Atmos Energy (ATO) 10-K 6 Nov 14 2014 FY Annual report Financial data

Document_and_Entity_Informatio

Document and Entity Information (USD $)	12 Months Ended
	Sep. 30, 2014	Oct. 31, 2014	Mar. 31, 2014
Document And Entity Information [Abstract]	'	'	'
Entity Registrant Name	'Atmos Energy Corporation	'	'
Entity Central Index Key	'0000731802	'	'
Current Fiscal Year End Date	'--09-30	'	'
Entity Filer Category	'Large Accelerated Filer	'	'
Document Type	'10-K	'	'
Document Period End Date	30-Sep-14	'	'
Document Fiscal Year Focus	'2014	'	'
Document Fiscal Period Focus	'FY	'	'
Amendment Flag	'false	'	'
Entity Common Stock Shares Outstanding	'	100,393,038	'
Entity Well Known Seasoned Issuer	'Yes	'	'
Entity Voluntary Filers	'No	'	'
Entity Current Reporting Status	'Yes	'	'
Entity Public Float	'	'	$4,659,809,695

CONSOLIDATED_BALANCE_SHEETS

CONSOLIDATED BALANCE SHEETS (USD $)	Sep. 30, 2014		Sep. 30, 2013
In Thousands, unless otherwise specified
ASSETS	'		'
Property, plant and equipment	$8,200,121		$7,446,272
Construction in progress	247,579		275,747
Total property, plant and equipment and construction in progress	8,447,700		7,722,019
Less accumulated depreciation and amortization	1,721,794		1,691,364
Net property, plant and equipment	6,725,906	[1]	6,030,655	[1]
Current assets	'		'
Cash and cash equivalents	42,258		66,199
Accounts receivable, less allowance for doubtful accounts of $23,992 in 2014 and $20,624 in 2013	343,400		301,992
Gas stored underground	278,917		244,741
Other current assets	111,265		64,201
Total current assets	775,840		677,133
Goodwill	742,029		741,363
Deferred charges and other assets	350,929		485,117
Total assets	8,594,704		7,934,268
Shareholders' equity	'		'
Common stock, no par value (stated at $.005 per share); 200,000,000 shares authorized; issued and outstanding: 2014 — 100,388,092 shares, 2013 — 90,640,211 shares	502		453
Additional paid-in capital	2,180,151		1,765,811
Accumulated other comprehensive income (loss)	-12,393		38,878
Retained earnings	917,972		775,267
Shareholders' equity	3,086,232		2,580,409
Long-term debt	2,455,986		2,455,671
Total capitalization	5,542,218		5,036,080
Current liabilities	'		'
Accounts payable and accrued liabilities	311,604		241,611
Other current liabilities	402,351		368,891
Short-term debt	196,695		367,984
Current maturities of long-term debt	0		0
Total current liabilities	910,650		978,486
Deferred income taxes	1,286,616		1,164,053
Regulatory cost of removal obligation	445,387		359,299
Pension and postretirement liabilities	340,963		358,787
Deferred credits and other liabilities	68,870		37,563
Total shareholders' equity and liabilities	$8,594,704		$7,934,268
[1]	Net property, plant and equipment includes plant acquisition adjustments of $(76.4) million and $(83.8) million at September 30, 2014 and 2013.

CONSOLIDATED_BALANCE_SHEETS_PA

CONSOLIDATED BALANCE SHEETS (PARENTHETICALS) (USD $)	Sep. 30, 2014	Sep. 30, 2013
In Thousands, except Share data, unless otherwise specified
Statement of Financial Position [Abstract]	'	'
Allowance for doubtful accounts	$23,992	$20,624
Common Stock, Par Value Per Share	$0	$0
Common Stock, Stated Value Per Share	$0.01	$0.01
Common Stock, Shares Authorized	200,000,000	200,000,000
Common Stock, Shares, Issued	100,388,092	90,640,211

CONSOLIDATED_STATEMENTS_OF_INC

CONSOLIDATED STATEMENTS OF INCOME (USD $)	3 Months Ended								12 Months Ended
In Thousands, except Per Share data, unless otherwise specified	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2012	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2012
Operating revenues	'	'	'	'	'	'	'	'	'	'	'
Operating revenues	$778,728	$942,718	$1,964,322	$1,255,148	$674,374	$857,935	$1,308,996	$1,034,155	$4,940,916	$3,875,460	$3,436,162
Purchased gas cost	'	'	'	'	'	'	'	'	'	'	'
Purchased gas cost	'	'	'	'	'	'	'	'	3,358,490	2,463,410	2,112,423
Gross profit	337,659	359,533	496,277	388,957	300,440	316,497	432,751	362,362	1,582,426	1,412,050	1,323,739
Operating expenses	'	'	'	'	'	'	'	'	'	'	'
Operation and maintenance	'	'	'	'	'	'	'	'	505,154	488,020	453,613
Depreciation and amortization	'	'	'	'	'	'	'	'	253,987	235,079	237,525
Taxes, other than income	'	'	'	'	'	'	'	'	211,936	187,072	181,073
Asset impairments	'	'	'	'	'	'	'	'	0	0	5,288
Total operating expenses	'	'	'	'	'	'	'	'	971,077	910,171	877,499
Operating income	83,944	106,605	250,080	170,720	50,383	86,396	210,178	154,922	611,349	501,879	446,240
Miscellaneous income (expense), net	'	'	'	'	'	'	'	'	-5,235	-197	-14,644
Interest charges	'	'	'	'	'	'	'	'	129,295	128,385	141,174
Income from continuing operations before income taxes	'	'	'	'	'	'	'	'	476,819	373,297	290,422
Income tax expense	'	'	'	'	'	'	'	'	187,002	142,599	98,226
Income from continuing operations	'	'	'	'	7,536	33,474	112,340	77,348	289,817	230,698	192,196
Income from discontinued operations, net of tax	'	'	'	'	0	0	4,085	3,117	0	7,202	18,172
Gain on sale of discontinued operations, net of tax	'	'	'	'	0	5,294	0	0	0	5,294	6,349
Net income	23,713	45,721	133,367	87,016	7,536	38,768	116,425	80,465	289,817	243,194	216,717
Income per share from continuing operations - basic (usd per share)	'	'	'	'	$0.08	$0.37	$1.24	$0.85	$2.96	$2.54	$2.12
Income per share from discontinued operations - basic (usd per share)	'	'	'	'	$0	$0.06	$0.04	$0.04	$0	$0.14	$0.27
Net income per share — basic (usd per share)	$0.23	$0.45	$1.38	$0.94	$0.08	$0.43	$1.28	$0.89	$2.96	$2.68	$2.39
Income per share from continuing operations - diluted (usd per share)	'	'	'	'	$0.08	$0.36	$1.23	$0.85	$2.96	$2.50	$2.10
Income per share from discontinued operations - diluted (usd per share)	'	'	'	'	$0	$0.06	$0.04	$0.03	$0	$0.14	$0.27
Net income per share — diluted (usd per share)	$0.23	$0.45	$1.38	$0.94	$0.08	$0.42	$1.27	$0.88	$2.96	$2.64	$2.37
Weighted average shares outstanding:	'	'	'	'	'	'	'	'	'	'	'
Basic (shares)	'	'	'	'	'	'	'	'	97,606	90,533	90,150
Diluted (shares)	'	'	'	'	'	'	'	'	97,608	91,711	91,172
Regulated Distribution Segment [Member]	'	'	'	'	'	'	'	'	'	'	'
Operating revenues	'	'	'	'	'	'	'	'	'	'	'
Operating revenues	409,014	517,707	1,290,960	843,865	360,386	467,144	905,176	666,787	3,061,546	2,399,493	2,145,330
Purchased gas cost	'	'	'	'	'	'	'	'	'	'	'
Purchased gas cost	'	'	'	'	'	'	'	'	1,885,031	1,318,257	1,122,587
Gross profit	'	'	'	'	'	'	'	'	1,176,515	1,081,236	1,022,743
Operating expenses	'	'	'	'	'	'	'	'	'	'	'
Operation and maintenance	'	'	'	'	'	'	'	'	387,228	375,188	353,879
Depreciation and amortization	'	'	'	'	'	'	'	'	208,376	195,581	202,026
Taxes, other than income	'	'	'	'	'	'	'	'	196,343	167,374	162,377
Asset impairments	'	'	'	'	'	'	'	'	'	'	0
Total operating expenses	'	'	'	'	'	'	'	'	791,947	738,143	718,282
Operating income	'	'	'	'	'	'	'	'	384,568	343,093	304,461
Miscellaneous income (expense), net	'	'	'	'	'	'	'	'	-381	2,535	-12,657
Interest charges	'	'	'	'	'	'	'	'	94,918	98,296	110,642
Income from continuing operations before income taxes	'	'	'	'	'	'	'	'	289,269	247,332	181,162
Income tax expense	'	'	'	'	'	'	'	'	117,684	96,476	57,314
Income from continuing operations	'	'	'	'	'	'	'	'	'	150,856	123,848
Income from discontinued operations, net of tax	'	'	'	'	'	'	'	'	'	7,202	18,172
Gain on sale of discontinued operations, net of tax	'	'	'	'	'	'	'	'	'	5,649	6,349
Net income	'	'	'	'	'	'	'	'	171,585	163,707	148,369
Regulated Pipeline Segment [Member]	'	'	'	'	'	'	'	'	'	'	'
Operating revenues	'	'	'	'	'	'	'	'	'	'	'
Operating revenues	86,314	87,189	73,615	71,341	72,330	74,041	61,848	60,681	318,459	268,900	247,351
Purchased gas cost	'	'	'	'	'	'	'	'	'	'	'
Purchased gas cost	'	'	'	'	'	'	'	'	0	0	0
Gross profit	'	'	'	'	'	'	'	'	318,459	268,900	247,351
Operating expenses	'	'	'	'	'	'	'	'	'	'	'
Operation and maintenance	'	'	'	'	'	'	'	'	91,466	76,686	71,521
Depreciation and amortization	'	'	'	'	'	'	'	'	41,031	35,302	31,438
Taxes, other than income	'	'	'	'	'	'	'	'	13,143	17,059	15,568
Asset impairments	'	'	'	'	'	'	'	'	'	'	0
Total operating expenses	'	'	'	'	'	'	'	'	145,640	129,047	118,527
Operating income	'	'	'	'	'	'	'	'	172,819	139,853	128,824
Miscellaneous income (expense), net	'	'	'	'	'	'	'	'	-3,181	-2,285	-1,051
Interest charges	'	'	'	'	'	'	'	'	36,280	30,678	29,414
Income from continuing operations before income taxes	'	'	'	'	'	'	'	'	133,358	106,890	98,359
Income tax expense	'	'	'	'	'	'	'	'	47,167	38,630	35,300
Income from continuing operations	'	'	'	'	'	'	'	'	'	68,260	63,059
Income from discontinued operations, net of tax	'	'	'	'	'	'	'	'	'	0	0
Gain on sale of discontinued operations, net of tax	'	'	'	'	'	'	'	'	'	0	'
Net income	'	'	'	'	'	'	'	'	86,191	68,260	63,059
Nonregulated Segment [Member]	'	'	'	'	'	'	'	'	'	'	'
Operating revenues	'	'	'	'	'	'	'	'	'	'	'
Operating revenues	396,855	465,033	757,683	447,721	337,264	421,808	428,948	399,894	2,067,292	1,587,914	1,348,982
Purchased gas cost	'	'	'	'	'	'	'	'	'	'	'
Purchased gas cost	'	'	'	'	'	'	'	'	1,979,337	1,524,583	1,293,858
Gross profit	'	'	'	'	'	'	'	'	87,955	63,331	55,124
Operating expenses	'	'	'	'	'	'	'	'	'	'	'
Operation and maintenance	'	'	'	'	'	'	'	'	26,963	37,569	29,697
Depreciation and amortization	'	'	'	'	'	'	'	'	4,580	4,196	4,061
Taxes, other than income	'	'	'	'	'	'	'	'	2,450	2,639	3,128
Asset impairments	'	'	'	'	'	'	'	'	'	'	5,288
Total operating expenses	'	'	'	'	'	'	'	'	33,993	44,404	42,174
Operating income	'	'	'	'	'	'	'	'	53,962	18,927	12,950
Miscellaneous income (expense), net	'	'	'	'	'	'	'	'	2,216	2,316	1,035
Interest charges	'	'	'	'	'	'	'	'	1,986	2,168	3,084
Income from continuing operations before income taxes	'	'	'	'	'	'	'	'	54,192	19,075	10,901
Income tax expense	'	'	'	'	'	'	'	'	22,151	7,493	5,612
Income from continuing operations	'	'	'	'	'	'	'	'	'	11,582	5,289
Income from discontinued operations, net of tax	'	'	'	'	'	'	'	'	'	0	0
Gain on sale of discontinued operations, net of tax	'	'	'	'	'	'	'	'	'	-355	'
Net income	'	'	'	'	'	'	'	'	32,041	11,227	5,289
Intersegment Elimination [Member]	'	'	'	'	'	'	'	'	'	'	'
Operating revenues	'	'	'	'	'	'	'	'	'	'	'
Operating revenues	-113,455	-127,211	-157,936	-107,779	-95,606	-105,058	-86,976	-93,207	-506,381	-380,847	-305,501
Purchased gas cost	'	'	'	'	'	'	'	'	'	'	'
Purchased gas cost	'	'	'	'	'	'	'	'	-505,878	-379,430	-304,022
Gross profit	'	'	'	'	'	'	'	'	-503	-1,417	-1,479
Operating expenses	'	'	'	'	'	'	'	'	'	'	'
Operation and maintenance	'	'	'	'	'	'	'	'	-503	-1,423	-1,484
Depreciation and amortization	'	'	'	'	'	'	'	'	0	0	0
Taxes, other than income	'	'	'	'	'	'	'	'	0	0	0
Asset impairments	'	'	'	'	'	'	'	'	'	'	0
Total operating expenses	'	'	'	'	'	'	'	'	-503	-1,423	-1,484
Operating income	'	'	'	'	'	'	'	'	0	6	5
Miscellaneous income (expense), net	'	'	'	'	'	'	'	'	-3,889	-2,763	-1,971
Interest charges	'	'	'	'	'	'	'	'	-3,889	-2,757	-1,966
Income from continuing operations before income taxes	'	'	'	'	'	'	'	'	0	0	0
Income tax expense	'	'	'	'	'	'	'	'	0	0	0
Income from continuing operations	'	'	'	'	'	'	'	'	'	0	0
Income from discontinued operations, net of tax	'	'	'	'	'	'	'	'	'	0	0
Gain on sale of discontinued operations, net of tax	'	'	'	'	'	'	'	'	'	0	'
Net income	'	'	'	'	'	'	'	'	$0	$0	$0

CONSOLIDATED_STATEMENTS_OF_INC1

CONSOLIDATED STATEMENTS OF INCOME (PARENTHETICALS) (USD $)	12 Months Ended
In Thousands, unless otherwise specified	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2012
Income Statement [Abstract]	'	'	'
Discontinued Operation Tax Effect Of Income Loss From Discontinued Operation During Phase Out Period	$0	$3,986	$10,066
Discontinued Operation, Tax Effect of Income (Loss) from Disposal of Discontinued Operation	$0	$2,909	$3,519

CONSOLIDATED_STATEMENTS_OF_COM

CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME (USD $)	12 Months Ended
In Thousands, unless otherwise specified	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2012
Statement of Comprehensive Income [Abstract]	'	'	'
Net income	$289,817	$243,194	$216,717
Other comprehensive income (loss), net of tax [Abstract]	'	'	'
Net unrealized holding gains (losses) on available-for-sale securities, net of tax of $1,199, $(186) and $1,881	2,214	-213	3,103
Amortization and unrealized gain (loss) on interest rate agreements, net of tax of $(32,353), $47,236 and $(5,388)	-56,287	82,179	-10,116
Net unrealized gains on commodity cash flow hedges, net of tax of $1,791, $2,889 and $5,029	2,802	4,519	7,866
Total other comprehensive income (loss)	-51,271	86,485	853
Total comprehensive income	$238,546	$329,679	$217,570

CONSOLIDATED_STATEMENTS_OF_COM1

CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME (PARENTHETICAL) (USD $)	12 Months Ended
In Thousands, unless otherwise specified	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2012
Other Comprehensive Income (Loss), Tax, Portion Attributable to Parent, Parenthetical Disclosures [Abstract]	'	'	'
Unrealized holding gains (losses) on available-for-sale securities, tax	$1,199	($186)	$1,881
Amortization and unrealized gain (loss) on interest rate agreements, tax	-32,353	47,236	-5,388
Unrealized gains (losses) on commodity cash flow hedges, tax	$1,791	$2,889	$5,029

CONSOLIDATED_STATEMENT_OF_SHAR

CONSOLIDATED STATEMENT OF SHAREHOLDERS' EQUITY (USD $)	Total	Common Stock [Member]	Additional Paid In Capital [Member]	Accumulated Other Comprehensive Income [Member]	Retained Earnings [Member]
In Thousands, except Share data, unless otherwise specified
Common shareholders' equity, beginning balance at Sep. 30, 2011	$2,255,421	$451	$1,732,935	($48,460)	$570,495
Common stock shares outstanding, balance at Sep. 30, 2011	'	90,296,482	'	'	'
Net income	216,717	'	'	'	216,717
Other comprehensive income (loss)	853	'	'	853	'
Repurchase of common stock, shares	'	-387,991	'	'	'
Repurchase of common stock, amount	-12,535	-2	-12,533	'	'
Repurchase of equity awards, shares	'	-153,255	'	'	'
Repurchase of equity awards, amount	-5,219	0	-5,219	'	'
Cash dividends	-125,796	'	'	'	-125,796
Common stock issued:	'	'	'	'	'
Direct stock purchase plan, shares	'	0	'	'	'
Direct stock purchase plan, amount	-65	0	-65	'	'
1998 Long-term incentive plan, shares	'	482,289	'	'	'
1998 Long-term incentive plan, amount	12,037	2	12,519	'	-484
Employee stock-based compensation	17,752	'	17,752	'	'
Outside directors stock-for-fee plan, shares	'	2,375	'	'	'
Outside directors stock-for-fee-plan, amount	78	'	78	'	'
Common shareholders' equity, ending balance at Sep. 30, 2012	2,359,243	451	1,745,467	-47,607	660,932
Common stock shares outstanding, ending balance at Sep. 30, 2012	'	90,239,900	'	'	'
Net income	243,194	'	'	'	243,194
Other comprehensive income (loss)	86,485	'	'	86,485	'
Repurchase of equity awards, shares	'	-133,449	'	'	'
Repurchase of equity awards, amount	-5,150	0	-5,150	'	'
Cash dividends	-128,115	'	'	'	-128,115
Common stock issued:	'	'	'	'	'
Direct stock purchase plan, amount	-50	0	-50	'	'
1998 Long-term incentive plan, shares	'	531,672	'	'	'
1998 Long-term incentive plan, amount	8,788	2	9,530	'	-744
Employee stock-based compensation	15,934	'	15,934	'	'
Outside directors stock-for-fee plan, shares	'	2,088	'	'	'
Outside directors stock-for-fee-plan, amount	80	'	80	'	'
Common shareholders' equity, ending balance at Sep. 30, 2013	2,580,409	453	1,765,811	38,878	775,267
Common stock shares outstanding, ending balance at Sep. 30, 2013	'	90,640,211	'	'	'
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:	'	'	'	'	'
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	'	'
Stock Issued During Period, Value, New Issues	390,205	46	390,159	'	'
Stock Issued During Period, Shares, New Issues	'	9,200,000	'	'	'
Common shareholders' equity, ending balance at Sep. 30, 2014	$3,086,232	$502	$2,180,151	($12,393)	$917,972
Common stock shares outstanding, ending balance at Sep. 30, 2014	'	100,388,092	'	'	'

CONSOLIDATED_STATEMENT_OF_SHAR1

CONSOLIDATED STATEMENT OF SHAREHOLDERS' EQUITY (PARENTHETICALS) (USD $)	12 Months Ended
	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2012
Statement of Stockholders' Equity [Abstract]	'	'	'
Cash dividends per share	$1.48	$1.40	$1.38

CONSOLIDATED_STATEMENTS_OF_CAS

CONSOLIDATED STATEMENTS OF CASH FLOWS (USD $)	12 Months Ended
In Thousands, unless otherwise specified	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2012
CASH FLOWS FROM OPERATING ACTIVITIES	'	'	'
Net income	$289,817	$243,194	$216,717
Adjustments to reconcile net income to net cash provided by operating activities:	'	'	'
Asset impairments	0	0	5,288
Gain on sale of discontinued operations	0	-8,203	-9,868
Depreciation and amortization:	'	'	'
Charged to depreciation and amortization	253,987	236,928	246,093
Charged to other accounts	969	679	484
Deferred income taxes	189,952	141,336	104,319
Stock-based compensation	25,531	17,814	19,222
Debt financing costs	9,409	8,480	8,147
Other	-428	-2,887	-493
Changes in assets and liabilities:	'	'	'
(Increase) decreased in accounts receivable	-41,408	-73,669	32,578
Decrease in gas stored underground	-31,996	31,979	28,417
(Increase) decrease in other current assets	-24,411	15,644	20,989
(Increase) decrease in deferred charges and other assets	30,662	111,069	-50,055
Increase (decrease) in account payable and accrued liabilities	55,041	31,912	-64,234
Increase (decrease) in other current liabilities	2,413	-44,491	7,889
Increase (decrease) in deferred credits and other liabilities	-19,552	-96,658	21,424
Net cash provided by operating activities	739,986	613,127	586,917
CASH FLOWS USED IN INVESTING ACTIVITIES	'	'	'
Capital expenditures	-835,251	-845,033	-732,858
Proceeds from the sale of discontinued operations	0	153,023	128,223
Other, net	-2,325	-4,904	-4,625
Net cash used in investing activities	-837,576	-696,914	-609,260
CASH FLOWS FROM FINANCING ACTIVITIES	'	'	'
Net increase (decrease) in short-term debt	-165,865	-208,070	354,141
Net proceeds from issuance of long-term debt	0	493,793	0
Net proceeds from equity offering	390,205	0	0
Settlement of Treasury lock agreement	0	-66,626	0
Repayment of long-term debt	0	-131	-257,034
Cash dividends paid	-146,248	-128,115	-125,796
Repurchase of common stock	0	0	-12,535
Repurchase of equity awards	-8,717	-5,150	-5,219
Issuance of common stock	4,274	46	1,606
Net cash provided by (used in) financing activities	73,649	85,747	-44,837
Net increase (decrease) in cash and cash equivalents	-23,941	1,960	-67,180
Cash and cash equivalents at beginning of period	66,199	64,239	131,419
Cash and cash equivalents at end of period	42,258	66,199	64,239
CASH PAID (RECEIVED) DURING THE PERIOD FOR:	'	'	'
Interest	156,606	148,461	150,606
Income taxes	($610)	$10,008	($432)

Nature_of_Business

Nature of Business	12 Months Ended
	Sep. 30, 2014
Organization, Consolidation and Presentation of Financial Statements [Abstract]	'
Nature of Business	'
	Nature of Business
	Atmos Energy Corporation (“Atmos Energy” or the “Company”) and our subsidiaries are engaged primarily in the regulated natural gas distribution and pipeline businesses as well as certain other nonregulated businesses. Through our regulated distribution business, we deliver natural gas through sales and transportation arrangements to over three million residential, commercial, public-authority and industrial customers through our six regulated distribution divisions in the service areas described below:
	Division		Service Area
	Atmos Energy Colorado-Kansas Division		Colorado, Kansas
	Atmos Energy Kentucky/Mid-States Division		Kentucky, Tennessee, Virginia(1)
	Atmos Energy Louisiana Division		Louisiana
	Atmos Energy Mid-Tex Division		Texas, including the Dallas/Fort Worth metropolitan area
	Atmos Energy Mississippi Division		Mississippi
	Atmos Energy West Texas Division		West Texas
	(1)	Denotes location where we have more limited service areas.
	In addition, we transport natural gas for others through our distribution system. Our distribution business is subject to federal and state regulation and/or regulation by local authorities in each of the states in which our regulated distribution divisions operate. Our corporate headquarters and shared-services function are located in Dallas, Texas, and our customer support centers are located in Amarillo and Waco, Texas.
	During fiscal 2013 and fiscal 2012, we sold our regulated distribution operations in four states to streamline our regulated operations. On April 1, 2013, we completed the divestiture of our regulated distribution operations in Georgia, representing approximately 64,000 customers, and in August 2012, we completed the sale of our regulated distribution operations in Missouri, Illinois and Iowa, representing approximately 84,000 customers.
	Our regulated pipeline business, which is also subject to federal and state regulation, consists of the regulated operations of our Atmos Pipeline–Texas Division, a division of the Company. This division transports natural gas to our Mid-Tex Division, transports natural gas for third parties and manages five underground storage reservoirs in Texas. We also provide ancillary services customary to the pipeline industry including parking arrangements, lending and sales of inventory on hand.
	Our nonregulated businesses operate primarily in the Midwest and Southeast through various wholly-owned subsidiaries of Atmos Energy Holdings, Inc., (AEH). AEH is a wholly-owned subsidiary of the Company and based in Houston, Texas. Through AEH, we provide natural gas management and transportation services to municipalities, regulated distribution companies, including certain divisions of Atmos Energy and third parties.

Significant_Accounting_Policie

Significant Accounting Policies	12 Months Ended
	Sep. 30, 2014
Accounting Policies [Abstract]	'
Summary of Significant Accounting Policies	'
	Summary of Significant Accounting Policies
	Principles of consolidation — The accompanying consolidated financial statements include the accounts of Atmos Energy Corporation and its wholly-owned subsidiaries. All material intercompany transactions have been eliminated; however, we have not eliminated intercompany profits when such amounts are probable of recovery under the affiliates’ rate regulation process.
	Basis of comparison — Certain prior-year amounts have been reclassified to conform with the current year presentation.
	Use of estimates — The preparation of financial statements in conformity with accounting principles generally accepted in the United States requires management to make estimates and assumptions that affect the reported amounts of assets, liabilities, revenues and expenses. The most significant estimates include the allowance for doubtful accounts, unbilled revenues, legal and environmental accruals, insurance accruals, pension and postretirement obligations, deferred income taxes, asset retirement obligations, impairment of long-lived assets, risk management and trading activities, fair value measurements and the valuation of goodwill and other long-lived assets. Actual results could differ from those estimates.
	Regulation — Our regulated distribution and regulated pipeline operations are subject to regulation with respect to rates, service, maintenance of accounting records and various other matters by the respective regulatory authorities in the states in which we operate. Our accounting policies recognize the financial effects of the ratemaking and accounting practices and policies of the various regulatory commissions. Accounting principles generally accepted in the United States require cost-based, rate-regulated entities that meet certain criteria to reflect the authorized recovery of costs due to regulatory decisions in their financial statements. As a result, certain costs that would normally be expensed under accounting principles generally accepted in the United States are permitted to be capitalized or deferred on the balance sheet because it is probable they can be recovered through rates. Further, regulation may impact the period in which revenues or expenses are recognized. The amounts to be recovered or recognized are based upon historical experience and our understanding of the regulations.
	We record regulatory assets as a component of other current assets and deferred charges and other assets for costs that have been deferred for which future recovery through customer rates is considered probable. Regulatory liabilities are recorded either on the face of the balance sheet or as a component of current liabilities, deferred income taxes or deferred credits and other liabilities when it is probable that revenues will be reduced for amounts that will be credited to customers through the ratemaking process. Significant regulatory assets and liabilities as of September 30, 2014 and 2013 included the following:
		30-Sep
		2014		2013
		(In thousands)
	Regulatory assets:
	Pension and postretirement benefit costs(1)	$	162,777	$	187,977
	Merger and integration costs, net	4,730		5,250
	Deferred gas costs	20,069		15,152
	Regulatory cost of removal asset	—		10,008
	Rate case costs	3,757		6,329
	Texas Rule 8.209(2)	26,948		30,364
	APT annual adjustment mechanism	8,479		5,853
	Recoverable loss on reacquired debt	18,877		21,435
	Other	4,672		4,380
		$	250,309	$	286,748
	Regulatory liabilities:
	Deferred gas costs	$	35,063	$	16,481
	Deferred franchise fees	5,268		1,689
	Regulatory cost of removal obligation	490,448		427,524
	Other	14,980		7,887
		$	545,759	$	453,581
	-1	Includes $18.8 million and $17.4 million of pension and postretirement expense deferred pursuant to regulatory authorization.
	-2	Texas Rule 8.209 is a Railroad Commission rule that allows for the deferral of all expenses associated with capital expenditures incurred pursuant to this rule, including the recording of interest on the deferred expenses until the next rate proceeding (rate case or annual rate filing), at which time investment and costs would be recovered through base rates.
	Currently, authorized rates do not include a return on certain of our merger and integration costs; however, we recover the amortization of these costs. Merger and integration costs, net, are generally amortized on a straight-line basis over estimated useful lives ranging up to 20 years. During the fiscal years ended September 30, 2014, 2013 and 2012, we recognized $0.5 million in amortization expense related to these costs.
	Revenue recognition — Sales of natural gas to our regulated distribution customers are billed on a monthly basis; however, the billing cycle periods for certain classes of customers do not necessarily coincide with accounting periods used for financial reporting purposes. We follow the revenue accrual method of accounting for regulated distribution segment revenues whereby revenues applicable to gas delivered to customers, but not yet billed under the cycle billing method, are estimated and accrued and the related costs are charged to expense.
	On occasion, we are permitted to implement new rates that have not been formally approved by our state regulatory commissions, which are subject to refund. As permitted by accounting principles generally accepted in the United States, we recognize this revenue and establish a reserve for amounts that could be refunded based on our experience for the jurisdiction in which the rates were implemented.
	Rates established by regulatory authorities are adjusted for increases and decreases in our purchased gas costs through purchased gas cost adjustment mechanisms. Purchased gas cost adjustment mechanisms provide gas distribution companies a method of recovering purchased gas costs on an ongoing basis without filing a rate case to address all of their non-gas costs. There is no gross profit generated through purchased gas cost adjustments, but they provide a dollar-for-dollar offset to increases or decreases in our regulated distribution segment’s gas costs. The effects of these purchased gas cost adjustment mechanisms are recorded as deferred gas costs on our balance sheet.
	Operating revenues for our regulated pipeline and nonregulated segments are recognized in the period in which actual volumes are transported and storage services are provided.
	Operating revenues for our nonregulated segment and the associated carrying value of natural gas inventory (inclusive of storage costs) are recognized when we sell the gas and physically deliver it to our customers. Operating revenues include realized gains and losses arising from the settlement of financial instruments used in our nonregulated activities and unrealized gains and losses arising from changes in the fair value of natural gas inventory designated as a hedged item in a fair value hedge and the associated financial instruments. For the fiscal years ended September 30, 2014, 2013 and 2012, we included unrealized gains (losses) on open contracts of $9.6 million, $9.0 million and $(8.0) million as a component of nonregulated revenues.
	Cash and cash equivalents — We consider all highly liquid investments with an original maturity of three months or less to be cash equivalents.
	Accounts receivable and allowance for doubtful accounts — Accounts receivable arise from natural gas sales to residential, commercial, industrial, municipal and other customers. We establish an allowance for doubtful accounts to reduce the net receivable balance to the amount we reasonably expect to collect based on our collection experience or where we are aware of a specific customer’s inability or reluctance to pay. However, if circumstances change, our estimate of the recoverability of accounts receivable could be affected. Circumstances which could affect our estimates include, but are not limited to, customer credit issues, the level of natural gas prices, customer deposits and general economic conditions. Accounts are written off once they are deemed to be uncollectible.
	Gas stored underground — Our gas stored underground is comprised of natural gas injected into storage to support the winter season withdrawals for our regulated distribution operations and natural gas held by our nonregulated segment to conduct their operations. The average cost method is used for all our regulated operations, except for certain jurisdictions in the Kentucky/Mid-States Division, where it is valued on the first-in first-out method basis, in accordance with regulatory requirements. Our nonregulated segment utilizes the average cost method; however, most of this inventory is hedged and is therefore reported at fair value at the end of each month. Gas in storage that is retained as cushion gas to maintain reservoir pressure is classified as property, plant and equipment and is valued at cost.
	Regulated property, plant and equipment — Regulated property, plant and equipment is stated at original cost, net of contributions in aid of construction. The cost of additions includes direct construction costs, payroll related costs (taxes, pensions and other fringe benefits), administrative and general costs and an allowance for funds used during construction. The allowance for funds used during construction represents the estimated cost of funds used to finance the construction of major projects and are capitalized in the rate base for ratemaking purposes when the completed projects are placed in service. Interest expense of $1.5 million, $1.9 million and $2.6 million was capitalized in 2014, 2013 and 2012.
	Major renewals, including replacement pipe, and betterments that are recoverable under our regulatory rate base are capitalized while the costs of maintenance and repairs that are not recoverable through rates are charged to expense as incurred. The costs of large projects are accumulated in construction in progress until the project is completed. When the project is completed, tested and placed in service, the balance is transferred to the regulated plant in service account included in the rate base and depreciation begins.
	Regulated property, plant and equipment is depreciated at various rates on a straight-line basis. These rates are approved by our regulatory commissions and are comprised of two components: one based on average service life and one based on cost of removal. Accordingly, we recognize our cost of removal expense as a component of depreciation expense. The related cost of removal accrual is reflected as a regulatory liability on the consolidated balance sheet. At the time property, plant and equipment is retired, removal expenses less salvage, are charged to the regulatory cost of removal accrual. The composite depreciation rate was 3.3 percent, 3.3 percent and 3.6 percent for the fiscal years ended September 30, 2014, 2013 and 2012.
	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 50 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, 2014 and 2013, we had asset retirement obligations of $10.5 million and $6.8 million. Additionally, we had $5.9 million and $3.3 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.
	During fiscal 2012, we recorded a pre-tax noncash impairment loss of $5.3 million related to our gathering systems in Kentucky. See Note 14 for further details.
	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, 2014 and 2013, all of our marketable securities were classified as available-for-sale. In accordance with the authoritative accounting standards, these securities are reported at market value with unrealized gains and losses shown as a component of accumulated other comprehensive income (loss). We regularly evaluate the performance of these investments on an individual investment by investment basis for impairment, taking into consideration the fund’s purpose, volatility and current returns. If a determination is made that a decline in fair value is other than temporary, the related investment is written down to its estimated fair value.
	Financial instruments and hedging activities — We use financial instruments to mitigate commodity price risk in our regulated distribution and nonregulated segments and interest rate risk. The objectives and strategies for using financial instruments have been tailored to our regulated and nonregulated businesses and are discussed in Note 12.
	We record all of our financial instruments on the balance sheet at fair value, with changes in fair value ultimately recorded in the income statement. These financial instruments are reported as risk management assets and liabilities and are classified as current or noncurrent other assets or liabilities based upon the anticipated settlement date of the underlying financial instrument.
	The timing of when changes in fair value of our financial instruments are recorded in the income statement depends on whether the financial instrument has been designated and qualifies as a part of a hedging relationship or if regulatory rulings require a different accounting treatment. Changes in fair value for financial instruments that do not meet one of these criteria are recognized in the income statement as they occur.
	Financial Instruments Associated with Commodity Price Risk
	In our regulated distribution segment, the costs associated with and the gains and losses arising from the use of financial instruments to mitigate commodity price risk are included in our purchased gas cost adjustment mechanisms in accordance with regulatory requirements. Therefore, changes in the fair value of these financial instruments are initially recorded as a component of deferred gas costs and recognized in the consolidated statement of income as a component of purchased gas cost when the related costs are recovered through our rates and recognized in revenue in accordance with accounting principles generally accepted in the United States. Accordingly, there is no earnings impact on our regulated distribution segment as a result of the use of financial instruments.
	In our nonregulated segment, we have designated most of the natural gas inventory held by this operating segment as the hedged item in a fair-value hedge. This inventory is marked to market at the end of each month based on the Gas Daily index, with changes in fair value recognized as unrealized gains or losses in revenue 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.
	Additionally, we have elected to treat fixed-price forward contracts used in our nonregulated segment to deliver natural gas as normal purchases and normal sales. As such, these deliveries are recorded on an accrual basis in accordance with our revenue recognition policy. Financial instruments used to mitigate the commodity price risk associated with these contracts have been designated as cash flow hedges of anticipated purchases and sales at indexed prices. Accordingly, unrealized gains and losses on these open financial instruments are recorded as a component of accumulated other comprehensive income, and are recognized in earnings as a component of purchased gas cost when the hedged volumes are sold.
	Gains and losses from hedge ineffectiveness are recognized in the income statement. Fair value and cash flow hedge ineffectiveness arising from natural gas market price differences between the locations of the hedged inventory and the delivery location specified in the financial instruments is referred to as basis ineffectiveness. Ineffectiveness arising from changes in the fair value of the fair value hedges due to changes in the difference between the spot price and the futures price, as well as the difference between the timing of the settlement of the futures and the valuation of the underlying physical commodity is referred to as timing ineffectiveness. Hedge ineffectiveness, to the extent incurred, is reported as a component of purchased gas cost.
	Our nonregulated segment also utilizes master netting agreements with significant counterparties that allow us to offset gains and losses arising from financial instruments that may be settled in cash with gains and losses arising from financial instruments that may be settled with the physical commodity. Assets and liabilities from risk management activities, as well as accounts receivable and payable, reflect the master netting agreements in place. Additionally, the accounting guidance for master netting arrangements requires us to include the fair value of cash collateral or the obligation to return cash in the amounts that have been netted under master netting agreements used to offset gains and losses arising from financial instruments. As of September 30, 2014 and 2013, the Company netted $25.8 million and $24.8 million of cash held in margin accounts into its current and noncurrent risk management assets and liabilities.
	Financial Instruments Associated with Interest Rate Risk
	We manage interest rate risk, primarily when we plan to issue new long-term debt or to refinance existing long-term debt. We manage this risk through the use of forward starting interest rate swaps, interest rate swaps, and prior to fiscal 2012, Treasury lock agreements, to fix the Treasury yield component of the interest cost associated with anticipated financings. We designate these financial instruments as cash flow hedges at the time the agreements are executed. Unrealized gains and losses associated with the instruments are recorded as a component of accumulated other comprehensive income (loss). When the instruments settle, the realized gain or loss is recorded as a component of accumulated other comprehensive income (loss) and recognized as a component of interest expense over the life of the related financing arrangement. Hedge ineffectiveness to the extent incurred is reported as a component of interest expense.
	Fair Value Measurements — We report certain assets and liabilities at fair value, which is defined as the price that would be received to sell an asset or paid to transfer a liability in an orderly transaction between market participants at the measurement date (exit price). We primarily use quoted market prices and other observable market pricing information in valuing our financial assets and liabilities and minimize the use of unobservable pricing inputs in our measurements.
	Fair-value estimates also consider our own creditworthiness and the creditworthiness of the counterparties involved. Our counterparties consist primarily of financial institutions and major energy companies. This concentration of counterparties may materially impact our exposure to credit risk resulting from market, economic or regulatory conditions. We seek to minimize counterparty credit risk through an evaluation of their financial condition and credit ratings and the use of collateral requirements under certain circumstances.
	Amounts reported at fair value are subject to potentially significant volatility based upon changes in market prices, including, but not limited to, the valuation of the portfolio of our contracts, maturity and settlement of these contracts and newly originated transactions and interest rates, each of which directly affect the estimated fair value of our financial instruments. We believe the market prices and models used to value these financial instruments represent the best information available with respect to closing exchange and over-the-counter quotations, time value and volatility factors underlying the contracts. Values are adjusted to reflect the potential impact of an orderly liquidation of our positions over a reasonable period of time under then current market conditions.
	Authoritative accounting literature establishes a fair value hierarchy that prioritizes the inputs used to measure fair value based on observable and unobservable data. The hierarchy categorizes the inputs into three levels, with the highest priority given to unadjusted quoted prices in active markets for identical assets and liabilities (Level 1) and the lowest priority given to unobservable inputs (Level 3). The levels of the hierarchy are described below:
Level 1 — Represents unadjusted quoted prices in active markets for identical assets or liabilities. An active market for the asset or liability is defined as a market in which transactions for the asset or liability occur with sufficient frequency and volume to provide pricing information on an ongoing basis. Prices actively quoted on national exchanges are used to determine the fair value of most of our assets and liabilities recorded on our balance sheet at fair value. Within our nonregulated operations, we utilize a mid-market pricing convention (the mid-point between the bid and ask prices), as permitted under current accounting standards. Values derived from these sources reflect the market in which transactions involving these financial instruments are executed.
Our Level 1 measurements consist primarily of exchange-traded financial instruments, gas stored underground that has been designated as the hedged item in a fair value hedge and our available-for-sale securities. The Level 1 measurements for investments in our Master Trust, Supplemental Executive Benefit Plan and postretirement benefit plan consist primarily of exchange-traded financial instruments.
Level 2 — Represents pricing inputs other than quoted prices included in Level 1 that are either directly or indirectly observable for the asset or liability as of the reporting date. These inputs are derived principally from, or corroborated by, observable market data. Our Level 2 measurements primarily consist of non-exchange-traded financial instruments, such as over-the-counter options and swaps and municipal and corporate bonds where market data for pricing is observable. The Level 2 measurements for investments in our Master Trust, Supplemental Executive Benefit Plan and postretirement benefit plan consist primarily of non-exchange traded financial instruments such as common collective trusts and investments in limited partnerships.
Level 3 — Represents generally unobservable pricing inputs which are developed based on the best information available, including our own internal data, in situations where there is little if any market activity for the asset or liability at the measurement date. The pricing inputs utilized reflect what a market participant would use to determine fair value. We utilize models and other valuation methods to determine fair value when external sources are not available. We believe the market prices and models used to value these assets and liabilities represent the best information available with respect to closing exchange and over-the-counter quotations, time value and volatility factors underlying the assets and liabilities.
As of September 30, 2014, our Master Trust owned one real estate investment with a value less than $0.2 million that qualifies as a Level 3 fair value measurement. The valuation technique used was a real estate appraisal obtained from an independent third party that consisted of several unobservable inputs such as comparable land and building sales values per square foot. Currently, we have no other assets or liabilities recorded at fair value that would qualify for Level 3 reporting.
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 in 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 reduces or increases future pension or postretirement plan costs over a period of approximately seven to nine years.
The market-related value of our plan assets represents the fair market value of the plan assets, adjusted to smooth out short-term market fluctuations over a five-year period. The use of this calculation will delay the impact of current market fluctuations on the pension expense for the period.
We use a corridor approach to amortize actuarial gains and losses. Under this approach, net gains or losses in excess of ten percent of the larger of the pension benefit obligation or the market-related value of the assets are amortized on a straight-line basis. The period of amortization is the average remaining service of active participants who are expected to receive benefits under the plan.
We estimate the assumed health care cost trend rate used in determining our annual postretirement net cost based upon our actual health care cost experience, the effects of recently enacted legislation and general economic conditions. Our assumed rate of retirement is estimated based upon the annual review of our participant census information as of the measurement date.
Income taxes — Income taxes are determined based on the liability method, which results in income tax assets and liabilities arising from temporary differences. Temporary differences are differences between the tax bases of assets and liabilities and their reported amounts in the financial statements that will result in taxable or deductible amounts in future years. The liability method requires the effect of tax rate changes on current and accumulated deferred income taxes to be reflected in the period in which the rate change was enacted. The liability method also requires that deferred tax assets be reduced by a valuation allowance unless it is more likely than not that the assets will be realized.
The Company may recognize the tax benefit from uncertain tax positions only if it is at least more likely than not that the tax position will be sustained on examination by the taxing authorities, based on the technical merits of the position. The tax benefits recognized in the financial statements from such a position should be measured based on the largest benefit that has a greater than fifty percent likelihood of being realized upon settlement with the taxing authorities. We recognize accrued interest related to unrecognized tax benefits as a component of interest expense. We recognize penalties related to unrecognized tax benefits as a component of miscellaneous income (expense) in accordance with regulatory requirements.
Tax collections — We are allowed to recover from customers revenue-related taxes that are imposed upon us. We record such taxes as operating expenses and record the corresponding customer charges as operating revenues. However, we do collect and remit various other taxes on behalf of various governmental authorities, and we record these amounts in our consolidated balance sheets on a net basis. We do not collect income taxes from our customers on behalf of governmental authorities.
Contingencies — In the normal course of business, we are confronted with issues or events that may result in a contingent liability. These generally relate to lawsuits, claims made by third parties or the action of various regulatory agencies. For such matters, we record liabilities when they are considered probable and reasonably estimable, based on currently available facts and our estimates of the ultimate outcome or resolution of the liability in the future. Actual results may differ from estimates, depending on actual outcomes or changes in the facts or expectations surrounding each potential exposure.
Subsequent events — Except as disclosed in Note 5 concerning the October 15, 2014 issuance of $500 million, 4.125% senior notes, no events occurred subsequent to the balance sheet date that would require recognition or disclosure in the financial statements.
Recent accounting pronouncements — Disclosure requirements for offsetting arrangements for financial instruments became effective for us beginning on October 1, 2013. We have presented these disclosures in Note 12. In connection with the adoption of this standard, prior-year risk management assets and liabilities have been reclassified to conform with the current-year presentation. The adoption of this standard and reclassification did not have an impact on our financial position, results of operations or cash flows.
In April 2014, the Financial Accounting Standards Board (FASB) issued updated guidance for discontinued operations that limits discontinued operations reporting to disposals of components of an entity that represent strategic shifts that have a major effect on an entity’s operations and financial results and requires additional disclosures related to discontinued operations. This standard will become effective for us beginning on October 1, 2015. The adoption of this guidance is not expected to impact our financial position, results of operations or cash flows.
In May 2014, the 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 will become effective for us beginning on October 1, 2017 and can be applied either retrospectively to each period presented or as a cumulative-effect adjustment as of the date of adoption. We are currently evaluating the impact this standard may have on our financial position, results of operations and cash flows.
In August 2014, the FASB issued guidance that requires management to evaluate whether there are conditions or events that raise substantial doubt about an entity’s ability to continue as a going concern. If such conditions or events exist, disclosures are required that enable users of the financial statements to understand the nature of the conditions or events, management's evaluation of the circumstances and management's plans to mitigate the conditions or events that raise substantial doubt about the entity’s ability to continue as a going concern. We will be required to perform an annual assessment of our ability to continue as a going concern when this standard becomes effective for us on October 1, 2017; however, the adoption of this guidance is not expected to impact our financial position, results of operations or cash flows.

