)	$ 1,315	$ (393)	$ 3,794	$ 4,542	$ 1,509	$ 4,562	$ 9,452	$ 19,486
Undistributed Earnings From Discontinued Operations Allocated To Participating Securities									8	19	48
Net Income Loss From Discontinued Operations Available To Common Stockholders Basic									$ 4,554	$ 9,433	$ 19,438
Earnings Per Share, Basic	$ 0.33	$ 0.69	$ 1.38	$ 1	$ 0.23	$ 0.55	$ 1.35	$ 0.96	$ 3.38	$ 3.09	$ 2.96
Income from Discontinued Operation, Net of Tax, Per Basic Share	0	0.05	(0.01)	0.01	0	0.04	0.04	0.02	$ 0.05	$ 0.09	$ 0.20
Income from continuing operations available to common shareholders									$ 345,004	$ 305,016	$ 269,668
Diluted Earnings per Share
Effect of dilutive stock options and other shares									0	0	0
Effect of dilutive stock options and other shares, discontinued operations									0	0	0
Net Income available to common shareholders									$ 345,004	$ 305,016	$ 269,668
Additional dilutive stock options and other shares									0	0	2
Diluted weighted average shares outstanding (shares)									103,524	101,892	97,608
Diluted net income per share	0.33	0.69	1.38	1	0.23	0.55	1.35	0.96	$ 3.38	$ 3.09	$ 2.96000
Net Income Loss From Discontinued Operations Available To Common Stockholders Diluted									$ 4,554	$ 9,433	$ 19,438
Income from Discontinued Operation, Net of Tax, Per Diluted Share	0	0.05	(0.01)	0.01	0	0.04	0.04	0.02	$ 0.05	$ 0.09	$ 0.20
Income from Continuing Operations, Per Diluted Share	$ 0.33	$ 0.64	$ 1.39	$ 0.99	$ 0.23	$ 0.51	$ 1.31	$ 0.94	$ 3.33	$ 3	$ 2.76

Debt (Details)

Debt (Details) - USD ($)	Jan. 01, 2017	Oct. 25, 2016	Oct. 20, 2016	Oct. 05, 2016	Oct. 15, 2014	Sep. 30, 2016	Sep. 30, 2015
Debt Instrument [Line Items]
Debt Instrument Carrying Amount						$ 2,460,000,000	$ 2,460,000,000
Debt Issuance Costs, Net						16,951,000	17,873,000
Debt Instrument Unamortized Discount						4,270,000	4,612,000
Current maturities of long-term debt						250,000,000	0
Long-term Debt, Excluding Current Maturities						2,188,779,000	2,437,515,000
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						$ 829,800,000	$ 457,900,000
Commercial Paper Weighted Average Interest Rate						0.81%	0.42%
Term Loan Agreement, Maximum Borrowing Capacity						$ 200,000,000
Term Loan Agreement, Incremental Borrowings						1,000,000
Term Loan Agreement, Amount Outstanding						0
Long-term Debt, Fiscal Year Maturity [Abstract]
2,017						250,000,000
2,018						0
2,019						450,000,000
2,020						0
2,021						0
Thereafter						$ 1,760,000,000
Subsequent Event [Member]
Line Of Credit Facility [Line Items]
Line Of Credit Facility Maximum Borrowing Capacity				$ 1,600,000,000
Subsequent Event, Date	Jan. 1, 2017	Oct. 25, 2016	Oct. 20, 2016	Oct. 5, 2016
Subsequent Event, Description		On October 25, 2016 , the uncommitted $25 million bilateral credit facility was renewed through July 31, 2017. These facilities are used primarily to issue letters of credit.	the Society of Actuaries released its annually-updated mortality improvement scale for pension plans incorporating new assumptions surrounding life expectancies in the United States. As of September 30, 2016, we updated our assumed mortality rates to incorporate the updated mortality table.	we amended our existing $1.25 billion unsecured credit facility (the five-year unsecured credit facility) which increased the committed loan to $1.5 billion and extended the facility through September 25, 2021.
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						50.00%
Unregulated Operation [Member]
Line Of Credit Facility [Line Items]
Line of Credit Facility, Remaining Borrowing Capacity						$ 32,800,000
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%
Debt Instrument Carrying Amount					$ 500,000,000
Extinguishment of Debt, Amount					$ 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
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
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
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
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
Unsecured Senior Notes Due 2044 [Member]
Debt Instrument [Line Items]
Debt Instrument Interest Rate Stated Percentage					4.125%	4.125%	4.125%
Debt Instrument, Maturity Date						Oct. 15, 2044	Oct. 15, 2044
Debt Instrument Carrying Amount					$ 500,000,000	$ 500,000,000	$ 500,000,000
Debt Instrument Interest Rate Effective Percentage					4.086%
Net Proceeds From Issuance of Debt					$ 494,000,000
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
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
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
Line of Credit Facility, Accordion Feature						250,000,000
Commercial Paper [Member] | Regulated Operation [Member] | Five Year Unsecured Revolving Credit Agreement [Member] | Subsequent Event [Member]
Line Of Credit Facility [Line Items]
Line Of Credit Facility Maximum Borrowing Capacity				$ 1,500,000,000
Line of Credit Facility, Maximum Borrowing Capacity with Accordion Feature				$ 1,750,000,000
Commercial Paper [Member] | Minimum [Member] | Regulated Operation [Member] | Five Year Unsecured Revolving Credit Agreement [Member] | Subsequent Event [Member]
Line Of Credit Facility [Line Items]
Debt Instrument, Basis Spread on Variable Rate				0.00%
Commercial Paper [Member] | Maximum [Member] | Regulated Operation [Member] | Five Year Unsecured Revolving Credit Agreement [Member] | Subsequent Event [Member]
Line Of Credit Facility [Line Items]
Debt Instrument, Basis Spread on Variable Rate				1.25%
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						197,000,000
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] | Unregulated Operation [Member] | $25 Million Uncommitted Facility [Member] | Subsequent Event [Member]
Line Of Credit Facility [Line Items]
Line Of Credit Facility Maximum Borrowing Capacity		$ 25,000,000
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
Line of Credit Facility, Remaining Borrowing Capacity						$ 4,100,000
Debt Instrument, Basis Spread on Variable Rate						1.50%
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

Shareholders' Equity Components

Shareholders' Equity Components (Details) - USD ($)	Feb. 18, 2014	Feb. 29, 2016	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2014
Accumulated Other Comprehensive Income (Loss) [Line Items]
Shareholders' equity, beginning balance			$ 3,194,797,000	$ 3,086,232,000	$ 2,580,409,000
Net current-period other comprehensive income (loss)			(78,692,000)	(96,937,000)	(51,271,000)
Shareholders' equity, ending balance			3,463,059,000	$ 3,194,797,000	3,086,232,000
Shareholders' Equity Other Disclosures [Abstract]
Debt and Equity Securities Authorized for Issuance			2,500,000,000
Debt And Equity Securities Available For Issuance			2,400,000,000
ATM Equity Distribution Offering Price Maximum Amount			$ 200,000,000
ATM Equity Distribution, Shares Issued			1,360,756
ATM Agent Commission Proceeds Percentage			1.00%
ATM Equity Distribution, Net Proceeds			$ 98,600,000
ATM Equity Distribution, Gross Proceeds			$ 100,000,000
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Share-based Compensation Arrangement by Share-based Payment Award, Number of Shares Authorized			11,200,000	8,700,000
Share-based Compensation Arrangement by Share-based Payment Award, Number of Additional Shares Authorized		2,500,000
Stock Issued During Period, Shares, New Issues	9,200,000
Shares Issued At Overallotment Option	1,200,000
Share Price	$ 44
Net proceeds from equity offering	$ 390,205,000		$ 98,574,000	$ 0	390,205,000
Accumulated Net Unrealized Investment Gain (Loss) [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Shareholders' equity, beginning balance			4,949,000	7,662,000
Other comprehensive income (loss) before reclassifications			(263,000)	(2,173,000)
Amounts reclassified from accumulated other comprehensive income			(202,000)	(540,000)
Net current-period other comprehensive income (loss)			(465,000)	(2,713,000)
Shareholders' equity, ending balance			4,484,000	4,949,000	7,662,000
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			(88,842,000)	(18,381,000)
Other comprehensive income (loss) before reclassifications			(99,029,000)	(71,003,000)
Amounts reclassified from accumulated other comprehensive income			347,000	542,000
Net current-period other comprehensive income (loss)			(98,682,000)	(70,461,000)
Shareholders' equity, ending balance			(187,524,000)	(88,842,000)	(18,381,000)
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			(25,437,000)	(1,674,000)
Other comprehensive income (loss) before reclassifications			(11,662,000)	(49,211,000)
Amounts reclassified from accumulated other comprehensive income			32,117,000	25,448,000
Net current-period other comprehensive income (loss)			20,455,000	(23,763,000)
Shareholders' equity, ending balance			(4,982,000)	(25,437,000)	(1,674,000)
Accumulated Other Comprehensive Income [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Shareholders' equity, beginning balance			(109,330,000)	(12,393,000)	38,878,000
Other comprehensive income (loss) before reclassifications			(110,954,000)	(122,387,000)
Amounts reclassified from accumulated other comprehensive income			32,262,000	25,450,000
Net current-period other comprehensive income (loss)			(78,692,000)	(96,937,000)	(51,271,000)
Shareholders' equity, ending balance			$ (188,022,000)	$ (109,330,000)	$ (12,393,000)