Segment_Information

Segment Information	12 Months Ended
	Sep. 30, 2014
Segment Reporting [Abstract]	'
Segment Information	'
	Segment Information
	Atmos Energy Corporation and its subsidiaries are engaged primarily in the regulated natural gas distribution and pipeline business as well as other nonregulated businesses. We distribute natural gas through sales and transportation arrangements to over three million residential, commercial, public authority and industrial customers through our six regulated distribution divisions, which cover service areas located in eight states. In addition, we transport natural gas for others through our distribution system.
	Through our nonregulated business, we provide natural gas management and transportation services to municipalities, regulated distribution companies, including certain divisions of Atmos Energy and third parties.
	We operate the Company through the following three segments:
	•	The regulated distribution segment, includes our regulated distribution and related sales operations.
	•	The regulated pipeline segment, includes the regulated pipeline and storage operations of our Atmos Pipeline — Texas Division.
	•	The nonregulated segment, is comprised of our nonregulated natural gas management, nonregulated natural gas transmission, storage and other services.
	Our determination of reportable segments considers the strategic operating units under which we manage sales of various products and services to customers in differing regulatory environments. Although our regulated distribution segment operations are geographically dispersed, they are reported as a single segment as each regulated distribution division has similar economic characteristics. The accounting policies of the segments are the same as those described in the summary of significant accounting policies. We evaluate performance based on net income or loss of the respective operating units. Interest expense is allocated pro rata to each segment based upon our net investment in each segment. Income taxes are allocated to each segment as if each segment’s taxes were calculated on a separate return basis.
	Summarized income statements and capital expenditures by segment are shown in the following tables.
		Year Ended September 30, 2014
		Regulated			Regulated			Nonregulated			Eliminations			Consolidated
		Distribution			Pipeline
		(In thousands)
	Operating revenues from external parties	$	3,056,212		$	92,166		$	1,792,538		$	—		$	4,940,916
	Intersegment revenues	5,334			226,293			274,754			(506,381		)	—
		3,061,546			318,459			2,067,292			(506,381		)	4,940,916
	Purchased gas cost	1,885,031			—			1,979,337			(505,878		)	3,358,490
	Gross profit	1,176,515			318,459			87,955			(503		)	1,582,426
	Operating expenses
	Operation and maintenance	387,228			91,466			26,963			(503		)	505,154
	Depreciation and amortization	208,376			41,031			4,580			—			253,987
	Taxes, other than income	196,343			13,143			2,450			—			211,936
	Total operating expenses	791,947			145,640			33,993			(503		)	971,077
	Operating income	384,568			172,819			53,962			—			611,349
	Miscellaneous income (expense)	(381		)	(3,181		)	2,216			(3,889		)	(5,235		)
	Interest charges	94,918			36,280			1,986			(3,889		)	129,295
	Income before income taxes	289,269			133,358			54,192			—			476,819
	Income tax expense	117,684			47,167			22,151			—			187,002
	Net income	$	171,585		$	86,191		$	32,041		$	—		$	289,817
	Capital expenditures	$	584,065		$	249,347		$	1,839		$	—		$	835,251
		Year Ended September 30, 2013
		Regulated			Regulated			Nonregulated			Eliminations			Consolidated
		Distribution			Pipeline
		(In thousands)
	Operating revenues from external parties	$	2,394,418		$	89,011		$	1,392,031		$	—		$	3,875,460
	Intersegment revenues	5,075			179,889			195,883			(380,847		)	—
		2,399,493			268,900			1,587,914			(380,847		)	3,875,460
	Purchased gas cost	1,318,257			—			1,524,583			(379,430		)	2,463,410
	Gross profit	1,081,236			268,900			63,331			(1,417		)	1,412,050
	Operating expenses
	Operation and maintenance	375,188			76,686			37,569			(1,423		)	488,020
	Depreciation and amortization	195,581			35,302			4,196			—			235,079
	Taxes, other than income	167,374			17,059			2,639			—			187,072
	Total operating expenses	738,143			129,047			44,404			(1,423		)	910,171
	Operating income	343,093			139,853			18,927			6			501,879
	Miscellaneous income (expense)	2,535			(2,285		)	2,316			(2,763		)	(197		)
	Interest charges	98,296			30,678			2,168			(2,757		)	128,385
	Income from continuing operations before income taxes	247,332			106,890			19,075			—			373,297
	Income tax expense	96,476			38,630			7,493			—			142,599
	Income from continuing operations	150,856			68,260			11,582			—			230,698
	Income from discontinued operations, net of tax	7,202			—			—			—			7,202
	Gain (loss) on sale of discontinued operations, net of tax	5,649			—			(355		)	—			5,294
	Net income	$	163,707		$	68,260		$	11,227		$	—		$	243,194
	Capital expenditures	$	528,599		$	313,230		$	3,204		$	—		$	845,033
		Year Ended September 30, 2012
		Regulated			Regulated			Nonregulated			Eliminations			Consolidated
		Distribution			Pipeline
		(In thousands)
	Operating revenues from external parties	$	2,144,376		$	92,604		$	1,199,182		$	—		$	3,436,162
	Intersegment revenues	954			154,747			149,800			(305,501		)	—
		2,145,330			247,351			1,348,982			(305,501		)	3,436,162
	Purchased gas cost	1,122,587			—			1,293,858			(304,022		)	2,112,423
	Gross profit	1,022,743			247,351			55,124			(1,479		)	1,323,739
Operating expenses
Operation and maintenance	353,879			71,521			29,697			(1,484		)	453,613
Depreciation and amortization	202,026			31,438			4,061			—			237,525
Taxes, other than income	162,377			15,568			3,128			—			181,073
Asset impairments	—			—			5,288			—			5,288
Total operating expenses	718,282			118,527			42,174			(1,484		)	877,499
Operating income	304,461			128,824			12,950			5			446,240
Miscellaneous income (expense)	(12,657		)	(1,051		)	1,035			(1,971		)	(14,644		)
Interest charges	110,642			29,414			3,084			(1,966		)	141,174
Income from continuing operations before income taxes	181,162			98,359			10,901			—			290,422
Income tax expense	57,314			35,300			5,612			—			98,226
Income from continuing operations	123,848			63,059			5,289			—			192,196
Income from discontinued operations, net of tax	18,172			—			—			—			18,172
Gain on sale of discontinued operations, net of tax	6,349			—			—			—			6,349
Net income	$	148,369		$	63,059		$	5,289		$	—		$	216,717
Capital expenditures	$	546,818		$	175,768		$	10,272		$	—		$	732,858
The following table summarizes our revenues by products and services for the fiscal year ended September 30.
	2014			2013			2012
	(In thousands)
Regulated distribution revenues:
Gas sales revenues:
Residential	$	1,933,099		$	1,512,495		$	1,351,479
Commercial	876,042			661,930			587,651
Industrial	90,536			81,155			71,960
Public authority and other	64,779			60,557			54,334
Total gas sales revenues	2,964,456			2,316,137			2,065,424
Transportation revenues	64,049			55,938			53,924
Other gas revenues	27,707			22,343			25,028
Total regulated distribution revenues	3,056,212			2,394,418			2,144,376
Regulated pipeline revenues	92,166			89,011			92,604
Nonregulated revenues	1,792,538			1,392,031			1,199,182
Total operating revenues	$	4,940,916		$	3,875,460		$	3,436,162
Balance sheet information at September 30, 2014 and 2013 by segment is presented in the following tables.
	30-Sep-14
	Regulated			Regulated			Nonregulated			Eliminations			Consolidated
	Distribution			Pipeline
	(In thousands)
ASSETS
Property, plant and equipment, net	$	5,202,761		$	1,464,572		$	58,573		$	—		$	6,725,906
Investment in subsidiaries	952,171			—			(2,096		)	(950,075		)	—
Current assets
Cash and cash equivalents	33,303			—			8,955			—			42,258
Assets from risk management activities	23,102			—			22,725			—			45,827
Other current assets	490,408			14,009			526,161			(342,823		)	687,755
Intercompany receivables	790,442			—			—			(790,442		)	—
Total current assets	1,337,255			14,009			557,841			(1,133,265		)	775,840
Goodwill	574,816			132,502			34,711			—			742,029
Noncurrent assets from risk management activities	13,038			—			—			—			13,038
Deferred charges and other assets	309,965			21,826			6,100			—			337,891
	$	8,390,006		$	1,632,909		$	655,129		$	(2,083,340	)	$	8,594,704
CAPITALIZATION AND LIABILITIES
Shareholders’ equity	$	3,086,232		$	482,612		$	469,559		$	(952,171	)	$	3,086,232
Long-term debt	2,455,986			—			—			—			2,455,986
Total capitalization	5,542,218			482,612			469,559			(952,171		)	5,542,218
Current liabilities
Short-term debt	522,695			—			—			(326,000		)	196,695
Liabilities from risk management activities	1,730			—			—			—			1,730
Other current liabilities	559,765			24,790			142,397			(14,727		)	712,225
Intercompany payables	—			763,635			26,807			(790,442		)	—
Total current liabilities	1,084,190			788,425			169,204			(1,131,169		)	910,650
Deferred income taxes	913,260			361,688			11,668			—			1,286,616
Noncurrent liabilities from risk management activities	20,126			—			—			—			20,126
Regulatory cost of removal obligation	445,387			—			—			—			445,387
Pension and postretirement liabilities	340,963			—			—			—			340,963
Deferred credits and other liabilities	43,862			184			4,698			—			48,744
	$	8,390,006		$	1,632,909		$	655,129		$	(2,083,340	)	$	8,594,704
	30-Sep-13
	Regulated			Regulated			Nonregulated			Eliminations			Consolidated
	Distribution			Pipeline
	(In thousands)
ASSETS
Property, plant and equipment, net	$	4,719,873		$	1,249,767		$	61,015		$	—		$	6,030,655
Investment in subsidiaries	831,136			—			(2,096		)	(829,040		)	—
Current assets
Cash and cash equivalents	4,237			—			61,962			—			66,199
Assets from risk management activities	1,837			—			10,129			—			11,966
Other current assets	428,366			11,709			452,126			(293,233		)	598,968
Intercompany receivables	783,738			—			—			(783,738		)	—
Total current assets	1,218,178			11,709			524,217			(1,076,971		)	677,133
Goodwill	574,190			132,462			34,711			—			741,363
Noncurrent assets from risk management activities	109,354			—			—			—			109,354
Deferred charges and other assets	347,687			19,227			8,849			—			375,763
	$	7,800,418		$	1,413,165		$	626,696		$	(1,906,011	)	$	7,934,268
CAPITALIZATION AND LIABILITIES
Shareholders’ equity	$	2,580,409		$	396,421		$	434,715		$	(831,136	)	$	2,580,409
Long-term debt	2,455,671			—			—			—			2,455,671
Total capitalization	5,036,080			396,421			434,715			(831,136		)	5,036,080
Current liabilities
Short-term debt	645,984			—			—			(278,000		)	367,984
Liabilities from risk management activities	1,543			—			—			—			1,543
Other current liabilities	491,681			20,288			110,306			(13,316		)	608,959
Intercompany payables	—			712,768			70,970			(783,738		)	—
Total current liabilities	1,139,208			733,056			181,276			(1,075,054		)	978,486
Deferred income taxes	871,360			283,554			8,960			179			1,164,053
Noncurrent liabilities from risk management activities	—			—			—			—			—
Regulatory cost of removal obligation	359,299			—			—			—			359,299
Pension and postretirement liabilities	358,787			—			—			—			358,787
Deferred credits and other liabilities	35,684			134			1,745			—			37,563
	$	7,800,418		$	1,413,165		$	626,696		$	(1,906,011	)	$	7,934,268

Earnings_Per_Share

Earnings Per Share	12 Months Ended
	Sep. 30, 2014
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:
		2014		2013		2012
		(In thousands, except per share data)
	Basic Earnings Per Share from continuing operations
	Income from continuing operations	$	289,817	$	230,698	$	192,196
	Less: Income from continuing operations allocated to participating securities	711		775		793
	Income from continuing operations available to common shareholders	$	289,106	$	229,923	$	191,403
	Basic weighted average shares outstanding	97,606		90,533		90,150
	Income from continuing operations per share — Basic	$	2.96	$	2.54	$	2.12
	Basic Earnings Per Share from discontinued operations
	Income from discontinued operations	$	—	$	12,496	$	24,521
	Less: Income from discontinued operations allocated to participating securities	—		42		101
	Income from discontinued operations available to common shareholders	$	—	$	12,454	$	24,420
	Basic weighted average shares outstanding	97,606		90,533		90,150
	Income from discontinued operations per share — Basic	$	—	$	0.14	$	0.27
	Net income per share — Basic	$	2.96	$	2.68	$	2.39
	Diluted Earnings Per Share from continuing operations
	Income from continuing operations available to common shareholders	$	289,106	$	229,923	$	191,403
	Effect of dilutive stock options and other shares	—		5		4
	Income from continuing operations available to common shareholders	$	289,106	$	229,928	$	191,407
	Basic weighted average shares outstanding	97,606		90,533		90,150
	Additional dilutive stock options and other shares	2		1,178		1,022
	Diluted weighted average shares outstanding	97,608		91,711		91,172
	Income from continuing operations per share — Diluted	$	2.96	$	2.5	$	2.1
	Diluted Earnings Per Share from discontinued operations
	Income from discontinued operations available to common shareholders	$	—	$	12,454	$	24,420
	Effect of dilutive stock options and other shares	—		—		—
	Income from discontinued operations available to common shareholders	$	—	$	12,454	$	24,420
	Basic weighted average shares outstanding	97,606		90,533		90,150
	Additional dilutive stock options and other shares	2		1,178		1,022
	Diluted weighted average shares outstanding	97,608		91,711		91,172
	Income from discontinued operations per share — Diluted	$	—	$	0.14	$	0.27
	Net income per share — Diluted	$	2.96	$	2.64	$	2.37
	There were no out-of-the-money options excluded from the computation of diluted earnings per share for the fiscal years ended September 30, 2013 and 2012. As of September 30, 2014 there were no outstanding options.
	2014 Equity Offering
	On February 18, 2014, we completed the public offering of 9,200,000 shares of our common stock including the underwriters’ exercise of their overallotment option of 1,200,000 shares under our existing shelf registration statement. The offering was priced at $44.00 per share and generated net proceeds of $390.2 million, which were used to repay short-term debt outstanding under our commercial paper program, to fund infrastructure spending primarily to enhance the safety and reliability of our system and for general corporate purposes.
	Share Repurchase Program
	On September 28, 2011 our Board of Directors approved a program authorizing the repurchase of up to five million shares of common stock over a 5-year period. The program is primarily intended to minimize the dilutive effect of equity grants under various benefit related incentive compensation plans of the Company. The program may be terminated or limited at any time. Shares may be repurchased in the open market or in privately negotiated transactions in amounts the Company deems appropriate. As of September 30, 2014, a total of 387,991 shares had been repurchased for an aggregate value of $12.5 million, with no shares repurchased since the first quarter of fiscal 2012.

Debt

Debt	12 Months Ended
	Sep. 30, 2014
Debt Disclosure [Abstract]	'
Debt	'
	Debt
	Long-term debt
	Long-term debt at September 30, 2014 and 2013 consisted of the following:
		2014		2013
		(In thousands)
	Unsecured 4.95% Senior Notes, due October 2014	$	500,000	$	500,000
	Unsecured 6.35% Senior Notes, due 2017	250,000		250,000
	Unsecured 8.50% Senior Notes, due 2019	450,000		450,000
	Unsecured 5.95% Senior Notes, due 2034	200,000		200,000
	Unsecured 5.50% Senior Notes, due 2041	400,000		400,000
	Unsecured 4.15% Senior Notes, due 2043	500,000		500,000
	Medium term 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	4,014		4,329
	Current maturities	—		—
		$	2,455,986	$	2,455,671
	On October 15, 2014, we issued $500 million of 4.125% 30-year unsecured senior notes, which replaced, on a long-term basis, our $500 million unsecured 4.95% senior notes. The effective rate of these notes is 4.086%, after giving effect to the offering costs and the settlement of the associated forward starting interest rate swaps discussed in Note 12. The net proceeds of approximately $494 million were used to repay our $500 million 4.95% senior unsecured notes at maturity on October 15, 2014. Our $500 million 4.95% senior unsecured notes are presented as long-term debt at September 30, 2014 as we demonstrated the ability and intent to refinance through the issuance of new unsecured senior notes.
	We issued $500 million Unsecured 4.15% Senior Notes on January 11, 2013. The effective rate of these notes is 4.67%, after giving effect to offering costs and the settlement of the associated Treasury lock agreements discussed in Note 12. Of the net proceeds of approximately $494 million, $234 million was used to partially repay our commercial paper borrowings and for general corporate purposes. The remaining $260 million was used to repay a short-term financing facility executed on September 27, 2012 to repay commercial paper borrowings used to redeem our $250 million Unsecured 5.125% Senior Notes were scheduled to mature in January 2013. This facility bore interest at a LIBOR-based rate plus a company specific spread.
	Short-term debt
	Our short-term debt is utilized to fund ongoing working capital needs, such as our seasonal requirements for gas supply, general corporate liquidity and capital expenditures. Our short-term borrowings typically reach their highest levels in the winter months.
	We currently finance our short-term borrowing requirements through a combination of a $1.25 billion commercial paper program, four committed revolving credit facilities and one uncommitted revolving credit facility, with a total availability from third-party lenders of approximately $1.3 billion of working capital funding. At September 30, 2014 and 2013, there was $196.7 million and $368.0 million outstanding under our commercial paper program with weighted average interest rates of 0.23% and 0.25%, with average maturities of less than one month. We also use intercompany credit facilities to supplement the funding provided by these third-party committed credit facilities. These facilities are described in greater detail below.
	Regulated Operations
	We fund our regulated operations as needed, primarily through our commercial paper program and three committed revolving credit facilities with third-party lenders that provide approximately $1.3 billion of working capital funding. The first facility is a five-year unsecured facility that was amended on August 22, 2014 to 1) increase the borrowing capacity from $950 million to $1.25 billion with an accordion feature, which, if utilized would increase the borrowing capacity to $1.5 billion and 2) extend the expiration date from August 2018 to August 2019. The credit facility bears interest at a base rate or at a LIBOR-based rate for the applicable interest period, plus a spread ranging from zero percent to two percent, based on the Company’s credit ratings. This credit facility serves primarily as a backup liquidity facility for our commercial paper program. At September 30, 2014, there were no borrowings under this facility, but we had $196.7 million of commercial paper outstanding leaving $1,053.3 million available.
	The second facility is a $25 million unsecured facility that bears interest at a daily negotiated rate, generally based on the Federal Funds rate plus a variable margin. This facility was renewed on April 1, 2014. At September 30, 2014, there were no borrowings outstanding under this facility.
	The third facility which was renewed on September 30, 2014 for $10 million is a committed revolving credit facility, used primarily to issue letters of credit and bears interest at a LIBOR-based rate plus 1.5 percent. At September 30, 2014, there were no borrowings outstanding under this credit facility; however, letters of credit totaling $5.9 million had been issued under the facility at September 30, 2014, which reduced the amount available by a corresponding amount.
	The availability of funds under these credit facilities is subject to conditions specified in the respective credit agreements, all of which we currently satisfy. These conditions include our compliance with financial covenants and the continued accuracy of representations and warranties contained in these agreements. We are required by the financial covenants in each of these facilities to maintain, at the end of each fiscal quarter, a ratio of total debt to total capitalization of no greater than 70 percent. At September 30, 2014, our total-debt-to-total-capitalization ratio, as defined, was 48 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, 2014. There was $326.0 million outstanding under this facility at September 30, 2014.
	Nonregulated Operations
	Atmos Energy Marketing, LLC (AEM), which is wholly owned by AEH, had two $25 million 364-day bilateral credit facilities that expired in December 2013. In December 2013, one of the $25 million 364-day uncommitted bilateral facilities was extended to December 2014. The other $25 million committed bilateral facility was replaced with a $15 million committed 364-day bilateral credit facility in December 2013. These facilities are used primarily to issue letters of credit. Due to outstanding letters of credit, the total amount available to us under these bilateral credit facilities was $32.2 million at September 30, 2014.
	AEH has a $500 million intercompany demand credit facility with AEC. This facility bears interest at a rate equal to the greater of (i) the one-month LIBOR rate plus 3.00 percent or (ii) the rate for AEM’s borrowings under its committed line of credit facility plus 0.75 percent. Applicable state regulatory commissions have approved our use of this facility through December 31, 2014. There were no borrowings outstanding under this facility at September 30, 2014.
	Shelf Registration
	We filed a shelf registration statement with the Securities and Exchange Commission (SEC) on March 28, 2013, that originally permitted us to issue a total of $1.75 billion in common stock and/or debt securities. On February 18, 2014, we completed the public offering of 9,200,000 shares of our common stock, which generated net proceeds of $390.2 million. After giving effect to this issuance and the aforementioned $500 million senior note issuance completed in October 2014, $845 million of securities remained available for issuance under the shelf registration statement until March 28, 2016.
	Debt Covenants
	In addition to the financial covenants described above, our credit facilities and public indentures contain usual and customary covenants for our business, including covenants substantially limiting liens, substantial asset sales and mergers.
	Additionally, our public debt indentures relating to our senior notes and debentures, as well as our revolving credit agreements, each contain a default provision that is triggered if outstanding indebtedness arising out of any other credit agreements in amounts ranging from in excess of $15 million to in excess of $100 million becomes due by acceleration or is not paid at maturity.
	We were in compliance with all of our debt covenants as of September 30, 2014. If we were unable to comply with our debt covenants, we would likely be required to repay our outstanding balances on demand, provide additional collateral or take other corrective actions.
	Maturities of long-term debt at September 30, 2014 were as follows (in thousands):
	2015	$	500,000
	2016	—
	2017	250,000
	2018	—
	2019	450,000
	Thereafter	1,260,000
		$	2,460,000

Retirement_and_Postretirement_

Retirement and Post-retirement Employee Benefit Plans	12 Months Ended
	Sep. 30, 2014
Compensation and Retirement Disclosure [Abstract]	'
Retirement and Post-Retirement Employee Benefit Plans	'
	Retirement and Post-Retirement Employee Benefit Plans
	We have both funded and unfunded noncontributory defined benefit plans that together cover most of our employees. We also maintain post-retirement plans that provide health care benefits to retired employees. Finally, we sponsor defined contribution plans that cover substantially all employees. These plans are discussed in further detail below.
	As a rate regulated entity, we generally recover our pension costs in our rates over a period of up to 15 years. The amounts that have not yet been recognized in net periodic pension cost that have been recorded as regulatory assets are as follows:
		Defined				Supplemental				Postretirement				Total
		Benefits Plans				Executive				Plans
						Retirement Plans
		(In thousands)
	30-Sep-14
	Unrecognized transition obligation	$	—			$	—			$	354			$	354
	Unrecognized prior service credit	(1,927		)		—				(6,168		)		(8,095		)
	Unrecognized actuarial loss	109,767				34,447				7,531				151,745
		$	107,840			$	34,447			$	1,717			$	144,004
	30-Sep-13
	Unrecognized transition obligation	$	—			$	—			$	628			$	628
	Unrecognized prior service credit	(91		)		—				(5,961		)		(6,052		)
	Unrecognized actuarial loss	108,621				31,466				35,961				176,048
		$	108,530			$	31,466			$	30,628			$	170,624
	Defined Benefit Plans
	Employee Pension Plans
	As of September 30, 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 are held within the Atmos Energy Corporation Master Retirement Trust (the Master Trust).
	The Plan is a cash balance pension plan that was established effective January 1999 and covers most of the employees of Atmos Energy’s regulated operations. Opening account balances were established for participants as of January 1999 equal to the present value of their respective accrued benefits under the pension plans which were previously in effect as of December 31, 1998. The Plan credits an allocation to each participant’s account at the end of each year according to a formula based on the participant’s age, service and total pay (excluding incentive pay).
	The Plan also provides for an additional annual allocation based upon a participant’s age as of January 1, 1999 for those participants who were participants in the prior pension plans. The Plan credited this additional allocation each year through December 31, 2008. In addition, at the end of each year, a participant’s account is credited with interest on the employee’s prior year account balance. A special grandfather benefit also applied through December 31, 2008, for participants who were at least age 50 as of January 1, 1999 and who were participants in one of the prior plans on December 31, 1998. Participants are fully vested in their account balances after three years of service and may choose to receive their account balances as a lump sum or an annuity. In August 2010, the Board of Directors of Atmos Energy approved a proposal to close the Plan to new participants effective October 1, 2010. Additionally, employees participating in the Plan as of October 1, 2010 were allowed to make a one-time election to migrate from the Plan into our defined contribution plan, which was enhanced, effective January 1, 2011.
	The Union Plan is a defined benefit plan that covers substantially all full-time union employees in our Mississippi Division. Under this plan, benefits are based upon years of benefit service and average final earnings. Participants vest in the plan after five years and will receive their benefit in an annuity. 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 will transfer to the Plan. Opening account balances will be established at the time of transfer equal to the present value of their respective accrued benefits under the Union Plan at December 31, 2014. In addition, effective January 1, 2015, current retirees in the Union Plan as well as those participants who have terminated and are vested in the Union Plan will transfer to the Plan with the same provisions that were in place at the time of their retirement or termination.
	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 2014 and 2013 we contributed $27.1 million and $32.7 million in cash to the Plans to achieve a desired level of funding while maximizing the tax deductibility of this payment. Based upon market conditions at September 30, 2014, the current funded position of the Plans and the funding requirements under the PPA, we do not anticipate a minimum required contribution for fiscal 2015. 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, 2014 and 2013.
		Targeted		Actual
		Allocation  Range		Allocation
				September 30
	Security Class			2014			2013
	Domestic equities	35%-55%		51.9	%		46.5	%
	International equities	10%-20%		15.3	%		16.1	%
	Fixed income	10%-30%		9.7	%		14.9	%
	Company stock	5%-15%		12.9	%		12.6	%
	Other assets	5%-15%		10.2	%		9.9	%
	At September 30, 2014 and 2013, the Plan held 1,169,700 shares of our common stock, which represented 12.9 percent and 12.6 percent of total Master Trust assets. These shares generated dividend income for the Plan of approximately $1.7 million and $1.6 million during fiscal 2014 and 2013.
	Our employee pension plan expenses and liabilities are determined on an actuarial basis and are affected by numerous assumptions and estimates including the market value of plan assets, estimates of the expected return on plan assets and assumed discount rates and demographic data. We review the estimates and assumptions underlying our employee pension plans annually based upon a September 30 measurement date. The development of our assumptions is fully described in our significant accounting policies in Note 2. The actuarial assumptions used to determine the pension liability for the Plans were determined as of September 30, 2014 and 2013 and the actuarial assumptions used to determine the net periodic pension cost for the Plans were determined as of September 30, 2013, 2012 and 2011. These assumptions are presented in the following table:
		Pension						Pension Cost
		Liability
		2014			2013			2014			2013			2012
	Discount rate	4.43	%		4.95	%		4.95	%		4.04	%		5.05	%
	Rate of compensation increase	3.5	%		3.5	%		3.5	%		3.5	%		3.5	%
	Expected return on plan assets	7.25	%		7.25	%		7.25	%		7.75	%		7.75	%
	The following table presents the Plans’ accumulated benefit obligation, projected benefit obligation and funded status as of September 30, 2014 and 2013:
		2014				2013
		(In thousands)
	Accumulated benefit obligation	$	466,182			$	446,133
	Change in projected benefit obligation:
	Benefit obligation at beginning of year	$	455,799			$	480,031
	Service cost	15,345				17,754
	Interest cost	22,330				19,334
	Actuarial (gain) loss	26,611				(29,822		)
	Benefits paid	(24,519		)		(25,073		)
	Plan amendments	(1,972		)		—
	Divestitures	—				(6,425		)
	Benefit obligation at end of year	493,594				455,799
	Change in plan assets:
	Fair value of plan assets at beginning of year	396,887				343,144
	Actual return on plan assets	35,289				52,496
	Employer contributions	27,110				32,745
	Benefits paid	(24,519		)		(25,073		)
Divestitures	—				(6,425		)
Fair value of plan assets at end of year	434,767				396,887
Reconciliation:
Funded status	(58,827		)		(58,912		)
Unrecognized prior service cost	—				—
Unrecognized net loss	—				—
Net amount recognized	$	(58,827	)		$	(58,912	)
Net periodic pension cost for the Plans for fiscal 2014, 2013 and 2012 is recorded as operating expense and included the following components:
	Fiscal Year Ended September 30
	2014				2013				2012
	(In thousands)
Components of net periodic pension cost:
Service cost	$	15,345			$	17,754			$	15,084
Interest cost	22,330				19,334				21,568
Expected return on assets	(23,601		)		(22,955		)		(21,474		)
Amortization of prior service credit	(136		)		(141		)		(141		)
Recognized actuarial loss	13,777				19,066				14,451
Net periodic pension cost	$	27,715			$	33,058			$	29,488
The following table sets forth by level, within the fair value hierarchy, the Master Trust’s assets at fair value as of September 30, 2014 and 2013. As required by authoritative accounting literature, assets are categorized in their entirety based on the lowest level of input that is significant to the fair value measurement. The methods used to determine fair value for the assets held by the Master Trust are fully described in Note 2. In addition to the assets shown below, the Master Trust had net accounts receivable of $2.7 million and $0.4 million at September 30, 2014 and 2013 which materially approximates fair value due to the short-term nature of these assets.
	Assets at Fair Value as of September 30, 2014
	Level 1				Level 2				Level 3				Total
	(In thousands)
Investments:
Common stocks — domestic equities	$	155,107			$	—			$	—			$	155,107
Money market funds	—				11,226				—				11,226
Registered investment companies:
Domestic funds	63,850				—				—				63,850
International funds	48,134				—				—				48,134
Common/collective trusts — domestic funds	—				61,208				—				61,208
Government securities:
Mortgage-backed securities	—				12,520				—				12,520
U.S. treasuries	3,117				562				—				3,679
Corporate bonds	—				25,734				—				25,734
Limited partnerships	—				50,496				—				50,496
Real estate	—				—				155				155
Total investments at fair value	$	270,208			$	161,746			$	155			$	432,109
	Assets at Fair Value as of September 30, 2013
	Level 1				Level 2				Level 3				Total
	(In thousands)
Investments:
Common stocks — domestic equities	$	143,543			$	—			$	—			$	143,543
Money market funds	—				12,266				—				12,266
Registered investment companies:
Domestic funds	30,200				—				—				30,200
International funds	47,036				—				—				47,036
Common/collective trusts — domestic funds	—				57,627				—				57,627
Government securities:
Mortgage-backed securities	—				18,446				—				18,446
U.S. treasuries	4,117				663				—				4,780
Corporate bonds	—				35,012				—				35,012
Limited partnerships	—				47,417				—				47,417
Real estate	—				—				155				155
Total investments at fair value	$	224,896			$	171,431			$	155			$	396,482
The fair value of our Level 3 real estate assets was determined using a real estate appraisal obtained from an independent third party that consisted of several unobservable inputs such as comparable land sales values per square foot in the range of $0.94 to $2.98 and comparable building sales values per square foot in the range of $23.13 to $30.42.
Supplemental Executive Retirement Plans
We have three nonqualified supplemental plans which provide additional pension, disability and death benefits to our officers, division presidents and certain other employees of the Company.
The first plan is referred to as the Supplemental Executive Benefits Plan (SEBP) and covers our officers, division presidents and certain other employees of the Company who were employed on or before August 12, 1998. The SEBP is a defined benefit arrangement which provides a benefit equal to 75 percent of covered compensation under which benefits paid from the underlying qualified defined benefit plan are an offset to the benefits under the SEBP.
In August 1998, we adopted the Supplemental Executive Retirement Plan (SERP) (formerly known as the Performance-Based Supplemental Executive Benefits Plan), which covers all officers or division presidents selected to participate in the plan between August 12, 1998 and August 5, 2009, any corporate officer who may be appointed to the Management Committee after August 5, 2009 and any other employees selected by our Board of Directors at its discretion. The SERP is a defined benefit arrangement which provides a benefit equal to 60 percent of covered compensation under which benefits paid from the underlying qualified defined benefit plan are an offset to the benefits under the SERP.
Effective August 5, 2009, we adopted a new defined benefit Supplemental Executive Retirement Plan (the 2009 SERP), for corporate officers (other than such officer who is appointed as a member of the Company’s Management Committee), division presidents or any other employees selected at the discretion of the Board. Under the 2009 SERP, a nominal account has been established for each participant, to which the Company contributes at the end of each calendar year an amount equal to ten percent of the total of each participant’s base salary and cash incentive compensation earned during each prior calendar year, beginning December 31, 2009. The benefits vest after three years of service and attainment of age 55 and earn interest credits at the same annual rate as the Company’s Pension Account Plan (currently 4.69%).
On October 2, 2013, due to the retirement of one of our executives, we recognized a settlement loss of $4.5 million associated with our SEBP and made a $16.8 million benefit payment.
On April 1, 2013, due to the retirement of certain executives, we recognized a settlement loss of $3.2 million associated with the supplemental plans and revalued the net periodic pension cost for the remainder of fiscal 2013. The revaluation of the net periodic pension cost resulted in an increase in the discount rate, effective April 1, 2013, to 4.21 percent, which reduced our net periodic pension cost by approximately $0.1 million for the remainder of the fiscal year.
Similar to our employee pension plans, we review the estimates and assumptions underlying our supplemental plans annually based upon a September 30 measurement date using the same techniques as our employee pension plans. The actuarial assumptions used to determine the pension liability for the supplemental plans were determined as of September 30, 2014 and 2013 and the actuarial assumptions used to determine the net periodic pension cost for the supplemental plans were determined as of September 30, 2013, 2012 and 2011. These assumptions are presented in the following table:
	Pension						Pension Cost
	Liability
	2014			2013			2014			2013				2012
Discount rate	4.43	%		4.95	%		4.95	%		4.04	%	(1)		5.05	%
Rate of compensation increase	3.5	%		3.5	%		3.5	%		3.5	%			3.5	%
-1	The discount rate for the supplemental plans increased from 4.04% to 4.21% effective April 1, 2013 due to a settlement loss recorded in fiscal 2013.
The following table presents the supplemental plans’ accumulated benefit obligation, projected benefit obligation and funded status as of September 30, 2014 and 2013:
	2014				2013
	(In thousands)
Accumulated benefit obligation	$	106,276			$	109,817
Change in projected benefit obligation:
Benefit obligation at beginning of year	$	117,080			$	130,186
Service cost	3,607				3,039
Interest cost	4,966				4,755
Actuarial (gain) loss	9,468				(6,451		)
Benefits paid	(5,085		)		(4,375		)
Settlements	(16,817		)		(10,074		)
Benefit obligation at end of year	113,219				117,080
Change in plan assets:
Fair value of plan assets at beginning of year	—				—
Employer contribution	21,902				14,449
Benefits paid	(5,085		)		(4,375		)
Settlements	(16,817		)		(10,074		)
Fair value of plan assets at end of year	—				—
Reconciliation:
Funded status	(113,219		)		(117,080		)
Unrecognized prior service cost	—				—
Unrecognized net loss	—				—
Accrued pension cost	$	(113,219	)		$	(117,080	)
Assets for the supplemental plans are held in separate rabbi trusts. At September 30, 2014 and 2013, assets held in the rabbi trusts consisted of available-for-sale securities of $46.2 million and $44.5 million, which are included in our fair value disclosures in Note 14.
Net periodic pension cost for the supplemental plans for fiscal 2014, 2013 and 2012 is recorded as operating expense and included the following components:
	Fiscal Year Ended September 30
	2014				2013				2012
	(In thousands)
Components of net periodic pension cost:
Service cost	$	3,607			$	3,039			$	2,108
Interest cost	4,966				4,755				5,142
Amortization of transition asset	—				—				—
Amortization of prior service cost	—				—				—
Recognized actuarial loss	1,948				2,918				2,118
Settlements	4,539				3,160				—
Net periodic pension cost	$	15,060			$	13,872			$	9,368
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				Supplemental
	Plans				Plans
	(In thousands)
2015	$	33,592			$	11,381
2016	32,811				4,617
2017	33,131				17,260
2018	33,501				14,772
2019	34,846				7,675
2020-2024	182,998				32,843
Postretirement Benefits
We sponsor the Retiree Medical Plan for Retirees and Disabled Employees of Atmos Energy Corporation (the Atmos Retiree Medical Plan). This plan provides medical and prescription drug protection to all qualified participants based on their date of retirement. The Atmos Retiree Medical Plan provides different levels of benefits depending on the level of coverage chosen by the participants and the terms of predecessor plans; however, we generally pay 80 percent of the projected net claims and administrative costs and participants pay the remaining 20 percent of this cost.
As of September 30, 2009, the Board of Directors approved a change to the cost sharing methodology for employees who had not met the participation requirements by that date for the Atmos Retiree Medical Plan. Starting on January 1, 2015, the contribution rates that will apply to all non-grandfathered participants will be determined using a new cost sharing methodology by which Atmos Energy will limit its contribution to a three percent cost increase in claims and administrative costs each year. If medical costs covered by the Atmos Retiree Medical Plan increase more than three percent annually, participants will be responsible for the additional costs.
Generally, our funding policy is to contribute annually an amount in accordance with the requirements of ERISA. However, additional voluntary contributions are made annually as considered necessary. Contributions are intended to provide not only for benefits attributed to service to date but also for those expected to be earned in the future. We expect to contribute between $20 million and $25 million to our postretirement benefits plan during fiscal 2015.
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, 2014 and 2013.
	Actual
	Allocation
	September 30
Security Class	2014			2013
Diversified investment funds	99.7	%		96.8	%
Cash and cash equivalents	0.3	%		3.2	%
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, 2014 and 2013 and the actuarial assumptions used to determine the net periodic pension cost for the postretirement plan were determined as of September 30, 2013, 2012 and 2011. The assumptions are presented in the following table:
	Postretirement						Postretirement Cost
	Liability
	2014			2013			2014			2013			2012
Discount rate	4.43	%		4.95	%		4.95	%		4.04	%		5.05	%
Expected return on plan assets	4.6	%		4.6	%		4.6	%		4.7	%		5	%
Initial trend rate	7.5	%		8	%		8	%		8	%		8	%
Ultimate trend rate	5	%		5	%		5	%		5	%		5	%
Ultimate trend reached in	2020			2020			2020			2019			2018
The following table presents the postretirement plan’s benefit obligation and funded status as of September 30, 2014 and 2013:
	2014				2013
	(In thousands)
Change in benefit obligation:
Benefit obligation at beginning of year	$	312,148			$	308,315
Service cost	16,784				18,800
Interest cost	15,951				12,964
Plan participants’ contributions	4,435				3,815
Actuarial (gain) loss	(18,963		)		(13,801		)
Benefits paid	(13,580		)		(14,458		)
Plan amendments	(1,657		)		—
Divestitures	—				(3,487		)
Benefit obligation at end of year	315,118				312,148
Change in plan assets:
Fair value of plan assets at beginning of year	106,413				77,072
Actual return on plan assets	14,003				13,432
Employer contributions	23,550				26,552
Plan participants’ contributions	4,435				3,815
Benefits paid	(13,580		)		(14,458		)
Fair value of plan assets at end of year	134,821				106,413
Reconciliation:
Funded status	(180,297		)		(205,735		)
Unrecognized transition obligation	—				—
Unrecognized prior service cost	—				—
Unrecognized net loss	—				—
Accrued postretirement cost	$	(180,297	)		$	(205,735	)
Net periodic postretirement cost for fiscal 2014, 2013 and 2012 is recorded as operating expense and included the components presented below.
	Fiscal Year Ended September 30
	2014				2013				2012
	(In thousands)
Components of net periodic postretirement cost:
Service cost	$	16,784			$	18,800			$	16,353
Interest cost	15,951				12,964				13,861
Expected return on assets	(5,167		)		(3,988		)		(2,607		)
Amortization of transition obligation	274				1,081				1,511
Amortization of prior service credit	(1,450		)		(1,450		)		(1,450		)
Recognized actuarial loss	631				4,196				2,648
Net periodic postretirement cost	$	27,023			$	31,603			$	30,316
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				One-Percentage
	Point Increase				Point Decrease
	(In thousands)
Effect on total service and interest cost components	$	4,533			$	(3,700	)
Effect on postretirement benefit obligation	$	40,922			$	(34,169	)
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, 2014 and 2013. 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, 2014
	Level 1				Level 2				Level 3				Total
	(In thousands)
Investments:
Money market funds	$	—			$	434			$	—			$	434
Registered investment companies:
Domestic funds	11,398				—				—				11,398
International funds	122,989				—				—				122,989
Total investments at fair value	$	134,387			$	434			$	—			$	134,821
	Assets at Fair Value as of September 30, 2013
	Level 1				Level 2				Level 3				Total
	(In thousands)
Investments:
Money market funds	$	—			$	3,356			$	—			$	3,356
Registered investment companies:
Domestic funds	9,614				—				—				9,614
International funds	93,443				—				—				93,443
Total investments at fair value	$	103,057			$	3,356			$	—			$	106,413
Estimated Future Benefit Payments
The following benefit payments paid by us, retirees and prescription drug subsidy payments for our postretirement benefit plans, which reflect expected future service, as appropriate, are expected to be paid in the following fiscal years. Company payments for fiscal 2015 include contributions to our postretirement plan trusts.
	Company				Retiree				Subsidy				Total
	Payments				Payments				Payments				Postretirement
													Benefits
	(In thousands)
2015	$	22,177			$	3,582			$	—			$	25,759
2016	15,008				4,615				—				19,623
2017	17,551				5,796				—				23,347
2018	19,660				7,148				—				26,808
2019	21,302				8,549				—				29,851
2020-2024	127,741				63,524				—				191,265
Defined Contribution Plans
As of September 30, 2014, we maintained three defined contribution benefit plans: the Atmos Energy Corporation Retirement Savings Plan and Trust (the Retirement Savings Plan), the Atmos Energy Corporation Savings Plan for MVG Union Employees (the Union 401K Plan) and the Atmos Energy Holdings, LLC 401K Profit-Sharing Plan (the AEH 401K Profit-Sharing Plan).
The Retirement Savings Plan covers substantially all employees in our regulated operations and is subject to the provisions of Section 401(k) of the Internal Revenue Code. Effective January 1, 2007, employees automatically become participants of the Retirement Savings Plan on the date of employment. Participants may elect a salary reduction up to a maximum of 65 percent of eligible compensation, as defined by the Plan, not to exceed the maximum allowed by the Internal Revenue Service. New participants are automatically enrolled in the Plan at a salary reduction amount of four percent of eligible compensation, from which they may opt out. We match 100 percent of a participant’s contributions, limited to four percent of the participant’s salary, in our common stock. However, participants have the option to immediately transfer this matching contribution into other funds held within the plan. Participants are eligible to receive matching contributions after completing one year of service. Participants are also permitted to take out loans against their accounts subject to certain restrictions. In August 2010, the Board of Directors of Atmos Energy approved a proposal to close the Pension Account Plan to new participants effective October 1, 2010. New employees participate in our defined contribution plan, which was enhanced, effective January 1, 2011. Employees participating in the Pension Account Plan as of October 1, 2010 were allowed to make a one-time election to migrate from the Plan into the Retirement Savings Plan, effective January 1, 2011. Under the enhanced plan, 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.
The Union 401K Plan covers substantially all Mississippi Division employees who are members of the International Chemical Workers Union Council, United Food and Commercial Workers Union International (the Union) and is subject to the provisions of Section 401(k) of the Internal Revenue Code. Employees of the Union automatically become participants of the Union 401K plan on the date of union membership. We match 50 percent of a participant’s contribution in cash, limited to six percent of the participant’s eligible contribution. Participants are also permitted to take out loans against their accounts subject to certain restrictions. In June 2014, active collectively bargained employees of Atmos Energy’s Mississippi Division voted to decertify the Union.  As a result, effective July 19, 2014, active participants of the Union 401K Plan were eligible to participate in the Retirement Savings Plan. Participants that do not actively elect to participate in the Retirement Savings Plan will be automatically enrolled in the Retirement Savings Plan at a salary reduction level of four percent, which they may opt out of within 30 days. In addition, participants may elect to transfer their funds from the Union 401K Plan to the Retirement Savings Plan. Effective January 1, 2015, all remaining participant balances will transfer to the Retirement Savings Plan. Following this transfer, the Union 401K Plan will be terminated.
Matching contributions to the Retirement Savings Plan and the Union 401K Plan are expensed as incurred and amounted to $10.9 million, $10.4 million and $10.5 million for fiscal years 2014, 2013 and 2012. 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 2014, 2013 or 2012. At September 30, 2014 and 2013, the Retirement Savings Plan held 4.5 percent and 4.9 percent of our outstanding common stock.
The AEH 401K Profit-Sharing Plan covers substantially all AEH employees and is subject to the provisions of Section 401(k) of the Internal Revenue Code. Participants may elect a salary reduction up to a maximum of 75 percent of eligible compensation, as defined by the Plan, not to exceed the maximum allowed by the Internal Revenue Service. The Company may elect to make safe harbor contributions up to four percent of the employee’s salary which vest immediately. The Company may also make discretionary profit sharing contributions to the AEH 401K Profit-Sharing Plan. Participants become fully vested in the discretionary profit-sharing contributions after three years of service. Participants are also permitted to take out loans against their accounts subject to certain restrictions. Discretionary contributions to the AEH 401K Profit-Sharing Plan are expensed as incurred and amounted to $1.4 million, $1.1 million and $1.2 million for fiscal years 2014, 2013 and 2012.