Shareholders' Equity AOCI Affec

Shareholders' Equity AOCI Affected Line Item in the Statement of Income (Details) - USD ($) $ in Thousands	12 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2014
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Operation and maintenance	$ (538,592)	$ (516,406)	$ (482,476)
Interest charges	(114,812)	(116,241)	(129,276)
Purchased gas cost	(746,192)	(1,295,675)	(1,722,060)
Income (loss) before income taxes	542,184	495,172	444,943
Income Tax Expense (Benefit)	(196,642)	(189,549)	$ (174,612)
Reclassification out of Accumulated Other Comprehensive Income [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Income (loss) from continuing operations	(32,262)	(25,450)
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	318	850
Income (loss) before income taxes	318	850
Income Tax Expense (Benefit)	(116)	(310)
Income (loss) from continuing operations	202	540
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	(53,197)	(42,569)
Income Tax Expense (Benefit)	20,733	16,579
Income (loss) from continuing operations	(32,464)	(25,990)
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	(546)	(853)
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	$ (52,651)	$ (41,716)

Retirement and Post-Retiremen52

Retirement and Post-Retirement Employee Benefit Plans Defined Benefit Plans Disclosure (Details) - USD ($) $ in Thousands	Jan. 01, 2017	Oct. 25, 2016	Oct. 20, 2016	Oct. 05, 2016	Oct. 02, 2013	Sep. 30, 2016		Sep. 30, 2015	Sep. 30, 2014
Defined Benefit Pension Plans and Defined Benefit Postretirement Plans Disclosure [Abstract]
Remaining Recovery Period of Regulatory Assets for which No Return on Investment During Recovery Period is Provided						15 years
Available-for-sale Securities, Supplemental Executive Benefit Plans						$ 41,300		$ 41,700
Pension and Other Postretirement Plans Costs [Member] | Unrecognized Transition Obligation [Member]
Net Periodic Benefit Cost Not Yet Recognized, Recorded as Regulatory Assets [Abstract]
Net Regulatory Assets								82
Pension and Other Postretirement Plans Costs [Member] | Unrecognized Prior Service Credit [Member]
Net Periodic Benefit Cost Not Yet Recognized, Recorded as Regulatory Assets [Abstract]
Net Regulatory Assets						(4,389)		(6,259)
Pension and Other Postretirement Plans Costs [Member] | Unrecognized Actuarial (Gain) Loss [Member]
Net Periodic Benefit Cost Not Yet Recognized, Recorded as Regulatory Assets [Abstract]
Net Regulatory Assets						124,288		110,714
Pension and Other Postretirement Plans Costs [Member] | Total Unrecognized in Net Periodic Pension Cost [Member]
Net Periodic Benefit Cost Not Yet Recognized, Recorded as Regulatory Assets [Abstract]
Net Regulatory Assets						$ 119,899		$ 104,537
Subsequent Event [Member]
Subsequent Event [Line Items]
Subsequent Event, Date	Jan. 1, 2017	Oct. 25, 2016	Oct. 20, 2016	Oct. 5, 2016
Subsequent Event, Description		On October 25, 2016 , the uncommitted $25 million bilateral credit facility was renewed through July 31, 2017. These facilities are used primarily to issue letters of credit.	the Society of Actuaries released its annually-updated mortality improvement scale for pension plans incorporating new assumptions surrounding life expectancies in the United States. As of September 30, 2016, we updated our assumed mortality rates to incorporate the updated mortality table.	we amended our existing $1.25 billion unsecured credit facility (the five-year unsecured credit facility) which increased the committed loan to $1.5 billion and extended the facility through September 25, 2021.
Pension Plans, Defined Benefit [Member]
Defined Benefit Plan Weighted Average Assumptions Used In Calculating Net Periodic Benefit Cost Abstract
Discount rate						4.55%		4.43%	4.95%
Rate of compensation increase						3.50%		3.50%	3.50%
Expected return on plan assets						7.00%		7.25%	7.25%
Defined Benefit Plan Weighted Average Assumptions Used In Calculating Benefit Obligation Abstract
Discount rate						3.73%		4.55%
Rate of compensation increase						3.50%		3.50%
Expected return on plan assets						7.00%		7.00%
Defined Benefit Plan Change In Benefit Obligation Roll Forward
Accumulated benefit obligation						$ 516,924		$ 485,921
Benefit obligation at beginning of year						508,599		493,594
Service cost						16,419		16,231	$ 15,345
Interest cost						23,193		21,850	22,330
Actuarial (gain) loss						41,847		7,420
Benefits paid						(44,578)	[1]	(30,496)
Benefit obligation at end of year						545,480		508,599	$ 493,594
Funded Status of Plan Reconciliation
Funded status						(71,530)		(57,667)
Unrecognized prior service cost						0		0
Unrecognized net loss						0		0
Net amount recognized						(71,530)		$ (57,667)
Estimated Future Benefits Payment, Total
FY2017						31,306
FY2018						32,047
FY2019						33,674
FY2020						35,232
FY2021						37,279
2022-2026						202,442
Defined Benefit Pension Plans and Defined Benefit Postretirement Plans Disclosure [Abstract]
Defined Benefit Plan, One-Time Voluntary Pension Buyout						$ 12,800
Pension Plans, Defined Benefit [Member] | Minimum [Member]
Defined Benefit Pension Plans and Defined Benefit Postretirement Plans Disclosure [Abstract]
Defined Benefit Plan, Investment Performance Review Period						3 years
Pension Plans, Defined Benefit [Member] | Maximum [Member]
Defined Benefit Pension Plans and Defined Benefit Postretirement Plans Disclosure [Abstract]
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						40.50%		41.30%
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						15.50%		14.90%
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						11.20%		11.00%
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						15.10%		15.20%
Number of shares of Atmos Energy common stock in Master Trust						956,700		1,169,700
Amount of dividend income from Atmos Energy common stock in Master Trust						$ 1,800		$ 1,800
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						17.70%		17.60%
Pension Plans, Defined Benefit [Member] | Pension Costs [Member] | Unrecognized Transition Obligation [Member]
Net Periodic Benefit Cost Not Yet Recognized, Recorded as Regulatory Assets [Abstract]
Net Regulatory Assets								$ 0
Pension Plans, Defined Benefit [Member] | Pension Costs [Member] | Unrecognized Prior Service Credit [Member]
Net Periodic Benefit Cost Not Yet Recognized, Recorded as Regulatory Assets [Abstract]
Net Regulatory Assets						$ (1,509)		(1,735)
Pension Plans, Defined Benefit [Member] | Pension Costs [Member] | Unrecognized Actuarial (Gain) Loss [Member]
Net Periodic Benefit Cost Not Yet Recognized, Recorded as Regulatory Assets [Abstract]
Net Regulatory Assets						127,028		120,948
Pension Plans, Defined Benefit [Member] | Pension Costs [Member] | Total Unrecognized in Net Periodic Pension Cost [Member]
Net Periodic Benefit Cost Not Yet Recognized, Recorded as Regulatory Assets [Abstract]
Net Regulatory Assets						$ 125,519		$ 119,213
Pension Account Plan, Defined Benefit [Member]
Defined Benefit Pension Plans and Defined Benefit Postretirement Plans Disclosure [Abstract]
Defined Benefit Plan, Vesting Period						3 years
Supplemental Employee Retirement Plan [Member]
Defined Benefit Plan Weighted Average Assumptions Used In Calculating Net Periodic Benefit Cost Abstract
Discount rate						4.55%		4.43%	4.95%
Rate of compensation increase						3.50%		3.50%	3.50%
Defined Benefit Plan Weighted Average Assumptions Used In Calculating Benefit Obligation Abstract
Discount rate						3.73%		4.55%
Rate of compensation increase						3.50%		3.50%
Defined Benefit Plan Change In Benefit Obligation Roll Forward
Accumulated benefit obligation						$ 137,616		$ 118,835
Benefit obligation at beginning of year						122,393		113,219
Service cost						2,371		3,971	$ 3,607
Interest cost						5,185		4,943	4,966
Actuarial (gain) loss						17,229		4,811
Benefits paid						(4,604)		(4,551)
Benefit obligation at end of year						142,574		122,393	113,219
Funded Status of Plan Reconciliation
Funded status						(142,574)		(122,393)
Unrecognized prior service cost						0		0
Unrecognized net loss						0		0
Net amount recognized						(142,574)		(122,393)
Estimated Future Benefits Payment, Total
FY2017						36,604
FY2018						14,289
FY2019						7,181
FY2020						4,395
FY2021						4,306
2022-2026						60,658
Defined Benefit Pension Plans and Defined Benefit Postretirement Plans Disclosure [Abstract]
Settlements						0		0	$ 4,539
Supplemental Employee Retirement Plan [Member] | Supplemental Executive Benefit Plan Costs [Member] | Unrecognized Transition Obligation [Member]
Net Periodic Benefit Cost Not Yet Recognized, Recorded as Regulatory Assets [Abstract]
Net Regulatory Assets								0
Supplemental Employee Retirement Plan [Member] | Supplemental Executive Benefit Plan Costs [Member] | Unrecognized Prior Service Credit [Member]
Net Periodic Benefit Cost Not Yet Recognized, Recorded as Regulatory Assets [Abstract]
Net Regulatory Assets						0		0
Supplemental Employee Retirement Plan [Member] | Supplemental Executive Benefit Plan Costs [Member] | Unrecognized Actuarial (Gain) Loss [Member]
Net Periodic Benefit Cost Not Yet Recognized, Recorded as Regulatory Assets [Abstract]
Net Regulatory Assets						51,558		36,915
Supplemental Employee Retirement Plan [Member] | Supplemental Executive Benefit Plan Costs [Member] | Total Unrecognized in Net Periodic Pension Cost [Member]
Net Periodic Benefit Cost Not Yet Recognized, Recorded as Regulatory Assets [Abstract]
Net Regulatory Assets						$ 51,558		$ 36,915
Supplemental Executive Benefit Plan, Defined Benefit [Member]
Defined Benefit Plan Change In Benefit Obligation Roll Forward
Benefits paid					$ (16,800)
Defined Benefit Pension Plans and Defined Benefit Postretirement Plans Disclosure [Abstract]
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]
Defined Benefit Pension Plans and Defined Benefit Postretirement Plans Disclosure [Abstract]
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%
Defined Benefit Pension Plans and Defined Benefit Postretirement Plans Disclosure [Abstract]
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]
Defined Benefit Plan Weighted Average Assumptions Used In Calculating Net Periodic Benefit Cost Abstract
Discount rate						4.55%		4.43%	4.95%
Expected return on plan assets						4.45%		4.60%	4.60%
Initial Trend						7.50%		7.50%	8.00%
Ultimate trend rate						5.00%		5.00%	5.00%
Ultimate trend rate reached in						2,021		2,020	2,020
Defined Benefit Plan Weighted Average Assumptions Used In Calculating Benefit Obligation Abstract
Discount rate						3.73%		4.55%
Expected return on plan assets						4.45%		4.45%
Initial trend rate						7.50%		7.50%
Ultimate trend rate						5.00%		5.00%
Ultimate trend reached in						2,022		2,021
Defined Benefit Plan Change In Benefit Obligation Roll Forward
Benefit obligation at beginning of year						$ 267,179		$ 315,118
Service cost						10,823		15,583	$ 16,784
Interest cost						12,424		14,385	15,951
Plan participants' contributions						4,289		4,563
Actuarial (gain) loss						(1,052)		(69,962)
Benefits paid						(14,441)		(12,508)
Benefit obligation at end of year						279,222		267,179	$ 315,118
Funded Status of Plan Reconciliation
Funded status						(120,245)		(129,170)
Unrecognized prior service cost						0		0
Unrecognized transition obligation						0		0
Unrecognized net loss						0		0
Net amount recognized						(120,245)		$ (129,170)
Estimated company benefit payments
FY2017						15,806
FY2018						11,602
FY2019						12,165
FY2020						13,246
FY2021						14,210
2022-2026						84,642
Estimated retiree benefit payments
FY2017						3,679
FY2018						3,992
FY2019						4,036
FY2020						4,756
FY2021						5,420
2022-2026						36,837
Disclosure Of Expected Gross Prescription Drug Subsidy Receipts Abstract
FY2017						0
FY2018						0
FY2019						0
FY2020						0
FY2021						0
2022-2026						0
Estimated Future Benefits Payment, Total
FY2017						19,485
FY2018						15,594
FY2019						16,201
FY2020						18,002
FY2021						19,630
2022-2026						121,479
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						4,539
Effect of One Percentage Point Decrease on Service and Interest Cost Components						(3,596)
Effect of One Percentage Point Increase on Accumulated Postretirement Benefit Obligation						42,079
Effect of One Percentage Point Decrease on Accumulated Postretirement Benefit Obligation						$ (34,531)
Defined Benefit Pension Plans and Defined Benefit Postretirement Plans Disclosure [Abstract]
Defined Benefit Plan, Employer Claims Paid						80.00%
Defined Benefit Plan, Employee Paid Claims						20.00%
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						$ 10,000
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						$ 20,000
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						97.20%		97.50%
Defined Benefit Pension Plans and Defined Benefit Postretirement Plans Disclosure [Abstract]
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						2.80%		2.50%
Other Postretirement Benefit Plans, Defined Benefit [Member] | Postretirement Benefit Costs [Member] | Unrecognized Transition Obligation [Member]
Net Periodic Benefit Cost Not Yet Recognized, Recorded as Regulatory Assets [Abstract]
Net Regulatory Assets								$ 82
Other Postretirement Benefit Plans, Defined Benefit [Member] | Postretirement Benefit Costs [Member] | Unrecognized Prior Service Credit [Member]
Net Periodic Benefit Cost Not Yet Recognized, Recorded as Regulatory Assets [Abstract]
Net Regulatory Assets						$ (2,880)		(4,524)
Other Postretirement Benefit Plans, Defined Benefit [Member] | Postretirement Benefit Costs [Member] | Unrecognized Actuarial (Gain) Loss [Member]
Net Periodic Benefit Cost Not Yet Recognized, Recorded as Regulatory Assets [Abstract]
Net Regulatory Assets						(54,298)		(47,149)
Other Postretirement Benefit Plans, Defined Benefit [Member] | Postretirement Benefit Costs [Member] | Total Unrecognized in Net Periodic Pension Cost [Member]
Net Periodic Benefit Cost Not Yet Recognized, Recorded as Regulatory Assets [Abstract]
Net Regulatory Assets						$ (57,178)		$ (51,591)
[1]	Includes $12.8 million of one-time payments to eligible deferred vested participants who elected to receive a lump-sum payout of their pension benefits during fiscal 2016.