Stock_and_Other_Compensation_P

Stock and Other Compensation Plans	12 Months Ended
	Sep. 30, 2014
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]	'
Stock and Other Compensation Plans	'
	Stock and Other Compensation Plans
	Stock-Based Compensation Plans
	Total stock-based compensation expense was $25.5 million, $17.8 million and $19.2 million for the fiscal years ended September 30, 2014, 2013 and 2012, primarily related to restricted stock costs.
	1998 Long-Term Incentive Plan
	In August 1998, the Board of Directors approved and adopted the 1998 Long-Term Incentive Plan (LTIP), which became effective in October 1998 after approval by our shareholders. The LTIP is a comprehensive, long-term incentive compensation plan providing for discretionary awards of incentive stock options, non-qualified stock options, stock appreciation rights, bonus stock, time-lapse restricted stock, time-lapse restricted stock units, performance-based restricted stock units and stock units to certain employees and non-employee directors of the Company and our subsidiaries. The objectives of this plan include attracting and retaining the best personnel, providing for additional performance incentives and promoting our success by providing employees with the opportunity to acquire common stock.
	As of September 30, 2014, we were authorized to grant awards for up to a maximum of 8.7 million shares of common stock under this plan subject to certain adjustment provisions. As of September 30, 2014, 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 845,139 shares were available for future issuance.
	Restricted Stock Unit Award Grants
	As noted above, the LTIP provides for discretionary awards of restricted stock units to help attract, retain and reward employees of Atmos Energy and its subsidiaries. Certain of these awards vest based upon the passage of time and other awards vest based upon the passage of time and the achievement of specified performance targets. The fair value of the awards granted is based on the market price of our stock at the date of grant. The associated expense is recognized ratably over the vesting period.
	Employees who are granted time-lapse restricted stock units under our LTIP have a nonforfeitable right to dividend equivalents that are paid at the same rate 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 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, 2014, 2013 and 2012:
		2014				2013				2012
		Number of		Weighted		Number of		Weighted		Number of		Weighted
		Restricted		Average		Restricted		Average		Restricted		Average
		Units		Grant-Date		Units		Grant-Date		Units		Grant-Date
				Fair				Fair				Fair
				Value				Value				Value
	Nonvested at beginning of year	1,052,844		$	36.2	1,262,582		$	32.46	1,264,142		$	29.56
	Granted	464,438		45.05		473,775		40.48		532,711		33.44
	Vested	(524,532	)	32.67		(657,795	)	32.2		(494,308	)	26.32
	Forfeited	(4,113	)	39		(25,718	)	33.42		(39,963	)	29.83
	Nonvested at end of year	988,637		$	42.22	1,052,844		$	36.2	1,262,582		$	32.46
	As of September 30, 2014, there was $5.3 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, 2014, 2013 and 2012 was $17.1 million, $21.2 million and $13.0 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_Consolidat

Details of Selected Consolidated Balance Sheet Captions	12 Months Ended
	Sep. 30, 2014
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, 2014 and 2013:
		September 30
		2014			2013
		(In thousands)
	Billed accounts receivable	$	262,937		$	230,712
	Unbilled revenue	62,484			58,710
	Other accounts receivable	41,971			33,194
	Total accounts receivable	367,392			322,616
	Less: allowance for doubtful accounts	(23,992		)	(20,624		)
	Net accounts receivable	$	343,400		$	301,992
	Other current assets
	Other current assets as of September 30, 2014 and 2013 were comprised of the following accounts.
		September 30
		2014			2013
		(In thousands)
	Assets from risk management activities	$	45,827		$	11,966
	Deferred gas costs	20,069			15,152
	Taxes receivable	5,481			3,141
	Prepaid expenses	25,039			21,666
	Materials and supplies	5,704			5,511
	Other	9,145			6,765
	Total	$	111,265		$	64,201
	Property, plant and equipment
	Property, plant and equipment was comprised of the following as of September 30, 2014 and 2013:
		September 30
		2014			2013
		(In thousands)
	Production plant	$	4,821		$	5,020
	Storage plant	275,579			262,246
	Transmission plant	1,622,846			1,362,662
	Distribution plant	5,522,794			5,061,711
	General plant	735,223			716,189
	Intangible plant	38,858			38,444
		8,200,121			7,446,272
	Construction in progress	247,579			275,747
		8,447,700			7,722,019
	Less: accumulated depreciation and amortization	(1,721,794		)	(1,691,364		)
	Net property, plant and equipment(1)	$	6,725,906		$	6,030,655
	(1)	Net property, plant and equipment includes plant acquisition adjustments of $(76.4) million and $(83.8) million at September 30, 2014 and 2013.
	Goodwill
	The following presents our goodwill balance allocated by segment and changes in the balance for the fiscal year ended September 30, 2014:
		Regulated			Regulated			Nonregulated		Total
		Distribution			Pipeline
		(In thousands)
	Balance as of September 30, 2013	$	574,190		$	132,462		$	34,711	$	741,363
	Deferred tax adjustments on prior acquisitions(1)	626			40			—		666
	Balance as of September 30, 2014	$	574,816		$	132,502		$	34,711	$	742,029
	(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 2014.
	Deferred charges and other assets
	Deferred charges and other assets as of September 30, 2014 and 2013 were comprised of the following accounts.
		September 30
		2014			2013
		(In thousands)
	Marketable securities	$	79,613		$	72,682
	Regulatory assets	230,240			273,287
	Deferred financing costs	13,698			15,199
	Assets from risk management activities	13,038			109,354
	Other	14,340			14,595
	Total	$	350,929		$	485,117
	Accounts payable and accrued liabilities
Accounts payable and accrued liabilities as of September 30, 2014 and 2013 were comprised of the following accounts.
	September 30
	2014			2013
	(In thousands)
Trade accounts payable	$	77,860		$	70,116
Accrued gas payable	179,425			121,202
Accrued liabilities	54,319			50,293
Total	$	311,604		$	241,611
Other current liabilities
Other current liabilities as of September 30, 2014 and 2013 were comprised of the following accounts.
	September 30
	2014			2013
	(In thousands)
Customer credit balances and deposits	$	82,085		$	76,313
Accrued employee costs	46,445			54,034
Deferred gas costs	35,063			16,481
Accrued interest	36,768			36,744
Liabilities from risk management activities	1,730			1,543
Taxes payable	77,601			66,960
Pension and postretirement obligations	11,380			22,940
Current deferred tax liability	48,751			14,697
Regulatory cost of removal accrual	45,061			68,225
Other	17,467			10,954
Total	$	402,351		$	368,891
Deferred credits and other liabilities
Deferred credits and other liabilities as of September 30, 2014 and 2013 were comprised of the following accounts.
	September 30
	2014			2013
	(In thousands)
Customer advances for construction	$	9,883		$	11,723
Regulatory liabilities	4,472			1,123
Asset retirement obligation	10,508			6,764
Liabilities from risk management activities	20,126			—
Other	23,881			17,953
Total	$	68,870		$	37,563

Leases

Leases	12 Months Ended
	Sep. 30, 2014
Leases [Abstract]	'
Leases	'
	Leases
	Capital and Operating 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 20 years and generally provide for the payment of taxes, insurance and maintenance by the lessee. Renewal options exist for certain of these leases. We have also entered into capital leases for division offices and operating facilities. Property, plant and equipment included amounts for capital leases of $1.3 million at September 30, 2014 and 2013. Accumulated depreciation for these capital leases totaled $1.1 million and $1.0 million at September 30, 2014 and 2013. Depreciation expense for these assets is included in consolidated depreciation expense on the consolidated statement of income.
	The related future minimum lease payments at September 30, 2014 were as follows:
		Capital		Operating
		Leases		Leases
		(In thousands)
	2015	$	186	$	16,673
	2016	186		16,021
	2017	186		16,330
	2018	78		15,907
	2019	—		15,138
	Thereafter	—		75,620
	Total minimum lease payments	636		$	155,689
	Less amount representing interest	123
	Present value of net minimum lease payments	$	513
	Consolidated lease and rental expense amounted to $31.7 million, $32.4 million and $33.6 million for fiscal 2014, 2013 and 2012.

Commitments_and_Contingencies

Commitments and Contingencies	12 Months Ended
	Sep. 30, 2014
Commitments and Contingencies Disclosure [Abstract]	'
Commitments and Contingencies	'
	Commitments and Contingencies
	Litigation
	Beginning in April 2009, Atmos Energy and two subsidiaries of AEH, Atmos Energy Marketing, LLC (AEM) and Atmos Gathering Company, LLC (AGC) (collectively, the Atmos Entities), were involved in a lawsuit filed in the Circuit Court of Edmonson County, Kentucky related to our Park City Gathering Project. The dispute which gave rise to the litigation involves the amount of royalties due from a third party producer to landowners (who own the mineral rights) for natural gas produced from the landowners’ properties. The third party producer was operating pursuant to leases between the landowners and certain investors/working interest owners. The third party producer filed a petition in bankruptcy, which was subsequently dismissed due to the lack of meaningful assets to reorganize or liquidate.
	Although certain Atmos Energy companies entered into contracts with the third party producer to gather, treat and ultimately sell natural gas produced from the landowners’ properties, no Atmos Energy company had a contractual relationship with the landowners or the investors/working interest owners. After the lawsuit was filed, the landowners were successful in terminating for non-payment of royalties the leases related to the production of natural gas from their properties. Subsequent to termination, the investors/working interest owners under such leases filed additional claims against us for the termination of the leases.
	During the trial, the landowners and the investors/working interest owners requested an award of compensatory damages plus punitive damages against us. On December 17, 2010, the jury returned a verdict in favor of the landowners and investor/working interest owners and awarded compensatory damages of $3.8 million and punitive damages of $27.5 million payable by Atmos Energy and the two AEH subsidiaries.
	A hearing was held on February 28, 2011 to hear a number of motions, including a motion to dismiss the jury verdict and a motion for a new trial. The motions to dismiss the jury verdict and for a new trial were denied. However, the total punitive damages award was reduced from $27.5 million to $24.7 million. On October 17, 2011, we filed our brief of appellants with the Kentucky Court of Appeals (Court), appealing the verdict of the trial court. The appellees in this case subsequently filed their appellees’ brief with the Court on January 16, 2012, with our reply brief being filed with the Court on March 19, 2012. Oral arguments were held in the case on August 27, 2012.
	In an opinion handed down on January 25, 2013, the Court of Appeals overturned the $28.5 million jury verdict returned against the Atmos Entities. In a unanimous decision by a three-judge panel, the Court of Appeals reversed the claims asserted by the landowners and investors/working interest owners. The Court of Appeals concluded that all of such claims that the Atmos Entities appealed should have been dismissed by the trial court as a matter of law. The Court of Appeals let stand the jury verdict on one claim that Atmos Energy and our subsidiaries chose not to appeal, which was a trespass claim. The jury had awarded a total of $10,000 in compensatory damages to one landowner on that claim. The Court of Appeals vacated all of the other damages awarded by the jury and remanded the case to the trial court for a new trial, solely on the issue of whether punitive damages should be awarded to that landowner and, if so, in what amount.
	The investors/working interest owners, on February 25, 2013, and the landowners, on March 19, 2013, each filed with the Supreme Court of Kentucky, separate motions for discretionary review of the opinion of the Court of Appeals. We filed a response to the motion filed by the investors/working owners on March 27, 2013 and to the landowners’ motion on April 17, 2013. The Kentucky Supreme Court denied the motions for discretionary review on February 12, 2014 and the decision of the Court of Appeals became final on February 21, 2014.  We had previously accrued what we believed to be an adequate amount for the anticipated resolution of this matter. This accrual was reversed during the second fiscal quarter of fiscal 2014 as the appellate process in this case had been completed. Atmos Energy had also filed a motion with the trial court, the Circuit Court of Edmonson County, Kentucky, on March 10, 2014, seeking a ruling that the remaining landowner was not entitled to any punitive damages on the sole remaining claim of trespass.  On May 19, 2014, the Edmonson County Circuit Court entered judgment dismissing any claim for punitive damages relating to the trespass claim. There was no appeal of this judgment. The lawsuit in Edmonson County has now been fully resolved.
	In addition, in a related matter, on July 12, 2011, the Atmos Entities filed a lawsuit in the United States District Court, Western District of Kentucky, Atmos Energy Corporation et al.vs. Resource Energy Technologies, LLC and Robert Thorpe and John F. Charles, against the third party producer and its affiliates to recover all costs, including attorneys’ fees, incurred by the Atmos Entities, which are associated with the defense and appeal of the case discussed above as well as for all damages awarded to the plaintiffs in such case against the Atmos Entities. The total amount of damages being claimed in the lawsuit is about $3.5 million, plus interest that continues to accrue. This lawsuit is based upon the indemnification provisions agreed to by the third party producer in favor of Atmos Gathering that are contained in an agreement entered into between Atmos Gathering and the third party producer in May 2009. The defendants filed a motion to dismiss the case on August 25, 2011, with Atmos Energy filing a brief in response to such motion on September 19, 2011. On March 27, 2012 the court denied the motion to dismiss. Atmos Energy filed a motion for partial summary judgment against the defendants with the District Court on July 15, 2014 and filed an Amended Complaint on July 18, 2014.
	On August 28, 2014, the court entered an order authorizing the withdrawal of the lawyer representing the estate of Robert Thorpe, giving the Thorpe Estate until October 2, 2014 to engage a new lawyer. On September 29, 2014, Resource Energy Technologies, LLC and John Charles, individually, entered into an agreed-upon judgment in favor of the Atmos Entities in the amount of $3.6 million, which resolved all claims by the Atmos Entities against those defendants and which dismissed with prejudice all counterclaims against the Atmos Entities. That judgment was settled with the Atmos Entities for $15,000, based on information obtained in discovery that showed those defendants lacked the ability to pay. The only claims remaining in the case are the Atmos Entities’ claims against the Thorpe Estate. The Thorpe Estate has not responded to the motion for partial summary judgment or the amended complaint. In a hearing held on October 7, 2014, the court was advised that the Thorpe Estate was insolvent and without funds to hire another attorney. The court has entered an order to show cause setting the case for a hearing on December 3, 2014 and indicated that if the Thorpe Estate fails to appear, an order of default will be entered.
	Tennessee Business License Tax
	Atmos Energy, through its affiliate, AEM, has been involved in a dispute with the Tennessee Department of Revenue (TDOR) regarding sales business tax audits over a period of several years. The cumulative assessment approximated $12 million as of March 31, 2014, which AEM challenged. We had previously accrued in prior years what we believed to be an adequate amount for the anticipated resolution of this matter. With respect to certain issues, AEM and the TDOR filed competing Partial Motions for Summary Judgment with the Chancery Court. On August 2, 2013, the Chancery Court granted the TDOR's Partial Motion for Summary Judgment and denied AEM's Partial Motion for Summary Judgment. An agreed order of dismissal with prejudice between AEM and TDOR was approved by the Chancery Court and entered on May 2, 2014, whereby AEM agreed to pay $6.2 million to TDOR to resolve all business tax-related liabilities outstanding through September 2014. The State of Tennessee also passed related legislation, effective July 1, 2014, that should help minimize any disputes over this type of sales business tax in the future.
	We are a party to other litigation and claims that have arisen in the ordinary course of our business. While the results of such litigation and claims cannot be predicted with certainty, we believe the final outcome of such litigation and claims both individually and in the aggregate will not have a material adverse effect on our financial condition, results of operations or cash flows.
	Environmental Matters
	We are a party to environmental matters and claims that have arisen in the ordinary course of our business. While the ultimate results of response actions to these environmental matters and claims cannot be predicted with certainty, we believe the final outcome of such response actions will not have a material adverse effect on our financial condition, results of operations or cash flows because we believe that the expenditures related to such response actions will either be recovered through rates, shared with other parties or are adequately covered by insurance.
	Purchase Commitments
	Our regulated distribution divisions maintain supply contracts with several vendors that generally cover a period of up to one year. Commitments for estimated base gas volumes are established under these contracts on a monthly basis at contractually negotiated prices. Commitments for incremental daily purchases are made as necessary during the month in accordance with the terms of the individual contract.
	Our Mid-Tex Division also maintains a limited number of long-term supply contracts to ensure a reliable source of gas for our customers in its service area which obligate it to purchase specified volumes at prices indexed to natural gas distribution hubs. At September 30, 2014, we were committed to purchase 49.7 Bcf within one year and 69.8 Bcf within one to three years under indexed contracts. Purchases under these contracts totaled $140.9 million, $89.0 million and $72.2 million for 2014, 2013, 2012.
	Our nonregulated segment has commitments to purchase physical quantities of natural gas under contracts indexed to the forward NYMEX strip or fixed price contracts. At September 30, 2014, we were committed to purchase 111.5 Bcf within one year, 19.8 Bcf within one to three years and 0.5 Bcf after three years under indexed contracts. We are committed to purchase 7.8 Bcf within one year under fixed price contracts with prices ranging from $1.96 to $4.49 per Mcf. Purchases under these contracts totaled $1,687.5 million, $1,246.1 million and $978.8 million for 2014, 2013 and 2012.
	In addition, our nonregulated segment maintains long-term contracts related to storage and transportation. The estimated contractual demand fees for contracted storage and transportation under these contracts as of September 30, 2014 are as follows (in thousands):
	2015	$	7,426
	2016	2,117
	2017	1,437
	2018	773
	2019	143
	Thereafter	214
		$	12,110
	Other Contingencies
	In December 2007, the Company received data requests from the Division of Investigations of the Office of Enforcement of the Federal Energy Regulatory Commission (the “Commission”) in connection with its investigation into possible violations of the Commission’s posting and competitive bidding regulations for pre-arranged released firm capacity on natural gas pipelines.
	The Company and the Commission entered into a stipulation and consent agreement, which was approved by the Commission on December 9, 2011, thereby resolving this investigation. The Commission’s findings of violations were limited to the nonregulated operations of the Company. Under the terms of the agreement, the Company paid to the United States Treasury a total civil penalty of approximately $6.4 million and to energy assistance programs approximately $5.6 million in disgorgement of unjust profits plus interest for violations identified during the investigation. The resolution of this matter did not have a material adverse impact on the Company’s financial position, results of operations or cash flows and none of the payments were charged to any of the Company’s customers. In addition, none of the services the Company provides to any of its regulated or nonregulated customers were affected by the agreement.
	In July 2010, the Dodd-Frank Act was enacted, representing an extensive overhaul of the framework for regulation of U.S. financial markets. The Dodd-Frank Act required various regulatory agencies, including the SEC and the Commodities Futures Trading Commission, to establish regulations for implementation of many of the provisions of the Dodd-Frank Act. A number of those regulations have been adopted; we have enacted new procedures and modified existing business practices and contractual arrangements to comply with such regulations. We expect additional regulations to be issued, which should provide additional clarity regarding the extent of the impact of this legislation on us. The costs of participating in financial markets for hedging certain risks inherent in our business may be further increased when these expected additional regulations are adopted. We also anticipate that the Commodities Futures Trading Commission will issue additional related reporting and disclosure obligations.

Income_Taxes

Income Taxes	12 Months Ended
	Sep. 30, 2014
Income Tax Disclosure [Abstract]	'
Income Taxes	'
	Income Taxes
	The components of income tax expense from continuing operations for 2014, 2013 and 2012 were as follows:
		2014			2013			2012
		(In thousands)
	Current
	Federal	$	—		$	—		$	631
	State	5,527			8,178			6,888
	Deferred
	Federal	169,106			124,836			103,971
	State	12,375			9,605			(13,237		)
	Investment tax credits	(6		)	(20		)	(27		)
		$	187,002		$	142,599		$	98,226
	Reconciliations of the provision for income taxes computed at the statutory rate to the reported provisions for income taxes from continuing operations for 2014, 2013 and 2012 are set forth below:
		2014			2013			2012
		(In thousands)
	Tax at statutory rate of 35%	$	166,887		$	130,655		$	101,648
	Common stock dividends deductible for tax reporting	(2,307		)	(2,153		)	(2,096		)
	State taxes (net of federal benefit)	11,636			11,559			(4,127		)
	Change in valuation allowance	6,969			1,085			—
	Other, net	3,817			1,453			2,801
	Income tax expense	$	187,002		$	142,599		$	98,226
	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, 2014 and 2013 are presented below:
		2014			2013
		(In thousands)
	Deferred tax assets:
	Employee benefit plans	$	116,157		$	115,970
	Interest rate agreements	10,565			—
	Net operating loss carryforwards	236,626			196,296
	Charitable and other credit carryforwards	21,614			20,939
	Other	28,849			38,013
	Total deferred tax assets	413,811			371,218
	Valuation allowance	(6,969		)	(1,085		)
	Net deferred tax assets	406,842			370,133
	Deferred tax liabilities:
	Difference in net book value and net tax value of assets	(1,655,894		)	(1,445,450		)
	Pension funding	(17,890		)	(23,480		)
	Gas cost adjustments	(31,252		)	(19,182		)
	Interest rate agreements	—			(21,726		)
	Other	(37,173		)	(39,045		)
	Total deferred tax liabilities	(1,742,209		)	(1,548,883		)
	Net deferred tax liabilities	$	(1,335,367	)	$	(1,178,750	)
	Deferred credits for rate regulated entities	$	(109	)	$	(51	)
	At September 30, 2014, we had $224.2 million of federal net operating loss carryforwards, $12.4 million of state net operating loss carryforwards (net of federal effects), $10.1 million of federal alternative minimum tax credit carryforwards, $1.0 million of state tax credits and $10.5 million in charitable contribution carryforwards. The alternative minimum tax credit carryforwards do not expire. The federal net operating loss carryforwards are available to offset taxable income and will begin to expire in 2029. Depending on the jurisdiction in which the state net operating loss was generated, the state net operating loss carryforwards will begin to expire between 2016 and 2030. The state tax credits will begin to expire in 2018.
	The Company’s charitable contribution carryforwards expire in 2014 - 2019. We believe it is more likely than not that the benefit from certain charitable contribution carryforwards will not be realized. Due to the uncertainty of realizing a benefit from the deferred tax asset recorded for charitable contribution carryforwards, a valuation allowance of 7.0 million and 1.1 million was recognized for the years ended September 30, 2014 and 2013.
	At September 30, 2014, we had recorded liabilities associated with unrecognized tax benefits totaling $12.6 million. The following table reconciles the beginning and ending balance of our unrecognized tax benefits:
		2014			2013
		(In thousands)
	Unrecognized tax benefits - beginning balance	$	4,158		$	2,817
	Increase resulting from prior period tax positions	3,846			—
	Increase resulting from current period tax positions	4,625			1,341
	Unrecognized tax benefits - ending balance	12,629			4,158
	Accrued interest and penalties	411			—
	Gross unrecognized tax benefits	13,040			4,158
	Less: deferred federal and state income tax benefits	(4,564		)	(1,455		)
	Total unrecognized tax benefits that, if recognized, would impact the effective income tax rate as of the end of the year	$	8,476		$	2,703
	Additionally, results for fiscal 2012 were favorably impacted by a state tax benefit of $13.6 million (net of federal effects). Due to the completion of the sale of our Missouri, Iowa and Illinois service areas in the fiscal fourth quarter, the Company updated its analysis of the tax rate at which deferred taxes would reverse in the future to reflect the sale of these service areas. The updated analysis supported a reduction in the deferred tax rate which when applied to the balance of taxable income deferred to future periods resulted in a reduction of the Company’s overall deferred tax liability.
	We file income tax returns in the U.S. federal jurisdiction as well as in various states where we have operations. We have concluded substantially all U.S. federal income tax matters through fiscal year 2007.

Financial_Instruments

Financial Instruments	12 Months Ended
	Sep. 30, 2014
Derivative Instruments and Hedging Activities Disclosure [Abstract]	'
Financial Instruments	'
	Financial Instruments
	We use financial instruments to mitigate commodity price risk and interest rate risk. The objectives and strategies for using financial instruments have been tailored to our regulated and nonregulated businesses. Currently, we utilize financial instruments in our regulated distribution and nonregulated segments. We currently do not manage commodity price risk with financial instruments in our regulated pipeline segment.
	Our financial instruments do not contain any credit-risk-related or other contingent features that could cause accelerated payments when our financial instruments are in net liability positions.
	As discussed in Note 2, we report our financial instruments as risk management assets and liabilities, each of which is classified as current or noncurrent based upon the anticipated settlement date of the underlying financial instrument. The following table shows the fair values of our risk management assets and liabilities by segment at September 30, 2014 and 2013:
		Regulated				Nonregulated				Total
		Distribution
		(In thousands)
	30-Sep-14
	Assets from risk management activities, current(1)	$	23,102			$	22,725			$	45,827
	Assets from risk management activities, noncurrent	13,038				—				13,038
	Liabilities from risk management activities, current(1)	(1,730		)		—				(1,730		)
	Liabilities from risk management activities, noncurrent(1)	(20,126		)		—				(20,126		)
	Net assets	$	14,284			$	22,725			$	37,009
	30-Sep-13
	Assets from risk management activities, current(2)	$	1,837			$	10,129			$	11,966
	Assets from risk management activities, noncurrent	109,354				—				109,354
	Liabilities from risk management activities, current(2)	(1,543		)		—				(1,543		)
	Liabilities from risk management activities, noncurrent(2)	—				—				—
	Net assets	$	109,648			$	10,129			$	119,777
	(1)	Includes $25.8 million of cash held on deposit to collateralize certain financial instruments. Of this amount, $3.1 million was used to offset current and noncurent risk management liabilities under master netting arrangements and the remaining $22.7 million is classified as current risk management assets.
	(2)	Includes $24.8 million of cash held on deposit to collateralize certain financial instruments. Of this amount, $14.7 million was used to offset current and noncurrent risk management liabilities under master netting arrangements and the remaining $10.1 million is classified as current risk management assets.
	Regulated Commodity Risk Management Activities
	Although our purchased gas cost adjustment mechanisms essentially insulate our regulated distribution segment from commodity price risk, our customers are exposed to the effects of volatile natural gas prices. We manage this exposure through a combination of physical storage, fixed-price forward contracts and financial instruments, primarily over-the-counter swap and option contracts, in an effort to minimize the impact of natural gas price volatility on our customers during the winter heating season.
	Our regulated distribution gas supply department is responsible for executing this segment’s commodity risk management activities in conformity with regulatory requirements. In jurisdictions where we are permitted to mitigate commodity price risk through financial instruments, the relevant regulatory authorities may establish the level of heating season gas purchases that can be hedged. Historically, if the regulatory authority does not establish this level, we seek to hedge between 25 and 50 percent of anticipated heating season gas purchases using financial instruments. For the 2013-2014 heating season (generally October through March), in the jurisdictions where we are permitted to utilize financial instruments, we hedged approximately 32 percent, or approximately 24.8 Bcf of the winter flowing gas requirements at a weighted average cost of approximately $4.02 per Mcf. We have not designated these financial instruments as hedges.
	Nonregulated Commodity Risk Management Activities
	In our nonregulated operations, we buy, sell and deliver natural gas at competitive prices by aggregating and purchasing gas supply, arranging transportation and storage logistics and effectively managing commodity price risk.
	As a result of these activities, our nonregulated segment is exposed to risks associated with changes in the market price of natural gas. We manage our exposure to such risks through a combination of physical storage and financial instruments, including futures, over-the-counter and exchange-traded options and swap contracts with counterparties. Future contracts provide the right to buy or sell the commodity at a fixed price in the future. Option contracts provide the right, but not the requirement, to buy or sell the commodity at a fixed price. Swap contracts require receipt of payment for the commodity based on the difference between a fixed price and the market price on the settlement date.
	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 deliver gas to customers. These financial instruments have maturity dates ranging from one to 61 months. We use financial instruments, designated as fair value hedges, to hedge natural gas inventory used in these operations. We also use storage and basis swaps, futures and various over-the-counter and exchange-traded options primarily to protect the economic value of our fixed price and storage books. These financial instruments have not been designated as hedges.
	Our nonregulated risk management activities are controlled through various risk management policies and procedures. Our Audit Committee has oversight responsibility for our nonregulated risk management limits and policies. A risk committee, comprised of corporate and business unit officers, is responsible for establishing and enforcing our nonregulated risk management policies and procedures.
	Under our risk management policies, we seek to match our financial instrument positions to our physical storage positions as well as our expected current and future sales and purchase obligations in order to maintain no open positions at the end of each trading day. The determination of our net open position as of any day, however, requires us to make assumptions as to future circumstances, including the use of gas by our customers in relation to our anticipated storage and market positions. Because the price risk associated with any net open position at the end of each day may increase if the assumptions are not realized, we review these assumptions as part of our daily monitoring activities. Our operations can also be affected by intraday fluctuations of gas prices, since the price of natural gas purchased or sold for future delivery earlier in the day may not be hedged until later in the day. At times, limited net open positions related to our existing and anticipated commitments may occur. At the close of business on September 30, 2014, our nonregulated segment had net open positions (including existing storage and related financial contracts) of 0.1 Bcf.
	Interest Rate Risk Management Activities
	We periodically manage interest rate risk through the use of forward starting interest rate swaps, interest rate swaps, and prior to fiscal 2012, Treasury lock agreements, 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 anticipated issuance of $500 million and $250 million unsecured senior notes in fiscal 2015 and fiscal 2017, which we designated as cash flow hedges at the time the agreements were executed. In fiscal 2014, we entered into forward starting interest rate swaps to effectively fix the Treasury yield component associated with $400 million of the anticipated issuance of $450 million unsecured senior notes in fiscal 2019, which we designated as cash flow hedges at the time the agreements were executed. Accordingly, unrealized gains and losses associated with the forward starting interest rate swaps 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.
	In August 2011, we entered into three Treasury lock agreements to fix the Treasury yield component of the interest cost associated with $350 million out of a total $500 million of senior notes that were issued on January 11, 2013. We designated these Treasury locks as cash flow hedges. The Treasury locks were settled on January 8, 2013 with a payment of $66.6 million to the counterparties due to a decrease in the 30-year Treasury rates between inception of the Treasury locks and settlement. Because the Treasury locks were effective, the $66.6 million unrealized loss 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 the fourth quarter of fiscal 2012 we entered into an interest rate swap to fix the LIBOR component of our $260 million short-term financing facility through December 27, 2012. We recorded an immaterial loss upon settlement of the swap, which was recorded as a component of interest expense as we did not designate the interest rate swap as a hedge.
	In prior years, we entered into several Treasury lock agreements to fix the Treasury yield component of the interest cost of financing for various issuances of long-term debt and senior notes. The gains and losses realized upon settlement of these Treasury locks were recorded as a component of accumulated other comprehensive income (loss) when they were settled and are being recognized as a component of interest expense over the life of the associated notes from the date of settlement. The remaining amortization periods for the settled Treasury locks extend through fiscal 2043.
	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, 2014, our financial instruments were comprised of both long and short commodity positions. A long position is a contract to purchase the commodity, while a short position is a contract to sell the commodity. As of September 30, 2014, we had net long/(short) commodity contracts outstanding in the following quantities:
	Contract Type		Hedge		Regulated			Nonregulated
			Designation		Distribution
					Quantity (MMcf)
	Commodity contracts		Fair Value		—			(10,298	)
			Cash Flow		—			49,290
			Not designated		31,812			96,711
					31,812			135,703
	Financial Instruments on the Balance Sheet
	The following tables present the fair value and balance sheet classification of our financial instruments by operating segment as of September 30, 2014 and 2013. The gross amounts of recognized assets and liabilities are netted within our Consolidated Balance Sheets to the extent that we have netting arrangements with the counterparties.
				Regulated Distribution								Nonregulated
		Balance Sheet Location		Assets				Liabilities				Assets			Liabilities
				(In thousands)
	30-Sep-14
	Designated As Hedges:
	Commodity contracts	Other current assets /		$	—			$	—			$	8,912		$	(7,082	)
		Other current liabilities
	Interest rate contracts	Other current assets /		21,869				—				—			—
		Other current liabilities
	Commodity contracts	Deferred charges and other assets /		—				—				757			(2,459		)
		Deferred credits and other liabilities
	Interest rate contracts	Deferred charges and other assets /		12,608				(19,835		)		—			—
		Deferred credits and other liabilities
	Total			34,477				(19,835		)		9,669			(9,541		)
	Not Designated As Hedges:
Commodity contracts	Other current assets /		1,233				(1,730		)		43,677			(47,729		)
	Other current liabilities
Commodity contracts	Deferred charges and other assets /		430				(291		)		15,677			(14,786		)
	Deferred credits and other liabilities
Total			1,663				(2,021		)		59,354			(62,515		)
Gross Financial Instruments			36,140				(21,856		)		69,023			(72,056		)
Gross Amounts Offset on Consolidated Balance Sheet:
Contract netting			—				—				(69,023		)	69,023
Net Financial Instruments			36,140				(21,856		)		—			(3,033		)
Cash collateral			—				—				22,725			3,033
Net Assets/Liabilities from Risk Management Activities			$	36,140			$	(21,856	)		$	22,725		$	—
			Regulated Distribution								Nonregulated
	Balance Sheet Location		Assets				Liabilities				Assets			Liabilities
			(In thousands)
30-Sep-13
Designated As Hedges:
Commodity contracts	Other current assets /		$	—			$	—			$	9,094		$	(12,173	)
	Other current liabilities
Commodity contracts	Deferred charges and other assets /		—				—				416			(1,639		)
	Deferred credits and other liabilities
Interest rate contracts	Deferred charges and other assets /		107,512				—				—			—
	Deferred credits and other liabilities
Total			107,512				—				9,510			(13,812		)
Not Designated As Hedges:
Commodity contracts	Other current assets /		1,837				(1,543		)		65,388			(70,876		)
	Other current liabilities
Commodity contracts	Deferred charges and other assets /		1,842				—				40,982			(45,892		)
	Deferred credits and other liabilities
Total			3,679				(1,543		)		106,370			(116,768		)
Gross Financial Instruments			111,191				(1,543		)		115,880			(130,580		)
Gross Amounts Offset on Consolidated Balance Sheet:
Contract netting			—				—				(115,875		)	115,875
Net Financial Instruments			111,191				(1,543		)		5			(14,705		)
Cash collateral			—				—				10,124			14,705
Net Assets/Liabilities from Risk Management Activities			$	111,191			$	(1,543	)		$	10,129		$	—
Impact of Financial Instruments on the Income Statement
Hedge ineffectiveness for our nonregulated segment is recorded as a component of unrealized gross profit and primarily results from differences in the location and timing of the derivative instrument and the hedged item. Hedge ineffectiveness could materially affect our results of operations for the reported period. For the years ended September 30, 2014, 2013 and 2012, we recognized a gain arising from fair value and cash flow hedge ineffectiveness of $1.9 million, $18.2 million and $23.1 million. Additional information regarding ineffectiveness recognized in the income statement is included in the tables below.
Fair Value Hedges
The impact of our nonregulated commodity contracts designated as fair value hedges and the related hedged item on our consolidated income statement for the years ended September 30, 2014, 2013 and 2012 is presented below.
	Fiscal Year Ended September 30
	2014				2013				2012
	(In thousands)
Commodity contracts	$	(792	)		$	2,165			$	30,266
Fair value adjustment for natural gas inventory designated as the hedged item	2,486				15,938				(5,797		)
Total decrease in purchased gas cost	$	1,694			$	18,103			$	24,469
The decrease in purchased gas cost is comprised of the following:
Basis ineffectiveness	$	(919	)		$	(208	)		$	1,170
Timing ineffectiveness	2,613				18,311				23,299
	$	1,694			$	18,103			$	24,469
Basis ineffectiveness arises from natural gas market price differences between the locations of the hedged inventory and the delivery location specified in the hedge instruments. Timing ineffectiveness arises due to changes in the difference between the spot price and the futures price, as well as the difference between the timing of the settlement of the futures and the valuation of the underlying physical commodity. As the commodity contract nears the settlement date, spot-to-forward price differences should converge, which should reduce or eliminate the impact of this ineffectiveness on purchased gas cost.
To the extent that the Company’s natural gas inventory does not qualify as a hedged item in a fair-value hedge, or has not been designated as such, the natural gas inventory is valued at the lower of cost or market. During the year ended September 30, 2012, we recorded a $1.7 million charge to write down nonqualifying natural gas inventory to market. We did not record a writedown for nonqualifying natural gas inventory for the years ended September 30, 2014 and 2013.
Cash Flow Hedges
The impact of cash flow hedges on our consolidated income statements for the years ended September 30, 2014, 2013 and 2012 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, 2014
	Regulated				Nonregulated				Consolidated
	Distribution
	(In thousands)
Gain reclassified from AOCI for effective portion of commodity contracts	$	—			$	8,365			$	8,365
Gain arising from ineffective portion of commodity contracts	—				198				198
Total impact on purchased gas cost	—				8,563				8,563
Net loss on settled interest rate agreements reclassified from AOCI into interest expense	(4,230		)		—				(4,230		)
Total impact from cash flow hedges	$	(4,230	)		$	8,563			$	4,333
	Fiscal Year Ended September 30, 2013
	Regulated				Nonregulated				Consolidated
	Distribution
	(In thousands)
Loss reclassified from AOCI for effective portion of commodity contracts	$	—			$	(10,778	)		$	(10,778	)
Gain arising from ineffective portion of commodity contracts	—				97				97
Total impact on purchased gas cost	—				(10,681		)		(10,681		)
Net loss on settled interest rate agreements reclassified from AOCI into interest expense	(3,489		)		—				(3,489		)
Total impact from cash flow hedges	$	(3,489	)		$	(10,681	)		$	(14,170	)
	Fiscal Year Ended September 30, 2012
	Regulated				Nonregulated				Consolidated
	Distribution
	(In thousands)
Loss reclassified from AOCI for effective portion of commodity contracts	$	—			$	(62,678	)		$	(62,678	)
Loss arising from ineffective portion of commodity contracts	—				(1,369		)		(1,369		)
Total impact on purchased gas cost	—				(64,047		)		(64,047		)
Net loss on settled interest rate agreements reclassified from AOCI into interest expense	(2,009		)		—				(2,009		)
Total impact from cash flow hedges	$	(2,009	)		$	(64,047	)		$	(66,056	)
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, 2014 and 2013. 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
	2014				2013
	(In thousands)
Increase (decrease) in fair value:
Interest rate agreements	$	(58,973	)		$	79,963
Forward commodity contracts	7,904				(2,057		)
Recognition of (gains) losses in earnings due to settlements:
Interest rate agreements	2,686				2,216
Forward commodity contracts	(5,102		)		6,576
Total other comprehensive income (loss) from hedging, net of tax(1)	$	(53,485	)		$	86,698
(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, 2014. However, the table below does not include the expected recognition in earnings of the interest rate agreements entered into in October 2012 and fiscal 2014 as those financial instruments have not yet settled.
	Interest Rate				Commodity				Total
	Agreements				Contracts
	(In thousands)
2015	$	(804	)		$	(632	)		$	(1,436	)
2016	(634		)		(907		)		(1,541		)
2017	(735		)		(107		)		(842		)
2018	(936		)		(38		)		(974		)
2019	(961		)		10				(951		)
Thereafter	(23,609		)		—				(23,609		)
Total(1)	$	(27,679	)		$	(1,674	)		$	(29,353	)
(1)	Utilizing an income tax rate ranging from approximately 37 percent to 39 percent based on the effective rates in each taxing jurisdiction.
Financial Instruments Not Designated as Hedges
The impact of financial instruments that have not been designated as hedges on our consolidated income statements for the years ended September 30, 2014, 2013 and 2012 was an increase (decrease) in purchased gas cost of $(5.0) million, $3.0 million and $(2.5) million. Note that this presentation does not reflect the expected gains or losses arising from the underlying physical transactions associated with these financial instruments. Therefore, this presentation is not indicative of the economic gross profit we realized when the underlying physical and financial transactions were settled.
As discussed above, financial instruments used in our regulated distribution segment are not designated as hedges. However, there is no earnings impact on our regulated distribution segment as a result of the use of these financial instruments because the gains and losses arising from the use of these financial instruments are recognized in the consolidated statement of income as a component of purchased gas cost when the related costs are recovered through our rates and recognized in revenue. Accordingly, the impact of these financial instruments is excluded from this presentation.