Retirement and Post-Retiremen53

Retirement and Post-Retirement Employee Benefit Plans Fair Value Disclosures (Details) - USD ($) $ in Thousands		Sep. 30, 2016	Sep. 30, 2015
Schedule of Total Investments at Fair Value [Line Items]
Available-for-sale Securities		$ 72,701	$ 74,200
Fair Value Inputs Level 1 [Member]
Schedule of Total Investments at Fair Value [Line Items]
Available-for-sale Securities		38,677	40,619
Fair Value Inputs Level 2 [Member]
Schedule of Total Investments at Fair Value [Line Items]
Available-for-sale Securities	[1]	34,024	33,581
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]
Available-for-sale Securities		471,310	448,544
Fair value of accounts receivable		2,600	2,400
Pension Plans, Defined Benefit [Member] | Equity Securities [Member]
Schedule of Total Investments at Fair Value [Line Items]
Available-for-sale Securities		157,111	159,304
Pension Plans, Defined Benefit [Member] | Money Market Funds [Member]
Schedule of Total Investments at Fair Value [Line Items]
Available-for-sale Securities		11,522	11,787
Pension Plans, Defined Benefit [Member] | Mutual Fund [Member]
Schedule of Total Investments at Fair Value [Line Items]
Available-for-sale Securities		87,396	81,960
Pension Plans, Defined Benefit [Member] | Common Collective Trusts [Member]
Schedule of Total Investments at Fair Value [Line Items]
Available-for-sale Securities		105,124	93,081
Pension Plans, Defined Benefit [Member] | Mortgage-backed securities [Member]
Schedule of Total Investments at Fair Value [Line Items]
Available-for-sale Securities		15,223	14,359
Pension Plans, Defined Benefit [Member] | U.S. Treasuries [Member]
Schedule of Total Investments at Fair Value [Line Items]
Available-for-sale Securities		5,567	6,084
Pension Plans, Defined Benefit [Member] | Corporate Debt Securities [Member]
Schedule of Total Investments at Fair Value [Line Items]
Available-for-sale Securities		31,929	28,973
Pension Plans, Defined Benefit [Member] | Limited Partnership Interest [Member]
Schedule of Total Investments at Fair Value [Line Items]
Available-for-sale Securities		57,438	52,996
Pension Plans, Defined Benefit [Member] | Fair Value Inputs Level 1 [Member]
Schedule of Total Investments at Fair Value [Line Items]
Available-for-sale Securities		249,211	246,543
Pension Plans, Defined Benefit [Member] | Fair Value Inputs Level 1 [Member] | Equity Securities [Member]
Schedule of Total Investments at Fair Value [Line Items]
Available-for-sale Securities		157,111	159,304
Pension Plans, Defined Benefit [Member] | Fair Value Inputs Level 1 [Member] | Money Market Funds [Member]
Schedule of Total Investments at Fair Value [Line Items]
Available-for-sale Securities		0	0
Pension Plans, Defined Benefit [Member] | Fair Value Inputs Level 1 [Member] | Mutual Fund [Member]
Schedule of Total Investments at Fair Value [Line Items]
Available-for-sale Securities		87,396	81,960
Pension Plans, Defined Benefit [Member] | Fair Value Inputs Level 1 [Member] | Common Collective Trusts [Member]
Schedule of Total Investments at Fair Value [Line Items]
Available-for-sale Securities		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]
Available-for-sale Securities		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]
Available-for-sale Securities		4,704	5,279
Pension Plans, Defined Benefit [Member] | Fair Value Inputs Level 1 [Member] | Corporate Debt Securities [Member]
Schedule of Total Investments at Fair Value [Line Items]
Available-for-sale Securities		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]
Available-for-sale Securities		0	0
Pension Plans, Defined Benefit [Member] | Fair Value Inputs Level 2 [Member]
Schedule of Total Investments at Fair Value [Line Items]
Available-for-sale Securities		222,099	202,001
Pension Plans, Defined Benefit [Member] | Fair Value Inputs Level 2 [Member] | Equity Securities [Member]
Schedule of Total Investments at Fair Value [Line Items]
Available-for-sale Securities		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]
Available-for-sale Securities		11,522	11,787
Pension Plans, Defined Benefit [Member] | Fair Value Inputs Level 2 [Member] | Mutual Fund [Member]
Schedule of Total Investments at Fair Value [Line Items]
Available-for-sale Securities		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]
Available-for-sale Securities		105,124	93,081
Pension Plans, Defined Benefit [Member] | Fair Value Inputs Level 2 [Member] | Mortgage-backed securities [Member]
Schedule of Total Investments at Fair Value [Line Items]
Available-for-sale Securities		15,223	14,359
Pension Plans, Defined Benefit [Member] | Fair Value Inputs Level 2 [Member] | U.S. Treasuries [Member]
Schedule of Total Investments at Fair Value [Line Items]
Available-for-sale Securities		863	805
Pension Plans, Defined Benefit [Member] | Fair Value Inputs Level 2 [Member] | Corporate Debt Securities [Member]
Schedule of Total Investments at Fair Value [Line Items]
Available-for-sale Securities		31,929	28,973
Pension Plans, Defined Benefit [Member] | Fair Value Inputs Level 2 [Member] | Limited Partnership Interest [Member]
Schedule of Total Investments at Fair Value [Line Items]
Available-for-sale Securities		57,438	52,996
Pension Plans, Defined Benefit [Member] | 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] | Fair Value Inputs Level 3 [Member] | Equity Securities [Member]
Schedule of Total Investments at Fair Value [Line Items]
Available-for-sale Securities		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]
Available-for-sale Securities		0	0
Pension Plans, Defined Benefit [Member] | Fair Value Inputs Level 3 [Member] | Mutual Fund [Member]
Schedule of Total Investments at Fair Value [Line Items]
Available-for-sale Securities		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]
Available-for-sale Securities		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]
Available-for-sale Securities		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]
Available-for-sale Securities		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]
Available-for-sale Securities		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]
Available-for-sale Securities		0	0
Other Postretirement Benefit Plans, Defined Benefit [Member]
Schedule of Total Investments at Fair Value [Line Items]
Available-for-sale Securities		158,977	138,009
Other Postretirement Benefit Plans, Defined Benefit [Member] | Money Market Funds [Member]
Schedule of Total Investments at Fair Value [Line Items]
Available-for-sale Securities		4,470	3,486
Other Postretirement Benefit Plans, Defined Benefit [Member] | Mutual Fund [Member]
Schedule of Total Investments at Fair Value [Line Items]
Available-for-sale Securities		154,507	134,523
Other Postretirement Benefit Plans, Defined Benefit [Member] | Fair Value Inputs Level 1 [Member]
Schedule of Total Investments at Fair Value [Line Items]
Available-for-sale Securities		154,507	134,523
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]
Available-for-sale Securities		0	0
Other Postretirement Benefit Plans, Defined Benefit [Member] | Fair Value Inputs Level 1 [Member] | Mutual Fund [Member]
Schedule of Total Investments at Fair Value [Line Items]
Available-for-sale Securities		154,507	134,523
Other Postretirement Benefit Plans, Defined Benefit [Member] | Fair Value Inputs Level 2 [Member]
Schedule of Total Investments at Fair Value [Line Items]
Available-for-sale Securities		4,470	3,486
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]
Available-for-sale Securities		4,470	3,486
Other Postretirement Benefit Plans, Defined Benefit [Member] | Fair Value Inputs Level 2 [Member] | Mutual Fund [Member]
Schedule of Total Investments at Fair Value [Line Items]
Available-for-sale Securities		0	0
Other Postretirement Benefit Plans, Defined Benefit [Member] | Fair Value Inputs Level 3 [Member]
Schedule of Total Investments at Fair Value [Line Items]
Available-for-sale Securities		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]
Available-for-sale Securities		0	0
Other Postretirement Benefit Plans, Defined Benefit [Member] | Fair Value Inputs Level 3 [Member] | Mutual Fund [Member]
Schedule of Total Investments at Fair Value [Line Items]
Available-for-sale Securities		$ 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-Retiremen54

Retirement and Post-Retirement Employee Benefit Plans Fair Value of Plan Assets (Details) - USD ($) $ in Thousands	12 Months Ended
	Sep. 30, 2016		Sep. 30, 2015
Pension Plans, Defined Benefit [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets at beginning of year	$ 450,932		$ 434,767
Actual return on plan assets	52,596		8,661
Employer contributions	15,000		38,000
Benefits paid	(44,578)	[1]	(30,496)
Fair value of plan assets at end of year	473,950		450,932
Supplemental Employee Retirement Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets at beginning of year	0		0
Employer contributions	4,604		4,551
Benefits paid	(4,604)		(4,551)
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	138,009		134,821
Actual return on plan assets	14,528		(8,851)
Employer contributions	16,592		19,984
Plan participants' contributions	4,289		4,563
Benefits paid	(14,441)		(12,508)
Fair value of plan assets at end of year	$ 158,977		$ 138,009
[1]	Includes $12.8 million of one-time payments to eligible deferred vested participants who elected to receive a lump-sum payout of their pension benefits during fiscal 2016.

Retirement and Post-Retiremen55

Retirement and Post-Retirement Employee Benefit Plans Net Periodic Cost (Details) - USD ($) $ in Thousands	12 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2014
Pension Plans, Defined Benefit [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost	$ 16,419	$ 16,231	$ 15,345
Interest cost	23,193	21,850	22,330
Expected return on assets	(27,522)	(25,744)	(23,601)
Amortization of prior service cost	(226)	(192)	(136)
Recognized actuarial loss	10,693	13,322	13,777
Net periodic pension cost	22,557	25,467	27,715
Supplemental Employee Retirement Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost	2,371	3,971	3,607
Interest cost	5,185	4,943	4,966
Amortization of transition asset	0	0	0
Amortization of prior service cost	0	0	0
Recognized actuarial loss	2,586	2,343	1,948
Settlements	0	0	4,539
Net periodic pension cost	10,142	11,257	15,060
Other Postretirement Benefit Plans, Defined Benefit [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost	10,823	15,583	16,784
Interest cost	12,424	14,385	15,951
Expected return on assets	(6,264)	(6,431)	(5,167)
Amortization of transition asset	82	272	274
Amortization of prior service cost	(1,644)	(1,644)	(1,450)
Recognized actuarial loss	(2,167)	0	631
Net periodic pension cost	$ 13,254	$ 22,165	$ 27,023

Retirement and Post-Retiremen56

Retirement and Post-Retirement Employee Benefit Plans Defined Contribution Plans (Details) - USD ($) $ in Thousands	12 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2014
Retirement Savings Plan [Member]
Defined Contribution Plan Disclosure [Line Items]
Defined Contribution Plan, Maximum Annual Contributions Per Employee, Percent	65.00%
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	4.20%	4.30%
Defined Contribution Plan, Vesting Period	3 years
AEH 401K Profit-Sharing Plan [Member]
Defined Contribution Plan Disclosure [Line Items]
Defined Contribution Plan, Employer Discretionary Contribution Amount	$ 300	$ 1,100	$ 1,400
Retirement Savings Plan and Union 401K Plan [Member]
Defined Contribution Plan Disclosure [Line Items]
Defined Contribution Plan, Cost Recognized	12,600	11,500	10,900
Defined Contribution Plan, Employer Discretionary Contribution Amount	$ 0	$ 0	$ 0

Stock and Other Compensation 57

Stock and Other Compensation Plans (Details) - USD ($)	12 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2014
Share-based Compensation, Allocation and Classification in Financial Statements [Abstract]
Stock Based Compensation Expense	$ 24,600,000	$ 27,500,000	$ 25,500,000
Share-based Compensation, Capitalized Amount	9,800,000	11,500,000	10,800,000
Share Based Compensation, Tax Benefit	$ 5,000,000	$ 4,700,000	$ 3,100,000
Authorized Shares	11,200,000	8,700,000
Share-based Compensation Arrangement by Share-based Payment Award, Number of Shares Available	2,400,000
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Additional Disclosures [Abstract]
Nonvested at beginning of year-Shares	878,104	988,637	1,052,844
Nonvested at beginning of year-Weighted Average	$ 48.24	$ 42.22	$ 36.20
Granted-Shares	357,323	444,543	464,438
Granted-Weighted Average	$ 65.98	$ 50.50	$ 45.05
Vested-Shares	(448,136)	(551,688)	(524,532)
Vested-Weighted Average	$ 45.88	$ 39.28	$ 32.67
Forfeited-Shares	(4,860)	(3,388)	(4,113)
Forfeited-Weighted Average	$ 53.52	$ 48.55	$ 39
Nonvested at end of year-Shares	782,431	878,104	988,637
Nonvested at end of year-Weighted Average	$ 57.66	$ 48.24	$ 42.22
Unrecognized Compensation Cost	$ 11,400,000
Weighted Average Recognized Period	1 year 7 months
Fair Value Restricted Stock Vested	$ 20,600,000	$ 21,700,000	$ 17,100,000
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 Consolida58