Accumulated_Other_Comprehensiv

Accumulated Other Comprehensive Income	12 Months Ended
	Sep. 30, 2014
Equity [Abstract]	'
Accumulated Other Comprehensive Income	'
	Accumulated Other Comprehensive Income
	We record deferred gains (losses) in accumulated other comprehensive income (AOCI) related to available-for-sale securities, interest rate agreement cash flow hedges and commodity contract cash flow hedges. Deferred gains (losses) for our available-for-sale securities and commodity contract cash flow hedges are recognized in earnings upon settlement, while deferred gains (losses) related to our interest rate agreement cash flow hedges are recognized in earnings as they are amortized. The following tables provide the components of our accumulated other comprehensive income (loss) balances, net of the related tax effects allocated to each component of other comprehensive income.
		Available-			Interest			Commodity			Total
		for-Sale			Rate			Contracts
		Securities			Agreement			Cash Flow
					Cash Flow			Hedges
					Hedges
		(In thousands)
	30-Sep-13	$	5,448		$	37,906		$	(4,476	)	$	38,878
	Other comprehensive income (loss) before reclassifications	3,009			(58,973		)	7,904			(48,060		)
	Amounts reclassified from accumulated other comprehensive income	(795		)	2,686			(5,102		)	(3,211		)
	Net current-period other comprehensive income (loss)	2,214			(56,287		)	2,802			(51,271		)
	30-Sep-14	$	7,662		$	(18,381	)	$	(1,674	)	$	(12,393	)
		Available-			Interest			Commodity			Total
		for-Sale			Rate			Contracts
		Securities			Agreement			Cash Flow
					Cash Flow			Hedges
					Hedges
		(In thousands)
	30-Sep-12	$	5,661		$	(44,273	)	$	(8,995	)	$	(47,607	)
	Other comprehensive income (loss) before reclassifications	1,162			79,963			(2,057		)	79,068
	Amounts reclassified from accumulated other comprehensive income	(1,375		)	2,216			6,576			7,417
	Net current-period other comprehensive income (loss)	(213		)	82,179			4,519			86,485
	30-Sep-13	$	5,448		$	37,906		$	(4,476	)	$	38,878
	The following tables detail reclassifications out of AOCI for the fiscal years ended September 30, 2014 and 2013. Amounts in parentheses below indicate decreases to net income in the statement of income.
		Fiscal Year Ended September 30, 2014
	Accumulated Other Comprehensive Income Components	Amount Reclassified from			Affected Line Item in the
		Accumulated Other			Statement of Income
		Comprehensive Income
		(In thousands)
	Available-for-sale securities	$	1,252		Operation and maintenance expense
		1,252			Total before tax
		(457		)	Tax expense
		$	795		Net of tax
	Cash flow hedges
	Interest rate agreements	$	(4,230	)	Interest charges
	Commodity contracts	8,365			Purchased gas cost
		4,135			Total before tax
		(1,719		)	Tax expense
		$	2,416		Net of tax
	Total reclassifications	$	3,211		Net of tax
		Fiscal Year Ended September 30, 2013
	Accumulated Other Comprehensive Income Components	Amount Reclassified from			Affected Line Item in the
		Accumulated Other			Statement of Income
		Comprehensive Income
		(In thousands)
	Available-for-sale securities	$	2,166		Operation and maintenance expense
		2,166			Total before tax
		(791		)	Tax expense
		$	1,375		Net of tax
	Cash flow hedges
	Interest rate agreements	$	(3,489	)	Interest charges
	Commodity contracts	(10,778		)	Purchased gas cost
		(14,267		)	Total before tax
		5,475			Tax benefit
		$	(8,792	)	Net of tax
	Total reclassifications	$	(7,417	)	Net of tax

Fair_Value_Measurements

Fair Value Measurements	12 Months Ended
	Sep. 30, 2014
Fair Value Disclosures [Abstract]	'
Fair Value Measurements	'
	Fair Value Measurements
	We report certain assets and liabilities at fair value, which is defined as the price that would be received to sell an asset or paid to transfer a liability in an orderly transaction between market participants at the measurement date (exit price). We record cash and cash equivalents, accounts receivable and accounts payable at carrying value, which substantially approximates fair value due to the short-term nature of these assets and liabilities. For other financial assets and liabilities, we primarily use quoted market prices and other observable market pricing information to minimize the use of unobservable pricing inputs in our measurements when determining fair value. The methods used to determine fair value for our assets and liabilities are fully described in Note 2.
	Fair value measurements also apply to the valuation of our pension and post-retirement plan assets. The fair value of these assets is presented in Note 6.
	Quantitative Disclosures
	Financial Instruments
	The classification of our fair value measurements requires judgment regarding the degree to which market data are observable or corroborated by observable market data. The following tables summarize, by level within the fair value hierarchy, our assets and liabilities that were accounted for at fair value on a recurring basis as of September 30, 2014 and 2013. 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		Significant		Significant			Netting and			30-Sep-14
		Prices in		Other		Other			Cash
		Active		Observable		Unobservable			Collateral(2)
		Markets		Inputs		Inputs
		(Level 1)		(Level 2)(1)		(Level 3)
		(In thousands)
	Assets:
	Financial instruments
	Regulated distribution segment	$	—	$	36,140	$	—		$	—		$	36,140
	Nonregulated segment	25		68,998		—			(46,298		)	22,725
	Total financial instruments	25		105,138		—			(46,298		)	58,865
	Hedged portion of gas stored underground	40,492		—		—			—			40,492
	Available-for-sale securities
	Money market funds	—		2,185		—			—			2,185
	Registered investment companies	44,014		—		—			—			44,014
	Bonds	—		33,414		—			—			33,414
	Total available-for-sale securities	44,014		35,599		—			—			79,613
	Total assets	$	84,531	$	140,737	$	—		$	(46,298	)	$	178,970
	Liabilities:
	Financial instruments
	Regulated distribution segment	$	—	$	21,856	$	—		$	—		$	21,856
	Nonregulated segment	12		72,044		—			(72,056		)	—
	Total liabilities	$	12	$	93,900	$	—		$	(72,056	)	$	21,856
		Quoted		Significant		Significant			Netting and			30-Sep-13
		Prices in		Other		Other			Cash
		Active		Observable		Unobservable			Collateral(3)
		Markets		Inputs		Inputs
		(Level 1)		(Level 2)(1)		(Level 3)
		(In thousands)
	Assets:
	Financial instruments
	Regulated distribution segment	$	—	$	111,191	$	—		$	—		$	111,191
	Nonregulated segment	745		115,135		—			(105,751		)	10,129
	Total financial instruments	745		226,326		—			(105,751		)	121,320
	Hedged portion of gas stored underground	44,758		—		—			—			44,758
	Available-for-sale securities
	Money market funds	—		4,428		—			—			4,428
	Registered investment companies	40,094		—		—			—			40,094
	Bonds	—		28,160		—			—			28,160
	Total available-for-sale securities	40,094		32,588		—			—			72,682
	Total assets	$	85,597	$	258,914	$	—		$	(105,751	)	$	238,760
	Liabilities:
	Financial instruments
	Regulated distribution segment	$	—	$	1,543	$	—		$	—		$	1,543
	Nonregulated segment	158		130,422		—			(130,580		)	—
	Total liabilities	$	158	$	131,965	$	—		$	(130,580	)	$	1,543
	(1)	Our Level 2 measurements consist of over-the-counter options and swaps, which are valued using a market-based approach in which observable market prices are adjusted for criteria specific to each instrument, such as the strike price, notional amount or basis differences, municipal and corporate bonds, which are valued based on the most recent available quoted market prices and money market funds which are valued at cost.
	(2)	This column reflects adjustments to our gross financial instrument assets and liabilities to reflect netting permitted under our master netting agreements and the relevant authoritative accounting literature. In addition, as of September 30, 2014 we had $25.8 million of cash held in margin accounts to collateralize certain financial instruments. Of this amount, $3.1 million was used to offset current and noncurrent risk management liabilities under master netting agreements and the remaining $22.7 million is classified as current risk management assets.
	(3)	This column reflects adjustments to our gross financial instrument assets and liabilities to reflect netting permitted under our master netting agreements and the relevant authoritative accounting literature. In addition, as of September 30, 2013 we had $24.8 million of cash held in margin accounts to collateralize certain financial instruments. Of this amount, $14.7 million was used to offset current and noncurrent risk management liabilities under master netting agreements and the remaining $10.1 million is classified as current risk management assets.
	Available-for-sale securities are comprised of the following:
		Amortized		Gross		Gross			Fair
		Cost		Unrealized		Unrealized			Value
				Gain		Loss
		(In thousands)
	As of September 30, 2014
	Domestic equity mutual funds	$	26,633	$	10,136	$	—		$	36,769
	Foreign equity mutual funds	5,382		1,863		—			7,245
Bonds	33,266		161		(13		)	33,414
Money market funds	2,185		—		—			2,185
	$	67,466	$	12,160	$	(13	)	$	79,613
As of September 30, 2013
Domestic equity mutual funds	$	27,043	$	7,476	$	(23	)	$	34,496
Foreign equity mutual funds	4,536		1,062		—			5,598
Bonds	28,016		168		(24		)	28,160
Money market funds	4,428		—		—			4,428
	$	64,023	$	8,706	$	(47	)	$	72,682
At September 30, 2014 and 2013, our available-for-sale securities included $46.2 million and $44.5 million related to assets held in separate rabbi trusts for our supplemental executive retirement plans as discussed in Note 6. At September 30, 2014 we maintained investments in bonds that have contractual maturity dates ranging from October 2014 through September 2018. During the years ended September 30, 2014 and 2013, we recognized gains of $1.3 million and $2.2 million on the sale of certain assets in the rabbi trusts.
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.
Atmos Gathering Company (AGC) owns and operates the Park City and Shrewsbury gathering systems in Kentucky. The Park City gathering system consists of a 23-mile low pressure pipeline and a nitrogen removal unit that was constructed in 2008. The Shrewsbury production, gathering and processing assets were acquired in 2008 at which time we sold the production assets to a third party. As a result of the sale of the production assets, we obtained a 10-year production payment note under which we were to be paid from future production generated from the assets.
As discussed in Note 10, AGC was involved in a lawsuit with the Park City gathering system. Due to the lawsuit and a low natural gas price environment, the assets have generated operating losses. As a result of these developments and management’s decision to focus our nonregulated operations on delivered gas and transportation services, in fiscal 2012, we performed an impairment assessment of these assets and determined the assets to be impaired. We reduced the carrying value of the assets to their estimated fair value of approximately $0.5 million and recorded a pre-tax noncash impairment loss of approximately $5.3 million. We used a combination of a market and income approach in a weighted average discounted cash flow analysis that included significant inputs such as our weighted average cost of capital and assumptions regarding future natural gas prices. This is a Level 3 fair value measurement because the inputs used are unobservable. Based on this analysis, we determined the assets to be impaired.
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, 2014:
	30-Sep-14
	(In thousands)
Carrying Amount	$	2,460,000
Fair Value	$	2,769,541

Concentration_of_Credit_Risk

Concentration of Credit Risk	12 Months Ended
	Sep. 30, 2014
Risks and Uncertainties [Abstract]	'
Concentration of Credit Risk	'
	Concentration of Credit Risk
	Credit risk is the risk of financial loss to us if a customer fails to perform its contractual obligations. We engage in transactions for the purchase and sale of products and services with major companies in the energy industry and with industrial, commercial, residential and municipal energy consumers. These transactions principally occur in the southern and midwestern regions of the United States. We believe that this geographic concentration does not contribute significantly to our overall exposure to credit risk. Credit risk associated with trade accounts receivable for the regulated distribution segment is mitigated by the large number of individual customers and diversity in our customer base. The credit risk for our other segments is not significant.

Discontinued_Operations

Discontinued Operations	12 Months Ended
	Sep. 30, 2014
Discontinued Operations and Disposal Groups [Abstract]	'
Discontinued Operations	'
	Discontinued Operations
	On April 1, 2013, we completed the sale of substantially all of our regulated distribution assets and certain related nonregulated assets located in Georgia to Liberty Energy (Georgia) Corp., an affiliate of Algonquin Power & Utilities Corp. for a cash price of approximately $153 million, pursuant to an asset purchase agreement executed on August 8, 2012. In connection with the sale, we recognized a pre-tax gain of approximately $8.2 million.
	On August 1, 2012, we completed the sale of substantially all of our regulated distribution assets located in Missouri, Illinois and Iowa to Liberty Energy (Midstates) Corp., an affiliate of Algonquin Power & Utilities Corp. for a cash price of approximately $128 million, pursuant to an asset purchase agreement executed on May 12, 2011. In connection with the sale, we recognized a pre-tax gain of approximately $9.9 million.
	As required under generally accepted accounting principles, the operating results of our Georgia, Missouri, Illinois and Iowa operations have been aggregated and reported on the consolidated statements of income as income from discontinued operations, net of income tax. Expenses related to general corporate overhead and interest expense allocated to their operations are not included in discontinued operations.
	The following table presents statement of income data related to discontinued operations in our Georgia, Missouri, Illinois and Iowa service areas. At September 30, 2014 and 2013 we did not have any assets or liabilities held for sale.
		Year Ended September 30
		2013		2012
		(In thousands)
	Operating revenues	$	37,962	$	114,703
	Purchased gas cost	21,464		62,902
	Gross profit	16,498		51,801
	Operating expenses	5,858		24,174
	Operating income	10,640		27,627
	Other nonoperating income	548		611
	Income from discontinued operations before income taxes	11,188		28,238
	Income tax expense	3,986		10,066
	Income from discontinued operations	7,202		18,172
	Gain on sale of discontinued operations, net of tax	5,294		6,349
	Net income from discontinued operations	$	12,496	$	24,521

Selected_Quarterly_Financial_D

Selected Quarterly Financial Data	12 Months Ended
	Sep. 30, 2014
Quarterly Financial Information Disclosure [Abstract]	'
Selected Quarterly Financial Data (Unaudited)	'
	Selected Quarterly Financial Data (Unaudited)
	Summarized unaudited quarterly financial data is presented below. The sum of net income per share by quarter may not equal the net income per share for the fiscal year due to variations in the weighted average shares outstanding used in computing such amounts. Our businesses are seasonal due to weather conditions in our service areas. For further information on its effects on quarterly results, see the “Results of Operations” discussion included in the “Management’s Discussion and Analysis of Financial Condition and Results of Operations” section herein.
		Quarter Ended
		December 31			March 31			June 30			September 30
		(In thousands, except per share data)
	Fiscal year 2014:
	Operating revenues
	Regulated distribution	$	843,865		$	1,290,960		$	517,707		$	409,014
	Regulated pipeline	71,341			73,615			87,189			86,314
	Nonregulated	447,721			757,683			465,033			396,855
	Intersegment eliminations	(107,779		)	(157,936		)	(127,211		)	(113,455		)
		1,255,148			1,964,322			942,718			778,728
	Gross profit	388,957			496,277			359,533			337,659
	Operating income	170,720			250,080			106,605			83,944
	Net income	87,016			133,367			45,721			23,713
	Net income per share — basic	$	0.94		$	1.38		$	0.45		$	0.23
	Net income per share — diluted	$	0.94		$	1.38		$	0.45		$	0.23
		Quarter Ended
		December 31			March 31			June 30			September 30
		(In thousands, except per share data)
	Fiscal year 2013:
	Operating revenues
	Regulated distribution	$	666,787		$	905,176		$	467,144		$	360,386
	Regulated pipeline	60,681			61,848			74,041			72,330
	Nonregulated	399,894			428,948			421,808			337,264
	Intersegment eliminations	(93,207		)	(86,976		)	(105,058		)	(95,606		)
		1,034,155			1,308,996			857,935			674,374
	Gross profit	362,362			432,751			316,497			300,440
	Operating income	154,922			210,178			86,396			50,383
	Income from continuing operations	77,348			112,340			33,474			7,536
	Income from discontinued operations	3,117			4,085			—			—
	Gain on sale of discontinued operations	—			—			5,294			—
	Net income	80,465			116,425			38,768			7,536
	Basic earnings per share
	Income per share from continuing operations	$	0.85		$	1.24		$	0.37		$	0.08
	Income per share from discontinued operations	$	0.04		0.04			$	0.06		$	—
	Net income per share — basic	$	0.89		$	1.28		$	0.43		$	0.08
	Diluted earnings per share
	Income per share from continuing operations	$	0.85		$	1.23		$	0.36		$	0.08
	Income per share from discontinued operations	$	0.03		$	0.04		$	0.06		$	—
	Net income per share — diluted	$	0.88		$	1.27		$	0.42		$	0.08

Schedule_II_Valuation_and_Qual

Schedule II - Valuation and Qualifying Accounts	12 Months Ended
	Sep. 30, 2014
Valuation and Qualifying Accounts [Abstract]	'
Schedule II Valuation and Qualifying Accounts	'
	ATMOS ENERGY CORPORATION
	Valuation and Qualifying Accounts
	Three Years Ended September 30, 2014
				Additions
		Balance at		Charged to		Charged to		Deductions			Balance
		beginning		cost &		other					at end
		of period		expenses		accounts					of period
				(In thousands)
	2014
	Allowance for doubtful accounts	$	20,624	$	19,491	$	—	$	16,123	(1)	$	23,992
	2013
	Allowance for doubtful accounts	$	9,425	$	14,484	$	—	$	3,285	(1)	$	20,624
	2012
	Allowance for doubtful accounts	$	7,440	$	8,901	$	—	$	6,916	(1)	$	9,425
	(1)	Uncollectible accounts written off.

Summary_of_Significant_Account

Summary of Significant Accounting Policies (Policy)	12 Months Ended
	Sep. 30, 2014
Accounting Policies [Abstract]	'
Principles of consolidation	'
	Principles of consolidation — The accompanying consolidated financial statements include the accounts of Atmos Energy Corporation and its wholly-owned subsidiaries. All material intercompany transactions have been eliminated; however, we have not eliminated intercompany profits when such amounts are probable of recovery under the affiliates’ rate regulation process.
Basis of comparison	'
	Basis of comparison — Certain prior-year amounts have been reclassified to conform with the current year presentation.
Use of estimates	'
	Use of estimates — The preparation of financial statements in conformity with accounting principles generally accepted in the United States requires management to make estimates and assumptions that affect the reported amounts of assets, liabilities, revenues and expenses. The most significant estimates include the allowance for doubtful accounts, unbilled revenues, legal and environmental accruals, insurance accruals, pension and postretirement obligations, deferred income taxes, asset retirement obligations, 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	'
	Currently, authorized rates do not include a return on certain of our merger and integration costs; however, we recover the amortization of these costs. Merger and integration costs, net, are generally amortized on a straight-line basis over estimated useful lives ranging up to 20 years
	Regulation — Our regulated distribution and regulated pipeline operations are subject to regulation with respect to rates, service, maintenance of accounting records and various other matters by the respective regulatory authorities in the states in which we operate. Our accounting policies recognize the financial effects of the ratemaking and accounting practices and policies of the various regulatory commissions. Accounting principles generally accepted in the United States require cost-based, rate-regulated entities that meet certain criteria to reflect the authorized recovery of costs due to regulatory decisions in their financial statements. As a result, certain costs that would normally be expensed under accounting principles generally accepted in the United States are permitted to be capitalized or deferred on the balance sheet because it is probable they can be recovered through rates. Further, regulation may impact the period in which revenues or expenses are recognized. The amounts to be recovered or recognized are based upon historical experience and our understanding of the regulations.
	We record regulatory assets as a component of other current assets and deferred charges and other assets for costs that have been deferred for which future recovery through customer rates is considered probable. Regulatory liabilities are recorded either on the face of the balance sheet or as a component of current liabilities, deferred income taxes or deferred credits and other liabilities when it is probable that revenues will be reduced for amounts that will be credited to customers through the ratemaking process.
Revenue recognition	'
	Revenue recognition — Sales of natural gas to our regulated distribution customers are billed on a monthly basis; however, the billing cycle periods for certain classes of customers do not necessarily coincide with accounting periods used for financial reporting purposes. We follow the revenue accrual method of accounting for regulated distribution segment revenues whereby revenues applicable to gas delivered to customers, but not yet billed under the cycle billing method, are estimated and accrued and the related costs are charged to expense.
	On occasion, we are permitted to implement new rates that have not been formally approved by our state regulatory commissions, which are subject to refund. As permitted by accounting principles generally accepted in the United States, we recognize this revenue and establish a reserve for amounts that could be refunded based on our experience for the jurisdiction in which the rates were implemented.
	Rates established by regulatory authorities are adjusted for increases and decreases in our purchased gas costs through purchased gas cost adjustment mechanisms. Purchased gas cost adjustment mechanisms provide gas distribution companies a method of recovering purchased gas costs on an ongoing basis without filing a rate case to address all of their non-gas costs. There is no gross profit generated through purchased gas cost adjustments, but they provide a dollar-for-dollar offset to increases or decreases in our regulated distribution segment’s gas costs. The effects of these purchased gas cost adjustment mechanisms are recorded as deferred gas costs on our balance sheet.
	Operating revenues for our regulated pipeline and nonregulated segments are recognized in the period in which actual volumes are transported and storage services are provided.
	Operating revenues for our nonregulated segment and the associated carrying value of natural gas inventory (inclusive of storage costs) are recognized when we sell the gas and physically deliver it to our customers. Operating revenues include realized gains and losses arising from the settlement of financial instruments used in our nonregulated activities and unrealized gains and losses arising from changes in the fair value of natural gas inventory designated as a hedged item in a fair value hedge and the associated financial instruments.
Cash and cash equivalents	'
	Cash and cash equivalents — We consider all highly liquid investments with an original maturity of three months or less to be cash equivalents.
Accounts receivable and allowance for doubtful accounts	'
	Accounts receivable and allowance for doubtful accounts — Accounts receivable arise from natural gas sales to residential, commercial, industrial, municipal and other customers. We establish an allowance for doubtful accounts to reduce the net receivable balance to the amount we reasonably expect to collect based on our collection experience or where we are aware of a specific customer’s inability or reluctance to pay. However, if circumstances change, our estimate of the recoverability of accounts receivable could be affected. Circumstances which could affect our estimates include, but are not limited to, customer credit issues, the level of natural gas prices, customer deposits and general economic conditions. Accounts are written off once they are deemed to be uncollectible.
Gas stored underground	'
	Gas stored underground — Our gas stored underground is comprised of natural gas injected into storage to support the winter season withdrawals for our regulated distribution operations and natural gas held by our nonregulated segment to conduct their operations. The average cost method is used for all our regulated operations, except for certain jurisdictions in the Kentucky/Mid-States Division, where it is valued on the first-in first-out method basis, in accordance with regulatory requirements. Our nonregulated segment utilizes the average cost method; however, most of this inventory is hedged and is therefore reported at fair value at the end of each month. Gas in storage that is retained as cushion gas to maintain reservoir pressure is classified as property, plant and equipment and is valued at cost.
Property, plant and equipment	'
	Regulated property, plant and equipment — Regulated property, plant and equipment is stated at original cost, net of contributions in aid of construction. The cost of additions includes direct construction costs, payroll related costs (taxes, pensions and other fringe benefits), administrative and general costs and an allowance for funds used during construction. The allowance for funds used during construction represents the estimated cost of funds used to finance the construction of major projects and are capitalized in the rate base for ratemaking purposes when the completed projects are placed in service. Interest expense of $1.5 million, $1.9 million and $2.6 million was capitalized in 2014, 2013 and 2012.
	Major renewals, including replacement pipe, and betterments that are recoverable under our regulatory rate base are capitalized while the costs of maintenance and repairs that are not recoverable through rates are charged to expense as incurred. The costs of large projects are accumulated in construction in progress until the project is completed. When the project is completed, tested and placed in service, the balance is transferred to the regulated plant in service account included in the rate base and depreciation begins.
	Regulated property, plant and equipment is depreciated at various rates on a straight-line basis. These rates are approved by our regulatory commissions and are comprised of two components: one based on average service life and one based on cost of removal. Accordingly, we recognize our cost of removal expense as a component of depreciation expense. The related cost of removal accrual is reflected as a regulatory liability on the consolidated balance sheet. At the time property, plant and equipment is retired, removal expenses less salvage, are charged to the regulatory cost of removal accrual. The composite depreciation rate was 3.3 percent, 3.3 percent and 3.6 percent for the fiscal years ended September 30, 2014, 2013 and 2012.
	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 50 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, 2014 and 2013, we had asset retirement obligations of $10.5 million and $6.8 million. Additionally, we had $5.9 million and $3.3 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, 2014 and 2013, all of our marketable securities were classified as available-for-sale. In accordance with the authoritative accounting standards, these securities are reported at market value with unrealized gains and losses shown as a component of accumulated other comprehensive income (loss). We regularly evaluate the performance of these investments on an individual investment by investment basis for impairment, taking into consideration the fund’s purpose, volatility and current returns. If a determination is made that a decline in fair value is other than temporary, the related investment is written down to its estimated fair value.
Financial instruments and hedging activities	'
	Financial instruments and hedging activities — We use financial instruments to mitigate commodity price risk in our regulated distribution and nonregulated segments and interest rate risk. The objectives and strategies for using financial instruments have been tailored to our regulated and nonregulated businesses and are discussed in Note 12.
	We record all of our financial instruments on the balance sheet at fair value, with changes in fair value ultimately recorded in the income statement. These financial instruments are reported as risk management assets and liabilities and are classified as current or noncurrent other assets or liabilities based upon the anticipated settlement date of the underlying financial instrument.
	The timing of when changes in fair value of our financial instruments are recorded in the income statement depends on whether the financial instrument has been designated and qualifies as a part of a hedging relationship or if regulatory rulings require a different accounting treatment. Changes in fair value for financial instruments that do not meet one of these criteria are recognized in the income statement as they occur.
	Financial Instruments Associated with Commodity Price Risk
	In our regulated distribution segment, the costs associated with and the gains and losses arising from the use of financial instruments to mitigate commodity price risk are included in our purchased gas cost adjustment mechanisms in accordance with regulatory requirements. Therefore, changes in the fair value of these financial instruments are initially recorded as a component of deferred gas costs and recognized in the consolidated statement of income as a component of purchased gas cost when the related costs are recovered through our rates and recognized in revenue in accordance with accounting principles generally accepted in the United States. Accordingly, there is no earnings impact on our regulated distribution segment as a result of the use of financial instruments.
	In our nonregulated segment, we have designated most of the natural gas inventory held by this operating segment as the hedged item in a fair-value hedge. This inventory is marked to market at the end of each month based on the Gas Daily index, with changes in fair value recognized as unrealized gains or losses in revenue 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.
	Additionally, we have elected to treat fixed-price forward contracts used in our nonregulated segment to deliver natural gas as normal purchases and normal sales. As such, these deliveries are recorded on an accrual basis in accordance with our revenue recognition policy. Financial instruments used to mitigate the commodity price risk associated with these contracts have been designated as cash flow hedges of anticipated purchases and sales at indexed prices. Accordingly, unrealized gains and losses on these open financial instruments are recorded as a component of accumulated other comprehensive income, and are recognized in earnings as a component of purchased gas cost when the hedged volumes are sold.
	Gains and losses from hedge ineffectiveness are recognized in the income statement. Fair value and cash flow hedge ineffectiveness arising from natural gas market price differences between the locations of the hedged inventory and the delivery location specified in the financial instruments is referred to as basis ineffectiveness. Ineffectiveness arising from changes in the fair value of the fair value hedges due to changes in the difference between the spot price and the futures price, as well as the difference between the timing of the settlement of the futures and the valuation of the underlying physical commodity is referred to as timing ineffectiveness. Hedge ineffectiveness, to the extent incurred, is reported as a component of purchased gas cost.
	Our nonregulated segment also utilizes master netting agreements with significant counterparties that allow us to offset gains and losses arising from financial instruments that may be settled in cash with gains and losses arising from financial instruments that may be settled with the physical commodity. Assets and liabilities from risk management activities, as well as accounts receivable and payable, reflect the master netting agreements in place. Additionally, the accounting guidance for master netting arrangements requires us to include the fair value of cash collateral or the obligation to return cash in the amounts that have been netted under master netting agreements used to offset gains and losses arising from financial instruments. As of September 30, 2014 and 2013, the Company netted $25.8 million and $24.8 million of cash held in margin accounts into its current and noncurrent risk management assets and liabilities.
	Financial Instruments Associated with Interest Rate Risk
	We manage interest rate risk, primarily when we plan to issue new long-term debt or to refinance existing long-term debt. We manage this risk through the use of forward starting interest rate swaps, interest rate swaps, and prior to fiscal 2012, Treasury lock agreements, to fix the Treasury yield component of the interest cost associated with anticipated financings. We designate these financial instruments as cash flow hedges at the time the agreements are executed. Unrealized gains and losses associated with the instruments are recorded as a component of accumulated other comprehensive income (loss). When the instruments settle, the realized gain or loss is recorded as a component of accumulated other comprehensive income (loss) and recognized as a component of interest expense over the life of the related financing arrangement. Hedge ineffectiveness to the extent incurred is reported as a component of interest expense.
Fair Value Measurements	'
	Fair Value Measurements — We report certain assets and liabilities at fair value, which is defined as the price that would be received to sell an asset or paid to transfer a liability in an orderly transaction between market participants at the measurement date (exit price). We primarily use quoted market prices and other observable market pricing information in valuing our financial assets and liabilities and minimize the use of unobservable pricing inputs in our measurements.
	Fair-value estimates also consider our own creditworthiness and the creditworthiness of the counterparties involved. Our counterparties consist primarily of financial institutions and major energy companies. This concentration of counterparties may materially impact our exposure to credit risk resulting from market, economic or regulatory conditions. We seek to minimize counterparty credit risk through an evaluation of their financial condition and credit ratings and the use of collateral requirements under certain circumstances.
	Amounts reported at fair value are subject to potentially significant volatility based upon changes in market prices, including, but not limited to, the valuation of the portfolio of our contracts, maturity and settlement of these contracts and newly originated transactions and interest rates, each of which directly affect the estimated fair value of our financial instruments. We believe the market prices and models used to value these financial instruments represent the best information available with respect to closing exchange and over-the-counter quotations, time value and volatility factors underlying the contracts. Values are adjusted to reflect the potential impact of an orderly liquidation of our positions over a reasonable period of time under then current market conditions.
	Authoritative accounting literature establishes a fair value hierarchy that prioritizes the inputs used to measure fair value based on observable and unobservable data. The hierarchy categorizes the inputs into three levels, with the highest priority given to unadjusted quoted prices in active markets for identical assets and liabilities (Level 1) and the lowest priority given to unobservable inputs (Level 3). The levels of the hierarchy are described below:
	Level 1 — Represents unadjusted quoted prices in active markets for identical assets or liabilities. An active market for the asset or liability is defined as a market in which transactions for the asset or liability occur with sufficient frequency and volume to provide pricing information on an ongoing basis. Prices actively quoted on national exchanges are used to determine the fair value of most of our assets and liabilities recorded on our balance sheet at fair value. Within our nonregulated operations, we utilize a mid-market pricing convention (the mid-point between the bid and ask prices), as permitted under current accounting standards. Values derived from these sources reflect the market in which transactions involving these financial instruments are executed.
	Our Level 1 measurements consist primarily of exchange-traded financial instruments, gas stored underground that has been designated as the hedged item in a fair value hedge and our available-for-sale securities. The Level 1 measurements for investments in our Master Trust, Supplemental Executive Benefit Plan and postretirement benefit plan consist primarily of exchange-traded financial instruments.
	Level 2 — Represents pricing inputs other than quoted prices included in Level 1 that are either directly or indirectly observable for the asset or liability as of the reporting date. These inputs are derived principally from, or corroborated by, observable market data. Our Level 2 measurements primarily consist of non-exchange-traded financial instruments, such as over-the-counter options and swaps and municipal and corporate bonds where market data for pricing is observable. The Level 2 measurements for investments in our Master Trust, Supplemental Executive Benefit Plan and postretirement benefit plan consist primarily of non-exchange traded financial instruments such as common collective trusts and investments in limited partnerships.
	Level 3 — Represents generally unobservable pricing inputs which are developed based on the best information available, including our own internal data, in situations where there is little if any market activity for the asset or liability at the measurement date. The pricing inputs utilized reflect what a market participant would use to determine fair value. We utilize models and other valuation methods to determine fair value when external sources are not available. We believe the market prices and models used to value these assets and liabilities represent the best information available with respect to closing exchange and over-the-counter quotations, time value and volatility factors underlying the assets and liabilities.
	As of September 30, 2014, our Master Trust owned one real estate investment with a value less than $0.2 million that qualifies as a Level 3 fair value measurement. The valuation technique used was a real estate appraisal obtained from an independent third party that consisted of several unobservable inputs such as comparable land and building sales values per square foot. Currently, we have no other assets or liabilities recorded at fair value that would qualify for Level 3 reporting.
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 in 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 reduces or increases future pension or postretirement plan costs over a period of approximately seven to nine years.
	The market-related value of our plan assets represents the fair market value of the plan assets, adjusted to smooth out short-term market fluctuations over a five-year period. The use of this calculation will delay the impact of current market fluctuations on the pension expense for the period.
	We use a corridor approach to amortize actuarial gains and losses. Under this approach, net gains or losses in excess of ten percent of the larger of the pension benefit obligation or the market-related value of the assets are amortized on a straight-line basis. The period of amortization is the average remaining service of active participants who are expected to receive benefits under the plan.
	We estimate the assumed health care cost trend rate used in determining our annual postretirement net cost based upon our actual health care cost experience, the effects of recently enacted legislation and general economic conditions. Our assumed rate of retirement is estimated based upon the annual review of our participant census information as of the measurement date.
Income taxes	'
	Income taxes — Income taxes are determined based on the liability method, which results in income tax assets and liabilities arising from temporary differences. Temporary differences are differences between the tax bases of assets and liabilities and their reported amounts in the financial statements that will result in taxable or deductible amounts in future years. The liability method requires the effect of tax rate changes on current and accumulated deferred income taxes to be reflected in the period in which the rate change was enacted. The liability method also requires that deferred tax assets be reduced by a valuation allowance unless it is more likely than not that the assets will be realized.
	The Company may recognize the tax benefit from uncertain tax positions only if it is at least more likely than not that the tax position will be sustained on examination by the taxing authorities, based on the technical merits of the position. The tax benefits recognized in the financial statements from such a position should be measured based on the largest benefit that has a greater than fifty percent likelihood of being realized upon settlement with the taxing authorities. We recognize accrued interest related to unrecognized tax benefits as a component of interest expense. We recognize penalties related to unrecognized tax benefits as a component of miscellaneous income (expense) in accordance with regulatory requirements.
Contingencies	'
	Contingencies — In the normal course of business, we are confronted with issues or events that may result in a contingent liability. These generally relate to lawsuits, claims made by third parties or the action of various regulatory agencies. For such matters, we record liabilities when they are considered probable and reasonably estimable, based on currently available facts and our estimates of the ultimate outcome or resolution of the liability in the future. Actual results may differ from estimates, depending on actual outcomes or changes in the facts or expectations surrounding each potential exposure.
Earnings per share	'
	Since we have non-vested share-based payments with a nonforfeitable right to dividends or dividend equivalents (referred to as participating securities), we are required to use the two-class method of computing earnings per share. The Company’s non-vested restricted stock units, granted under the 1998 Long-Term Incentive Plan, for which vesting is predicated solely on the passage of time, are considered to be participating securities. The calculation of earnings per share using the two-class method excludes income attributable to these participating securities from the numerator and excludes the dilutive impact of those shares from the denominator.
Segment Reporting Policy	'
	Our determination of reportable segments considers the strategic operating units under which we manage sales of various products and services to customers in differing regulatory environments. Although our regulated distribution segment operations are geographically dispersed, they are reported as a single segment as each regulated distribution division has similar economic characteristics. The accounting policies of the segments are the same as those described in the summary of significant accounting policies. We evaluate performance based on net income or loss of the respective operating units. Interest expense is allocated pro rata to each segment based upon our net investment in each segment. Income taxes are allocated to each segment as if each segment’s taxes were calculated on a separate return basis.
Tax Collections	'
	Tax collections — We are allowed to recover from customers revenue-related taxes that are imposed upon us. We record such taxes as operating expenses and record the corresponding customer charges as operating revenues. However, we do collect and remit various other taxes on behalf of various governmental authorities, and we record these amounts in our consolidated balance sheets on a net basis. We do not collect income taxes from our customers on behalf of governmental authorities.

Nature_of_Business_Table

Nature of Business (Table)	12 Months Ended
	Sep. 30, 2014
Schedule of Divisions And Service Areas Table [Abstract]	'
Schedule of divisions and service areas	'
	Through our regulated distribution business, we deliver natural gas through sales and transportation arrangements to over three million residential, commercial, public-authority and industrial customers through our six regulated distribution divisions in the service areas described below:
	Division		Service Area
	Atmos Energy Colorado-Kansas Division		Colorado, Kansas
	Atmos Energy Kentucky/Mid-States Division		Kentucky, Tennessee, Virginia(1)
	Atmos Energy Louisiana Division		Louisiana
	Atmos Energy Mid-Tex Division		Texas, including the Dallas/Fort Worth metropolitan area
	Atmos Energy Mississippi Division		Mississippi
	Atmos Energy West Texas Division		West Texas
	(1)	Denotes location where we have more limited service areas.

Summary_of_Significant_Account1

Summary of Significant Accounting Policies (Table)	12 Months Ended
	Sep. 30, 2014
Regulatory Assets and Liabilities [Abstract]	'
Schedule Of Regulatory Assets And Liabilities	'					[1],[2]
	Significant regulatory assets and liabilities as of September 30, 2014 and 2013 included the following:
		30-Sep
		2014		2013
		(In thousands)
	Regulatory assets:
	Pension and postretirement benefit costs(1)	$	162,777	$	187,977
	Merger and integration costs, net	4,730		5,250
	Deferred gas costs	20,069		15,152
	Regulatory cost of removal asset	—		10,008
	Rate case costs	3,757		6,329
	Texas Rule 8.209(2)	26,948		30,364
	APT annual adjustment mechanism	8,479		5,853
	Recoverable loss on reacquired debt	18,877		21,435
	Other	4,672		4,380
		$	250,309	$	286,748
	Regulatory liabilities:
	Deferred gas costs	$	35,063	$	16,481
	Deferred franchise fees	5,268		1,689
	Regulatory cost of removal obligation	490,448		427,524
	Other	14,980		7,887
		$	545,759	$	453,581
[1]	Includes $18.8 million and $17.4 million of pension and postretirement expense deferred pursuant to regulatory authorization.
[2]	Texas Rule 8.209 is a Railroad Commission rule that allows for the deferral of all expenses associated with capital expenditures incurred pursuant to this rule, including the recording of interest on the deferred expenses until the next rate proceeding (rate case or annual rate filing), at which time investment and costs would be recovered through base rates.

Segment_Information_Table

Segment Information (Table)	12 Months Ended
	Sep. 30, 2014
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, 2014
		Regulated			Regulated			Nonregulated			Eliminations			Consolidated
		Distribution			Pipeline
		(In thousands)
	Operating revenues from external parties	$	3,056,212		$	92,166		$	1,792,538		$	—		$	4,940,916
	Intersegment revenues	5,334			226,293			274,754			(506,381		)	—
		3,061,546			318,459			2,067,292			(506,381		)	4,940,916
	Purchased gas cost	1,885,031			—			1,979,337			(505,878		)	3,358,490
	Gross profit	1,176,515			318,459			87,955			(503		)	1,582,426
	Operating expenses
	Operation and maintenance	387,228			91,466			26,963			(503		)	505,154
	Depreciation and amortization	208,376			41,031			4,580			—			253,987
	Taxes, other than income	196,343			13,143			2,450			—			211,936
	Total operating expenses	791,947			145,640			33,993			(503		)	971,077
	Operating income	384,568			172,819			53,962			—			611,349
	Miscellaneous income (expense)	(381		)	(3,181		)	2,216			(3,889		)	(5,235		)
	Interest charges	94,918			36,280			1,986			(3,889		)	129,295
	Income before income taxes	289,269			133,358			54,192			—			476,819
	Income tax expense	117,684			47,167			22,151			—			187,002
	Net income	$	171,585		$	86,191		$	32,041		$	—		$	289,817
	Capital expenditures	$	584,065		$	249,347		$	1,839		$	—		$	835,251
		Year Ended September 30, 2013
		Regulated			Regulated			Nonregulated			Eliminations			Consolidated
		Distribution			Pipeline
		(In thousands)
	Operating revenues from external parties	$	2,394,418		$	89,011		$	1,392,031		$	—		$	3,875,460
	Intersegment revenues	5,075			179,889			195,883			(380,847		)	—
		2,399,493			268,900			1,587,914			(380,847		)	3,875,460
	Purchased gas cost	1,318,257			—			1,524,583			(379,430		)	2,463,410
	Gross profit	1,081,236			268,900			63,331			(1,417		)	1,412,050
	Operating expenses
	Operation and maintenance	375,188			76,686			37,569			(1,423		)	488,020
	Depreciation and amortization	195,581			35,302			4,196			—			235,079
	Taxes, other than income	167,374			17,059			2,639			—			187,072
	Total operating expenses	738,143			129,047			44,404			(1,423		)	910,171
	Operating income	343,093			139,853			18,927			6			501,879
	Miscellaneous income (expense)	2,535			(2,285		)	2,316			(2,763		)	(197		)
	Interest charges	98,296			30,678			2,168			(2,757		)	128,385
	Income from continuing operations before income taxes	247,332			106,890			19,075			—			373,297
	Income tax expense	96,476			38,630			7,493			—			142,599
	Income from continuing operations	150,856			68,260			11,582			—			230,698
	Income from discontinued operations, net of tax	7,202			—			—			—			7,202
	Gain (loss) on sale of discontinued operations, net of tax	5,649			—			(355		)	—			5,294
	Net income	$	163,707		$	68,260		$	11,227		$	—		$	243,194
	Capital expenditures	$	528,599		$	313,230		$	3,204		$	—		$	845,033
		Year Ended September 30, 2012
		Regulated			Regulated			Nonregulated			Eliminations			Consolidated
		Distribution			Pipeline
		(In thousands)
	Operating revenues from external parties	$	2,144,376		$	92,604		$	1,199,182		$	—		$	3,436,162
	Intersegment revenues	954			154,747			149,800			(305,501		)	—
		2,145,330			247,351			1,348,982			(305,501		)	3,436,162
	Purchased gas cost	1,122,587			—			1,293,858			(304,022		)	2,112,423
	Gross profit	1,022,743			247,351			55,124			(1,479		)	1,323,739
	Operating expenses
	Operation and maintenance	353,879			71,521			29,697			(1,484		)	453,613
	Depreciation and amortization	202,026			31,438			4,061			—			237,525
	Taxes, other than income	162,377			15,568			3,128			—			181,073
	Asset impairments	—			—			5,288			—			5,288
	Total operating expenses	718,282			118,527			42,174			(1,484		)	877,499
	Operating income	304,461			128,824			12,950			5			446,240
	Miscellaneous income (expense)	(12,657		)	(1,051		)	1,035			(1,971		)	(14,644		)
Interest charges	110,642			29,414			3,084			(1,966		)	141,174
Income from continuing operations before income taxes	181,162			98,359			10,901			—			290,422
Income tax expense	57,314			35,300			5,612			—			98,226
Income from continuing operations	123,848			63,059			5,289			—			192,196
Income from discontinued operations, net of tax	18,172			—			—			—			18,172
Gain on sale of discontinued operations, net of tax	6,349			—			—			—			6,349
Net income	$	148,369		$	63,059		$	5,289		$	—		$	216,717
Capital expenditures	$	546,818		$	175,768		$	10,272		$	—		$	732,858
Revenue from External Customers by Products and Services	'
	The following table summarizes our revenues by products and services for the fiscal year ended September 30.
		2014			2013			2012
		(In thousands)
	Regulated distribution revenues:
	Gas sales revenues:
	Residential	$	1,933,099		$	1,512,495		$	1,351,479
	Commercial	876,042			661,930			587,651
	Industrial	90,536			81,155			71,960
	Public authority and other	64,779			60,557			54,334
	Total gas sales revenues	2,964,456			2,316,137			2,065,424
	Transportation revenues	64,049			55,938			53,924
	Other gas revenues	27,707			22,343			25,028
	Total regulated distribution revenues	3,056,212			2,394,418			2,144,376
	Regulated pipeline revenues	92,166			89,011			92,604
	Nonregulated revenues	1,792,538			1,392,031			1,199,182
	Total operating revenues	$	4,940,916		$	3,875,460		$	3,436,162
Schedule of segment reporting balance sheet information, by segment	'
	Balance sheet information at September 30, 2014 and 2013 by segment is presented in the following tables.
		30-Sep-14
		Regulated			Regulated			Nonregulated			Eliminations			Consolidated
		Distribution			Pipeline
		(In thousands)
	ASSETS
	Property, plant and equipment, net	$	5,202,761		$	1,464,572		$	58,573		$	—		$	6,725,906
	Investment in subsidiaries	952,171			—			(2,096		)	(950,075		)	—
	Current assets
	Cash and cash equivalents	33,303			—			8,955			—			42,258
	Assets from risk management activities	23,102			—			22,725			—			45,827
	Other current assets	490,408			14,009			526,161			(342,823		)	687,755
	Intercompany receivables	790,442			—			—			(790,442		)	—
	Total current assets	1,337,255			14,009			557,841			(1,133,265		)	775,840
	Goodwill	574,816			132,502			34,711			—			742,029
	Noncurrent assets from risk management activities	13,038			—			—			—			13,038
	Deferred charges and other assets	309,965			21,826			6,100			—			337,891
		$	8,390,006		$	1,632,909		$	655,129		$	(2,083,340	)	$	8,594,704
	CAPITALIZATION AND LIABILITIES
	Shareholders’ equity	$	3,086,232		$	482,612		$	469,559		$	(952,171	)	$	3,086,232
	Long-term debt	2,455,986			—			—			—			2,455,986
	Total capitalization	5,542,218			482,612			469,559			(952,171		)	5,542,218
	Current liabilities
	Short-term debt	522,695			—			—			(326,000		)	196,695
	Liabilities from risk management activities	1,730			—			—			—			1,730
	Other current liabilities	559,765			24,790			142,397			(14,727		)	712,225
	Intercompany payables	—			763,635			26,807			(790,442		)	—
	Total current liabilities	1,084,190			788,425			169,204			(1,131,169		)	910,650
	Deferred income taxes	913,260			361,688			11,668			—			1,286,616
	Noncurrent liabilities from risk management activities	20,126			—			—			—			20,126
	Regulatory cost of removal obligation	445,387			—			—			—			445,387
	Pension and postretirement liabilities	340,963			—			—			—			340,963
	Deferred credits and other liabilities	43,862			184			4,698			—			48,744
		$	8,390,006		$	1,632,909		$	655,129		$	(2,083,340	)	$	8,594,704
		30-Sep-13
		Regulated			Regulated			Nonregulated			Eliminations			Consolidated
		Distribution			Pipeline
		(In thousands)
	ASSETS
	Property, plant and equipment, net	$	4,719,873		$	1,249,767		$	61,015		$	—		$	6,030,655
	Investment in subsidiaries	831,136			—			(2,096		)	(829,040		)	—
	Current assets
	Cash and cash equivalents	4,237			—			61,962			—			66,199
	Assets from risk management activities	1,837			—			10,129			—			11,966
	Other current assets	428,366			11,709			452,126			(293,233		)	598,968
	Intercompany receivables	783,738			—			—			(783,738		)	—
	Total current assets	1,218,178			11,709			524,217			(1,076,971		)	677,133
	Goodwill	574,190			132,462			34,711			—			741,363
	Noncurrent assets from risk management activities	109,354			—			—			—			109,354
	Deferred charges and other assets	347,687			19,227			8,849			—			375,763
		$	7,800,418		$	1,413,165		$	626,696		$	(1,906,011	)	$	7,934,268
	CAPITALIZATION AND LIABILITIES
	Shareholders’ equity	$	2,580,409		$	396,421		$	434,715		$	(831,136	)	$	2,580,409
	Long-term debt	2,455,671			—			—			—			2,455,671
	Total capitalization	5,036,080			396,421			434,715			(831,136		)	5,036,080
	Current liabilities
	Short-term debt	645,984			—			—			(278,000		)	367,984
	Liabilities from risk management activities	1,543			—			—			—			1,543
	Other current liabilities	491,681			20,288			110,306			(13,316		)	608,959
	Intercompany payables	—			712,768			70,970			(783,738		)	—
	Total current liabilities	1,139,208			733,056			181,276			(1,075,054		)	978,486
	Deferred income taxes	871,360			283,554			8,960			179			1,164,053
	Noncurrent liabilities from risk management activities	—			—			—			—			—
Regulatory cost of removal obligation	359,299			—			—			—			359,299
Pension and postretirement liabilities	358,787			—			—			—			358,787
Deferred credits and other liabilities	35,684			134			1,745			—			37,563
	$	7,800,418		$	1,413,165		$	626,696		$	(1,906,011	)	$	7,934,268

Earnings_Per_Share_Table

Earnings Per Share (Table)	12 Months Ended
	Sep. 30, 2014
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:
		2014		2013		2012
		(In thousands, except per share data)
	Basic Earnings Per Share from continuing operations
	Income from continuing operations	$	289,817	$	230,698	$	192,196
	Less: Income from continuing operations allocated to participating securities	711		775		793
	Income from continuing operations available to common shareholders	$	289,106	$	229,923	$	191,403
	Basic weighted average shares outstanding	97,606		90,533		90,150
	Income from continuing operations per share — Basic	$	2.96	$	2.54	$	2.12
	Basic Earnings Per Share from discontinued operations
	Income from discontinued operations	$	—	$	12,496	$	24,521
	Less: Income from discontinued operations allocated to participating securities	—		42		101
	Income from discontinued operations available to common shareholders	$	—	$	12,454	$	24,420
	Basic weighted average shares outstanding	97,606		90,533		90,150
	Income from discontinued operations per share — Basic	$	—	$	0.14	$	0.27
	Net income per share — Basic	$	2.96	$	2.68	$	2.39
	Diluted Earnings Per Share from continuing operations
	Income from continuing operations available to common shareholders	$	289,106	$	229,923	$	191,403
	Effect of dilutive stock options and other shares	—		5		4
	Income from continuing operations available to common shareholders	$	289,106	$	229,928	$	191,407
	Basic weighted average shares outstanding	97,606		90,533		90,150
	Additional dilutive stock options and other shares	2		1,178		1,022
	Diluted weighted average shares outstanding	97,608		91,711		91,172
	Income from continuing operations per share — Diluted	$	2.96	$	2.5	$	2.1
	Diluted Earnings Per Share from discontinued operations
	Income from discontinued operations available to common shareholders	$	—	$	12,454	$	24,420
	Effect of dilutive stock options and other shares	—		—		—
	Income from discontinued operations available to common shareholders	$	—	$	12,454	$	24,420
	Basic weighted average shares outstanding	97,606		90,533		90,150
	Additional dilutive stock options and other shares	2		1,178		1,022
	Diluted weighted average shares outstanding	97,608		91,711		91,172
	Income from discontinued operations per share — Diluted	$	—	$	0.14	$	0.27
	Net income per share — Diluted	$	2.96	$	2.64	$	2.37

Debt_Table

Debt (Table)	12 Months Ended
	Sep. 30, 2014
Debt Disclosure [Abstract]	'
Debt instrument table	'
	Long-term debt at September 30, 2014 and 2013 consisted of the following:
		2014		2013
		(In thousands)
	Unsecured 4.95% Senior Notes, due October 2014	$	500,000	$	500,000
	Unsecured 6.35% Senior Notes, due 2017	250,000		250,000
	Unsecured 8.50% Senior Notes, due 2019	450,000		450,000
	Unsecured 5.95% Senior Notes, due 2034	200,000		200,000
	Unsecured 5.50% Senior Notes, due 2041	400,000		400,000
	Unsecured 4.15% Senior Notes, due 2043	500,000		500,000
	Medium term 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	4,014		4,329
	Current maturities	—		—
		$	2,455,986	$	2,455,671
Debt maturity schedule	'
	Maturities of long-term debt at September 30, 2014 were as follows (in thousands):
	2015	$	500,000
	2016	—
	2017	250,000
	2018	—
	2019	450,000
	Thereafter	1,260,000
		$	2,460,000

Recovered_Sheet1

Retirement and Post-Retirement Employee Benefit Plans (Table)	12 Months Ended
	Sep. 30, 2014
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				Supplemental				Postretirement				Total
		Benefits Plans				Executive				Plans
						Retirement Plans
		(In thousands)
	30-Sep-14
	Unrecognized transition obligation	$	—			$	—			$	354			$	354
	Unrecognized prior service credit	(1,927		)		—				(6,168		)		(8,095		)
	Unrecognized actuarial loss	109,767				34,447				7,531				151,745
		$	107,840			$	34,447			$	1,717			$	144,004
	30-Sep-13
	Unrecognized transition obligation	$	—			$	—			$	628			$	628
	Unrecognized prior service credit	(91		)		—				(5,961		)		(6,052		)
	Unrecognized actuarial loss	108,621				31,466				35,961				176,048
		$	108,530			$	31,466			$	30,628			$	170,624
Schedule of Allocation of Plan Assets	'
	The following table presents asset allocation information for the Master Trust as of September 30, 2014 and 2013.
		Targeted		Actual
		Allocation  Range		Allocation
				September 30
	Security Class			2014			2013
	Domestic equities	35%-55%		51.9	%		46.5	%
	International equities	10%-20%		15.3	%		16.1	%
	Fixed income	10%-30%		9.7	%		14.9	%
	Company stock	5%-15%		12.9	%		12.6	%
	Other assets	5%-15%		10.2	%		9.9	%
Schedule of Assumptions Used for Employee Pension Plans	'
	These assumptions are presented in the following table:
		Pension						Pension Cost
		Liability
		2014			2013			2014			2013			2012
	Discount rate	4.43	%		4.95	%		4.95	%		4.04	%		5.05	%
	Rate of compensation increase	3.5	%		3.5	%		3.5	%		3.5	%		3.5	%
	Expected return on plan assets	7.25	%		7.25	%		7.25	%		7.75	%		7.75	%
Schedule of Accumulated and Projected Benefit Obligations and Funded Status for Employee Pension Plans	'
	The following table presents the Plans’ accumulated benefit obligation, projected benefit obligation and funded status as of September 30, 2014 and 2013:
		2014				2013
		(In thousands)
	Accumulated benefit obligation	$	466,182			$	446,133
	Change in projected benefit obligation:
	Benefit obligation at beginning of year	$	455,799			$	480,031
	Service cost	15,345				17,754
	Interest cost	22,330				19,334
	Actuarial (gain) loss	26,611				(29,822		)
	Benefits paid	(24,519		)		(25,073		)
	Plan amendments	(1,972		)		—
	Divestitures	—				(6,425		)
	Benefit obligation at end of year	493,594				455,799
	Change in plan assets:
	Fair value of plan assets at beginning of year	396,887				343,144
	Actual return on plan assets	35,289				52,496
	Employer contributions	27,110				32,745
	Benefits paid	(24,519		)		(25,073		)
	Divestitures	—				(6,425		)
	Fair value of plan assets at end of year	434,767				396,887
	Reconciliation:
	Funded status	(58,827		)		(58,912		)
	Unrecognized prior service cost	—				—
	Unrecognized net loss	—				—
	Net amount recognized	$	(58,827	)		$	(58,912	)
Components of Net Periodic Pension Cost Table for Employee Pension Plans	'
	Net periodic pension cost for the Plans for fiscal 2014, 2013 and 2012 is recorded as operating expense and included the following components:
		Fiscal Year Ended September 30
		2014				2013				2012
		(In thousands)
	Components of net periodic pension cost:
	Service cost	$	15,345			$	17,754			$	15,084
	Interest cost	22,330				19,334				21,568
	Expected return on assets	(23,601		)		(22,955		)		(21,474		)
	Amortization of prior service credit	(136		)		(141		)		(141		)
	Recognized actuarial loss	13,777				19,066				14,451
	Net periodic pension cost	$	27,715			$	33,058			$	29,488
Schedule of Employee Pension Plans Investments at Fair Value	'
	In addition to the assets shown below, the Master Trust had net accounts receivable of $2.7 million and $0.4 million at September 30, 2014 and 2013 which materially approximates fair value due to the short-term nature of these assets.
		Assets at Fair Value as of September 30, 2014
		Level 1				Level 2				Level 3				Total
		(In thousands)
	Investments:
	Common stocks — domestic equities	$	155,107			$	—			$	—			$	155,107
	Money market funds	—				11,226				—				11,226
	Registered investment companies:
	Domestic funds	63,850				—				—				63,850
	International funds	48,134				—				—				48,134
	Common/collective trusts — domestic funds	—				61,208				—				61,208
	Government securities:
	Mortgage-backed securities	—				12,520				—				12,520
	U.S. treasuries	3,117				562				—				3,679
	Corporate bonds	—				25,734				—				25,734
	Limited partnerships	—				50,496				—				50,496
	Real estate	—				—				155				155
	Total investments at fair value	$	270,208			$	161,746			$	155			$	432,109
		Assets at Fair Value as of September 30, 2013
		Level 1				Level 2				Level 3				Total
		(In thousands)
	Investments:
	Common stocks — domestic equities	$	143,543			$	—			$	—			$	143,543
	Money market funds	—				12,266				—				12,266
	Registered investment companies:
	Domestic funds	30,200				—				—				30,200
	International funds	47,036				—				—				47,036
	Common/collective trusts — domestic funds	—				57,627				—				57,627
	Government securities:
	Mortgage-backed securities	—				18,446				—				18,446
	U.S. treasuries	4,117				663				—				4,780
	Corporate bonds	—				35,012				—				35,012
	Limited partnerships	—				47,417				—				47,417
	Real estate	—				—				155				155
	Total investments at fair value	$	224,896			$	171,431			$	155			$	396,482
Schedule of Assumptions Used for Supplemental Plans	'
	The actuarial assumptions used to determine the pension liability for the supplemental plans were determined as of September 30, 2014 and 2013 and the actuarial assumptions used to determine the net periodic pension cost for the supplemental plans were determined as of September 30, 2013, 2012 and 2011. These assumptions are presented in the following table:
		Pension						Pension Cost
		Liability
		2014			2013			2014			2013				2012
	Discount rate	4.43	%		4.95	%		4.95	%		4.04	%	(1)		5.05	%
	Rate of compensation increase	3.5	%		3.5	%		3.5	%		3.5	%			3.5	%
	-1	The discount rate for the supplemental plans increased from 4.04% to 4.21% effective April 1, 2013 due to a settlement loss recorded in fiscal 2013.
Schedule of Accumulated and Projected Benefit Obligations and Funded Status for Supplemental Plans	'
	The following table presents the supplemental plans’ accumulated benefit obligation, projected benefit obligation and funded status as of September 30, 2014 and 2013:
		2014				2013
		(In thousands)
	Accumulated benefit obligation	$	106,276			$	109,817
	Change in projected benefit obligation:
	Benefit obligation at beginning of year	$	117,080			$	130,186
	Service cost	3,607				3,039
	Interest cost	4,966				4,755
	Actuarial (gain) loss	9,468				(6,451		)
	Benefits paid	(5,085		)		(4,375		)
	Settlements	(16,817		)		(10,074		)
	Benefit obligation at end of year	113,219				117,080
	Change in plan assets:
	Fair value of plan assets at beginning of year	—				—
	Employer contribution	21,902				14,449
	Benefits paid	(5,085		)		(4,375		)
	Settlements	(16,817		)		(10,074		)
	Fair value of plan assets at end of year	—				—
	Reconciliation:
	Funded status	(113,219		)		(117,080		)
	Unrecognized prior service cost	—				—
	Unrecognized net loss	—				—
	Accrued pension cost	$	(113,219	)		$	(117,080	)
Components of Net Periodic Pension Cost Table for Supplemental Plans	'
	Net periodic pension cost for the supplemental plans for fiscal 2014, 2013 and 2012 is recorded as operating expense and included the following components:
		Fiscal Year Ended September 30
		2014				2013				2012
		(In thousands)
	Components of net periodic pension cost:
	Service cost	$	3,607			$	3,039			$	2,108
	Interest cost	4,966				4,755				5,142
	Amortization of transition asset	—				—				—
	Amortization of prior service cost	—				—				—
	Recognized actuarial loss	1,948				2,918				2,118
	Settlements	4,539				3,160				—
	Net periodic pension cost	$	15,060			$	13,872			$	9,368
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				Supplemental
		Plans				Plans
		(In thousands)
	2015	$	33,592			$	11,381
	2016	32,811				4,617
	2017	33,131				17,260
	2018	33,501				14,772
	2019	34,846				7,675
	2020-2024	182,998				32,843
Schedule of Allocation of Postretirement Benefit Plan Assets	'
	The following table presents asset allocation information for the postretirement benefit plan assets as of September 30, 2014 and 2013.
		Actual
		Allocation
		September 30
	Security Class	2014			2013
	Diversified investment funds	99.7	%		96.8	%
	Cash and cash equivalents	0.3	%		3.2	%
Schedule of Assumptions Used for Postretirement Benefit Plan	'
	The actuarial assumptions used to determine the pension liability for our postretirement plan were determined as of September 30, 2014 and 2013 and the actuarial assumptions used to determine the net periodic pension cost for the postretirement plan were determined as of September 30, 2013, 2012 and 2011. The assumptions are presented in the following table:
		Postretirement						Postretirement Cost
		Liability
		2014			2013			2014			2013			2012
	Discount rate	4.43	%		4.95	%		4.95	%		4.04	%		5.05	%
	Expected return on plan assets	4.6	%		4.6	%		4.6	%		4.7	%		5	%
	Initial trend rate	7.5	%		8	%		8	%		8	%		8	%
	Ultimate trend rate	5	%		5	%		5	%		5	%		5	%
	Ultimate trend reached in	2020			2020			2020			2019			2018
Schedule of Accumulated and Projected Benefit Obligations and Funded Status for Postretirement Benefit Plan	'
	The following table presents the postretirement plan’s benefit obligation and funded status as of September 30, 2014 and 2013:
		2014				2013
		(In thousands)
	Change in benefit obligation:
	Benefit obligation at beginning of year	$	312,148			$	308,315
	Service cost	16,784				18,800
	Interest cost	15,951				12,964
	Plan participants’ contributions	4,435				3,815
	Actuarial (gain) loss	(18,963		)		(13,801		)
	Benefits paid	(13,580		)		(14,458		)
	Plan amendments	(1,657		)		—
	Divestitures	—				(3,487		)
	Benefit obligation at end of year	315,118				312,148
	Change in plan assets:
	Fair value of plan assets at beginning of year	106,413				77,072
	Actual return on plan assets	14,003				13,432
	Employer contributions	23,550				26,552
	Plan participants’ contributions	4,435				3,815
	Benefits paid	(13,580		)		(14,458		)
	Fair value of plan assets at end of year	134,821				106,413
	Reconciliation:
	Funded status	(180,297		)		(205,735		)
	Unrecognized transition obligation	—				—
	Unrecognized prior service cost	—				—
	Unrecognized net loss	—				—
	Accrued postretirement cost	$	(180,297	)		$	(205,735	)
Components of Net Periodic Pension Cost Table for Postretirement Benefit Plan	'
	Net periodic postretirement cost for fiscal 2014, 2013 and 2012 is recorded as operating expense and included the components presented below.
		Fiscal Year Ended September 30
		2014				2013				2012
		(In thousands)
	Components of net periodic postretirement cost:
	Service cost	$	16,784			$	18,800			$	16,353
	Interest cost	15,951				12,964				13,861
	Expected return on assets	(5,167		)		(3,988		)		(2,607		)
	Amortization of transition obligation	274				1,081				1,511
	Amortization of prior service credit	(1,450		)		(1,450		)		(1,450		)
	Recognized actuarial loss	631				4,196				2,648
	Net periodic postretirement cost	$	27,023			$	31,603			$	30,316
Assumed Heath Care Cost Effect on Postretirement Benefit Plan Cost	'
	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				One-Percentage
		Point Increase				Point Decrease
		(In thousands)
	Effect on total service and interest cost components	$	4,533			$	(3,700	)
	Effect on postretirement benefit obligation	$	40,922			$	(34,169	)
Schedule of Postretirement Benefit Plans Investments at Fair Value	'
		Assets at Fair Value as of September 30, 2014
		Level 1				Level 2				Level 3				Total
		(In thousands)
	Investments:
	Money market funds	$	—			$	434			$	—			$	434
	Registered investment companies:
	Domestic funds	11,398				—				—				11,398
	International funds	122,989				—				—				122,989
	Total investments at fair value	$	134,387			$	434			$	—			$	134,821
		Assets at Fair Value as of September 30, 2013
		Level 1				Level 2				Level 3				Total
		(In thousands)
	Investments:
	Money market funds	$	—			$	3,356			$	—			$	3,356
	Registered investment companies:
	Domestic funds	9,614				—				—				9,614
	International funds	93,443				—				—				93,443
	Total investments at fair value	$	103,057			$	3,356			$	—			$	106,413
Schedule of Expected Benefit Payments for Postretirement Benefit Plan	'
	The following benefit payments paid by us, retirees and prescription drug subsidy payments for our postretirement benefit plans, which reflect expected future service, as appropriate, are expected to be paid in the following fiscal years. Company payments for fiscal 2015 include contributions to our postretirement plan trusts.
		Company				Retiree				Subsidy				Total
		Payments				Payments				Payments				Postretirement
														Benefits
		(In thousands)
	2015	$	22,177			$	3,582			$	—			$	25,759
	2016	15,008				4,615				—				19,623
	2017	17,551				5,796				—				23,347
	2018	19,660				7,148				—				26,808
	2019	21,302				8,549				—				29,851
	2020-2024	127,741				63,524				—				191,265

Stock_and_Other_Compensation_P1

Stock and Other Compensation Plans (Table)	12 Months Ended
	Sep. 30, 2014
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, 2014, 2013 and 2012:
		2014				2013				2012
		Number of		Weighted		Number of		Weighted		Number of		Weighted
		Restricted		Average		Restricted		Average		Restricted		Average
		Units		Grant-Date		Units		Grant-Date		Units		Grant-Date
				Fair				Fair				Fair
				Value				Value				Value
	Nonvested at beginning of year	1,052,844		$	36.2	1,262,582		$	32.46	1,264,142		$	29.56
	Granted	464,438		45.05		473,775		40.48		532,711		33.44
	Vested	(524,532	)	32.67		(657,795	)	32.2		(494,308	)	26.32
	Forfeited	(4,113	)	39		(25,718	)	33.42		(39,963	)	29.83
	Nonvested at end of year	988,637		$	42.22	1,052,844		$	36.2	1,262,582		$	32.46

Details_of_Selected_Consolidat1

Details of Selected Consolidated Balance Sheet Captions (Table)	12 Months Ended
	Sep. 30, 2014
Details Of Selected Consolidated Balance Sheet Captions Disclosure [Abstract]	'
Accounts Receivables Detail Table	'
	Accounts receivable was comprised of the following at September 30, 2014 and 2013:
		September 30
		2014			2013
		(In thousands)
	Billed accounts receivable	$	262,937		$	230,712
	Unbilled revenue	62,484			58,710
	Other accounts receivable	41,971			33,194
	Total accounts receivable	367,392			322,616
	Less: allowance for doubtful accounts	(23,992		)	(20,624		)
	Net accounts receivable	$	343,400		$	301,992
Other Current Assets Detail Table	'
	Other current assets as of September 30, 2014 and 2013 were comprised of the following accounts.
		September 30
		2014			2013
		(In thousands)
	Assets from risk management activities	$	45,827		$	11,966
	Deferred gas costs	20,069			15,152
	Taxes receivable	5,481			3,141
	Prepaid expenses	25,039			21,666
	Materials and supplies	5,704			5,511
	Other	9,145			6,765
	Total	$	111,265		$	64,201
Property, Plant and Equipment Detail Table	'
	Property, plant and equipment was comprised of the following as of September 30, 2014 and 2013:
		September 30
		2014			2013
		(In thousands)
	Production plant	$	4,821		$	5,020
	Storage plant	275,579			262,246
	Transmission plant	1,622,846			1,362,662
	Distribution plant	5,522,794			5,061,711
	General plant	735,223			716,189
	Intangible plant	38,858			38,444
		8,200,121			7,446,272
	Construction in progress	247,579			275,747
		8,447,700			7,722,019
	Less: accumulated depreciation and amortization	(1,721,794		)	(1,691,364		)
	Net property, plant and equipment(1)	$	6,725,906		$	6,030,655
	(1)	Net property, plant and equipment includes plant acquisition adjustments of $(76.4) million and $(83.8) million at September 30, 2014 and 2013.
Goodwill Detail Table	'
	The following presents our goodwill balance allocated by segment and changes in the balance for the fiscal year ended September 30, 2014:
		Regulated			Regulated			Nonregulated		Total
		Distribution			Pipeline
		(In thousands)
	Balance as of September 30, 2013	$	574,190		$	132,462		$	34,711	$	741,363
	Deferred tax adjustments on prior acquisitions(1)	626			40			—		666
	Balance as of September 30, 2014	$	574,816		$	132,502		$	34,711	$	742,029
	(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, 2014 and 2013 were comprised of the following accounts.
		September 30
		2014			2013
		(In thousands)
	Marketable securities	$	79,613		$	72,682
	Regulatory assets	230,240			273,287
	Deferred financing costs	13,698			15,199
	Assets from risk management activities	13,038			109,354
	Other	14,340			14,595
	Total	$	350,929		$	485,117
Accounts Payable and Accrued Liabilities	'
	Accounts payable and accrued liabilities as of September 30, 2014 and 2013 were comprised of the following accounts.
		September 30
		2014			2013
		(In thousands)
	Trade accounts payable	$	77,860		$	70,116
	Accrued gas payable	179,425			121,202
	Accrued liabilities	54,319			50,293
	Total	$	311,604		$	241,611
Other Current Liabilities Detail Table	'
	Other current liabilities as of September 30, 2014 and 2013 were comprised of the following accounts.
		September 30
		2014			2013
		(In thousands)
	Customer credit balances and deposits	$	82,085		$	76,313
	Accrued employee costs	46,445			54,034
	Deferred gas costs	35,063			16,481
	Accrued interest	36,768			36,744
	Liabilities from risk management activities	1,730			1,543
	Taxes payable	77,601			66,960
	Pension and postretirement obligations	11,380			22,940
	Current deferred tax liability	48,751			14,697
	Regulatory cost of removal accrual	45,061			68,225
	Other	17,467			10,954
	Total	$	402,351		$	368,891
Deferred Credits and Other Liabilities Detail Table	'
	Deferred credits and other liabilities as of September 30, 2014 and 2013 were comprised of the following accounts.
		September 30
		2014			2013
		(In thousands)
	Customer advances for construction	$	9,883		$	11,723
	Regulatory liabilities	4,472			1,123
	Asset retirement obligation	10,508			6,764
	Liabilities from risk management activities	20,126			—
	Other	23,881			17,953
	Total	$	68,870		$	37,563

Leases_Table

Leases (Table)	12 Months Ended
	Sep. 30, 2014
Leases [Abstract]	'
Schedule of Future Minimum Lease Payments	'
	The related future minimum lease payments at September 30, 2014 were as follows:
		Capital		Operating
		Leases		Leases
		(In thousands)
	2015	$	186	$	16,673
	2016	186		16,021
	2017	186		16,330
	2018	78		15,907
	2019	—		15,138
	Thereafter	—		75,620
	Total minimum lease payments	636		$	155,689
	Less amount representing interest	123
	Present value of net minimum lease payments	$	513

Commitments_and_Contingencies_

Commitments and Contingencies (Table)	12 Months Ended
	Sep. 30, 2014
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, 2014 are as follows (in thousands):
	2015	$	7,426
	2016	2,117
	2017	1,437
	2018	773
	2019	143
	Thereafter	214
		$	12,110

Income_Taxes_Table

Income Taxes (Table)	12 Months Ended
	Sep. 30, 2014
Income Tax Disclosure [Abstract]	'
Schedule of Components of Income Tax Expense (Benefit)	'
	The components of income tax expense from continuing operations for 2014, 2013 and 2012 were as follows:
		2014			2013			2012
		(In thousands)
	Current
	Federal	$	—		$	—		$	631
	State	5,527			8,178			6,888
	Deferred
	Federal	169,106			124,836			103,971
	State	12,375			9,605			(13,237		)
	Investment tax credits	(6		)	(20		)	(27		)
		$	187,002		$	142,599		$	98,226
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 2014, 2013 and 2012 are set forth below:
		2014			2013			2012
		(In thousands)
	Tax at statutory rate of 35%	$	166,887		$	130,655		$	101,648
	Common stock dividends deductible for tax reporting	(2,307		)	(2,153		)	(2,096		)
	State taxes (net of federal benefit)	11,636			11,559			(4,127		)
	Change in valuation allowance	6,969			1,085			—
	Other, net	3,817			1,453			2,801
	Income tax expense	$	187,002		$	142,599		$	98,226
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, 2014 and 2013 are presented below:
		2014			2013
		(In thousands)
	Deferred tax assets:
	Employee benefit plans	$	116,157		$	115,970
	Interest rate agreements	10,565			—
	Net operating loss carryforwards	236,626			196,296
	Charitable and other credit carryforwards	21,614			20,939
	Other	28,849			38,013
	Total deferred tax assets	413,811			371,218
	Valuation allowance	(6,969		)	(1,085		)
	Net deferred tax assets	406,842			370,133
	Deferred tax liabilities:
	Difference in net book value and net tax value of assets	(1,655,894		)	(1,445,450		)
	Pension funding	(17,890		)	(23,480		)
	Gas cost adjustments	(31,252		)	(19,182		)
	Interest rate agreements	—			(21,726		)
	Other	(37,173		)	(39,045		)
	Total deferred tax liabilities	(1,742,209		)	(1,548,883		)
	Net deferred tax liabilities	$	(1,335,367	)	$	(1,178,750	)
	Deferred credits for rate regulated entities	$	(109	)	$	(51	)
Schedule of Unrecognized Tax Benefits Roll Forward	'
	The following table reconciles the beginning and ending balance of our unrecognized tax benefits:
		2014			2013
		(In thousands)
	Unrecognized tax benefits - beginning balance	$	4,158		$	2,817
	Increase resulting from prior period tax positions	3,846			—
	Increase resulting from current period tax positions	4,625			1,341
	Unrecognized tax benefits - ending balance	12,629			4,158
	Accrued interest and penalties	411			—
	Gross unrecognized tax benefits	13,040			4,158
	Less: deferred federal and state income tax benefits	(4,564		)	(1,455		)
	Total unrecognized tax benefits that, if recognized, would impact the effective income tax rate as of the end of the year	$	8,476		$	2,703

Financial_Instruments_Table

Financial Instruments (Table)	12 Months Ended
	Sep. 30, 2014
Derivative Instruments and Hedging Activities Disclosure [Abstract]	'
Schedule of financial instrument assets and liabilities at fair value	'
	The following table shows the fair values of our risk management assets and liabilities by segment at September 30, 2014 and 2013:
		Regulated				Nonregulated				Total
		Distribution
		(In thousands)
	30-Sep-14
	Assets from risk management activities, current(1)	$	23,102			$	22,725			$	45,827
	Assets from risk management activities, noncurrent	13,038				—				13,038
	Liabilities from risk management activities, current(1)	(1,730		)		—				(1,730		)
	Liabilities from risk management activities, noncurrent(1)	(20,126		)		—				(20,126		)
	Net assets	$	14,284			$	22,725			$	37,009
	30-Sep-13
	Assets from risk management activities, current(2)	$	1,837			$	10,129			$	11,966
	Assets from risk management activities, noncurrent	109,354				—				109,354
	Liabilities from risk management activities, current(2)	(1,543		)		—				(1,543		)
	Liabilities from risk management activities, noncurrent(2)	—				—				—
	Net assets	$	109,648			$	10,129			$	119,777
	(1)	Includes $25.8 million of cash held on deposit to collateralize certain financial instruments. Of this amount, $3.1 million was used to offset current and noncurent risk management liabilities under master netting arrangements and the remaining $22.7 million is classified as current risk management assets.
	(2)	Includes $24.8 million of cash held on deposit to collateralize certain financial instruments. Of this amount, $14.7 million was used to offset current and noncurrent risk management liabilities under master netting arrangements and the remaining $10.1 million is classified as current risk management assets.
Outstanding commodity contracts volumes table	'
	As of September 30, 2014, we had net long/(short) commodity contracts outstanding in the following quantities:
	Contract Type		Hedge		Regulated			Nonregulated
			Designation		Distribution
					Quantity (MMcf)
	Commodity contracts		Fair Value		—			(10,298	)
			Cash Flow		—			49,290
			Not designated		31,812			96,711
					31,812			135,703
Financial instruments on the balance sheet	'
	The following tables present the fair value and balance sheet classification of our financial instruments by operating segment as of September 30, 2014 and 2013. The gross amounts of recognized assets and liabilities are netted within our Consolidated Balance Sheets to the extent that we have netting arrangements with the counterparties.
				Regulated Distribution								Nonregulated
		Balance Sheet Location		Assets				Liabilities				Assets			Liabilities
				(In thousands)
	30-Sep-14
	Designated As Hedges:
	Commodity contracts	Other current assets /		$	—			$	—			$	8,912		$	(7,082	)
		Other current liabilities
	Interest rate contracts	Other current assets /		21,869				—				—			—
		Other current liabilities
	Commodity contracts	Deferred charges and other assets /		—				—				757			(2,459		)
		Deferred credits and other liabilities
	Interest rate contracts	Deferred charges and other assets /		12,608				(19,835		)		—			—
		Deferred credits and other liabilities
	Total			34,477				(19,835		)		9,669			(9,541		)
	Not Designated As Hedges:
	Commodity contracts	Other current assets /		1,233				(1,730		)		43,677			(47,729		)
		Other current liabilities
	Commodity contracts	Deferred charges and other assets /		430				(291		)		15,677			(14,786		)
		Deferred credits and other liabilities
	Total			1,663				(2,021		)		59,354			(62,515		)
	Gross Financial Instruments			36,140				(21,856		)		69,023			(72,056		)
	Gross Amounts Offset on Consolidated Balance Sheet:
	Contract netting			—				—				(69,023		)	69,023
	Net Financial Instruments			36,140				(21,856		)		—			(3,033		)
	Cash collateral			—				—				22,725			3,033
	Net Assets/Liabilities from Risk Management Activities			$	36,140			$	(21,856	)		$	22,725		$	—
				Regulated Distribution								Nonregulated
		Balance Sheet Location		Assets				Liabilities				Assets			Liabilities
				(In thousands)
	30-Sep-13
	Designated As Hedges:
	Commodity contracts	Other current assets /		$	—			$	—			$	9,094		$	(12,173	)
		Other current liabilities
	Commodity contracts	Deferred charges and other assets /		—				—				416			(1,639		)
		Deferred credits and other liabilities
	Interest rate contracts	Deferred charges and other assets /		107,512				—				—			—
		Deferred credits and other liabilities
	Total			107,512				—				9,510			(13,812		)
	Not Designated As Hedges:
	Commodity contracts	Other current assets /		1,837				(1,543		)		65,388			(70,876		)
		Other current liabilities
	Commodity contracts	Deferred charges and other assets /		1,842				—				40,982			(45,892		)
		Deferred credits and other liabilities
	Total			3,679				(1,543		)		106,370			(116,768		)
	Gross Financial Instruments			111,191				(1,543		)		115,880			(130,580		)
	Gross Amounts Offset on Consolidated Balance Sheet:
	Contract netting			—				—				(115,875		)	115,875
	Net Financial Instruments			111,191				(1,543		)		5			(14,705		)
	Cash collateral			—				—				10,124			14,705
	Net Assets/Liabilities from Risk Management Activities			$	111,191			$	(1,543	)		$	10,129		$	—
Fair value hedges table	'
	The impact of our nonregulated commodity contracts designated as fair value hedges and the related hedged item on our consolidated income statement for the years ended September 30, 2014, 2013 and 2012 is presented below.
		Fiscal Year Ended September 30
		2014				2013				2012
		(In thousands)
	Commodity contracts	$	(792	)		$	2,165			$	30,266
	Fair value adjustment for natural gas inventory designated as the hedged item	2,486				15,938				(5,797		)
	Total decrease in purchased gas cost	$	1,694			$	18,103			$	24,469
	The decrease in purchased gas cost is comprised of the following:
	Basis ineffectiveness	$	(919	)		$	(208	)		$	1,170
	Timing ineffectiveness	2,613				18,311				23,299
		$	1,694			$	18,103			$	24,469
Cash flow hedges table	'
	The impact of cash flow hedges on our consolidated income statements for the years ended September 30, 2014, 2013 and 2012 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, 2014
		Regulated				Nonregulated				Consolidated
		Distribution
		(In thousands)
	Gain reclassified from AOCI for effective portion of commodity contracts	$	—			$	8,365			$	8,365
	Gain arising from ineffective portion of commodity contracts	—				198				198
	Total impact on purchased gas cost	—				8,563				8,563
	Net loss on settled interest rate agreements reclassified from AOCI into interest expense	(4,230		)		—				(4,230		)
	Total impact from cash flow hedges	$	(4,230	)		$	8,563			$	4,333
		Fiscal Year Ended September 30, 2013
		Regulated				Nonregulated				Consolidated
		Distribution
		(In thousands)
	Loss reclassified from AOCI for effective portion of commodity contracts	$	—			$	(10,778	)		$	(10,778	)
	Gain arising from ineffective portion of commodity contracts	—				97				97
	Total impact on purchased gas cost	—				(10,681		)		(10,681		)
	Net loss on settled interest rate agreements reclassified from AOCI into interest expense	(3,489		)		—				(3,489		)
	Total impact from cash flow hedges	$	(3,489	)		$	(10,681	)		$	(14,170	)
		Fiscal Year Ended September 30, 2012
		Regulated				Nonregulated				Consolidated
		Distribution
		(In thousands)
	Loss reclassified from AOCI for effective portion of commodity contracts	$	—			$	(62,678	)		$	(62,678	)
	Loss arising from ineffective portion of commodity contracts	—				(1,369		)		(1,369		)
	Total impact on purchased gas cost	—				(64,047		)		(64,047		)
	Net loss on settled interest rate agreements reclassified from AOCI into interest expense	(2,009		)		—				(2,009		)
	Total impact from cash flow hedges	$	(2,009	)		$	(64,047	)		$	(66,056	)
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, 2014 and 2013. 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
		2014				2013
		(In thousands)
	Increase (decrease) in fair value:
	Interest rate agreements	$	(58,973	)		$	79,963
	Forward commodity contracts	7,904				(2,057		)
	Recognition of (gains) losses in earnings due to settlements:
	Interest rate agreements	2,686				2,216
	Forward commodity contracts	(5,102		)		6,576
	Total other comprehensive income (loss) from hedging, net of tax(1)	$	(53,485	)		$	86,698
	(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, 2014. However, the table below does not include the expected recognition in earnings of the interest rate agreements entered into in October 2012 and fiscal 2014 as those financial instruments have not yet settled.
		Interest Rate				Commodity				Total
		Agreements				Contracts
		(In thousands)
	2015	$	(804	)		$	(632	)		$	(1,436	)
	2016	(634		)		(907		)		(1,541		)
	2017	(735		)		(107		)		(842		)
	2018	(936		)		(38		)		(974		)
	2019	(961		)		10				(951		)
	Thereafter	(23,609		)		—				(23,609		)
	Total(1)	$	(27,679	)		$	(1,674	)		$	(29,353	)
	(1)	Utilizing an income tax rate ranging from approximately 37 percent to 39 percent based on the effective rates in each taxing jurisdiction.