Details of Selected Consolidated Balance Sheet Captions (Details) - USD ($) $ in Thousands		12 Months Ended
		Sep. 30, 2016	Sep. 30, 2015
Accounts, Notes, Loans and Financing Receivable [Line Items]
Accounts Receivable, Gross, Current		$ 226,936	$ 226,267
Less: allowance for doubtful accounts		(11,056)	(12,934)
Net accounts receivable		215,880	213,333
Schedule of Other Current Assets [Abstract]
Assets from risk management activities current		3,029	378
Deferred gas cost		45,184	9,715
Taxes receivable		5,456	4,479
Prepaid expenses		21,489	21,654
Materials and supplies		5,825	12,587
Other		7,102	1,116
Total other current assets		88,085	49,929
Public Utilities, Property, Plant and Equipment [Abstract]
Production plant		66	131
Storage plant		353,523	286,011
Transmission plant		2,232,927	1,844,117
Distribution plant		6,598,990	6,019,001
General plant		732,606	740,863
Intangible plant		40,515	41,131
Property, plant and equipment		9,958,627	8,931,254
Construction in progress		183,879	280,421
Total property, plant and equipment and construction in progress		10,142,506	9,211,675
Less accumulated depreciation and amortization		(1,873,900)	(1,794,975)
Net property, plant and equipment	[1]	8,268,606	7,416,700
Plant acquisition adjustments		(59,800)	(68,100)
Goodwill [Line Items]
Goodwill, Beginning Balance	[2]	726,257
Goodwill, Other Changes	[3]	705
Goodwill, Ending Balance	[2]	726,962
Schedule of Other Noncurrent Assets [Abstract]
Marketable securities		72,701	74,200
Regulatory assets		214,890	182,573
Assets from risk management activities noncurrent		1,822	368
Other		15,606	18,283
Total		305,019	275,424
Schedule of Accounts Payable and Accrued Liabilities [Abstract]
Trade accounts payable		114,361	78,376
Accrued gas payable		47,107	56,468
Accrued liabilities		35,017	39,802
Total		196,485	174,646
Schedule of Other Current Liabilities [Abstract]
Customer deposits		81,219	99,043
Accrued employee costs		47,058	47,602
Deferred gas costs		20,180	28,100
Accrued interest		34,863	34,914
Liabilities from risk management activities current		56,771	9,568
Taxes payable		104,145	92,912
Pension and postretirement obligations		36,606	21,857
Regulatory cost of removal accrual		52,610	56,123
Current deferred tax liability		0	55,918
Other		5,633	1,653
Total		439,085	447,690
Schedule of Other Noncurrent Liabilities [Abstract]
Customer advances for construction		9,850	9,316
Regulatory liabilities		4,152	3,693
Asset retirement obligation		13,404	9,063
Liabilities from risk management activities noncurrent		184,048	110,539
Other		33,920	28,738
Total		245,374	161,349
Distribution Segment [Member]
Public Utilities, Property, Plant and Equipment [Abstract]
Net property, plant and equipment		6,208,465	5,656,788
Goodwill [Line Items]
Goodwill, Beginning Balance		583,285
Goodwill, Other Changes	[3]	665
Goodwill, Ending Balance		583,950
Pipeline and Storage Segment [Member]
Public Utilities, Property, Plant and Equipment [Abstract]
Net property, plant and equipment		2,060,141	1,759,912
Goodwill [Line Items]
Goodwill, Beginning Balance		142,972
Goodwill, Other Changes	[3]	40
Goodwill, Ending Balance		143,012
Trade Accounts Receivable [Member] | Billed Revenues [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Accounts Receivable, Gross, Current		120,128	120,482
Trade Accounts Receivable [Member] | Unbilled Revenues [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Accounts Receivable, Gross, Current		67,396	65,008
Other Accounts Receivable [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Accounts Receivable, Gross, Current		$ 39,412	$ 40,777
[1]	Net property, plant and equipment includes plant acquisition adjustments of $(59.8) million and $(68.1) million at September 30, 2016 and 2015.
[2]	Natural gas marketing had goodwill of $16.4 million at September 30, 2016 and 2015 classified as assets held for sale on the consolidated balance sheet.
[3]	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 2016.

Leases (Details)

Leases (Details) - USD ($) $ in Thousands	12 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2014
Operating Leases, Future Minimum Payments Due, Fiscal Year Maturity [Abstract]
2,017	$ 17,073
2,018	16,824
2,019	15,450
2,020	14,479
2,021	14,335
Operating Leases, Thereafter	47,714
Total Operating Lease Payments	125,875
Lease and Rental Expense	$ 32,600	$ 32,500	$ 31,700
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	18 years

Commitments and Contingencies60

Commitments and Contingencies (Details) $ in Thousands	12 Months Ended
	Sep. 30, 2016USD ($)$ / MMcfMMcf	Sep. 30, 2015USD ($)	Sep. 30, 2014USD ($)
Estimated Contractual Demand Fees [Abstract]
2,017	$ 9,065
2,018	2,336
2,019	424
2,020	400
2,021	327
Thereafter	678
Total Estimated Contractual Demand Fees	13,230
Mid-Tex Division [Member]
Long Term Purchase Commitment [Line Items]
Significant Purchase Commitment, Amount	85,300	$ 113,300	$ 140,900
Natural Gas Marketing Segment [Member]
Long Term Purchase Commitment [Line Items]
Significant Purchase Commitment, Amount	$ 763,200	$ 1,141,300	$ 1,687,500
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	28,500
Long Term Purchase Commitment Minimum Quantity Required One To Three Years | MMcf	4,200
Long Term Purchase Commitment Minimum Quantity Required After Three Years | MMcf	600
Inventories Under Indexed Contracts [Member] | Natural Gas Marketing Segment [Member]
Long Term Purchase Commitment [Line Items]
Long Term Purchase Commitment Minimum Quantity Required Within One Year | MMcf	93,500
Long Term Purchase Commitment Minimum Quantity Required One To Three Years | MMcf	9,100
Long Term Purchase Commitment Minimum Quantity Required After Three Years | MMcf	200
Inventories Under Fixed Price Contracts [Member] | Natural Gas Marketing Segment [Member]
Long Term Purchase Commitment [Line Items]
Long Term Purchase Commitment Minimum Quantity Required Within One Year | MMcf	11,900
Long Term Purchase Commitment Minimum Quantity Required One To Three Years | MMcf	1,300
Purchase Commitment Amount Minimum | $ / MMcf	0.25
Purchase Commitment Amount Maximum | $ / MMcf	3.16

Income Taxes (Details)

Income Taxes (Details) - USD ($) $ in Thousands	12 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2014
Current income taxes
Federal	$ 0	$ 0	$ 0
State	5,667	6,513	5,192
Deferred income taxes
Federal	178,630	170,649	158,362
State	12,350	12,393	11,064
Investment tax credits	(5)	(6)	(6)
Income tax expense	196,642	189,549	174,612
Deferred tax assets
Employee benefit plans	122,682	121,619
Interest rate agreements	107,782	51,067
Tax net operating loss carryforwards	514,391	313,224
Tax credit carryforward	22,273	22,281
Other	23,648	36,695
Total deferred tax assets	790,776	544,886
Valuation allowance	(10,481)	(10,872)
Net deferred tax assets	780,295	534,014
Deferred tax liabilities
Difference in net book value and net tax value of assets	(2,259,278)	(1,890,886)
Pension funding	(30,652)	(35,247)
Gas Cost Adjustments	(54,725)	(43,634)
Other	(38,696)	(31,480)
Total deferred tax liabilities	(2,383,351)	(2,001,247)
Net deferred tax liabilities	(1,603,056)	(1,467,233)
Deferred credits for rate regulated entities	861	412
Deferred Tax Assets, Charitable Contribution Carryforwards [Abstract]
Deferred Tax Assets, Charitable Contribution Carryforwards	$ 11,000
Charitable Contribution Carryforwards, Expiration Date, Minimum	Dec. 31, 2017
Charitable Contribution Carryforwards, Expiration Date, Maximum	Dec. 31, 2021
Valuation and Qualifying Accounts Disclosure [Line Items]
Expiration of Deferred Tax Assets	$ 200
Reconciliation of Unrecognized Tax Benefits [Roll Forward]
Unrecognized Tax Benefits, Beginning Balance	17,069	12,629
Unrecognized Tax Benefits, Increase Resulting from Prior Period Tax Positions		1,009
Unrecognized Tax Benefits, Decrease Resulting from Prior Period Tax Positions	(290)
Unrecognized Tax Benefits, Increase Resulting from Current Period Tax Positions	3,519	3,431
Unrecognized Tax Benefits, Ending Balance	20,298	17,069	$ 12,629
Unrecognized Tax Benefits, Deferred Federal and State Income Tax Benefits	(7,104)	(5,974)
Unrecognized Tax Benefits that Would Impact Effective Tax Rate	13,194	11,095
Unrecognized Tax Benefits, Income Tax Penalties and Interest Expense	2,500	500
Unrecognized Tax Benefits, Income Tax Penalties and Interest Accrued	3,300	800
Valuation Allowance of Deferred Tax Assets [Member]
Valuation and Qualifying Accounts Disclosure [Line Items]
Valuation Allowances and Reserves, Charged to Cost and Expense	1,100	$ 5,000
Valuation Allowances and Reserves, Deductions	1,400
State and Local Jurisdiction [Member]
Operating Loss Carryforwards [Line Items]
Operating Loss Carryforwards	20,400
Operating Loss Carryforwards, Federal Tax Effects	$ 11,000
State and Local Jurisdiction [Member] | Minimum [Member]
Operating Loss Carryforwards [Line Items]
Operating Loss Carryforwards, Expiration Date	Dec. 31, 2017
State and Local Jurisdiction [Member] | Maximum [Member]
Operating Loss Carryforwards [Line Items]
Operating Loss Carryforwards, Expiration Date	Dec. 31, 2031
Domestic Tax Authority [Member]
Operating Loss Carryforwards [Line Items]
Operating Loss Carryforwards	$ 494,000
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	Sep. 30, 2016USD ($)
State and Local Jurisdiction [Member]
Tax Credit Carryforward [Line Items]
Tax Credit Carryforward, Amount	$ 1.1
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, 2016	Sep. 30, 2015	Sep. 30, 2014
Effective Income Tax Rate Reconciliation, Amount [Abstract]
Tax at statutory rate of 35%	$ 189,764	$ 173,310	$ 155,730
Common stock dividends deductible for tax reporting	(2,570)	(2,413)	(2,307)
State taxes (net of federal benefit)	11,133	12,289	10,566
Change in valuation allowance	1,324	4,998	6,969
Other, net	(3,009)	1,365	3,654
Income tax expense (benefit)	$ 196,642	$ 189,549	$ 174,612

Financial Instruments Financial

Financial Instruments Financial Instruments at Fair Value (Details) - USD ($)	Sep. 30, 2016		Sep. 30, 2015
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Derivative Asset, Current	$ 3,029,000		$ 378,000
Derivative Asset, Noncurrent	1,822,000		368,000
Derivative Liability, Current	(56,771,000)		(9,568,000)
Derivative Liability, Noncurrent	(184,048,000)		(110,539,000)
Regulated Distribution Segment [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Derivative Asset, Current	3,029,000	[1]	378,000
Derivative Asset, Noncurrent	1,822,000		368,000
Derivative Liability, Current	(56,771,000)	[1]	(9,568,000)
Derivative Liability, Noncurrent	(184,048,000)	[1]	(110,539,000)
Derivative Assets (Liabilities), at Fair Value, Net	(235,968,000)		(119,361,000)
Cash Held In Margin Accounts Used to Offset Risk Management Liabilities	25,700,000		0
Nonregulated Segment [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Cash Held in Margin Accounts	$ 24,700,000		$ 43,500,000
[1]	Includes $25.7 million of cash held on deposit to collateralize certain distribution financial instruments, which were used to offset current and noncurrent risk management liabilities.

Financial Instruments Balance S

Financial Instruments Balance Sheet Location (Details) - USD ($) $ in Thousands	Sep. 30, 2016		Sep. 30, 2015
Derivatives, Fair Value [Line Items]
Derivative Asset	$ 11,626		$ 9,600
Derivative Liability	(240,819)		(120,107)
Distribution Segment [Member]
Derivatives, Fair Value [Line Items]
Derivative Asset, Fair Value, Gross Asset	4,851		746
Derivative Asset, Contract Netting	0		0
Derivative Asset, Net of Contract Netting	4,851		746
Derivative, Collateral, Right to Reclaim Cash	0		0
Derivative Asset	4,851		746
Derivative Liability, Fair Value, Gross Liability	(266,489)		(120,107)
Derivative Liability, Contract Netting	0		0
Derivative Liability, Net of Contract Netting	(266,489)		(120,107)
Derivative Liability, Collateral, Right to Reclaim Cash, Offset	25,670		0
Derivative Liability	(240,819)		(120,107)
Distribution Segment [Member] | Designated as Hedging Instrument [Member]
Derivatives, Fair Value [Line Items]
Derivative Asset, Fair Value, Gross Asset	0		0
Derivative Liability, Fair Value, Gross Liability	(266,489)		(110,539)
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
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	0		0
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
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		0
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
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	(68,481)		0
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
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	(198,008)		(110,539)
Distribution Segment [Member] | Not Designated as Hedging Instrument [Member]
Derivatives, Fair Value [Line Items]
Derivative Asset, Fair Value, Gross Asset	4,851		746
Derivative Liability, Fair Value, Gross Liability	0		(9,568)
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	3,029		378
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	1,822		368
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	0		(9,568)
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		0
Natural Gas Marketing Segment [Member]
Derivatives, Fair Value [Line Items]
Derivative Asset, Fair Value, Gross Asset	39,290		91,363
Derivative Asset, Contract Netting	(39,290)		(91,363)
Derivative Asset, Net of Contract Netting	0		0
Derivative, Collateral, Right to Reclaim Cash	6,775		8,854
Derivative Asset	6,775	[1]	8,854	[2]
Derivative Liability, Fair Value, Gross Liability	(57,195)		(125,983)
Derivative Liability, Contract Netting	39,290		91,363
Derivative Liability, Net of Contract Netting	(17,905)		(34,620)
Derivative Liability, Collateral, Right to Reclaim Cash, Offset	17,905		34,620
Derivative Liability	0	[1]	0	[2]
Natural Gas Marketing Segment [Member] | Designated as Hedging Instrument [Member]
Derivatives, Fair Value [Line Items]
Derivative Asset, Fair Value, Gross Asset	8,790		11,806
Derivative Liability, Fair Value, Gross Liability	(25,682)		(45,985)
Natural Gas Marketing 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	6,612		11,680
Natural Gas Marketing 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		0
Natural Gas Marketing 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	2,178		126
Natural Gas Marketing 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
Natural Gas Marketing 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	(21,903)		(36,067)
Natural Gas Marketing 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		0
Natural Gas Marketing 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	(3,779)		(9,918)
Natural Gas Marketing 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
Natural Gas Marketing Segment [Member] | Not Designated as Hedging Instrument [Member]
Derivatives, Fair Value [Line Items]
Derivative Asset, Fair Value, Gross Asset	30,500		79,557
Derivative Liability, Fair Value, Gross Liability	(31,513)		(79,998)
Natural Gas Marketing 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	18,157		65,239
Natural Gas Marketing 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	12,343		14,318
Natural Gas Marketing 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	(18,812)		(65,780)
Natural Gas Marketing 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	$ (12,701)		$ (14,218)
[1]	Natural gas marketing's risk management assets and liabilities have been classified as held for sale at September 30, 2016 related to the divestiture of our natural gas marketing business.
[2]	Natural gas marketing's risk management assets and liabilities have been classified as held for sale at September 30, 2015 related to the divestiture of our natural gas marketing business.

Financial Instruments Descripti

Financial Instruments Descriptions (Details) $ in Millions	1 Months Ended	12 Months Ended
	Oct. 31, 2014USD ($)	Sep. 30, 2016USD ($)$ / McfMMcf	Sep. 30, 2015USD ($)	Sep. 30, 2014USD ($)
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		33.00%
Hedge Volume Of Actual Heating Season Gas | MMcf		23,000
Weighted Average Cost Of Actual Heating Season Gas | $ / Mcf		3.14
Minimum Length Of Time Hedged In Cash Flow Hedge		1 month
Maximum Length of Time Hedged in Cash Flow Hedge		63 months
Net Open Positions | MMcf		100
Gain (Loss) On Hedge Ineffectiveness		$ 21.6	$ 0.2	$ 1.9
Regulated Segments Effective Income Tax Rate Reconciliation At Federal Statutory Income Tax Rate		37.00%	37.00%
Nonregulated Segment Effective Income Tax Rate Reconciliation At Federal Statutory Income Tax Rate		39.00%	39.00%
Gain (Loss) On Derivative Instruments Not Designated Hedges Net Pretax		$ (15.5)	$ 15.5	$ (5)
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		210
Anticipated Debt Issuance, 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, 2016MMcf
Distribution Segment [Member]
Commodity Contract Outstanding Volumes [Line Items]
Investment Contract Volume	18,595
Distribution Segment [Member] | Not Designated as Hedging Instrument [Member]
Commodity Contract Outstanding Volumes [Line Items]
Investment Contract Volume	18,595
Distribution Segment [Member] | Fair Value Hedging [Member]
Commodity Contract Outstanding Volumes [Line Items]
Investment Contract Volume	0
Distribution Segment [Member] | Cash Flow Hedging [Member]
Commodity Contract Outstanding Volumes [Line Items]
Investment Contract Volume	0
Natural Gas Marketing Segment [Member]
Commodity Contract Outstanding Volumes [Line Items]
Investment Contract Volume	91,030
Natural Gas Marketing Segment [Member] | Not Designated as Hedging Instrument [Member]
Commodity Contract Outstanding Volumes [Line Items]
Investment Contract Volume	71,147
Natural Gas Marketing Segment [Member] | Fair Value Hedging [Member]
Commodity Contract Outstanding Volumes [Line Items]
Investment Contract Volume	(19,395)
Natural Gas Marketing Segment [Member] | Cash Flow Hedging [Member]
Commodity Contract Outstanding Volumes [Line Items]
Investment Contract Volume	39,278