Accumulated_Other_Comprehensiv1

Accumulated Other Comprehensive Income (Table)	12 Months Ended
	Sep. 30, 2014
Equity [Abstract]	'
Schedule of Accumulated Other Comprehensive Income (Loss)	'
	The following tables provide the components of our accumulated other comprehensive income (loss) balances, net of the related tax effects allocated to each component of other comprehensive income.
		Available-			Interest			Commodity			Total
		for-Sale			Rate			Contracts
		Securities			Agreement			Cash Flow
					Cash Flow			Hedges
					Hedges
		(In thousands)
	30-Sep-13	$	5,448		$	37,906		$	(4,476	)	$	38,878
	Other comprehensive income (loss) before reclassifications	3,009			(58,973		)	7,904			(48,060		)
	Amounts reclassified from accumulated other comprehensive income	(795		)	2,686			(5,102		)	(3,211		)
	Net current-period other comprehensive income (loss)	2,214			(56,287		)	2,802			(51,271		)
	30-Sep-14	$	7,662		$	(18,381	)	$	(1,674	)	$	(12,393	)
		Available-			Interest			Commodity			Total
		for-Sale			Rate			Contracts
		Securities			Agreement			Cash Flow
					Cash Flow			Hedges
					Hedges
		(In thousands)
	30-Sep-12	$	5,661		$	(44,273	)	$	(8,995	)	$	(47,607	)
	Other comprehensive income (loss) before reclassifications	1,162			79,963			(2,057		)	79,068
	Amounts reclassified from accumulated other comprehensive income	(1,375		)	2,216			6,576			7,417
	Net current-period other comprehensive income (loss)	(213		)	82,179			4,519			86,485
	30-Sep-13	$	5,448		$	37,906		$	(4,476	)	$	38,878
Reclassification out of Accumulated Other Comprehensive Income	'
	The following tables detail reclassifications out of AOCI for the fiscal years ended September 30, 2014 and 2013. Amounts in parentheses below indicate decreases to net income in the statement of income.
		Fiscal Year Ended September 30, 2014
	Accumulated Other Comprehensive Income Components	Amount Reclassified from			Affected Line Item in the
		Accumulated Other			Statement of Income
		Comprehensive Income
		(In thousands)
	Available-for-sale securities	$	1,252		Operation and maintenance expense
		1,252			Total before tax
		(457		)	Tax expense
		$	795		Net of tax
	Cash flow hedges
	Interest rate agreements	$	(4,230	)	Interest charges
	Commodity contracts	8,365			Purchased gas cost
		4,135			Total before tax
		(1,719		)	Tax expense
		$	2,416		Net of tax
	Total reclassifications	$	3,211		Net of tax
		Fiscal Year Ended September 30, 2013
	Accumulated Other Comprehensive Income Components	Amount Reclassified from			Affected Line Item in the
		Accumulated Other			Statement of Income
		Comprehensive Income
		(In thousands)
	Available-for-sale securities	$	2,166		Operation and maintenance expense
		2,166			Total before tax
		(791		)	Tax expense
		$	1,375		Net of tax
	Cash flow hedges
	Interest rate agreements	$	(3,489	)	Interest charges
	Commodity contracts	(10,778		)	Purchased gas cost
		(14,267		)	Total before tax
		5,475			Tax benefit
		$	(8,792	)	Net of tax
	Total reclassifications	$	(7,417	)	Net of tax

Fair_Value_Measurements_Table

Fair Value Measurements (Table)	12 Months Ended
	Sep. 30, 2014
Fair Value Disclosures [Abstract]	'
Fair value measurements table	'
	The following tables summarize, by level within the fair value hierarchy, our assets and liabilities that were accounted for at fair value on a recurring basis as of September 30, 2014 and 2013. 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		Significant		Significant			Netting and			30-Sep-14
		Prices in		Other		Other			Cash
		Active		Observable		Unobservable			Collateral(2)
		Markets		Inputs		Inputs
		(Level 1)		(Level 2)(1)		(Level 3)
		(In thousands)
	Assets:
	Financial instruments
	Regulated distribution segment	$	—	$	36,140	$	—		$	—		$	36,140
	Nonregulated segment	25		68,998		—			(46,298		)	22,725
	Total financial instruments	25		105,138		—			(46,298		)	58,865
	Hedged portion of gas stored underground	40,492		—		—			—			40,492
	Available-for-sale securities
	Money market funds	—		2,185		—			—			2,185
	Registered investment companies	44,014		—		—			—			44,014
	Bonds	—		33,414		—			—			33,414
	Total available-for-sale securities	44,014		35,599		—			—			79,613
	Total assets	$	84,531	$	140,737	$	—		$	(46,298	)	$	178,970
	Liabilities:
	Financial instruments
	Regulated distribution segment	$	—	$	21,856	$	—		$	—		$	21,856
	Nonregulated segment	12		72,044		—			(72,056		)	—
	Total liabilities	$	12	$	93,900	$	—		$	(72,056	)	$	21,856
		Quoted		Significant		Significant			Netting and			30-Sep-13
		Prices in		Other		Other			Cash
		Active		Observable		Unobservable			Collateral(3)
		Markets		Inputs		Inputs
		(Level 1)		(Level 2)(1)		(Level 3)
		(In thousands)
	Assets:
	Financial instruments
	Regulated distribution segment	$	—	$	111,191	$	—		$	—		$	111,191
	Nonregulated segment	745		115,135		—			(105,751		)	10,129
	Total financial instruments	745		226,326		—			(105,751		)	121,320
	Hedged portion of gas stored underground	44,758		—		—			—			44,758
	Available-for-sale securities
	Money market funds	—		4,428		—			—			4,428
	Registered investment companies	40,094		—		—			—			40,094
	Bonds	—		28,160		—			—			28,160
	Total available-for-sale securities	40,094		32,588		—			—			72,682
	Total assets	$	85,597	$	258,914	$	—		$	(105,751	)	$	238,760
	Liabilities:
	Financial instruments
	Regulated distribution segment	$	—	$	1,543	$	—		$	—		$	1,543
	Nonregulated segment	158		130,422		—			(130,580		)	—
	Total liabilities	$	158	$	131,965	$	—		$	(130,580	)	$	1,543
	(1)	Our Level 2 measurements consist of over-the-counter options and swaps, which are valued using a market-based approach in which observable market prices are adjusted for criteria specific to each instrument, such as the strike price, notional amount or basis differences, municipal and corporate bonds, which are valued based on the most recent available quoted market prices and money market funds which are valued at cost.
	(2)	This column reflects adjustments to our gross financial instrument assets and liabilities to reflect netting permitted under our master netting agreements and the relevant authoritative accounting literature. In addition, as of September 30, 2014 we had $25.8 million of cash held in margin accounts to collateralize certain financial instruments. Of this amount, $3.1 million was used to offset current and noncurrent risk management liabilities under master netting agreements and the remaining $22.7 million is classified as current risk management assets.
	(3)	This column reflects adjustments to our gross financial instrument assets and liabilities to reflect netting permitted under our master netting agreements and the relevant authoritative accounting literature. In addition, as of September 30, 2013 we had $24.8 million of cash held in margin accounts to collateralize certain financial instruments. Of this amount, $14.7 million was used to offset current and noncurrent risk management liabilities under master netting agreements and the remaining $10.1 million is classified as current risk management assets.
Available for sale securities	'
	Available-for-sale securities are comprised of the following:
		Amortized		Gross		Gross			Fair
		Cost		Unrealized		Unrealized			Value
				Gain		Loss
		(In thousands)
	As of September 30, 2014
	Domestic equity mutual funds	$	26,633	$	10,136	$	—		$	36,769
	Foreign equity mutual funds	5,382		1,863		—			7,245
	Bonds	33,266		161		(13		)	33,414
	Money market funds	2,185		—		—			2,185
		$	67,466	$	12,160	$	(13	)	$	79,613
	As of September 30, 2013
	Domestic equity mutual funds	$	27,043	$	7,476	$	(23	)	$	34,496
	Foreign equity mutual funds	4,536		1,062		—			5,598
	Bonds	28,016		168		(24		)	28,160
	Money market funds	4,428		—		—			4,428
		$	64,023	$	8,706	$	(47	)	$	72,682
Other fair value measurements table	'
	The following table presents the carrying value and fair value of our debt as of September 30, 2014:
		30-Sep-14
		(In thousands)
	Carrying Amount	$	2,460,000
	Fair Value	$	2,769,541

Discontinued_Operations_Table

Discontinued Operations (Table)	12 Months Ended
	Sep. 30, 2014
Discontinued Operations and Disposal Groups [Abstract]	'
Discontinued operations income statement detail table	'
	The following table presents statement of income data related to discontinued operations in our Georgia, Missouri, Illinois and Iowa service areas. At September 30, 2014 and 2013 we did not have any assets or liabilities held for sale.
		Year Ended September 30
		2013		2012
		(In thousands)
	Operating revenues	$	37,962	$	114,703
	Purchased gas cost	21,464		62,902
	Gross profit	16,498		51,801
	Operating expenses	5,858		24,174
	Operating income	10,640		27,627
	Other nonoperating income	548		611
	Income from discontinued operations before income taxes	11,188		28,238
	Income tax expense	3,986		10,066
	Income from discontinued operations	7,202		18,172
	Gain on sale of discontinued operations, net of tax	5,294		6,349
	Net income from discontinued operations	$	12,496	$	24,521

Selected_Quarterly_Financial_D1

Selected Quarterly Financial Data (Table)	12 Months Ended
	Sep. 30, 2014
Quarterly Financial Information Disclosure [Abstract]	'
Schedule of Quarterly Financial Information	'
	Summarized unaudited quarterly financial data is presented below. The sum of net income per share by quarter may not equal the net income per share for the fiscal year due to variations in the weighted average shares outstanding used in computing such amounts. Our businesses are seasonal due to weather conditions in our service areas. For further information on its effects on quarterly results, see the “Results of Operations” discussion included in the “Management’s Discussion and Analysis of Financial Condition and Results of Operations” section herein.
		Quarter Ended
		December 31			March 31			June 30			September 30
		(In thousands, except per share data)
	Fiscal year 2014:
	Operating revenues
	Regulated distribution	$	843,865		$	1,290,960		$	517,707		$	409,014
	Regulated pipeline	71,341			73,615			87,189			86,314
	Nonregulated	447,721			757,683			465,033			396,855
	Intersegment eliminations	(107,779		)	(157,936		)	(127,211		)	(113,455		)
		1,255,148			1,964,322			942,718			778,728
	Gross profit	388,957			496,277			359,533			337,659
	Operating income	170,720			250,080			106,605			83,944
	Net income	87,016			133,367			45,721			23,713
	Net income per share — basic	$	0.94		$	1.38		$	0.45		$	0.23
	Net income per share — diluted	$	0.94		$	1.38		$	0.45		$	0.23
		Quarter Ended
		December 31			March 31			June 30			September 30
		(In thousands, except per share data)
	Fiscal year 2013:
	Operating revenues
	Regulated distribution	$	666,787		$	905,176		$	467,144		$	360,386
	Regulated pipeline	60,681			61,848			74,041			72,330
	Nonregulated	399,894			428,948			421,808			337,264
	Intersegment eliminations	(93,207		)	(86,976		)	(105,058		)	(95,606		)
		1,034,155			1,308,996			857,935			674,374
	Gross profit	362,362			432,751			316,497			300,440
	Operating income	154,922			210,178			86,396			50,383
	Income from continuing operations	77,348			112,340			33,474			7,536
	Income from discontinued operations	3,117			4,085			—			—
	Gain on sale of discontinued operations	—			—			5,294			—
	Net income	80,465			116,425			38,768			7,536
	Basic earnings per share
	Income per share from continuing operations	$	0.85		$	1.24		$	0.37		$	0.08
	Income per share from discontinued operations	$	0.04		0.04			$	0.06		$	—
	Net income per share — basic	$	0.89		$	1.28		$	0.43		$	0.08
	Diluted earnings per share
	Income per share from continuing operations	$	0.85		$	1.23		$	0.36		$	0.08
	Income per share from discontinued operations	$	0.03		$	0.04		$	0.06		$	—
	Net income per share — diluted	$	0.88		$	1.27		$	0.42		$	0.08

Nature_of_Business_Details

Nature of Business (Details)	Sep. 30, 2014
	regulated_gas_distributions_divisions
	customers
Schedule of Number of Customers, Discontinued Operations [Line Items]	'
Number Of Customers, Regulated Distribution	3,000,000
Number Of Divisions, Regulated Distribution	6
Georgia [Member]	'
Schedule of Number of Customers, Discontinued Operations [Line Items]	'
Number Of Customers, Regulated Distribution	64,000
Missouri, Illinois and Iowa [Member]	'
Schedule of Number of Customers, Discontinued Operations [Line Items]	'
Number Of Customers, Regulated Distribution	84,000

Summary_of_Significant_Account2

Summary of Significant Accounting Policies (Details) (USD $)

12 Months Ended

0 Months Ended

12 Months Ended

Sep. 30, 2014

Sep. 30, 2013

Sep. 30, 2012

Oct. 15, 2014

Sep. 30, 2014

Sep. 30, 2014

Sep. 30, 2014

Sep. 30, 2014

Sep. 30, 2013

Sep. 30, 2014

Sep. 30, 2013

Sep. 30, 2014

Sep. 30, 2013

Sep. 30, 2014

Sep. 30, 2013

Sep. 30, 2014

Sep. 30, 2013

Sep. 30, 2014

Sep. 30, 2013

Sep. 30, 2014

Sep. 30, 2013

Sep. 30, 2014

Sep. 30, 2013

Sep. 30, 2014

Sep. 30, 2013

Sep. 30, 2014

Sep. 30, 2013

Sep. 30, 2014

Sep. 30, 2013

Sep. 30, 2014

Sep. 30, 2013

Sep. 30, 2014

Sep. 30, 2013

Subsequent Event [Member]

Supplemental Employee Retirement Plan, Defined Benefit [Member]

Minimum [Member]

Maximum [Member]

Deferred Gas Costs Liability [Member]

Deferred Gas Costs Liability [Member]

Deferred Franchise Fees Liability [Member]

Deferred Franchise Fees Liability [Member]

Regulatory Cost Of Removal Liability [Member]

Regulatory Cost Of Removal Liability [Member]

Miscellaneous Regulatory Liabilities [Member]

Miscellaneous Regulatory Liabilities [Member]

Pension And Postretirement Benefit Costs [Member]

Pension And Postretirement Benefit Costs [Member]

Merger And Integration Costs Net [Member]

Merger And Integration Costs Net [Member]

Deferred Gas Costs Asset [Member]

Deferred Gas Costs Asset [Member]

Regulatory Cost of Removal Asset [Member]

Regulatory Cost of Removal Asset [Member]

Rate Case Costs [Member]

Rate Case Costs [Member]

Texas 8.209 [Member]

Texas 8.209 [Member]

APT Annual Adjustment Mechanism Asset [Member]

APT Annual Adjustment Mechanism Asset [Member]

Recoverable Loss On Reacquired Debt [Member]

Recoverable Loss On Reacquired Debt [Member]

Deferred Miscellaneous Costs [Member]

Deferred Miscellaneous Costs [Member]

Fair Value Inputs Level 3 [Member]

Real Estate [Member]

Regulatory Assets [Line Items]

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Regulatory Assets

$250,309,000

$286,748,000

'

'

'

'

'

'

'

'

'

'

'

'

'

$162,777,000

[1]

$187,977,000

[1]

$4,730,000

$5,250,000

$20,069,000

$15,152,000

$0

$10,008,000

$3,757,000

$6,329,000

$26,948,000

[2]

$30,364,000

[2]

$8,479,000

$5,853,000

$18,877,000

$21,435,000

$4,672,000

$4,380,000

Regulatory Liabilities [Line Items]

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Regulatory Liabilities

545,759,000

453,581,000

'

'

'

'

'

35,063,000

16,481,000

5,268,000

1,689,000

490,448,000

427,524,000

14,980,000

7,887,000

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Regulatory Assets and Liabilities, Other Disclosures [Abstract]

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Regulatory Asset - Future Recoverable Pension Costs

18,800,000

17,400,000

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Regulatory Noncurrent Asset, Amortization Period

'P20Y

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Amortization of Regulatory Asset

500,000

500,000

500,000

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Property, Plant and Equipment [Line Items]

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Estimated useful lives for nonregulated property, plant and equipment

'

'

'

'

'

'3 years

'50 years

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Interest Costs Capitalized

1,500,000

1,900,000

2,600,000

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Composite depreciation rate for regulated property, plant and equipment

3.30%

3.30%

3.60%

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Other Information [Abstract]

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Unrealized gain (loss) on open contracts

9,600,000

9,000,000

-8,000,000

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Asset Retirement Obligation

10,500,000

6,800,000

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Asset Retirement Costs in Property, Plant and Equipment

5,900,000

3,300,000

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Asset Impairment Charges Park City

'

'

5,300,000

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Derivative, Cash Collateral

25,800,000

24,800,000

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Defined Benefit Plan Disclosure [Line Items]

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Investments, Fair Value Disclosure

'

'

'

'

$200,000

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Subsequent Event [Line Items]

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Subsequent Event, Date

'

'

'

15-Oct-14

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Subsequent Event, Description

'

'

'

' issuance of $500 million, 4.125% senior notes

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

[1]

Includes $18.8 million and $17.4 million of pension and postretirement expense deferred pursuant to regulatory authorization.

[2]

Texas Rule 8.209 is a Railroad Commission rule that allows for the deferral of all expenses associated with capital expenditures incurred pursuant to this rule, including the recording of interest on the deferred expenses until the next rate proceeding (rate case or annual rate filing), at which time investment and costs would be recovered through base rates.

Segment_Information_Details

Segment Information (Details) (USD $)

3 Months Ended

12 Months Ended

In Thousands, unless otherwise specified

Sep. 30, 2014

Jun. 30, 2014

Mar. 31, 2014

Dec. 31, 2013

Sep. 30, 2013

Jun. 30, 2013

Mar. 31, 2013

Dec. 31, 2012

Sep. 30, 2014

Sep. 30, 2013

Sep. 30, 2012

Sep. 30, 2011

state

segment

regulated_gas_distributions_divisions

state

customers

regulated_gas_distributions_divisions

customers

Segment Reporting Information Profit Loss [Abstract]

'

'

'

'

'

'

'

'

'

'

'

'

Operating revenues

$778,728

$942,718

$1,964,322

$1,255,148

$674,374

$857,935

$1,308,996

$1,034,155

$4,940,916

$3,875,460

$3,436,162

'

Purchased gas cost

'

'

'

'

'

'

'

'

3,358,490

2,463,410

2,112,423

'

Gross profit

337,659

359,533

496,277

388,957

300,440

316,497

432,751

362,362

1,582,426

1,412,050

1,323,739

'

Operating expenses

'

'

'

'

'

'

'

'

'

'

'

'

Operation and maintenance

'

'

'

'

'

'

'

'

505,154

488,020

453,613

'

Depreciation and amortization

'

'

'

'

'

'

'

'

253,987

235,079

237,525

'

Taxes, other than income

'

'

'

'

'

'

'

'

211,936

187,072

181,073

'

Asset impairments

'

'

'

'

'

'

'

'

0

0

5,288

'

Total operating expenses

'

'

'

'

'

'

'

'

971,077

910,171

877,499

'

Operating income

83,944

106,605

250,080

170,720

50,383

86,396

210,178

154,922

611,349

501,879

446,240

'

Miscellaneous income (expense), net

'

'

'

'

'

'

'

'

-5,235

-197

-14,644

'

Interest charges

'

'

'

'

'

'

'

'

129,295

128,385

141,174

'

Income (loss) before income taxes

'

'

'

'

'

'

'

'

476,819

373,297

290,422

'

Income tax expense

'

'

'

'

'

'

'

'

187,002

142,599

98,226

'

Income (loss) from continuing operations

'

'

'

'

7,536

33,474

112,340

77,348

289,817

230,698

192,196

'

Income from discontinued operations, net of tax

'

'

'

'

0

0

4,085

3,117

0

7,202

18,172

'

Gain (loss) on sale of discontinued operations, net of tax

'

'

'

'

0

5,294

0

0

0

5,294

6,349

'

Net income

23,713

45,721

133,367

87,016

7,536

38,768

116,425

80,465

289,817

243,194

216,717

'

Capital expenditures

'

'

'

'

'

'

'

'

835,251

845,033

732,858

'

Revenue from External Customers by Products and Services Table [Abstract]

'

'

'

'

'

'

'

'

'

'

'

'

Operating revenues

778,728

942,718

1,964,322

1,255,148

674,374

857,935

1,308,996

1,034,155

4,940,916

3,875,460

3,436,162

'

ASSETS

'

'

'

'

'

'

'

'

'

'

'

'

Net property, plant and equipment

6,725,906

[1]

'

'

'

6,030,655

[1]

'

'

'

6,725,906

[1]

6,030,655

[1]

'

'

Investment in subsidaries

0

'

'

'

0

'

'

'

0

0

'

'

Current assets

'

'

'

'

'

'

'

'

'

'

'

'

Cash and cash equivalents

42,258

'

'

'

66,199

'

'

'

42,258

66,199

64,239

131,419

Assets from risk management activities current

45,827

'

'

'

11,966

'

'

'

45,827

11,966

'

'

Other current assets

687,755

'

'

'

598,968

'

'

'

687,755

598,968

'

'

Intercompany receivables

0

'

'

'

0

'

'

'

0

0

'

'

Total current assets

775,840

'

'

'

677,133

'

'

'

775,840

677,133

'

'

Goodwill

742,029

'

'

'

741,363

'

'

'

742,029

741,363

'

'

Assets from risk management activities noncurrent

13,038

'

'

'

109,354

'

'

'

13,038

109,354

'

'

Deferred charges and other assets

337,891

'

'

'

375,763

'

'

'

337,891

375,763

'

'

Total Assets

8,594,704

'

'

'

7,934,268

'

'

'

8,594,704

7,934,268

'

'

CAPITALIZATION AND LIABILITIES

'

'

'

'

'

'

'

'

'

'

'

'

Shareholders' equity

3,086,232

'

'

'

2,580,409

'

'

'

3,086,232

2,580,409

2,359,243

2,255,421

Long-term debt

2,455,986

'

'

'

2,455,671

'

'

'

2,455,986

2,455,671

'

'

Total capitalization

5,542,218

'

'

'

5,036,080

'

'

'

5,542,218

5,036,080

'

'

Current liabilities

'

'

'

'

'

'

'

'

'

'

'

'

Current maturities of long-term debt

0

'

'

'

0

'

'

'

0

0

'

'

Short-term debt

196,695

'

'

'

367,984

'

'

'

196,695

367,984

'

'

Liabilities from risk management activities current

1,730

'

'

'

1,543

'

'

'

1,730

1,543

'

'

Other current liabilities

712,225

'

'

'

608,959

'

'

'

712,225

608,959

'

'

Intercompany payables

0

'

'

'

0

'

'

'

0

0

'

'

Total current liabilities

910,650

'

'

'

978,486

'

'

'

910,650

978,486

'

'

Deferred income taxes

1,286,616

'

'

'

1,164,053

'

'

'

1,286,616

1,164,053

'

'

Liabilities from risk management activities noncurrent

20,126

'

'

'

0

'

'

'

20,126

0

'

'

Regulatory cost of removal obligation

445,387

'

'

'

359,299

'

'

'

445,387

359,299

'

'

Pension and postretirement liabilities

340,963

'

'

'

358,787

'

'

'

340,963

358,787

'

'

Deferred credits and other liabilities

48,744

'

'

'

37,563

'

'

'

48,744

37,563

'

'

Total Equity and Liabilities

8,594,704

'

'

'

7,934,268

'

'

'

8,594,704

7,934,268

'

'

Number Of Customers, Regulated Distribution

3,000,000

'

'

'

'

'

'

'

3,000,000

'

'

'

Number Of Divisions, Regulated Distribution

6

'

'

'

'

'

'

'

6

'

'

'

Number of States in which Entity Operates

8

'

'

'

'

'

'

'

8

'

'

'

Number of Operating Segments

'

'

'

'

'

'

'

'

3

'

'

'

Reportable Subsegments [Member]

'

'

'

'

'

'

'

'

'

'

'

'

Segment Reporting Information Profit Loss [Abstract]

'

'

'

'

'

'

'

'

'

'

'

'

Revenues

'

'

'

'

'

'

'

'

4,940,916

3,875,460

3,436,162

'

Revenue from External Customers by Products and Services Table [Abstract]

'

'

'

'

'

'

'

'

'

'

'

'

Revenues

'

'

'

'

'

'

'

'

4,940,916

3,875,460

3,436,162

'

Intersubsegment Eliminations [Member]

'

'

'

'

'

'

'

'

'

'

'

'

Segment Reporting Information Profit Loss [Abstract]

'

'

'

'

'

'

'

'

'

'

'

'

Revenues

'

'

'

'

'

'

'

'

0

0

0

'

Revenue from External Customers by Products and Services Table [Abstract]

'

'

'

'

'

'

'

'

'

'

'

'

Revenues

'

'

'

'

'

'

'

'

0

0

0

'

Regulated Distribution Segment [Member]

'

'

'

'

'

'

'

'

'

'

'

'

Segment Reporting Information Profit Loss [Abstract]

'

'

'

'

'

'

'

'

'

'

'

'

Revenues

'

'

'

'

'

'

'

'

3,056,212

2,394,418

2,144,376

'

Operating revenues

409,014

517,707

1,290,960

843,865

360,386

467,144

905,176

666,787

3,061,546

2,399,493

2,145,330

'

Purchased gas cost

'

'

'

'

'

'

'

'

1,885,031

1,318,257

1,122,587

'

Gross profit

'

'

'

'

'

'

'

'

1,176,515

1,081,236

1,022,743

'

Operating expenses

'

'

'

'

'

'

'

'

'

'

'

'

Operation and maintenance

'

'

'

'

'

'

'

'

387,228

375,188

353,879

'

Depreciation and amortization

'

'

'

'

'

'

'

'

208,376

195,581

202,026

'

Taxes, other than income

'

'

'

'

'

'

'

'

196,343

167,374

162,377

'

Asset impairments

'

'

'

'

'

'

'

'

'

'

0

'

Total operating expenses

'

'

'

'

'

'

'

'

791,947

738,143

718,282

'

Operating income

'

'

'

'

'

'

'

'

384,568

343,093

304,461

'

Miscellaneous income (expense), net

'

'

'

'

'

'

'

'

-381

2,535

-12,657

'

Interest charges

'

'

'

'

'

'

'

'

94,918

98,296

110,642

'

Income (loss) before income taxes

'

'

'

'

'

'

'

'

289,269

247,332

181,162

'

Income tax expense

'

'

'

'

'

'

'

'

117,684

96,476

57,314

'

Income (loss) from continuing operations

'

'

'

'

'

'

'

'

'

150,856

123,848

'

Income from discontinued operations, net of tax

'

'

'

'

'

'

'

'

'

7,202

18,172

'

Gain (loss) on sale of discontinued operations, net of tax

'

'

'

'

'

'

'

'

'

5,649

6,349

'

Net income

'

'

'

'

'

'

'

'

171,585

163,707

148,369

'

Capital expenditures

'

'

'

'

'

'

'

'

584,065

528,599

546,818

'

Revenue from External Customers by Products and Services Table [Abstract]

'

'

'

'

'

'

'

'

'

'

'

'

Revenues

'

'

'

'

'

'

'

'

3,056,212

2,394,418

2,144,376

'

Operating revenues

409,014

517,707

1,290,960

843,865

360,386

467,144

905,176

666,787

3,061,546

2,399,493

2,145,330

'

ASSETS

'

'

'

'

'

'

'

'

'

'

'

'

Net property, plant and equipment

5,202,761

'

'

'

4,719,873

'

'

'

5,202,761

4,719,873

'

'

Investment in subsidaries

952,171

'

'

'

831,136

'

'

'

952,171

831,136

'

'

Current assets

'

'

'

'

'

'

'

'

'

'

'

'

Cash and cash equivalents

33,303

'

'

'

4,237

'

'

'

33,303

4,237

'

'

Assets from risk management activities current

23,102

'

'

'

1,837

'

'

'

23,102

1,837

'

'

Other current assets

490,408

'

'

'

428,366

'

'

'

490,408

428,366

'

'

Intercompany receivables

790,442

'

'

'

783,738

'

'

'

790,442

783,738

'

'

Total current assets

1,337,255

'

'

'

1,218,178

'

'

'

1,337,255

1,218,178

'

'

Goodwill

574,816

'

'

'

574,190

'

'

'

574,816

574,190

'

'

Assets from risk management activities noncurrent

13,038

'

'

'

109,354

'

'

'

13,038

109,354

'

'

Deferred charges and other assets

309,965

'

'

'

347,687

'

'

'

309,965

347,687

'

'

Total Assets

8,390,006

'

'

'

7,800,418

'

'

'

8,390,006

7,800,418

'

'

CAPITALIZATION AND LIABILITIES

'

'

'

'

'

'

'

'

'

'

'

'

Shareholders' equity

3,086,232

'

'

'

2,580,409

'

'

'

3,086,232

2,580,409

'

'

Long-term debt

2,455,986

'

'

'

2,455,671

'

'

'

2,455,986

2,455,671

'

'

Total capitalization

5,542,218

'

'

'

5,036,080

'

'

'

5,542,218

5,036,080

'

'

Current liabilities

'

'

'

'

'

'

'

'

'

'

'

'

Short-term debt

522,695

'

'

'

645,984

'

'

'

522,695

645,984

'

'

Liabilities from risk management activities current

1,730

'

'

'

1,543

'

'

'

1,730

1,543

'

'

Other current liabilities

559,765

'

'

'

491,681

'

'

'

559,765

491,681

'

'

Intercompany payables

0

'

'

'

0

'

'

'

0

0

'

'

Total current liabilities

1,084,190

'

'

'

1,139,208

'

'

'

1,084,190

1,139,208

'

'

Deferred income taxes

913,260

'

'

'

871,360

'

'

'

913,260

871,360

'

'

Liabilities from risk management activities noncurrent

20,126

'

'

'

0

'

'

'

20,126

0

'

'

Regulatory cost of removal obligation

445,387

'

'

'

359,299

'

'

'

445,387

359,299

'

'

Pension and postretirement liabilities

340,963

'

'

'

358,787

'

'

'

340,963

358,787

'

'

Deferred credits and other liabilities

43,862

'

'

'

35,684

'

'

'

43,862

35,684

'

'

Total Equity and Liabilities

8,390,006

'

'

'

7,800,418

'

'

'

8,390,006

7,800,418

'

'

Regulated Distribution Segment [Member] | Gas Sales Revenues [Member]

'

'

'

'

'

'

'

'

'

'

'

'

Segment Reporting Information Profit Loss [Abstract]

'

'

'

'

'

'

'

'

'

'

'

'

Revenues

'

'

'

'

'

'

'

'

2,964,456

2,316,137

2,065,424

'

Revenue from External Customers by Products and Services Table [Abstract]

'

'

'

'

'

'

'

'

'

'

'

'

Revenues

'

'

'

'

'

'

'

'

2,964,456

2,316,137

2,065,424

'

Regulated Distribution Segment [Member] | Gas Sales Revenues [Member] | Residential Customers [Member]

'

'

'

'

'

'

'

'

'

'

'

'

Segment Reporting Information Profit Loss [Abstract]

'

'

'

'

'

'

'

'

'

'

'

'

Revenues

'

'

'

'

'

'

'

'

1,933,099

1,512,495

1,351,479

'

Revenue from External Customers by Products and Services Table [Abstract]

'

'

'

'

'

'

'

'

'

'

'

'

Revenues

'

'

'

'

'

'

'

'

1,933,099

1,512,495

1,351,479

'

Regulated Distribution Segment [Member] | Gas Sales Revenues [Member] | Commercial Customers [Member]

'

'

'

'

'

'

'

'

'

'

'

'

Segment Reporting Information Profit Loss [Abstract]

'

'

'

'

'

'

'

'

'

'

'

'

Revenues

'

'

'

'

'

'

'

'

876,042

661,930

587,651

'

Revenue from External Customers by Products and Services Table [Abstract]

'

'

'

'

'

'

'

'

'

'

'

'

Revenues

'

'

'

'

'

'

'

'

876,042

661,930

587,651

'

Regulated Distribution Segment [Member] | Gas Sales Revenues [Member] | Industrial Customers [Member]

'

'

'

'

'

'

'

'

'

'

'

'

Segment Reporting Information Profit Loss [Abstract]

'

'

'

'

'

'

'

'

'

'

'

'

Revenues

'

'

'

'

'

'

'

'

90,536

81,155

71,960

'

Revenue from External Customers by Products and Services Table [Abstract]

'

'

'

'

'

'

'

'

'

'

'

'

Revenues

'

'

'

'

'

'

'

'

90,536

81,155

71,960

'

Regulated Distribution Segment [Member] | Gas Sales Revenues [Member] | Public Authority and Other Customers [Member]

'

'

'

'

'

'

'

'

'

'

'

'

Segment Reporting Information Profit Loss [Abstract]

'

'

'

'

'

'

'

'

'

'

'

'

Revenues

'

'

'

'

'

'

'

'

64,779

60,557

54,334

'

Revenue from External Customers by Products and Services Table [Abstract]

'

'

'

'

'

'

'

'

'

'

'

'

Revenues

'

'

'

'

'

'

'

'

64,779

60,557

54,334

'

Regulated Distribution Segment [Member] | Gas Transportation Revenues [Member]

'

'

'

'

'

'

'

'

'

'

'

'

Segment Reporting Information Profit Loss [Abstract]

'

'

'

'

'

'

'

'

'

'

'

'

Revenues

'

'

'

'

'

'

'

'

64,049

55,938

53,924

'

Revenue from External Customers by Products and Services Table [Abstract]

'

'

'

'

'

'

'

'

'

'

'

'

Revenues

'

'

'

'

'

'

'

'

64,049

55,938

53,924

'

Regulated Distribution Segment [Member] | Other Gas Revenues [Member]

'

'

'

'

'

'

'

'

'

'

'

'

Segment Reporting Information Profit Loss [Abstract]

'

'

'

'

'

'

'

'

'

'

'

'

Revenues

'

'

'

'

'

'

'

'

27,707

22,343

25,028

'

Revenue from External Customers by Products and Services Table [Abstract]

'

'

'

'

'

'

'

'

'

'

'

'

Revenues

'

'

'

'

'

'

'

'

27,707

22,343

25,028

'

Regulated Distribution Segment [Member] | Reportable Subsegments [Member]

'

'

'

'

'

'

'

'

'

'

'

'

Segment Reporting Information Profit Loss [Abstract]

'

'

'

'

'

'

'

'

'

'

'

'

Revenues

'

'

'

'

'

'

'

'

3,056,212

2,394,418

2,144,376

'

Revenue from External Customers by Products and Services Table [Abstract]

'

'

'

'

'

'

'

'

'

'

'

'

Revenues

'

'

'

'

'

'

'

'

3,056,212

2,394,418

2,144,376

'

Regulated Distribution Segment [Member] | Intersubsegment Eliminations [Member]

'

'

'

'

'

'

'

'

'

'

'

'

Segment Reporting Information Profit Loss [Abstract]

'

'

'

'

'

'

'

'

'

'

'

'

Revenues

'

'

'

'

'

'

'

'

5,334

5,075

954

'

Revenue from External Customers by Products and Services Table [Abstract]

'

'

'

'

'

'

'

'

'

'

'

'

Revenues

'

'

'

'

'

'

'

'

5,334

5,075

954

'

Regulated Pipeline Segment [Member]

'

'

'

'

'

'

'

'

'

'

'

'

Segment Reporting Information Profit Loss [Abstract]

'

'

'

'

'

'

'

'

'

'

'

'

Revenues

'

'

'

'

'

'

'

'

92,166

89,011

92,604

'

Operating revenues

86,314

87,189

73,615

71,341

72,330

74,041

61,848

60,681

318,459

268,900

247,351

'

Purchased gas cost

'

'

'

'

'

'

'

'

0

0

0

'

Gross profit

'

'

'

'

'

'

'

'

318,459

268,900

247,351

'

Operating expenses

'

'

'

'

'

'

'

'

'

'

'

'

Operation and maintenance

'

'

'

'

'

'

'

'

91,466

76,686

71,521

'

Depreciation and amortization

'

'

'

'

'

'

'

'

41,031

35,302

31,438

'

Taxes, other than income

'

'

'

'

'

'

'

'

13,143

17,059

15,568

'

Asset impairments

'

'

'

'

'

'

'

'

'

'

0

'

Total operating expenses

'

'

'

'

'

'

'

'

145,640

129,047

118,527

'

Operating income

'

'

'

'

'

'

'

'

172,819

139,853

128,824

'

Miscellaneous income (expense), net

'

'

'

'

'

'

'

'

-3,181

-2,285

-1,051

'

Interest charges

'

'

'

'

'

'

'

'

36,280

30,678

29,414

'

Income (loss) before income taxes

'

'

'

'

'

'

'

'

133,358

106,890

98,359

'

Income tax expense

'

'

'

'

'

'

'

'

47,167

38,630

35,300

'

Income (loss) from continuing operations

'

'

'

'

'

'

'

'

'

68,260

63,059

'

Income from discontinued operations, net of tax

'

'

'

'

'

'

'

'

'

0

0

'

Gain (loss) on sale of discontinued operations, net of tax

'

'

'

'

'

'

'

'

'

0

'

'

Net income

'

'

'

'

'

'

'

'

86,191

68,260

63,059

'

Capital expenditures

'

'

'

'

'

'

'

'

249,347

313,230

175,768

'

Revenue from External Customers by Products and Services Table [Abstract]

'

'

'

'

'

'

'

'

'

'

'

'

Revenues

'

'

'

'

'

'

'

'

92,166

89,011

92,604

'

Operating revenues

86,314

87,189

73,615

71,341

72,330

74,041

61,848

60,681

318,459

268,900

247,351

'

ASSETS

'

'

'

'

'

'

'

'

'

'

'

'

Net property, plant and equipment

1,464,572

'

'

'

1,249,767

'

'

'

1,464,572

1,249,767

'

'

Investment in subsidaries

0

'

'

'

0

'

'

'

0

0

'

'

Current assets

'

'

'

'

'

'

'

'

'

'

'

'

Cash and cash equivalents

0

'

'

'

0

'

'

'

0

0

'

'

Assets from risk management activities current

0

'

'

'

0

'

'

'

0

0

'

'

Other current assets

14,009

'

'

'

11,709

'

'

'

14,009

11,709

'

'

Intercompany receivables

0

'

'

'

0

'

'

'

0

0

'

'

Total current assets

14,009

'

'

'

11,709

'

'

'

14,009

11,709

'

'

Goodwill

132,502

'

'

'

132,462

'

'

'

132,502

132,462

'

'

Assets from risk management activities noncurrent

0

'

'

'

0

'

'

'

0

0

'

'

Deferred charges and other assets

21,826

'

'

'

19,227

'

'

'

21,826

19,227

'

'

Total Assets

1,632,909

'

'

'

1,413,165

'

'

'

1,632,909

1,413,165

'

'

CAPITALIZATION AND LIABILITIES

'

'

'

'

'

'

'

'

'

'

'

'

Shareholders' equity

482,612

'

'

'

396,421

'

'

'

482,612

396,421

'

'

Long-term debt

0

'

'

'

0

'

'

'

0

0

'

'

Total capitalization

482,612

'

'

'

396,421

'

'

'

482,612

396,421

'

'

Current liabilities

'

'

'

'

'

'

'

'

'

'

'

'

Short-term debt

0

'

'

'

0

'

'

'

0

0

'

'

Liabilities from risk management activities current

0

'

'

'

0

'

'

'

0

0

'

'

Other current liabilities

24,790

'

'

'

20,288

'

'

'

24,790

20,288

'

'

Intercompany payables

763,635

'

'

'

712,768

'

'

'

763,635

712,768

'

'

Total current liabilities

788,425

'

'

'

733,056

'

'

'

788,425

733,056

'

'

Deferred income taxes

361,688

'

'

'

283,554

'

'

'

361,688

283,554

'

'

Liabilities from risk management activities noncurrent

0

'

'

'

0

'

'

'

0

0

'

'

Regulatory cost of removal obligation

0

'

'

'

0

'

'

'

0

0

'

'

Pension and postretirement liabilities

0

'

'

'

0

'

'

'

0

0

'

'

Deferred credits and other liabilities

184

'

'

'

134

'

'

'

184

134

'

'

Total Equity and Liabilities

1,632,909

'

'

'

1,413,165

'

'

'

1,632,909

1,413,165

'

'

Regulated Pipeline Segment [Member] | Reportable Subsegments [Member]

'

'

'

'

'

'

'

'

'

'

'

'

Segment Reporting Information Profit Loss [Abstract]

'

'

'

'

'

'

'

'

'

'

'

'

Revenues

'

'

'

'

'

'

'

'

92,166

89,011

92,604

'

Revenue from External Customers by Products and Services Table [Abstract]

'

'

'

'

'

'

'

'

'

'

'

'

Revenues

'

'

'

'

'

'

'

'

92,166

89,011

92,604

'

Regulated Pipeline Segment [Member] | Intersubsegment Eliminations [Member]

'

'

'

'

'

'

'

'

'

'

'

'

Segment Reporting Information Profit Loss [Abstract]

'

'

'

'

'

'

'

'

'

'

'

'

Revenues

'

'

'

'

'

'

'

'

226,293

179,889

154,747

'

Revenue from External Customers by Products and Services Table [Abstract]

'

'

'

'

'

'

'

'

'

'

'

'

Revenues

'

'

'

'

'

'

'

'

226,293

179,889

154,747

'

Nonregulated Segment [Member]

'

'

'

'

'

'

'

'

'

'

'

'

Segment Reporting Information Profit Loss [Abstract]

'

'

'

'

'

'

'

'

'

'

'

'

Revenues

'

'

'

'

'

'

'

'

1,792,538

1,392,031

1,199,182

'

Operating revenues

396,855

465,033

757,683

447,721

337,264

421,808

428,948

399,894

2,067,292

1,587,914

1,348,982

'

Purchased gas cost

'

'

'

'

'

'

'

'

1,979,337

1,524,583

1,293,858

'

Gross profit

'

'

'

'

'

'

'

'

87,955

63,331

55,124

'

Operating expenses

'

'

'

'

'

'

'

'

'

'

'

'

Operation and maintenance

'

'

'

'

'

'

'

'

26,963

37,569

29,697

'

Depreciation and amortization

'

'

'

'

'

'

'

'

4,580

4,196

4,061

'

Taxes, other than income

'

'

'

'

'

'

'

'

2,450

2,639

3,128

'

Asset impairments

'

'

'

'

'

'

'

'

'

'

5,288

'

Total operating expenses

'

'

'

'

'

'

'

'

33,993

44,404

42,174

'

Operating income

'

'

'

'

'

'

'

'

53,962

18,927

12,950

'

Miscellaneous income (expense), net

'

'

'

'

'

'

'

'

2,216

2,316

1,035

'

Interest charges

'

'

'

'

'

'

'

'

1,986

2,168

3,084

'

Income (loss) before income taxes

'

'

'

'

'

'

'

'

54,192

19,075

10,901

'

Income tax expense

'

'

'

'

'

'

'

'

22,151

7,493

5,612

'

Income (loss) from continuing operations

'

'

'

'

'

'

'

'

'

11,582

5,289

'

Income from discontinued operations, net of tax

'

'

'

'

'

'

'

'

'

0

0

'

Gain (loss) on sale of discontinued operations, net of tax

'

'

'

'

'

'

'

'

'

-355

'

'

Net income

'

'

'

'

'

'

'

'

32,041

11,227

5,289

'

Capital expenditures

'

'

'

'

'

'

'

'

1,839

3,204

10,272

'

Revenue from External Customers by Products and Services Table [Abstract]