Financial Instruments Fair Valu

Financial Instruments Fair Value Hedges and Cash Flow Hedges (Details) - USD ($) $ in Thousands	12 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2014
Effect of Fair Value Hedges on Results of Operations [Abstract]
Commodity contracts	$ 3,516	$ 10,311	$ (792)
Fair value adjustment for natural gas inventory designated as the hedged item	18,079	(9,768)	2,486
Total (increase) decrease in purchased gas cost	21,595	543	1,694
Fair Value Hedge Basis Ineffectiveness	(1,390)	811	(919)
Fair Value Hedge Timing Ineffectiveness	22,985	(268)	2,613
Cash Flow Hedge [Line Items]
Gain (loss) reclassified from AOCI into purchased gas cost for effective portion of commodity contracts	(52,651)	(41,716)	8,365
Gain (loss) arising from ineffective portion of commodity contracts	(19)	(325)	198
Total impact on purchased gas cost	(52,670)	(42,041)	8,563
Net loss on settled Treasury lock agreements reclassified from AOCI into interest expense	(546)	(853)	(4,230)
Total Impact from Cash Flow Hedges	$ (53,216)	$ (42,894)	$ 4,333

Financial Instruments Other Com

Financial Instruments Other Comprehensive Income (Details) - USD ($) $ in Thousands		12 Months Ended
		Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2014
Other Comprehensive Income [Abstract]
Interest rate agreements fair value		$ (99,029)	$ (71,003)
Forward commodity contracts fair value		(11,662)	(49,211)
Interest rate agreements		347	542
Forward commodity contracts		32,117	25,448
Total other comprehensive income (loss) from hedging, net of tax	[1]	(78,227)	(94,224)
Expected Earnings [Line Items]
FY2017		(4,430)
FY2018		(1,210)
FY2019		(1,087)
FY2020		(724)
FY2021		(696)
Thereafter		(15,139)
Cash Flow Hedge Gain (Loss) To Be Reclassiflied, Total	[2]	(23,286)
Interest Rate Contract [Member]
Other Comprehensive Income [Abstract]
Total other comprehensive income (loss) from hedging, net of tax		(98,682)	(70,461)	$ (56,287)
Expected Earnings [Line Items]
FY2017		(447)
FY2018		(649)
FY2019		(673)
FY2020		(698)
FY2021		(698)
Thereafter		(15,139)
Cash Flow Hedge Gain (Loss) To Be Reclassiflied, Total	[2]	(18,304)
Commodity Contract [Member]
Other Comprehensive Income [Abstract]
Total other comprehensive income (loss) from hedging, net of tax		20,455	$ (23,763)	$ 2,802
Expected Earnings [Line Items]
FY2017		(3,983)
FY2018		(561)
FY2019		(414)
FY2020		(26)
FY2021		2
Thereafter		0
Cash Flow Hedge Gain (Loss) To Be Reclassiflied, Total	[2]	$ (4,982)
[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.

Fair Value Measurements (Detail

Fair Value Measurements (Details) - USD ($)		Sep. 30, 2016		Sep. 30, 2015
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		$ (32,515,000)	[1]	$ (82,509,000)	[2]
Derivative Asset		11,626,000		9,600,000
Hedged portion of gas stored underground		52,578,000		43,901,000
Available-for-sale Securities		72,701,000		74,200,000
Total assets		136,905,000		127,701,000
Derivative Liability, Fair Value, Gross Asset and Right to Reclaim Cash, Offset		(82,865,000)	[1]	(125,983,000)	[2]
Derivative Liability		240,819,000		120,107,000
Additional Fair Value Elements [Abstract]
Debt Instrument Carrying Amount		2,460,000,000		2,460,000,000
Debt Instrument Fair Value		2,844,990,000
Money Market Funds [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Available-for-sale Securities		2,630,000		1,072,000
Equity Securities [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Available-for-sale Securities		38,677,000		40,619,000
Debt Securities [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Available-for-sale Securities		31,394,000		32,509,000
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		4,851,000		746,000
Derivative Liability, Fair Value, Gross Asset and Right to Reclaim Cash, Offset		(25,670,000)	[1]	0	[2]
Derivative Liability		240,819,000		120,107,000
Cash Held In Margin Accounts Used to Offset Risk Management Liabilities		25,670,000		0
Cash Held In Margin Accounts Classified Current Risk Management Asset		0		0
Natural Gas Marketing 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		(32,515,000)	[1]	(82,509,000)	[2]
Derivative Asset		6,775,000	[3]	8,854,000	[4]
Derivative Liability, Fair Value, Gross Asset and Right to Reclaim Cash, Offset		(57,195,000)	[1]	(125,983,000)	[2]
Derivative Liability		0	[3]	0	[4]
Cash Held in Margin Accounts		24,700,000		43,500,000
Cash Held In Margin Accounts Used to Offset Risk Management Liabilities		17,905,000		34,620,000
Cash Held In Margin Accounts Classified Current Risk Management Asset		6,775,000		8,854,000
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		0
Hedged portion of gas stored underground		52,578,000		43,901,000
Available-for-sale Securities		38,677,000		40,619,000
Total assets		91,255,000		84,520,000
Derivative Liability, Fair Value, Gross Liability Including Not Subject to Master Netting Arrangement		0		0
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		38,677,000		40,619,000
Fair Value Inputs Level 1 [Member] | Debt Securities [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Available-for-sale Securities		0		0
Fair Value Inputs Level 1 [Member] | 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] | Natural Gas Marketing 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 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	[5]	44,141,000		92,109,000
Hedged portion of gas stored underground	[5]	0		0
Available-for-sale Securities	[5]	34,024,000		33,581,000
Total assets	[5]	78,165,000		125,690,000
Derivative Liability, Fair Value, Gross Liability Including Not Subject to Master Netting Arrangement	[5]	323,684,000		246,090,000
Fair Value Inputs Level 2 [Member] | Money Market Funds [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Available-for-sale Securities	[5]	2,630,000		1,072,000
Fair Value Inputs Level 2 [Member] | Equity Securities [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Available-for-sale Securities	[5]	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	[5]	31,394,000		32,509,000
Fair Value Inputs Level 2 [Member] | 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	[5]	4,851,000		746,000
Derivative Liability, Fair Value, Gross Liability Including Not Subject to Master Netting Arrangement	[5]	266,489,000		120,107,000
Fair Value Inputs Level 2 [Member] | Natural Gas Marketing 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	[5]	39,290,000		91,363,000
Derivative Liability, Fair Value, Gross Liability Including Not Subject to Master Netting Arrangement	[5]	57,195,000		125,983,000
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] | 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] | Natural Gas Marketing 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, 2016, we had $25.7 million of cash held in margin accounts to collateralize certain distribution financial instruments, which were used to offset current and noncurrent risk management liabilities. As of September 30, 2016 we also had $24.7 million of cash held in margin accounts to collateralize certain natural gas marketing financial instruments. Of this amount, $17.9 million was used to offset current and noncurrent risk management liabilities under master netting agreements and the remaining $6.8 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, 2015 we had $43.5 million of cash held in margin accounts to collateralize certain natural gas marketing 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]	Natural gas marketing's risk management assets and liabilities have been classified as held for sale at September 30, 2016 related to the divestiture of our natural gas marketing business.
[4]	Natural gas marketing's risk management assets and liabilities have been classified as held for sale at September 30, 2015 related to the divestiture of our natural gas marketing business.
[5]	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, 2016	Sep. 30, 2015
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	$ 65,572	$ 66,399
Gross Unrealized Gain	7,729	8,343
Gross Unrealized Loss	(600)	(542)
Fair value	72,701	74,200
Available-for-sale Securities, Other Disclosure Items [Abstract]
Available-for-sale Securities, Supplemental Executive Benefit Plans	41,300	41,700
Equity Funds Domestic [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	26,692	27,643
Gross Unrealized Gain	6,419	7,332
Gross Unrealized Loss	(590)	(456)
Fair value	32,521	34,519
Equity Funds Foreign [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	4,954	5,261
Gross Unrealized Gain	1,202	905
Gross Unrealized Loss	0	(66)
Fair value	6,156	6,100
Debt Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	31,296	32,423
Gross Unrealized Gain	108	106
Gross Unrealized Loss	(10)	(20)
Fair value	31,394	32,509
Money Market Funds [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	2,630	1,072
Gross Unrealized Gain	0	0
Gross Unrealized Loss	0	0
Fair value	$ 2,630	$ 1,072