'

'

'

'

'

'

'

'

'

'

'

'

Revenues

'

'

'

'

'

'

'

'

1,792,538

1,392,031

1,199,182

'

Operating revenues

396,855

465,033

757,683

447,721

337,264

421,808

428,948

399,894

2,067,292

1,587,914

1,348,982

'

ASSETS

'

'

'

'

'

'

'

'

'

'

'

'

Net property, plant and equipment

58,573

'

'

'

61,015

'

'

'

58,573

61,015

'

'

Investment in subsidaries

-2,096

'

'

'

-2,096

'

'

'

-2,096

-2,096

'

'

Current assets

'

'

'

'

'

'

'

'

'

'

'

'

Cash and cash equivalents

8,955

'

'

'

61,962

'

'

'

8,955

61,962

'

'

Assets from risk management activities current

22,725

[2]

'

'

'

10,129

[3]

'

'

'

22,725

[2]

10,129

[3]

'

'

Other current assets

526,161

'

'

'

452,126

'

'

'

526,161

452,126

'

'

Intercompany receivables

0

'

'

'

0

'

'

'

0

0

'

'

Total current assets

557,841

'

'

'

524,217

'

'

'

557,841

524,217

'

'

Goodwill

34,711

'

'

'

34,711

'

'

'

34,711

34,711

'

'

Assets from risk management activities noncurrent

0

'

'

'

0

'

'

'

0

0

'

'

Deferred charges and other assets

6,100

'

'

'

8,849

'

'

'

6,100

8,849

'

'

Total Assets

655,129

'

'

'

626,696

'

'

'

655,129

626,696

'

'

CAPITALIZATION AND LIABILITIES

'

'

'

'

'

'

'

'

'

'

'

'

Shareholders' equity

469,559

'

'

'

434,715

'

'

'

469,559

434,715

'

'

Long-term debt

0

'

'

'

0

'

'

'

0

0

'

'

Total capitalization

469,559

'

'

'

434,715

'

'

'

469,559

434,715

'

'

Current liabilities

'

'

'

'

'

'

'

'

'

'

'

'

Short-term debt

0

'

'

'

0

'

'

'

0

0

'

'

Liabilities from risk management activities current

0

[2]

'

'

'

0

[3]

'

'

'

0

[2]

0

[3]

'

'

Other current liabilities

142,397

'

'

'

110,306

'

'

'

142,397

110,306

'

'

Intercompany payables

26,807

'

'

'

70,970

'

'

'

26,807

70,970

'

'

Total current liabilities

169,204

'

'

'

181,276

'

'

'

169,204

181,276

'

'

Deferred income taxes

11,668

'

'

'

8,960

'

'

'

11,668

8,960

'

'

Liabilities from risk management activities noncurrent

0

'

'

'

0

'

'

'

0

0

'

'

Regulatory cost of removal obligation

0

'

'

'

0

'

'

'

0

0

'

'

Pension and postretirement liabilities

0

'

'

'

0

'

'

'

0

0

'

'

Deferred credits and other liabilities

4,698

'

'

'

1,745

'

'

'

4,698

1,745

'

'

Total Equity and Liabilities

655,129

'

'

'

626,696

'

'

'

655,129

626,696

'

'

Nonregulated Segment [Member] | Reportable Subsegments [Member]

'

'

'

'

'

'

'

'

'

'

'

'

Segment Reporting Information Profit Loss [Abstract]

'

'

'

'

'

'

'

'

'

'

'

'

Revenues

'

'

'

'

'

'

'

'

1,792,538

1,392,031

1,199,182

'

Revenue from External Customers by Products and Services Table [Abstract]

'

'

'

'

'

'

'

'

'

'

'

'

Revenues

'

'

'

'

'

'

'

'

1,792,538

1,392,031

1,199,182

'

Nonregulated Segment [Member] | Intersubsegment Eliminations [Member]

'

'

'

'

'

'

'

'

'

'

'

'

Segment Reporting Information Profit Loss [Abstract]

'

'

'

'

'

'

'

'

'

'

'

'

Revenues

'

'

'

'

'

'

'

'

274,754

195,883

149,800

'

Revenue from External Customers by Products and Services Table [Abstract]

'

'

'

'

'

'

'

'

'

'

'

'

Revenues

'

'

'

'

'

'

'

'

274,754

195,883

149,800

'

Intersegment Elimination [Member]

'

'

'

'

'

'

'

'

'

'

'

'

Segment Reporting Information Profit Loss [Abstract]

'

'

'

'

'

'

'

'

'

'

'

'

Operating revenues

-113,455

-127,211

-157,936

-107,779

-95,606

-105,058

-86,976

-93,207

-506,381

-380,847

-305,501

'

Purchased gas cost

'

'

'

'

'

'

'

'

-505,878

-379,430

-304,022

'

Gross profit

'

'

'

'

'

'

'

'

-503

-1,417

-1,479

'

Operating expenses

'

'

'

'

'

'

'

'

'

'

'

'

Operation and maintenance

'

'

'

'

'

'

'

'

-503

-1,423

-1,484

'

Depreciation and amortization

'

'

'

'

'

'

'

'

0

0

0

'

Taxes, other than income

'

'

'

'

'

'

'

'

0

0

0

'

Asset impairments

'

'

'

'

'

'

'

'

'

'

0

'

Total operating expenses

'

'

'

'

'

'

'

'

-503

-1,423

-1,484

'

Operating income

'

'

'

'

'

'

'

'

0

6

5

'

Miscellaneous income (expense), net

'

'

'

'

'

'

'

'

-3,889

-2,763

-1,971

'

Interest charges

'

'

'

'

'

'

'

'

-3,889

-2,757

-1,966

'

Income (loss) before income taxes

'

'

'

'

'

'

'

'

0

0

0

'

Income tax expense

'

'

'

'

'

'

'

'

0

0

0

'

Income (loss) from continuing operations

'

'

'

'

'

'

'

'

'

0

0

'

Income from discontinued operations, net of tax

'

'

'

'

'

'

'

'

'

0

0

'

Gain (loss) on sale of discontinued operations, net of tax

'

'

'

'

'

'

'

'

'

0

'

'

Net income

'

'

'

'

'

'

'

'

0

0

0

'

Capital expenditures

'

'

'

'

'

'

'

'

0

0

0

'

Revenue from External Customers by Products and Services Table [Abstract]

'

'

'

'

'

'

'

'

'

'

'

'

Operating revenues

-113,455

-127,211

-157,936

-107,779

-95,606

-105,058

-86,976

-93,207

-506,381

-380,847

-305,501

'

ASSETS

'

'

'

'

'

'

'

'

'

'

'

'

Net property, plant and equipment

0

'

'

'

0

'

'

'

0

0

'

'

Investment in subsidaries

-950,075

'

'

'

-829,040

'

'

'

-950,075

-829,040

'

'

Current assets

'

'

'

'

'

'

'

'

'

'

'

'

Cash and cash equivalents

0

'

'

'

0

'

'

'

0

0

'

'

Assets from risk management activities current

0

'

'

'

0

'

'

'

0

0

'

'

Other current assets

-342,823

'

'

'

-293,233

'

'

'

-342,823

-293,233

'

'

Intercompany receivables

-790,442

'

'

'

-783,738

'

'

'

-790,442

-783,738

'

'

Total current assets

-1,133,265

'

'

'

-1,076,971

'

'

'

-1,133,265

-1,076,971

'

'

Goodwill

0

'

'

'

0

'

'

'

0

0

'

'

Assets from risk management activities noncurrent

0

'

'

'

0

'

'

'

0

0

'

'

Deferred charges and other assets

0

'

'

'

0

'

'

'

0

0

'

'

Total Assets

-2,083,340

'

'

'

-1,906,011

'

'

'

-2,083,340

-1,906,011

'

'

CAPITALIZATION AND LIABILITIES

'

'

'

'

'

'

'

'

'

'

'

'

Shareholders' equity

-952,171

'

'

'

-831,136

'

'

'

-952,171

-831,136

'

'

Long-term debt

0

'

'

'

0

'

'

'

0

0

'

'

Total capitalization

-952,171

'

'

'

-831,136

'

'

'

-952,171

-831,136

'

'

Current liabilities

'

'

'

'

'

'

'

'

'

'

'

'

Short-term debt

-326,000

'

'

'

-278,000

'

'

'

-326,000

-278,000

'

'

Liabilities from risk management activities current

0

'

'

'

0

'

'

'

0

0

'

'

Other current liabilities

-14,727

'

'

'

-13,316

'

'

'

-14,727

-13,316

'

'

Intercompany payables

-790,442

'

'

'

-783,738

'

'

'

-790,442

-783,738

'

'

Total current liabilities

-1,131,169

'

'

'

-1,075,054

'

'

'

-1,131,169

-1,075,054

'

'

Deferred income taxes

0

'

'

'

179

'

'

'

0

179

'

'

Liabilities from risk management activities noncurrent

0

'

'

'

0

'

'

'

0

0

'

'

Regulatory cost of removal obligation

0

'

'

'

0

'

'

'

0

0

'

'

Pension and postretirement liabilities

0

'

'

'

0

'

'

'

0

0

'

'

Deferred credits and other liabilities

0

'

'

'

0

'

'

'

0

0

'

'

Total Equity and Liabilities

-2,083,340

'

'

'

-1,906,011

'

'

'

-2,083,340

-1,906,011

'

'

Intersegment Elimination [Member] | Reportable Subsegments [Member]

'

'

'

'

'

'

'

'

'

'

'

'

Segment Reporting Information Profit Loss [Abstract]

'

'

'

'

'

'

'

'

'

'

'

'

Revenues

'

'

'

'

'

'

'

'

0

0

0

'

Revenue from External Customers by Products and Services Table [Abstract]

'

'

'

'

'

'

'

'

'

'

'

'

Revenues

'

'

'

'

'

'

'

'

0

0

0

'

Intersegment Elimination [Member] | Intersubsegment Eliminations [Member]

'

'

'

'

'

'

'

'

'

'

'

'

Segment Reporting Information Profit Loss [Abstract]

'

'

'

'

'

'

'

'

'

'

'

'

Revenues

'

'

'

'

'

'

'

'

-506,381

-380,847

-305,501

'

Revenue from External Customers by Products and Services Table [Abstract]

'

'

'

'

'

'

'

'

'

'

'

'

Revenues

'

'

'

'

'

'

'

'

($506,381)

($380,847)

($305,501)

'

[1]

Net property, plant and equipment includes plant acquisition adjustments of $(76.4) million and $(83.8) million at September 30, 2014 and 2013.

[2]

Includes $25.8 million of cash held on deposit to collateralize certain financial instruments. Of this amount, $3.1 million was used to offset current and noncurent risk management liabilities under master netting arrangements and the remaining $22.7 million is classified as current risk management assets.

[3]

Includes $24.8 million of cash held on deposit to collateralize certain financial instruments. Of this amount, $14.7 million was used to offset current and noncurrent risk management liabilities under master netting arrangements and the remaining $10.1 million is classified as current risk management assets.

Earnings_Per_Share_Details

Earnings Per Share (Details) (USD $)

0 Months Ended

3 Months Ended

12 Months Ended

Feb. 18, 2014

Sep. 30, 2014

Jun. 30, 2014

Mar. 31, 2014

Dec. 31, 2013

Sep. 30, 2013

Jun. 30, 2013

Mar. 31, 2013

Dec. 31, 2012

Sep. 30, 2014

Sep. 30, 2013

Sep. 30, 2012

Feb. 18, 2014

Basic Earnings per Share from Continuing Operations

'

'

'

'

'

'

'

'

'

'

'

'

'

Income from continuing operations

'

'

'

'

'

$7,536,000

$33,474,000

$112,340,000

$77,348,000

$289,817,000

$230,698,000

$192,196,000

'

Less: Income from continuing operations allocated to participating securities

'

'

'

'

'

'

'

'

'

711,000

775,000

793,000

'

Income from continuing operations available to common shareholders

'

'

'

'

'

'

'

'

'

289,106,000

229,923,000

191,403,000

'

Basic weighted average shares outstanding (shares)

'

'

'

'

'

'

'

'

'

97,606,000

90,533,000

90,150,000

'

Income per share from continuing operations - basic (usd per share)

'

'

'

'

'

$0.08

$0.37

$1.24

$0.85

$2.96

$2.54

$2.12

'

Basic Earnings per Share from Discontinued Operations

'

'

'

'

'

'

'

'

'

'

'

'

'

Income from discontinued operations

'

'

'

'

'

'

'

'

'

0

12,496,000

24,521,000

'

Less: Income from discontinued operations allocated to participating securities

'

'

'

'

'

'

'

'

'

0

42,000

101,000

'

Income from discontinued operations available to common shareholders

'

'

'

'

'

'

'

'

'

0

12,454,000

24,420,000

'

Income (loss) from discontinued operations per share - Basic (usd per share)

'

'

'

'

'

$0

$0.06

$0.04

$0.04

$0

$0.14

$0.27

'

Net income per share — basic (usd per share)

'

$0.23

$0.45

$1.38

$0.94

$0.08

$0.43

$1.28

$0.89

$2.96

$2.68

$2.39

'

Diluted Earnings per Share from Continuing Operations

'

'

'

'

'

'

'

'

'

'

'

'

'

Effect of dilutive stock options and other shares

'

'

'

'

'

'

'

'

'

0

5,000

4,000

'

Income (loss) from continuing operations available to common shareholders

'

'

'

'

'

'

'

'

'

289,106,000

229,928,000

191,407,000

'

Additional dilutive stock options and other shares

'

'

'

'

'

'

'

'

'

2,000

1,178,000

1,022,000

'

Diluted weighted average shares outstanding (shares)

'

'

'

'

'

'

'

'

'

97,608,000

91,711,000

91,172,000

'

Income per share from continuing operations - diluted (usd per share)

'

'

'

'

'

$0.08

$0.36

$1.23

$0.85

$2.96

$2.50

$2.10

'

Diluted Earnings per Share from Discontinued Operations

'

'

'

'

'

'

'

'

'

'

'

'

'

Effect of dilutive stock options and other shares

'

'

'

'

'

'

'

'

'

0

0

0

'

Income from discontinued operations available to common shareholders

'

'

'

'

'

'

'

'

'

0

12,454,000

24,420,000

'

Additional dilutive stock options and other shares

'

'

'

'

'

'

'

'

'

2,000

1,178,000

1,022,000

'

Diluted weighted average shares outstanding

'

'

'

'

'

'

'

'

'

97,608,000

91,711,000

91,172,000

'

Income per share from discontinued operations - diluted (usd per share)

'

'

'

'

'

$0

$0.06

$0.04

$0.03

$0

$0.14

$0.27

'

Net income per share — diluted (usd per share)

'

$0.23

$0.45

$1.38

$0.94

$0.08

$0.42

$1.27

$0.88

$2.96

$2.64

$2.37

'

Earnings Per Share Diluted Other Disclosures Abstract

'

'

'

'

'

'

'

'

'

'

'

'

'

Anti-dilutive stock options excluded from computation of diluted earnings per share

'

'

'

'

'

'

'

'

'

'

0

0

'

Stock Issued During Period, Shares, New Issues

9,200,000

'

'

'

'

'

'

'

'

'

'

'

'

Shares Issued At Overallotment Option

1,200,000

'

'

'

'

'

'

'

'

'

'

'

'

Net proceeds from equity offering

390,200,000

'

'

'

'

'

'

'

'

390,205,000

0

0

'

Share Price

'

'

'

'

'

'

'

'

'

'

'

'

$44

Stock Repurchase Program [Abstract]

'

'

'

'

'

'

'

'

'

'

'

'

'

Stock Repurchased During Period, Shares

'

'

'

'

'

'

'

'

'

'

'

387,991

'

Stock Repurchased During Period, Value

'

'

'

'

'

'

'

'

'

$12,500,000

'

'

'

Summary Of Stock Option Activity [Abstract]

'

'

'

'

'

'

'

'

'

'

'

'

'

Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercisable, Number

'

0

'

'

'

'

'

'

'

0

'

'

'

Debt_Details

Debt (Details) (USD $)

0 Months Ended

12 Months Ended

12 Months Ended

12 Months Ended

12 Months Ended

0 Months Ended

12 Months Ended

0 Months Ended

12 Months Ended

3 Months Ended

12 Months Ended

0 Months Ended

12 Months Ended

Feb. 18, 2014

Sep. 30, 2014

Sep. 30, 2013

Sep. 30, 2012

Sep. 30, 2014

Sep. 30, 2014

Sep. 30, 2014

Sep. 30, 2014

Sep. 30, 2013

Sep. 30, 2014

Sep. 30, 2014

Sep. 30, 2014

Sep. 30, 2014

Sep. 30, 2014

Sep. 30, 2013

Sep. 30, 2014

Sep. 30, 2014

Oct. 15, 2014

Sep. 30, 2014

Sep. 30, 2013

Oct. 15, 2014

Oct. 15, 2014

Sep. 30, 2014

Sep. 30, 2013

Sep. 30, 2014

Sep. 30, 2013

Sep. 30, 2014

Sep. 30, 2013

Sep. 30, 2014

Sep. 30, 2013

Sep. 30, 2013

Sep. 30, 2014

Sep. 30, 2013

Oct. 15, 2014

Oct. 15, 2014

Sep. 30, 2014

Sep. 30, 2014

Sep. 30, 2013

Sep. 30, 2014

Sep. 30, 2013

Sep. 30, 2014

Sep. 30, 2013

Sep. 30, 2013

credit_facility

Minimum [Member]

Maximum [Member]

Regulated Facilities [Member]

First Facility Regulated Operations [Member]

First Facility Regulated Operations [Member]

Second Facility Regulated Operations [Member]

Third Facility Regulated Operations [Member]

Intercompany Facility Regulated Operations [Member]

Nonregulated Facilities [Member]

Committed Facility Nonregulated Operations [Member]

Committed Facility Nonregulated Operations [Member]

Uncommitted Facility Nonregulated Operations [Member]

Intercompany Facility Nonregulated Operations [Member]

Subsequent Event [Member]

Unsecured Senior Notes Due 2014 [Member]

Unsecured Senior Notes Due 2014 [Member]

Unsecured Senior Notes Due 2014 [Member]

Unsecured Senior Notes Due 2014 [Member]

Unsecured Senior Notes Due 2017 [Member]

Unsecured Senior Notes Due 2017 [Member]

Unsecured Senior Notes Due 2019 [Member]

Unsecured Senior Notes Due 2019 [Member]

Unsecured Senior Notes Due 2034 [Member]

Unsecured Senior Notes Due 2034 [Member]

Unsecured Senior Notes Due 2041 [Member]

Unsecured Senior Notes Due 2041 [Member]

Unsecured Senior Notes Due 2043 [Member]

Unsecured Senior Notes Due 2043 [Member]

Unsecured Senior Notes Due 2043 [Member]

Unsecured Senior Notes Due 2044 [Member]

Unsecured Senior Notes Due 2044 [Member]

Bridge Loan [Member]

Medium Term Notes Due 2025 [Member]

Medium Term Notes Due 2025 [Member]

Unsecured Debentures Due 2028 [Member]

Unsecured Debentures Due 2028 [Member]

Rental Property Term Note [Member]

Rental Property Term Note [Member]

Unsecured Senior Notes Due 2013 [Member]

credit_facility

Subsequent Event [Member]

Subsequent Event [Member]

Subsequent Event [Member]

Subsequent Event [Member]

Debt Instrument [Line Items]

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Debt Instrument Interest Rate Stated Percentage

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

4.95%

4.95%

'

'

6.35%

6.35%

8.50%

8.50%

5.95%

5.95%

5.50%

5.50%

4.15%

4.15%

4.15%

'

4.13%

'

6.67%

6.67%

6.75%

6.75%

'

'

'

Debt Instrument Maturity Date

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

15-Oct-14

15-Oct-14

'

'

15-Jun-17

15-Jun-17

15-Mar-19

15-Mar-19

15-Oct-34

15-Oct-34

15-Jun-41

15-Jun-41

'

15-Jan-43

15-Jan-43

'

'

'

15-Dec-25

15-Dec-25

15-Jul-28

15-Jul-28

1-Jul-13

1-Jul-13

'

Debt Instrument Carrying Amount

'

$2,460,000,000

$2,460,000,000

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

$500,000,000

$500,000,000

'

$500,000,000

$250,000,000

$250,000,000

$450,000,000

$450,000,000

$200,000,000

$200,000,000

$400,000,000

$400,000,000

$500,000,000

$500,000,000

$500,000,000

'

$500,000,000

'

$10,000,000

$10,000,000

$150,000,000

$150,000,000

'

'

'

Debt Instrument Unamortized Discount

'

4,014,000

4,329,000

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Current maturities of long-term debt

'

0

0

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Debt Instrument Interest Rate Effective Percentage

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

4.67%

'

'

4.09%

'

'

'

'

'

'

'

'

Net Proceeds From Issuance of Debt

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

494,000,000

'

'

494,000,000

'

'

'

'

'

'

'

'

'

Remaining Proceeds From Issuance Of Debt

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

234,000,000

'

'

'

'

'

'

'

'

'

'

Extinguishment of Debt, Amount

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

500,000,000

'

'

'

'

'

'

'

'

'

'

'

'

'

'

260,000,000

'

'

'

'

'

'

250,000,000

Extinguishment of Debt, Interest Terms

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'0.0495

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'0.05125

Subsequent Event, Date

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

15-Oct-14

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Line Of Credit Facility [Line Items]

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Number of Credit Facilities

'

4

'

'

'

'

'

'

'

'

'

'

2

'

'

1

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Line Of Credit Facility Maximum Borrowing Capacity

'

1,300,000,000

25,000,000

'

'

'

1,300,000,000

1,250,000,000

950,000,000

25,000,000

10,000,000

500,000,000

'

15,000,000

25,000,000

25,000,000

500,000,000

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Line of Credit Facility, Term

'

'

'

'

'

'

'

'5 years

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Line Of Credit Facility Interest Rate Description

'

'

'

'

'

'

'

'a base rate or at a LIBOR-based rate for the applicable interest period, plus a spread ranging from zero percent to two percent, based on the Company’s credit ratings

'

'a daily negotiated rate, generally based on the Federal Funds rate plus a variable margin

'LIBOR-based rate plus 1.5 percent.

' 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

'

'

'

'

'a rate equal to the greater of (i) the one-month LIBOR rate plus 3.00 percent or (ii) the rate for AEM’s borrowings under its committed line of credit facility plus 0.75 percent

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Line Of Credit Facility Amount Outstanding

'

'

'

'

'

'

'

0

'

0

0

326,000,000

'

'

'

'

0

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Line of Credit Facility, Current Available Borrowing Capacity

'

'

'

'

'

'

'

1,053,300,000

'

'

'

'

32,200,000

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Line of Credit Facility, Maximum Borrowing Capacity with Accordion Feature

'

'

'

'

'

'

'

1,500,000,000

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Debt Instrument, Covenant, Excess Debt Trigger

'

'

'

'

15,000,000

100,000,000

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Regulated Operations Letters of Credit Outstanding, Amount

'

'

'

'

'

'

'

'

'

'

5,900,000

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Long-term Debt, Other Disclosures [Abstract]

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Authorized Commercial Paper

'

1,250,000,000

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Commercial Paper

'

196,700,000

368,000,000

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Commercial Paper Weighted Average Interest Rate

'

0.23%

0.25%

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Debt Covenant, Total Debt To Total Capital Ratio

'

70.00%

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Ratio of Total Debt to Total Capital

'

48.00%

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Debt and Equity Securities Authorized for Issuance

'

1,750,000,000

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Debt Instrument Covenant Compliance

'

'We were in compliance with all of our debt covenants as of September 30, 2014

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Debt And Equity Securities Available For Issuance

'

845,000,000

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Stock Issued During Period, Shares, New Issues

9,200,000

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Net proceeds from equity offering

390,200,000

390,205,000

0

0

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Long-term Debt, Fiscal Year Maturity [Abstract]

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

2015

'

500,000,000

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

2016

'

0

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

2017

'

250,000,000

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

2018

'

0

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

2019

'

450,000,000

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Thereafter

'

1,260,000,000

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Debt Instrument Carrying Amount

'

$2,460,000,000

$2,460,000,000

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

$500,000,000

$500,000,000

'

$500,000,000

$250,000,000

$250,000,000

$450,000,000

$450,000,000

$200,000,000

$200,000,000

$400,000,000

$400,000,000

$500,000,000

$500,000,000

$500,000,000

'

$500,000,000

'

$10,000,000

$10,000,000

$150,000,000

$150,000,000

'

'

'

Retirement_and_PostRetirement_1

Retirement and Post-Retirement Employee Benefit Plans Defined Benefit Plans Disclosure (Details) (USD $)

12 Months Ended

12 Months Ended

12 Months Ended

12 Months Ended

12 Months Ended

12 Months Ended

0 Months Ended

6 Months Ended

12 Months Ended

0 Months Ended

12 Months Ended

12 Months Ended

Sep. 30, 2014

Sep. 30, 2013

Sep. 30, 2014

Sep. 30, 2013

Sep. 30, 2012

Sep. 30, 2014

Sep. 30, 2013

Sep. 30, 2014

Sep. 30, 2013

Sep. 30, 2014

Sep. 30, 2013

Sep. 30, 2014

Sep. 30, 2013

Sep. 30, 2014

Sep. 30, 2013

Sep. 30, 2014

Sep. 30, 2013

Sep. 30, 2014

Apr. 02, 2013

Mar. 31, 2014

Sep. 30, 2013

Sep. 30, 2014

Sep. 30, 2013

Sep. 30, 2012

Oct. 02, 2013

Sep. 30, 2014

Sep. 30, 2014

Sep. 30, 2014

Sep. 30, 2014

Sep. 30, 2013

Sep. 30, 2012

Sep. 30, 2014

Sep. 30, 2013

Sep. 30, 2014

Sep. 30, 2013

Sep. 30, 2014

Sep. 30, 2014

Sep. 30, 2014

Pension Plans, Defined Benefit [Member]

Pension Plans, Defined Benefit [Member]

Pension Plans, Defined Benefit [Member]

Pension Plans, Defined Benefit [Member]

Pension Plans, Defined Benefit [Member]

Pension Plans, Defined Benefit [Member]

Pension Plans, Defined Benefit [Member]

Pension Plans, Defined Benefit [Member]

Pension Plans, Defined Benefit [Member]

Pension Plans, Defined Benefit [Member]

Pension Plans, Defined Benefit [Member]

Pension Plans, Defined Benefit [Member]

Pension Plans, Defined Benefit [Member]

Pension Account Plan, Defined Benefit [Member]

Pension Account Plan, Defined Benefit [Member]

Mississippi Valley Gas Union Retirement Plan, Defined Benefit [Member]

Supplemental Executive Retirement Plans, Defined Benefit [Member]

Supplemental Executive Retirement Plans, Defined Benefit [Member]

Supplemental Executive Retirement Plans, Defined Benefit [Member]

Supplemental Executive Retirement Plans, Defined Benefit [Member]

Supplemental Executive Retirement Plans, Defined Benefit [Member]

Supplemental Executive Retirement Plans, Defined Benefit [Member]

Supplemental Executive Benefit Plan, Defined Benefit [Member]

Supplemental Executive Benefit Plan, Defined Benefit [Member]

1998 Supplemental Executive Retirement Plan, Defined Benefit [Member]

2009 Supplemental Executive Retirement Plan, Defined Benefit [Member]

Other Postretirement Benefit Plans, Defined Benefit [Member]

Other Postretirement Benefit Plans, Defined Benefit [Member]

Other Postretirement Benefit Plans, Defined Benefit [Member]

Other Postretirement Benefit Plans, Defined Benefit [Member]

Other Postretirement Benefit Plans, Defined Benefit [Member]

Other Postretirement Benefit Plans, Defined Benefit [Member]

Other Postretirement Benefit Plans, Defined Benefit [Member]

Minimum [Member]

Maximum [Member]

Retirement Savings Plan [Member]

Domestic Equity Securities [Member]

Domestic Equity Securities [Member]

International Equity Securities [Member]

International Equity Securities [Member]

Fixed Income Securities [Member]

Fixed Income Securities [Member]

Company Stock [Member]

Company Stock [Member]

Other Investment Assets [Member]

Other Investment Assets [Member]

Diversified Investment Funds [Member]

Diversified Investment Funds [Member]

Cash and Cash Equivalents [Member]

Cash and Cash Equivalents [Member]

Pension Plans, Defined Benefit [Member]

Pension Plans, Defined Benefit [Member]

Net Periodic Benefit Cost Not Yet Recognized, Recorded as Regulatory Assets [Abstract]

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Unrecognized transition obligation

$354,000

$628,000

$0

$0

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

$0

$0

'

'

'

'

'

$354,000

$628,000

'

'

'

'

'

'

'

'

Unrecognized prior service cost

-8,095,000

-6,052,000

-1,927,000

-91,000

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

0

0

'

'

'

'

'

-6,168,000

-5,961,000

'

'

'

'

'

'

'

'

Unrecognized actuarial loss

151,745,000

176,048,000

109,767,000

108,621,000

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

34,447,000

31,466,000

'

'

'

'

'

7,531,000

35,961,000

'

'

'

'

'

'

'

'

Total unrecognized in net periodic cost

144,004,000

170,624,000

107,840,000

108,530,000

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

34,447,000

31,466,000

'

'

'

'

'

1,717,000

30,628,000

'

'

'

'

'

'

'

'

Current Year Benefit Plan Contributions [Abstract]

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Defined Benefit Plans, Estimated Future Employer Contributions in Next Fiscal Year Minimum

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

20,000,000

'

'

'

'

'

'

'

'

'

Defined Benefit Plans, Estimated Future Employer Contributions in Next Fiscal Year Maximum

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

25,000,000

'

'

'

'

'

'

'

'

'

Defined Benefit Plan, Assets, Target Allocations [Abstract]

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Defined Benefit Plan, Target Plan Asset Allocations Range Minimum

'

'

'

'

'

35.00%

'

10.00%

'

10.00%

'

5.00%

'

5.00%

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Defined Benefit Plan, Target Plan Asset Allocations Range Maximum

'

'

'

'

'

55.00%

'

20.00%

'

30.00%

'

15.00%

'

15.00%

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Defined Benefit Plan, Information about Plan Assets [Abstract]

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Defined Benefit Plan, Actual Plan Asset Allocations

'

'

'

'

'

51.90%

46.50%

15.30%

16.10%

9.70%

14.90%

12.90%

12.60%

10.20%

9.90%

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

99.70%

96.80%

0.30%

3.20%

'

'

'

Number of shares of Atmos Energy common stock in Master Trust

'

'

'

'

'

'

'

'

'

'

'

1,169,700

1,169,700

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Amount of dividend income from Atmos Energy common stock in Master Trust

'

'

'

'

'

'

'

'

'

'

'

1,700,000

1,600,000

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Defined Benefit Plan Weighted Average Assumptions Used In Calculating Net Periodic Benefit Cost Abstract

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Discount rate

'

'

4.95%

4.04%

5.05%

'

'

'

'

'

'

'

'

'

'

'

'

'

4.21%

4.04%

4.21%

4.95%

4.04%

5.05%

'

'

'

'

4.95%

4.04%

5.05%

'

'

'

'

'

'

'

Rate of compensation increase

'

'

3.50%

3.50%

3.50%

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

3.50%

3.50%

3.50%

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Expected return on plan assets

'

'

7.25%

7.75%

7.75%

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

4.60%

4.70%

5.00%

'

'

'

'

'

'

'

Initial Trend

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

8.00%

8.00%

8.00%

'

'

'

'

'

'

'

Ultimate trend rate

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

5.00%

5.00%

5.00%

'

'

'

'

'

'

'

Ultimate trend rate reached in

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'2020

'2019

'2018

'

'

'

'

'

'

'

Defined Benefit Plan Weighted Average Assumptions Used In Calculating Benefit Obligation Abstract

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Discount rate

'

'

4.43%

4.95%

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

4.95%

4.43%

4.95%

'

'

'

'

'

4.43%

4.95%

'

'

'

'

'

'

'

'

Rate of compensation increase

'

'

3.50%

3.50%

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

3.50%

3.50%

3.50%

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Expected return on plan assets

'

'

7.25%

7.25%

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

4.60%

4.60%

'

'

'

'

'

'

'

'

Initial trend rate

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

7.50%

8.00%

'

'

'

'

'

'

'

'

Ultimate trend rate

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

5.00%

5.00%

'

'

'

'

'

'

'

'

Ultimate trend reached in

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'2020

'2020

'

'

'

'

'

'

'

'

Interest crediting rate

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

4.69%

'

'

'

'

'

'

'

'

'

'

Accumulated benefit obligation

'

'

466,182,000

446,133,000

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

109,817,000

106,276,000

109,817,000

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Defined Benefit Plan Change In Benefit Obligation Roll Forward

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Benefit obligation at beginning of year

'

'

455,799,000

480,031,000

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

117,080,000

'

117,080,000

130,186,000

'

'

'

'

'

312,148,000

308,315,000

'

'

'

'

'

'

'

'

Service cost

'

'

15,345,000

17,754,000

15,084,000

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

3,607,000

3,039,000

2,108,000

'

'

'

'

16,784,000

18,800,000

16,353,000

'

'

'

'

'

'

'

Interest cost

'

'

22,330,000

19,334,000

21,568,000

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

4,966,000

4,755,000

5,142,000

'

'

'

'

15,951,000

12,964,000

13,861,000

'

'

'

'

'

'

'

Plan participants' contributions

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

4,435,000

3,815,000

'

'

'

'

'

'

'

'

Actuarial (gain) loss

'

'

26,611,000

-29,822,000

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

9,468,000

-6,451,000

'

'

'

'

'

-18,963,000

-13,801,000

'

'

'

'

'

'

'

'

Benefits paid

'

'

-24,519,000

-25,073,000

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

-5,085,000

-4,375,000

'

-16,800,000

'

'

'

-13,580,000

-14,458,000

'

'

'

'

'

'

'

'

Plan amendments

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

1,972,000

0

'

'

'

'

'

'

'

'

'

'

'

1,657,000

'

'

'

'

'

'

'

'

'

Divestitures

'

'

0

-6,425,000

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

0

-3,487,000

'

'

'

'

'

'

'

'

Settlements

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

-16,817,000

-10,074,000

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Benefit obligation at end of year

'

'

493,594,000

455,799,000

480,031,000

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

117,080,000

113,219,000

117,080,000

130,186,000

'

'

'

'

315,118,000

312,148,000

308,315,000

'

'

'

'

'

'

'

Funded Status Reconciliation [Abstract]

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Funded status

'

'

-58,827,000

-58,912,000

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

-117,080,000

-113,219,000

-117,080,000

'

'

'

'

'

-180,297,000

-205,735,000

'

'

'

'

'

'

'

'

Unrecognized prior service cost

'

'

0

0

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

0

0

0

'

'

'

'

'

0

0

'

'

'

'

'

'

'

'

Unrecognized transition obligation

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

0

0

'

'

'

'

'

'

'

'

Unrecognized net loss

'

'

0

0

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

0

0

0

'

'

'

'

'

0

0

'

'

'

'

'

'

'

'

Net amount recognized

'

'

-58,827,000

-58,912,000

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

-117,080,000

-113,219,000

-117,080,000

'

'

'

'

'

-180,297,000

-205,735,000

'

'

'

'

'

'

'

'

Estimated company benefit payments

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Estimated company benefit payments in year one

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

22,177,000

'

'

'

'

'

'

'

'

'

Estimated company benefit payments in year two

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

15,008,000

'

'

'

'

'

'

'

'

'

Estimated company benefit payments in year three

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

17,551,000

'

'

'

'

'

'

'

'

'

Estimated company benefit payments in year four

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

19,660,000

'

'

'

'

'

'

'

'

'

Estimated company benefit payments in year five

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

21,302,000

'

'

'

'

'

'

'

'

'

Estimated company benefit payments in five fiscal years thereafter

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

127,741,000

'

'

'

'

'

'

'

'

'

Estimated retiree benefit payments

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Estimated retiree benefit payments in year one

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

3,582,000

'

'

'

'

'

'

'

'

'

Estimated retiree benefit payments in year two

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

4,615,000

'

'

'

'

'

'

'

'

'

Estimated retiree benefit payments in year three

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

5,796,000

'

'

'

'

'

'

'

'

'

Estimated retiree benefit payments in year four

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

7,148,000

'

'

'

'

'

'

'

'

'

Estimated retiree benefit payments in year five

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

8,549,000

'

'

'

'

'

'

'

'

'

Estimated retiree benefit payments in five fiscal years thereafter

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

63,524,000

'

'

'

'

'

'

'

'

'

Disclosure Of Expected Gross Prescription Drug Subsidy Receipts Abstract

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Prescription drug subsidy receipts in year one

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

0

'

'

'

'

'

'

'

'

'

Prescription drug subsidy receipts in year two

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

0

'

'

'

'

'

'

'

'

'

Prescription drug subsidy receipts in year three

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

0

'

'

'

'

'

'

'

'

'

Prescription drug subsidy receipts in year four

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

0

'

'

'

'

'

'

'

'

'

Prescription drug subsidy receipts in year five

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

0

'

'

'

'

'

'

'

'

'

Prescription drug subsidy receipts in five fiscal years thereafter

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

0

'

'

'

'

'

'

'

'

'

Estimated Future Benefits Payment, Total

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Expected future benefit payments in year one, total

'

'

33,592,000

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

11,381,000

'

'

'

'

'

'

25,759,000

'

'

'

'

'

'

'

'

'

Expected future benefit payments in year two, total

'

'

32,811,000

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

4,617,000

'

'

'

'

'

'

19,623,000

'

'

'

'

'

'

'

'

'

Expected future benefit payments in year three, total

'

'

33,131,000

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

17,260,000

'

'

'

'

'

'

23,347,000

'

'

'

'

'

'

'

'

'

Expected future benefit payments in year four, total

'

'

33,501,000

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

14,772,000

'

'

'

'

'

'

26,808,000

'

'

'

'

'

'

'

'

'

Expected future benefit payments in year five, total

'

'

34,846,000

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

7,675,000

'

'

'

'

'

'

29,851,000

'

'

'

'

'

'

'

'

'

Expected future benefit payments in five fiscal years thereafter, total

'

'

182,998,000

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

32,843,000

'

'

'

'

'

'

191,265,000

'

'

'

'

'

'

'

'

'

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

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

4,533,000

'

'

'

'

'

'

'

'

'

Effect of One Percentage Point Decrease on Service and Interest Cost Components

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

-3,700,000

'

'

'

'

'

'

'

'

'

Effect of One Percentage Point Increase on Accumulated Postretirement Benefit Obligation

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

40,922,000

'

'

'

'

'

'

'

'

'

Effect of One Percentage Point Decrease on Accumulated Postretirement Benefit Obligation

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

-34,169,000

'

'

'

'

'

'

'

'

'

Defined Benefit Plan, Employer Claims Paid

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

80.00%

'

'

'

'

'

'

'

'

'

Defined Benefit Plan, Employee Paid Claims

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

20.00%

'

'

'

'

'

'

'

'

'

Defined Benefit Plan, Percent of Covered Compensation

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

75.00%

60.00%

'

'

'

'

'

'

'

'

'

'

'

Defined Benefit Plan, Vesting Period

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'3 years

'

'5 years

'

'

'

'

'

'

'

'

'

'3 years

'

'

'

'

'

'

'

'

'

'3 years

Defined Benefit Plan, Age Attained

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'55 years

'

'

'

'

'

'

'

'

'

'

Defined Benefit Plan, Investment Performance Review Period

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'3 years

'5 years

'

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.

'On April 1, 2013, due to the retirement of certain executives, we recognized a settlement loss of $3.2 million associated with the supplemental plans and revalued the net periodic pension cost for the remainder of fiscal 2013. The revaluation of the net periodic pension cost resulted in an increase in the discount rate, effective April 1, 2013, to 4.21 percent, which reduced our net periodic pension cost by approximately $0.1 million for the remainder of the fiscal year.