Discontinued Operations (Detail

Discontinued Operations (Details) - USD ($) $ / shares in Units, $ in Thousands	Jan. 01, 2017	Oct. 25, 2016	Oct. 20, 2016	Oct. 05, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2014	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2014
Disposal Group, Including Discontinued Operation, Income Statement Disclosures [Abstract]
Gross profit					$ 6,428	$ 15,815	$ 5,260	$ 9,469	$ 10,189	$ 13,672	$ 15,300	$ 10,078
Operating income					184	8,768	(1,640)	3,476	1,506	6,606	8,210	2,841
Discontinued Operation, Tax Effect of Discontinued Operation													$ 3,731	$ 6,141	$ 12,389
Net income from discontinued operations, net of tax					(610)	$ 5,050	$ (1,193)	$ 1,315	(393)	$ 3,794	$ 4,542	$ 1,509	4,562	9,452	19,486
Subsequent Event [Member]
Subsequent Event [Line Items]
Subsequent Event, Date	Jan. 1, 2017	Oct. 25, 2016	Oct. 20, 2016	Oct. 5, 2016
Disposal Group, Including Discontinued Operation, Cash Purchase Price	$ 38,300
Disposal Group, Including Discontinued Operation, Estimated Working Capital	103,200
Disposal Group, Including Discontinued Operation, Consideration	141,500
Disposal Group, Including Discontinued Operation, Consideration Placed in Escrow	$ 7,000
Discontinued Operation, Gain (Loss) on Disposal of Discontinued Operation, Net of Tax, Per Diluted Share	$ 0.03
Natural Gas Marketing Segment [Member] | Discontinued Operations, Held-for-sale or Disposed of by Sale [Member]
Disposal Group, Including Discontinued Operation, Income Statement Disclosures [Abstract]
Operating revenues													1,005,090	1,409,071	1,984,829
Purchased gas cost													968,118	1,359,832	1,923,745
Gross profit													36,972	49,239	61,084
Operating expenses													26,184	30,076	26,957
Operating income													10,788	19,163	34,127
Other nonoperating expense													(2,495)	(3,570)	(2,252)
Income from discontinued operations before income taxes													8,293	15,593	31,875
Discontinued Operation, Tax Effect of Discontinued Operation													3,731	6,141	12,389
Net income from discontinued operations, net of tax													4,562	9,452	19,486
Assets [Abstract]
Total assets of the disposal group					216,715				182,771				216,715	182,771
Liabilities [Abstract]
Total liabilities of the disposal group					150,118				145,488				150,118	145,488
Discontinued Operation, Alternative Cash Flow Information [Abstract]
Depreciation and Amortization, Discontinued Operations													2,304	2,388	2,315
Capital Expenditure, Discontinued Operations													321	226	1,559
Noncash Change in Commodity Contract Cash Flow Hedges													(33,533)	38,956	$ (4,593)
Natural Gas Marketing Segment [Member] | Discontinued Operations, Held-for-sale or Disposed of by Sale [Member] | Disposal Group Assets and Liabilities Held for Sale [Member]
Assets [Abstract]
Net property, plant and equipment					11,905				13,878				11,905	13,878
Accounts receivable					93,551				91,675				93,551	91,675
Gas stored underground					54,246				41,267				54,246	41,267
Disposal Group, Including Discontinued Operation, Derivative Asset, Current					8,743				8,854				8,743	8,854
Other current assets					5,968				7,108				5,968	7,108
Disposal Group, Including Discontinued Operation, Goodwill					16,445				16,445				16,445	16,445
Disposal Group, Including Discontinued Operation, Derivative Asset, Noncurrent					169				0				169	0
Deferred charges and other assets					266				62				266	62
Total assets of the disposal group					191,293				179,289				191,293	179,289
Liabilities [Abstract]
Accounts payable and accrued liabilities					72,268				76,170				72,268	76,170
Disposal Group, Including Discontinued Operation, Derivative Liability, Current					0				3,799				0	3,799
Other current liabilities					9,640				9,502				9,640	9,502
Deferred credits and other					316				347				316	347
Total liabilities of the disposal group					82,224				89,818				82,224	89,818
Natural Gas Marketing Segment [Member] | Discontinued Operations, Held-for-sale or Disposed of by Sale [Member] | Disposal Group Assets and Liabilities Not Held for Sale [Member]
Assets [Abstract]
Cash					25,417				4,008				25,417	4,008
Disposal Group, Including Discontinued Operation, Intercompany Receivable					0				2,960				0	2,960
Other assets					5				(3,486)				5	(3,486)
Liabilities [Abstract]
Intercompany note payable					35,000				50,000				35,000	50,000
Tax liabilities					15,471				(200)				15,471	(200)
Intercompany payables					14,139				0				14,139	0
Other liabilities					$ 3,284				$ 5,870				$ 3,284	$ 5,870

Selected Quarterly Financial 73

Selected Quarterly Financial Data (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended								12 Months Ended
	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2014	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2014
Operating Revenues by Segment [Line Items]
Operating revenues	$ 433,643	$ 456,212	$ 890,040	$ 674,753	$ 411,143	$ 455,505	$ 1,173,096	$ 887,241	$ 2,454,648	$ 2,926,985	$ 3,243,904
Operating revenue from discontinued operation, net of eliminations								371,524
Selected Quarterly Financial Information [Abstract]
Gross profit from continuing operations	369,716	391,629	512,684	434,427	344,265	368,134	505,571	413,340	1,708,456	1,631,310	1,521,844
Gross profit from discontinued operations	6,428	15,815	5,260	9,469	10,189	13,672	15,300	10,078
Operating income from continuing operations	84,449	128,396	251,656	192,729	74,347	111,001	242,000	184,884	657,230	612,232	577,222
Operating income (loss) from discontinued operations	184	8,768	(1,640)	3,476	1,506	6,606	8,210	2,841
Income from continuing operations	34,850	66,143	143,003	101,546	23,908	52,487	133,142	96,086	345,542	305,623	270,331
Income (loss) from discontinued operations	(610)	5,050	(1,193)	1,315	(393)	3,794	4,542	1,509	4,562	9,452	19,486
Net income	$ 34,240	$ 71,193	$ 141,810	$ 102,861	$ 23,515	$ 56,281	$ 137,684	$ 97,595	$ 350,104	$ 315,075	$ 289,817
Income per share from continuing operations - basic	$ 0.33	$ 0.64	$ 1.39	$ 0.99	$ 0.23	$ 0.51	$ 1.31	$ 0.94	$ 3.33	$ 3	$ 2.76
Income (loss) per share from discontinued operations - basic	0	0.05	(0.01)	0.01	0	0.04	0.04	0.02	0.05	0.09	0.20
Net income per share — basic (usd per share)	0.33	0.69	1.38	1	0.23	0.55	1.35	0.96	3.38	3.09	2.96
Income per share from continuing operations - diluted	0.33	0.64	1.39	0.99	0.23	0.51	1.31	0.94	3.33	3	2.76
Income (loss) per share from discontinued operations - diluted	0	0.05	(0.01)	0.01	0	0.04	0.04	0.02	0.05	0.09	0.20
Net income per share — diluted (usd per share)	$ 0.33	$ 0.69	$ 1.38	$ 1	$ 0.23	$ 0.55	$ 1.35	$ 0.96	$ 3.38	$ 3.09	$ 2.96000
Intersegment Elimination [Member]
Operating Revenues by Segment [Line Items]
Operating revenues	$ (82,432)	$ (82,548)	$ (74,240)	$ (73,106)	$ (72,783)	$ (72,985)	$ (68,879)	$ (64,687)	$ (312,326)	$ (279,334)	$ (232,857)
Selected Quarterly Financial Information [Abstract]
Gross profit from continuing operations									0	0	0
Operating income from continuing operations									0	0	0
Income from continuing operations									0	0	0
Income (loss) from discontinued operations									0	0	0
Net income									0	0	0
Distribution Segment [Member]
Operating Revenues by Segment [Line Items]
Operating revenues	403,303	424,905	862,127	649,443	382,031	429,482	1,145,082	864,767	2,339,778	2,821,362	3,139,221
Selected Quarterly Financial Information [Abstract]
Gross profit from continuing operations									1,281,202	1,246,915	1,186,352
Operating income from continuing operations									441,884	422,692	388,617
Income from continuing operations									233,830	205,820	174,458
Income (loss) from discontinued operations									0	0	0
Net income									233,830	205,820	174,458
Pipeline and Storage Segment [Member]
Operating Revenues by Segment [Line Items]
Operating revenues	112,772	113,855	102,153	98,416	101,895	99,008	96,893	$ 87,161	427,196	384,957	337,540
Selected Quarterly Financial Information [Abstract]
Gross profit from continuing operations									427,254	384,395	335,492
Operating income from continuing operations									215,346	189,540	188,605
Income from continuing operations									111,712	99,803	95,873
Income (loss) from discontinued operations									0	0	0
Net income									111,712	99,803	95,873
Natural Gas Marketing Segment [Member]
Operating Revenues by Segment [Line Items]
Operating revenues									0	0	0
Operating revenue from discontinued operation, net of eliminations	$ 244,876	$ 176,704	$ 242,253	$ 231,468	$ 245,759	$ 230,896	$ 366,972
Selected Quarterly Financial Information [Abstract]
Gross profit from continuing operations									0	0	0
Operating income from continuing operations									0	0	0
Income from continuing operations									0	0	0
Income (loss) from discontinued operations									4,562	9,452	19,486
Net income									$ 4,562	$ 9,452	$ 19,486

Valuation and Qualifying Accoun

Valuation and Qualifying Accounts (Details) - Allowance For Doubtful Accounts Member - USD ($) $ in Thousands		12 Months Ended
		Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2014
Valuation and Qualifying Accounts Disclosure [Line Items]
Balance at beginning of period		$ 12,934	$ 20,659	$ 18,462
Charged to costs & expenses		10,414	15,923	18,183
Charged to other accounts		0	0	0
Valuation Allowances and Reserves, Deductions	[1]	12,292	23,648	15,986
Balance at end of period		$ 11,056	$ 12,934	$ 20,659
[1]	Uncollectible accounts written off.