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Defined Benefit Plan, Recognized Net Gain (Loss) Due to Settlements

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

$3,200,000

'

'

($4,539,000)

($3,160,000)

$0

$4,500,000

'

'

'

'

'

'

'

'

'

'

'

'

'

Defined Benefit Plan, Funds Available for Investment in Common Stock and Convertible Securities

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

75.00%

'

'

'

'

'

'

'

'

'

Defined Benefit Plan, Percent of Contributed Compensation

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

10.00%

'

'

'

'

'

'

'

'

'

'

Remaining Recovery Period of Regulatory Assets for which No Return on Investment During Recovery Period is Provided

'15 years

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Defined Benefit Plan, Percent Limit on Future Contributions

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

3.00%

'

'

'

'

'

'

'

'

'

Retirement_and_PostRetirement_2

Retirement and Post-Retirement Employee Benefit Plans Fair Value Disclosures (Details) (USD $)	12 Months Ended
	Sep. 30, 2014	Sep. 30, 2013
Schedule of Total Investments at Fair Value [Line Items]	'	'
Available-for-sale Securities	$79,613,000	$72,682,000
Fair Value Inputs Level 1 [Member]	'	'
Schedule of Total Investments at Fair Value [Line Items]	'	'
Available-for-sale Securities	44,014,000	40,094,000
Fair Value Inputs Level 2 [Member]	'	'
Schedule of Total Investments at Fair Value [Line Items]	'	'
Available-for-sale Securities	35,599,000	32,588,000
Fair Value Inputs Level 3 [Member]	'	'
Schedule of Total Investments at Fair Value [Line Items]	'	'
Available-for-sale Securities	0	0
Pension Plans, Defined Benefit [Member]	'	'
Schedule of Total Investments at Fair Value [Line Items]	'	'
Investments, Fair Value Disclosure	432,109,000	396,482,000
Fair value of accounts receivable	2,700,000	400,000
Pension Plans, Defined Benefit [Member] | Equity Securities [Member]	'	'
Schedule of Total Investments at Fair Value [Line Items]	'	'
Investments, Fair Value Disclosure	155,107,000	143,543,000
Pension Plans, Defined Benefit [Member] | Money Market Funds [Member]	'	'
Schedule of Total Investments at Fair Value [Line Items]	'	'
Investments, Fair Value Disclosure	11,226,000	12,266,000
Pension Plans, Defined Benefit [Member] | Registered Investment Companies, Domestic [Member]	'	'
Schedule of Total Investments at Fair Value [Line Items]	'	'
Investments, Fair Value Disclosure	63,850,000	30,200,000
Pension Plans, Defined Benefit [Member] | Registered Investment Companies, International [Member]	'	'
Schedule of Total Investments at Fair Value [Line Items]	'	'
Investments, Fair Value Disclosure	48,134,000	47,036,000
Pension Plans, Defined Benefit [Member] | Common Collective Trusts [Member]	'	'
Schedule of Total Investments at Fair Value [Line Items]	'	'
Investments, Fair Value Disclosure	61,208,000	57,627,000
Pension Plans, Defined Benefit [Member] | Mortgage-backed securities [Member]	'	'
Schedule of Total Investments at Fair Value [Line Items]	'	'
Investments, Fair Value Disclosure	12,520,000	18,446,000
Pension Plans, Defined Benefit [Member] | U.S. Treasuries [Member]	'	'
Schedule of Total Investments at Fair Value [Line Items]	'	'
Investments, Fair Value Disclosure	3,679,000	4,780,000
Pension Plans, Defined Benefit [Member] | Corporate Debt Securities [Member]	'	'
Schedule of Total Investments at Fair Value [Line Items]	'	'
Investments, Fair Value Disclosure	25,734,000	35,012,000
Pension Plans, Defined Benefit [Member] | Limited Partnership Interest [Member]	'	'
Schedule of Total Investments at Fair Value [Line Items]	'	'
Investments, Fair Value Disclosure	50,496,000	47,417,000
Pension Plans, Defined Benefit [Member] | Real Estate Investment [Member]	'	'
Schedule of Total Investments at Fair Value [Line Items]	'	'
Investments, Fair Value Disclosure	155,000	155,000
Pension Plans, Defined Benefit [Member] | Fair Value Inputs Level 1 [Member]	'	'
Schedule of Total Investments at Fair Value [Line Items]	'	'
Investments, Fair Value Disclosure	270,208,000	224,896,000
Pension Plans, Defined Benefit [Member] | Fair Value Inputs Level 1 [Member] | Equity Securities [Member]	'	'
Schedule of Total Investments at Fair Value [Line Items]	'	'
Investments, Fair Value Disclosure	155,107,000	143,543,000
Pension Plans, Defined Benefit [Member] | Fair Value Inputs Level 1 [Member] | Money Market Funds [Member]	'	'
Schedule of Total Investments at Fair Value [Line Items]	'	'
Investments, Fair Value Disclosure	0	0
Pension Plans, Defined Benefit [Member] | Fair Value Inputs Level 1 [Member] | Registered Investment Companies, Domestic [Member]	'	'
Schedule of Total Investments at Fair Value [Line Items]	'	'
Investments, Fair Value Disclosure	63,850,000	30,200,000
Pension Plans, Defined Benefit [Member] | Fair Value Inputs Level 1 [Member] | Registered Investment Companies, International [Member]	'	'
Schedule of Total Investments at Fair Value [Line Items]	'	'
Investments, Fair Value Disclosure	48,134,000	47,036,000
Pension Plans, Defined Benefit [Member] | Fair Value Inputs Level 1 [Member] | Common Collective Trusts [Member]	'	'
Schedule of Total Investments at Fair Value [Line Items]	'	'
Investments, Fair Value Disclosure	0	0
Pension Plans, Defined Benefit [Member] | Fair Value Inputs Level 1 [Member] | Mortgage-backed securities [Member]	'	'
Schedule of Total Investments at Fair Value [Line Items]	'	'
Investments, Fair Value Disclosure	0	0
Pension Plans, Defined Benefit [Member] | Fair Value Inputs Level 1 [Member] | U.S. Treasuries [Member]	'	'
Schedule of Total Investments at Fair Value [Line Items]	'	'
Investments, Fair Value Disclosure	3,117,000	4,117,000
Pension Plans, Defined Benefit [Member] | Fair Value Inputs Level 1 [Member] | Corporate Debt Securities [Member]	'	'
Schedule of Total Investments at Fair Value [Line Items]	'	'
Investments, Fair Value Disclosure	0	0
Pension Plans, Defined Benefit [Member] | Fair Value Inputs Level 1 [Member] | Limited Partnership Interest [Member]	'	'
Schedule of Total Investments at Fair Value [Line Items]	'	'
Investments, Fair Value Disclosure	0	0
Pension Plans, Defined Benefit [Member] | Fair Value Inputs Level 1 [Member] | Real Estate Investment [Member]	'	'
Schedule of Total Investments at Fair Value [Line Items]	'	'
Investments, Fair Value Disclosure	0	0
Pension Plans, Defined Benefit [Member] | Fair Value Inputs Level 2 [Member]	'	'
Schedule of Total Investments at Fair Value [Line Items]	'	'
Investments, Fair Value Disclosure	161,746,000	171,431,000
Pension Plans, Defined Benefit [Member] | Fair Value Inputs Level 2 [Member] | Equity Securities [Member]	'	'
Schedule of Total Investments at Fair Value [Line Items]	'	'
Investments, Fair Value Disclosure	0	0
Pension Plans, Defined Benefit [Member] | Fair Value Inputs Level 2 [Member] | Money Market Funds [Member]	'	'
Schedule of Total Investments at Fair Value [Line Items]	'	'
Investments, Fair Value Disclosure	11,226,000	12,266,000
Pension Plans, Defined Benefit [Member] | Fair Value Inputs Level 2 [Member] | Registered Investment Companies, Domestic [Member]	'	'
Schedule of Total Investments at Fair Value [Line Items]	'	'
Investments, Fair Value Disclosure	0	0
Pension Plans, Defined Benefit [Member] | Fair Value Inputs Level 2 [Member] | Registered Investment Companies, International [Member]	'	'
Schedule of Total Investments at Fair Value [Line Items]	'	'
Investments, Fair Value Disclosure	0	0
Pension Plans, Defined Benefit [Member] | Fair Value Inputs Level 2 [Member] | Common Collective Trusts [Member]	'	'
Schedule of Total Investments at Fair Value [Line Items]	'	'
Investments, Fair Value Disclosure	61,208,000	57,627,000
Pension Plans, Defined Benefit [Member] | Fair Value Inputs Level 2 [Member] | Mortgage-backed securities [Member]	'	'
Schedule of Total Investments at Fair Value [Line Items]	'	'
Investments, Fair Value Disclosure	12,520,000	18,446,000
Pension Plans, Defined Benefit [Member] | Fair Value Inputs Level 2 [Member] | U.S. Treasuries [Member]	'	'
Schedule of Total Investments at Fair Value [Line Items]	'	'
Investments, Fair Value Disclosure	562,000	663,000
Pension Plans, Defined Benefit [Member] | Fair Value Inputs Level 2 [Member] | Corporate Debt Securities [Member]	'	'
Schedule of Total Investments at Fair Value [Line Items]	'	'
Investments, Fair Value Disclosure	25,734,000	35,012,000
Pension Plans, Defined Benefit [Member] | Fair Value Inputs Level 2 [Member] | Limited Partnership Interest [Member]	'	'
Schedule of Total Investments at Fair Value [Line Items]	'	'
Investments, Fair Value Disclosure	50,496,000	47,417,000
Pension Plans, Defined Benefit [Member] | Fair Value Inputs Level 2 [Member] | Real Estate Investment [Member]	'	'
Schedule of Total Investments at Fair Value [Line Items]	'	'
Investments, Fair Value Disclosure	0	0
Pension Plans, Defined Benefit [Member] | Fair Value Inputs Level 3 [Member]	'	'
Schedule of Total Investments at Fair Value [Line Items]	'	'
Investments, Fair Value Disclosure	155,000	155,000
Pension Plans, Defined Benefit [Member] | Fair Value Inputs Level 3 [Member] | Equity Securities [Member]	'	'
Schedule of Total Investments at Fair Value [Line Items]	'	'
Investments, Fair Value Disclosure	0	0
Pension Plans, Defined Benefit [Member] | Fair Value Inputs Level 3 [Member] | Money Market Funds [Member]	'	'
Schedule of Total Investments at Fair Value [Line Items]	'	'
Investments, Fair Value Disclosure	0	0
Pension Plans, Defined Benefit [Member] | Fair Value Inputs Level 3 [Member] | Registered Investment Companies, Domestic [Member]	'	'
Schedule of Total Investments at Fair Value [Line Items]	'	'
Investments, Fair Value Disclosure	0	0
Pension Plans, Defined Benefit [Member] | Fair Value Inputs Level 3 [Member] | Registered Investment Companies, International [Member]	'	'
Schedule of Total Investments at Fair Value [Line Items]	'	'
Investments, Fair Value Disclosure	0	0
Pension Plans, Defined Benefit [Member] | Fair Value Inputs Level 3 [Member] | Common Collective Trusts [Member]	'	'
Schedule of Total Investments at Fair Value [Line Items]	'	'
Investments, Fair Value Disclosure	0	0
Pension Plans, Defined Benefit [Member] | Fair Value Inputs Level 3 [Member] | Mortgage-backed securities [Member]	'	'
Schedule of Total Investments at Fair Value [Line Items]	'	'
Investments, Fair Value Disclosure	0	0
Pension Plans, Defined Benefit [Member] | Fair Value Inputs Level 3 [Member] | U.S. Treasuries [Member]	'	'
Schedule of Total Investments at Fair Value [Line Items]	'	'
Investments, Fair Value Disclosure	0	0
Pension Plans, Defined Benefit [Member] | Fair Value Inputs Level 3 [Member] | Corporate Debt Securities [Member]	'	'
Schedule of Total Investments at Fair Value [Line Items]	'	'
Investments, Fair Value Disclosure	0	0
Pension Plans, Defined Benefit [Member] | Fair Value Inputs Level 3 [Member] | Limited Partnership Interest [Member]	'	'
Schedule of Total Investments at Fair Value [Line Items]	'	'
Investments, Fair Value Disclosure	0	0
Pension Plans, Defined Benefit [Member] | Fair Value Inputs Level 3 [Member] | Real Estate Investment [Member]	'	'
Schedule of Total Investments at Fair Value [Line Items]	'	'
Investments, Fair Value Disclosure	155,000	155,000
Defined Benefit Plan, Plan Assets at Fair Value, Valuation Inputs	'The fair value of our Level 3 real estate assets was determined using a real estate appraisal obtained from an independent third party that consisted of several unobservable inputs such as comparable land sales values per square foot in the range of $0.94 to $2.98 and comparable building sales values per square foot in the range of $23.13 to $30.42.	'
Other Postretirement Benefit Plans, Defined Benefit [Member]	'	'
Schedule of Total Investments at Fair Value [Line Items]	'	'
Investments, Fair Value Disclosure	134,821,000	106,413,000
Other Postretirement Benefit Plans, Defined Benefit [Member] | Money Market Funds [Member]	'	'
Schedule of Total Investments at Fair Value [Line Items]	'	'
Investments, Fair Value Disclosure	434,000	3,356,000
Other Postretirement Benefit Plans, Defined Benefit [Member] | Registered Investment Companies, Domestic [Member]	'	'
Schedule of Total Investments at Fair Value [Line Items]	'	'
Investments, Fair Value Disclosure	11,398,000	9,614,000
Other Postretirement Benefit Plans, Defined Benefit [Member] | Registered Investment Companies, International [Member]	'	'
Schedule of Total Investments at Fair Value [Line Items]	'	'
Investments, Fair Value Disclosure	122,989,000	93,443,000
Other Postretirement Benefit Plans, Defined Benefit [Member] | Fair Value Inputs Level 1 [Member]	'	'
Schedule of Total Investments at Fair Value [Line Items]	'	'
Investments, Fair Value Disclosure	134,387,000	103,057,000
Other Postretirement Benefit Plans, Defined Benefit [Member] | Fair Value Inputs Level 1 [Member] | Money Market Funds [Member]	'	'
Schedule of Total Investments at Fair Value [Line Items]	'	'
Investments, Fair Value Disclosure	0	0
Other Postretirement Benefit Plans, Defined Benefit [Member] | Fair Value Inputs Level 1 [Member] | Registered Investment Companies, Domestic [Member]	'	'
Schedule of Total Investments at Fair Value [Line Items]	'	'
Investments, Fair Value Disclosure	11,398,000	9,614,000
Other Postretirement Benefit Plans, Defined Benefit [Member] | Fair Value Inputs Level 1 [Member] | Registered Investment Companies, International [Member]	'	'
Schedule of Total Investments at Fair Value [Line Items]	'	'
Investments, Fair Value Disclosure	122,989,000	93,443,000
Other Postretirement Benefit Plans, Defined Benefit [Member] | Fair Value Inputs Level 2 [Member]	'	'
Schedule of Total Investments at Fair Value [Line Items]	'	'
Investments, Fair Value Disclosure	434,000	3,356,000
Other Postretirement Benefit Plans, Defined Benefit [Member] | Fair Value Inputs Level 2 [Member] | Money Market Funds [Member]	'	'
Schedule of Total Investments at Fair Value [Line Items]	'	'
Investments, Fair Value Disclosure	434,000	3,356,000
Other Postretirement Benefit Plans, Defined Benefit [Member] | Fair Value Inputs Level 2 [Member] | Registered Investment Companies, Domestic [Member]	'	'
Schedule of Total Investments at Fair Value [Line Items]	'	'
Investments, Fair Value Disclosure	0	0
Other Postretirement Benefit Plans, Defined Benefit [Member] | Fair Value Inputs Level 2 [Member] | Registered Investment Companies, International [Member]	'	'
Schedule of Total Investments at Fair Value [Line Items]	'	'
Investments, Fair Value Disclosure	0	0
Other Postretirement Benefit Plans, Defined Benefit [Member] | Fair Value Inputs Level 3 [Member]	'	'
Schedule of Total Investments at Fair Value [Line Items]	'	'
Investments, Fair Value Disclosure	0	0
Other Postretirement Benefit Plans, Defined Benefit [Member] | Fair Value Inputs Level 3 [Member] | Money Market Funds [Member]	'	'
Schedule of Total Investments at Fair Value [Line Items]	'	'
Investments, Fair Value Disclosure	0	0
Other Postretirement Benefit Plans, Defined Benefit [Member] | Fair Value Inputs Level 3 [Member] | Registered Investment Companies, Domestic [Member]	'	'
Schedule of Total Investments at Fair Value [Line Items]	'	'
Investments, Fair Value Disclosure	0	0
Other Postretirement Benefit Plans, Defined Benefit [Member] | Fair Value Inputs Level 3 [Member] | Registered Investment Companies, International [Member]	'	'
Schedule of Total Investments at Fair Value [Line Items]	'	'
Investments, Fair Value Disclosure	0	0
Supplemental Executive Retirement Plans, Defined Benefit [Member]	'	'
Schedule of Total Investments at Fair Value [Line Items]	'	'
Available-for-sale Securities	$46,200,000	$44,500,000
Minimum [Member]	'	'
Schedule of Total Investments at Fair Value [Line Items]	'	'
Comparable Land Sale Values	0.94	'
Comparable Building Sales Values	23.13	'
Maximum [Member]	'	'
Schedule of Total Investments at Fair Value [Line Items]	'	'
Comparable Land Sale Values	2.98	'
Comparable Building Sales Values	30.42	'

Retirement_and_PostRetirement_3

Retirement and Post-Retirement Employee Benefit Plans Fair Value of Plan Assets (Details) (USD $)	12 Months Ended
In Thousands, unless otherwise specified	Sep. 30, 2014	Sep. 30, 2013
Pension Plans, Defined Benefit [Member]	'	'
Defined Benefit Plan Disclosure [Line Items]	'	'
Fair value of plan assets at beginning of year	$396,887	$343,144
Actual return on plan assets	35,289	52,496
Employer contributions	27,110	32,745
Benefits paid	-24,519	-25,073
Divestitures	0	-6,425
Fair value of plan assets at end of year	434,767	396,887
Other Postretirement Benefit Plans, Defined Benefit [Member]	'	'
Defined Benefit Plan Disclosure [Line Items]	'	'
Fair value of plan assets at beginning of year	106,413	77,072
Actual return on plan assets	14,003	13,432
Employer contributions	23,550	26,552
Plan participants' contributions	4,435	3,815
Benefits paid	-13,580	-14,458
Fair value of plan assets at end of year	134,821	106,413
Supplemental Executive Retirement Plans, Defined Benefit [Member]	'	'
Defined Benefit Plan Disclosure [Line Items]	'	'
Fair value of plan assets at beginning of year	0	0
Employer contributions	21,902	14,449
Benefits paid	-5,085	-4,375
Settlements	-16,817	-10,074
Fair value of plan assets at end of year	$0	$0

Retirement_and_PostRetirement_4

Retirement and Post-Retirement Employee Benefit Plans Net Periodic Cost (Details) (USD $)	0 Months Ended	12 Months Ended
	Apr. 02, 2013	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2012
Pension Plans, Defined Benefit [Member]	'	'	'	'
Defined Benefit Plan Disclosure [Line Items]	'	'	'	'
Service cost	'	$15,345,000	$17,754,000	$15,084,000
Interest cost	'	22,330,000	19,334,000	21,568,000
Expected return on assets	'	-23,601,000	-22,955,000	-21,474,000
Amortization of prior service cost	'	-136,000	-141,000	-141,000
Recognized actuarial loss	'	13,777,000	19,066,000	14,451,000
Net periodic pension cost	'	27,715,000	33,058,000	29,488,000
Other Postretirement Benefit Plans, Defined Benefit [Member]	'	'	'	'
Defined Benefit Plan Disclosure [Line Items]	'	'	'	'
Service cost	'	16,784,000	18,800,000	16,353,000
Interest cost	'	15,951,000	12,964,000	13,861,000
Expected return on assets	'	-5,167,000	-3,988,000	-2,607,000
Amortization of transition asset	'	274,000	1,081,000	1,511,000
Amortization of prior service cost	'	-1,450,000	-1,450,000	-1,450,000
Recognized actuarial loss	'	631,000	4,196,000	2,648,000
Net periodic pension cost	'	27,023,000	31,603,000	30,316,000
Supplemental Executive Retirement Plans, Defined Benefit [Member]	'	'	'	'
Defined Benefit Plan Disclosure [Line Items]	'	'	'	'
Service cost	'	3,607,000	3,039,000	2,108,000
Interest cost	'	4,966,000	4,755,000	5,142,000
Amortization of transition asset	'	0	0	0
Amortization of prior service cost	'	0	0	0
Recognized actuarial loss	'	1,948,000	2,918,000	2,118,000
Settlements	-3,200,000	4,539,000	3,160,000	0
Effect on Net Periodic Cost Due To Discount Rate Change, Remaining Fiscal Year	100,000	'	'	'
Net periodic pension cost	'	$15,060,000	$13,872,000	$9,368,000

Retirement_and_PostRetirement_5

Retirement and Post-Retirement Employee Benefit Plans Defined Contribution Plans (Details) (USD $)	12 Months Ended
In Millions, unless otherwise specified	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2012
Schedule of Defined Contribution Plans Disclosures [Line Items]	'	'	'
Defined Contribution, Employer Contribution Service Period Until Eligibility	'1 year	'	'
Percent of Atmos Energy common stock in Retirement Savings Plan	4.50%	4.90%	'
Retirement Savings Plan [Member]	'	'	'
Schedule of Defined Contribution Plans Disclosures [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 Matching Contribution, Percent of Match	100.00%	'	'
Union 401K Plan [Member]	'	'	'
Schedule of Defined Contribution Plans Disclosures [Line Items]	'	'	'
Defined Contribution Plan, Employer Matching Contribution, Percent of Employees' Gross Pay	6.00%	'	'
Defined Contribution Plan, Employer Matching Contribution, Percent of Match	50.00%	'	'
Retirement Savings Plan and Union 401K Plan [Member]	'	'	'
Schedule of Defined Contribution Plans Disclosures [Line Items]	'	'	'
Defined Contribution Plan, Cost Recognized	$10.90	$10.40	$10.50
AEH 401K Profit-Sharing Plan [Member]	'	'	'
Schedule of Defined Contribution Plans Disclosures [Line Items]	'	'	'
Defined Contribution Plan, Maximum Annual Contributions Per Employee, Percent	75.00%	'	'
Defined Contribution Plan, Employer Discretionary Contribution Amount	$1.40	$1.10	$1.20

Stock_and_Other_Compensation_P2

Stock and Other Compensation Plans (Details) (USD $)	12 Months Ended
	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2012
Share-based Compensation, Allocation and Classification in Financial Statements [Abstract]	'	'	'
Stock Based Compensation Expense	$25,500,000	$17,800,000	$19,200,000
Authorized Shares	8,700,000	'	'
Share-based Compensation Arrangement by Share-based Payment Award, Number of Shares Available	845,139	'	'
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Additional Disclosures [Abstract]	'	'	'
Nonvested at beginning of year-Shares	1,052,844	1,262,582	1,264,142
Nonvested at beginning of year-Weighted Average	$36.20	$32.46	$29.56
Granted-Shares	464,438	473,775	532,711
Granted-Weighted Average	$45.05	$40.48	$33.44
Vested-Shares	-524,532	-657,795	-494,308
Vested-Weighted Average	$32.67	$32.20	$26.32
Forfeited-Shares	-4,113	-25,718	-39,963
Forfeited-Weighted Average	$39	$33.42	$29.83
Nonvested at end of year-Shares	988,637	1,052,844	1,262,582
Nonvested at end of year-Weighted Average	$42.22	$36.20	$32.46
Unrecognized Compensation Cost	5,300,000	'	'
Weighted Average Recognized Period	'1 year 7 months 6 days	'	'
Fair Value Restricted Stock Vested	17,100,000	21,200,000	13,000,000
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_Consolidat2

Details of Selected Consolidated Balance Sheet Captions (Details) (USD $)	12 Months Ended
	Sep. 30, 2014		Sep. 30, 2013
Accounts, Notes, Loans and Financing Receivable [Line Items]	'		'
Accounts Receivable, Gross, Current	$367,392,000		$322,616,000
Less: allowance for doubtful accounts	-23,992,000		-20,624,000
Net accounts receivable	343,400,000		301,992,000
Schedule of Other Current Assets [Abstract]	'		'
Assets from risk management activities current	45,827,000		11,966,000
Deferred gas cost	20,069,000		15,152,000
Taxes receivable	5,481,000		3,141,000
Prepaid expenses	25,039,000		21,666,000
Materials and supplies	5,704,000		5,511,000
Other	9,145,000		6,765,000
Total other current assets	111,265,000		64,201,000
Property, Plant and Equipment [Line Items]	'		'
Property, plant and equipment	8,200,121,000		7,446,272,000
Construction in progress	247,579,000		275,747,000
Total property, plant and equipment and construction in progress	8,447,700,000		7,722,019,000
Less accumulated depreciation and amortization	-1,721,794,000		-1,691,364,000
Net property, plant and equipment	6,725,906,000	[1]	6,030,655,000	[1]
Public Utilities, Plant and Equipment, Amount of Acquisition Adjustments and Related Accumulated Depreciation	-76,400,000		-83,800,000
Goodwill [Line Items]	'		'
Goodwill, Beginning Balance	741,363,000		'
Goodwill, Other Changes	666,000	[2]	'
Goodwill, Ending Balance	742,029,000		'
Schedule of Other Noncurrent Assets [Abstract]	'		'
Marketable securities	79,613,000		72,682,000
Regulatory assets	230,240,000		273,287,000
Deferred financing costs	13,698,000		15,199,000
Assets from risk management activities noncurrent	13,038,000		109,354,000
Other	14,340,000		14,595,000
Total	350,929,000		485,117,000
Schedule of Accounts Payable and Accrued Liabilities [Abstract]	'		'
Trade accounts payable	77,860,000		70,116,000
Accrued gas payable	179,425,000		121,202,000
Accrued liabilities	54,319,000		50,293,000
Total	311,604,000		241,611,000
Schedule of Other Current Liabilities [Abstract]	'		'
Customer deposits	82,085,000		76,313,000
Accrued employee costs	46,445,000		54,034,000
Deferred gas costs	35,063,000		16,481,000
Accrued interest	36,768,000		36,744,000
Liabilities from risk management activities current	1,730,000		1,543,000
Taxes payable	77,601,000		66,960,000
Pension and postretirement obligations	11,380,000		22,940,000
Regulatory cost of removal accrual	45,061,000		68,225,000
Current deferred tax liability	48,751,000		14,697,000
Other	17,467,000		10,954,000
Total	402,351,000		368,891,000
Schedule of Other Noncurrent Liabilities [Abstract]	'		'
Customer advances for construction	9,883,000		11,723,000
Regulatory liabilities	4,472,000		1,123,000
Asset retirement obligation	10,508,000		6,764,000
Liabilities from risk management activities noncurrent	20,126,000		0
Other	23,881,000		17,953,000
Total	68,870,000		37,563,000
Regulated Distribution Segment [Member]	'		'
Schedule of Other Current Assets [Abstract]	'		'
Assets from risk management activities current	23,102,000		1,837,000
Property, Plant and Equipment [Line Items]	'		'
Net property, plant and equipment	5,202,761,000		4,719,873,000
Goodwill [Line Items]	'		'
Goodwill, Beginning Balance	574,190,000		'
Goodwill, Other Changes	626,000	[2]	'
Goodwill, Ending Balance	574,816,000		'
Schedule of Other Noncurrent Assets [Abstract]	'		'
Assets from risk management activities noncurrent	13,038,000		109,354,000
Schedule of Other Current Liabilities [Abstract]	'		'
Liabilities from risk management activities current	1,730,000		1,543,000
Schedule of Other Noncurrent Liabilities [Abstract]	'		'
Liabilities from risk management activities noncurrent	20,126,000		0
Regulated Pipeline Segment [Member]	'		'
Schedule of Other Current Assets [Abstract]	'		'
Assets from risk management activities current	0		0
Property, Plant and Equipment [Line Items]	'		'
Net property, plant and equipment	1,464,572,000		1,249,767,000
Goodwill [Line Items]	'		'
Goodwill, Beginning Balance	132,462,000		'
Goodwill, Other Changes	40,000	[2]	'
Goodwill, Ending Balance	132,502,000		'
Schedule of Other Noncurrent Assets [Abstract]	'		'
Assets from risk management activities noncurrent	0		0
Schedule of Other Current Liabilities [Abstract]	'		'
Liabilities from risk management activities current	0		0
Schedule of Other Noncurrent Liabilities [Abstract]	'		'
Liabilities from risk management activities noncurrent	0		0
Nonregulated Segment [Member]	'		'
Schedule of Other Current Assets [Abstract]	'		'
Assets from risk management activities current	22,725,000	[3]	10,129,000	[4]
Property, Plant and Equipment [Line Items]	'		'
Net property, plant and equipment	58,573,000		61,015,000
Goodwill [Line Items]	'		'
Goodwill, Beginning Balance	34,711,000		'
Goodwill, Other Changes	0	[2]	'
Goodwill, Ending Balance	34,711,000		'
Schedule of Other Noncurrent Assets [Abstract]	'		'
Assets from risk management activities noncurrent	0		0
Schedule of Other Current Liabilities [Abstract]	'		'
Liabilities from risk management activities current	0	[3]	0	[4]
Schedule of Other Noncurrent Liabilities [Abstract]	'		'
Liabilities from risk management activities noncurrent	0		0
Gas Gathering and Processing Equipment [Member]	'		'
Property, Plant and Equipment [Line Items]	'		'
Property, plant and equipment	4,821,000		5,020,000
Gas Storage Equipment [Member]	'		'
Property, Plant and Equipment [Line Items]	'		'
Property, plant and equipment	275,579,000		262,246,000
Gas Transmission Equipment [Member]	'		'
Property, Plant and Equipment [Line Items]	'		'
Property, plant and equipment	1,622,846,000		1,362,662,000
Gas Distribution Equipment [Member]	'		'
Property, Plant and Equipment [Line Items]	'		'
Property, plant and equipment	5,522,794,000		5,061,711,000
General Plant [Member]	'		'
Property, Plant and Equipment [Line Items]	'		'
Property, plant and equipment	735,223,000		716,189,000
Other Capitalized Property Plant and Equipment [Member]	'		'
Property, Plant and Equipment [Line Items]	'		'
Property, plant and equipment	38,858,000		38,444,000
Trade Accounts Receivable [Member] | Billed Revenues [Member]	'		'
Accounts, Notes, Loans and Financing Receivable [Line Items]	'		'
Accounts Receivable, Gross, Current	262,937,000		230,712,000
Trade Accounts Receivable [Member] | Unbilled Revenues [Member]	'		'
Accounts, Notes, Loans and Financing Receivable [Line Items]	'		'
Accounts Receivable, Gross, Current	62,484,000		58,710,000
Other Accounts Receivable [Member]	'		'
Accounts, Notes, Loans and Financing Receivable [Line Items]	'		'
Accounts Receivable, Gross, Current	$41,971,000		$33,194,000
[1]	Net property, plant and equipment includes plant acquisition adjustments of $(76.4) million and $(83.8) million at September 30, 2014 and 2013.
[2]	e 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
[3]	Includes $25.8 million of cash held on deposit to collateralize certain financial instruments. Of this amount, $3.1 million was used to offset current and noncurent risk management liabilities under master netting arrangements and the remaining $22.7 million is classified as current risk management assets.
[4]	Includes $24.8 million of cash held on deposit to collateralize certain financial instruments. Of this amount, $14.7 million was used to offset current and noncurrent risk management liabilities under master netting arrangements and the remaining $10.1 million is classified as current risk management assets.

Leases_Details

Leases (Details) (USD $)	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2014	Sep. 30, 2014
				Minimum [Member]	Maximum [Member]
Operating Leased Assets [Line Items]	'	'	'	'	'
Operating Lease, Term	'	'	'	'1 year	'20 years
Capital Leases of Lessee [Abstract]	'	'	'	'	'
Capital Leased Assets Gross	$1,300,000	$1,300,000	'	'	'
Capital Leases Accumulated Depreciation	1,100,000	1,000,000	'	'	'
Capital Leases, 2015	186,000	'	'	'	'
Capital Leases, 2016	186,000	'	'	'	'
Capital Leases, 2017	186,000	'	'	'	'
Capital Leases, 2018	78,000	'	'	'	'
Capital Leases, 2019	0	'	'	'	'
Capital Leases, thereafter	0	'	'	'	'
Total Capital Minimum Lease Payments	636,000	'	'	'	'
Capital Leases, less amount representing interest	123,000	'	'	'	'
Present value of net minimum lease payments	513,000	'	'	'	'
Operating Leases, 2015	16,673,000	'	'	'	'
Operating Leases, 2016	16,021,000	'	'	'	'
Operating Leases, 2017	16,330,000	'	'	'	'
Operating Leases, 2018	15,907,000	'	'	'	'
Operating Leases, 2019	15,138,000	'	'	'	'
Operating Leases, Thereafter	75,620,000	'	'	'	'
Total Operating Lease Payments	155,689,000	'	'	'	'
Lease and Rental Expense	$31,700,000	$32,400,000	$33,600,000	'	'

Commitments_and_Contingencies_1

Commitments and Contingencies (Details) (USD $)

0 Months Ended

12 Months Ended

2-May-14

Jan. 25, 2013

Dec. 09, 2011

Sep. 30, 2014

Sep. 30, 2014

Sep. 30, 2013

Sep. 30, 2012

Sep. 30, 2014

Sep. 30, 2013

Sep. 30, 2012

Sep. 30, 2014

Sep. 30, 2014

Sep. 30, 2014

Mid-Tex Division [Member]

Mid-Tex Division [Member]

Mid-Tex Division [Member]

Nonregulated Segment [Member]

Nonregulated Segment [Member]

Nonregulated Segment [Member]

Inventories Under Indexed Contracts [Member]

Inventories Under Indexed Contracts [Member]

Inventories Under Fixed Price Contracts [Member]

Mid-Tex Division [Member]

Nonregulated Segment [Member]

Nonregulated Segment [Member]

MMcf

MMcf

MMcf

Loss Contingency Information About Litigation Matters [Abstract]

'

'

'

'

'

'

'

'

'

'

'

'

'

Description of Pending Litigation

'

'

'

'Beginning in April 2009, Atmos Energy and two subsidiaries of AEH, Atmos Energy Marketing, LLC (AEM) and Atmos Gathering Company, LLC (AGC) (collectively, the Atmos Entities), were involved in a lawsuit filed in the Circuit Court of Edmonson County, Kentucky related to our Park City Gathering Project. The dispute which gave rise to the litigation involves the amount of royalties due from a third party producer to landowners (who own the mineral rights) for natural gas produced from the landowners’ properties. The third party producer was operating pursuant to leases between the landowners and certain investors/working interest owners. The third party producer filed a petition in bankruptcy, which was subsequently dismissed due to the lack of meaningful assets to reorganize or liquidate. Although certain Atmos Energy companies entered into contracts with the third party producer to gather, treat and ultimately sell natural gas produced from the landowners’ properties, no Atmos Energy company had a contractual relationship with the landowners or the investors/working interest owners. After the lawsuit was filed, the landowners were successful in terminating for non-payment of royalties the leases related to the production of natural gas from their properties. Subsequent to termination, the investors/working interest owners under such leases filed additional claims against us for the termination of the leases. During the trial, the landowners and the investors/working interest owners requested an award of compensatory damages plus punitive damages against us. On December 17, 2010, the jury returned a verdict in favor of the landowners and investor/working interest owners and awarded compensatory damages of $3.8 million and punitive damages of $27.5 million payable by Atmos Energy and the two AEH subsidiaries. A hearing was held on February 28, 2011 to hear a number of motions, including a motion to dismiss the jury verdict and a motion for a new trial. The motions to dismiss the jury verdict and for a new trial were denied. However, the total punitive damages award was reduced from $27.5 million to $24.7 million. On October 17, 2011, we filed our brief of appellants with the Kentucky Court of Appeals (Court), appealing the verdict of the trial court. The appellees in this case subsequently filed their appellees’ brief with the Court on January 16, 2012, with our reply brief being filed with the Court on March 19, 2012. Oral arguments were held in the case on August 27, 2012. In an opinion handed down on January 25, 2013, the Court of Appeals overturned the $28.5 million jury verdict returned against the Atmos Entities. In a unanimous decision by a three-judge panel, the Court of Appeals reversed the claims asserted by the landowners and investors/working interest owners. The Court of Appeals concluded that all of such claims that the Atmos Entities appealed should have been dismissed by the trial court as a matter of law. The Court of Appeals let stand the jury verdict on one claim that Atmos Energy and our subsidiaries chose not to appeal, which was a trespass claim. The jury had awarded a total of $10,000 in compensatory damages to one landowner on that claim. The Court of Appeals vacated all of the other damages awarded by the jury and remanded the case to the trial court for a new trial, solely on the issue of whether punitive damages should be awarded to that landowner and, if so, in what amount.The investors/working interest owners, on February 25, 2013, and the landowners, on March 19, 2013, each filed with the Supreme Court of Kentucky, separate motions for discretionary review of the opinion of the Court of Appeals. We filed a response to the motion filed by the investors/working owners on March 27, 2013 and to the landowners’ motion on April 17, 2013. The Kentucky Supreme Court denied the motions for discretionary review on February 12, 2014 and the decision of the Court of Appeals became final on February 21, 2014.  We had previously accrued what we believed to be an adequate amount for the anticipated resolution of this matter. This accrual was reversed during the second fiscal quarter of fiscal 2014 as the appellate process in this case had been completed. Atmos Energy had also filed a motion with the trial court, the Circuit Court of Edmonson County, Kentucky, on March 10, 2014, seeking a ruling that the remaining landowner was not entitled to any punitive damages on the sole remaining claim of trespass.  On May 19, 2014, the Edmonson County Circuit Court entered judgment dismissing any claim for punitive damages relating to the trespass claim. There was no appeal of this judgment. The lawsuit in Edmonson County has now been fully resolved.In addition, in a related matter, on July 12, 2011, the Atmos Entities filed a lawsuit in the United States District Court, Western District of Kentucky, Atmos Energy Corporation et al.vs. Resource Energy Technologies, LLC and Robert Thorpe and John F. Charles, against the third party producer and its affiliates to recover all costs, including attorneys’ fees, incurred by the Atmos Entities, which are associated with the defense and appeal of the case discussed above as well as for all damages awarded to the plaintiffs in such case against the Atmos Entities. The total amount of damages being claimed in the lawsuit is about $3.5 million, plus interest that continues to accrue. This lawsuit is based upon the indemnification provisions agreed to by the third party producer in favor of Atmos Gathering that are contained in an agreement entered into between Atmos Gathering and the third party producer in May 2009. The defendants filed a motion to dismiss the case on August 25, 2011, with Atmos Energy filing a brief in response to such motion on September 19, 2011. On March 27, 2012 the court denied the motion to dismiss. Atmos Energy filed a motion for partial summary judgment against the defendants with the District Court on July 15, 2014 and filed an Amended Complaint on July 18, 2014. On August 28, 2014, the court entered an order authorizing the withdrawal of the lawyer representing the estate of Robert Thorpe, giving the Thorpe Estate until October 2, 2014 to engage a new lawyer. On September 29, 2014, Resource Energy Technologies, LLC and John Charles, individually, entered into an agreed-upon judgment in favor of the Atmos Entities in the amount of $3.6 million, which resolved all claims by the Atmos Entities against those defendants and which dismissed with prejudice all counterclaims against the Atmos Entities. That judgment was settled with the Atmos Entities for $15,000, based on information obtained in discovery that showed those defendants lacked the ability to pay. The only claims remaining in the case are the Atmos Entities’ claims against the Thorpe Estate. The Thorpe Estate has not responded to the motion for partial summary judgment or the amended complaint. In a hearing held on October 7, 2014, the court was advised that the Thorpe Estate was insolvent and without funds to hire another attorney. The court has entered an order to show cause setting the case for a hearing on December 3, 2014 and indicated that if the Thorpe Estate fails to appear, an order of default will be entered.

'

'

'

'

'

'

'

'

'

Loss Contingency, Compensatory Damages Awarded, Value

'

$10,000

'

'

'

'

'

'

'

'

'

'

'

Litigation Settlement, Amount

'

'

'

3,600,000

'

'

'

'

'

'

'

'

'

Litigation Settlement, Judgment Amount Settled

'

'

'

15,000

'

'

'

'

'

'

'

'

'

Business License Tax [Abstract]

'

'

'

'

'

'

'

'

'

'

'

'

'

Business License Tax Examination, Description

'

'

'

'Atmos Energy, through its affiliate, AEM, has been involved in a dispute with the Tennessee Department of Revenue (TDOR) regarding sales business tax audits over a period of several years. The cumulative assessment approximated $12 million as of March 31, 2014, which AEM challenged. We had previously accrued in prior years what we believed to be an adequate amount for the anticipated resolution of this matter. With respect to certain issues, AEM and the TDOR filed competing Partial Motions for Summary Judgment with the Chancery Court. On August 2, 2013, the Chancery Court granted the TDOR's Partial Motion for Summary Judgment and denied AEM's Partial Motion for Summary Judgment. An agreed order of dismissal with prejudice between AEM and TDOR was approved by the Chancery Court and entered on May 2, 2014, whereby AEM agreed to pay $6.2 million to TDOR to resolve all business tax-related liabilities outstanding through September 2014. The State of Tennessee also passed related legislation, effective July 1, 2014, that should help minimize any disputes over this type of sales business tax in the future.

'

'

'

'

'

'

'

'

'

Business License Tax Examination, Settlement Amount

6,200,000

'

'

'

'

'

'

'

'

'

'

'

'

Long Term Purchase Commitment [Line Items]

'

'

'

'

'

'

'

'

'

'

'

'

'

Long Term Purchase Commitment Minimum Quantity Required Within One Year

'

'

'

'

'

'

'

'

'

'

49,700

111,500

7,800

Long Term Purchase Commitment Minimum Quantity Required One To Three Years

'

'

'

'

'

'

'

'

'

'

69,800

19,800

'

Long Term Purchase Commitment Minimum Quantity Required After Three Years

'

'

'

'

'

'

'

'

'

'

'

500

'

Purchase Commitment Amount Minimum

'

'

'

'

'

'

'

'

'

'

'

'

1.96

Purchase Commitment Amount Maximum

'

'

'

'

'

'

'

'

'

'

'

'

4.49

Significant Purchase Commitment, Amount

'

'

'

'

140,900,000

89,000,000

72,200,000

1,687,500,000

1,246,100,000

978,800,000

'

'

'

Estimated Contractual Demand Fees [Abstract]

'

'

'

'

'

'

'

'

'

'

'

'

'

2015

'

'

'

7,426,000

'

'

'

'

'

'

'

'

'

2016

'

'

'

2,117,000

'

'

'

'

'

'

'

'

'

2017

'

'

'

1,437,000

'

'

'

'

'

'

'

'

'

2018

'

'

'

773,000

'

'

'

'

'

'

'

'

'

2019

'

'

'

143,000

'

'

'

'

'

'

'

'

'

Thereafter

'

'

'

214,000

'

'

'

'

'

'

'

'

'

Total Estimated Contractual Demand Fees

'

'

'

12,110,000

'

'

'

'

'

'

'

'

'

Loss Contingency, Settlement [Abstract]

'

'

'

'

'

'

'

'

'

'

'

'

'

Loss Contingency, Civil Penalty Paid to United States Treasury

'

'

6,400,000

'

'

'

'

'

'

'

'

'

'

Loss Contingency, Civil Penalty Paid to Energy Assistance Programs

'

'

$5,600,000

'

'

'

'

'

'

'

'

'

'

Income_Taxes_Details

Income Taxes (Details) (USD $)	12 Months Ended
	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2012
Current income taxes	'	'	'
Federal	$0	$0	$631,000
State	5,527,000	8,178,000	6,888,000
Deferred income taxes	'	'	'
Federal	169,106,000	124,836,000	103,971,000
State	12,375,000	9,605,000	-13,237,000
Investment tax credits	-6,000	-20,000	-27,000
Income tax expense	187,002,000	142,599,000	98,226,000
Deferred tax assets	'	'	'
Employee benefit plans	116,157,000	115,970,000	'
Interest rate agreements	10,565,000	0	'
Tax net operating loss carryforwards	236,626,000	196,296,000	'
Tax credit carryforward	21,614,000	20,939,000	'
Other	28,849,000	38,013,000	'
Total deferred tax assets	413,811,000	371,218,000	'
Valuation allowance	-6,969,000	-1,085,000	'
Net deferred tax assets	406,842,000	370,133,000	'
Deferred tax liabilities	'	'	'
Difference in net book value and net tax value of assets	-1,655,894,000	-1,445,450,000	'
Pension funding	-17,890,000	-23,480,000	'
Gas Cost Adjustments	-31,252,000	-19,182,000	'
Interest rate agreements	0	-21,726,000	'
Other	-37,173,000	-39,045,000	'
Total deferred tax liabilities	-1,742,209,000	-1,548,883,000	'
Net deferred tax liabilities	-1,335,367,000	-1,178,750,000	'
Deferred credits for rate regulated entities	-109,000	-51,000	'
Deferred Tax Assets, Operating Loss and Tax Credit Carryforwards [Abstract]	'	'	'
Deferred Tax Assets, Tax Credit Carryforwards, Alternative Minimum Tax	10,100,000	'	'
Deferred Tax Assets, Operating Loss Carryforwards, Domestic	224,200,000	'	'
Deferred Tax Assets, Operating Loss Carryforwards, State and Local	12,400,000	'	'
Deferred Tax Assets, Tax Credit Carryforwards, State	1,000,000	'	'
Deferred Tax Assets, Charitable Contribution Carryforwards	10,500,000	'	'
Valuation Allowance [Abstract]	'	'	'
Valuation allowance	-6,969,000	-1,085,000	'
Reconciliation of Unrecognized Tax Benefits [Roll Forward]	'	'	'
Unrecognized Tax Benefits, Beginning Balance	4,158,000	2,817,000	'
Unrecognized Tax Benefits, Increase Resulting from Prior Period Tax Positions	3,846,000	0	'
Unrecognized Tax Benefits, Increase Resulting from Current Period Tax Positions	4,625,000	1,341,000	'
Unrecognized Tax Benefits, Ending Balance	12,629,000	4,158,000	2,817,000
Unrecognized Tax Benefits, Income Tax Penalties and Interest Accrued	411,000	0	'
Unrecognized Tax Benefits, Gross	13,040,000	4,158,000	'
Unrecognized Tax Benefits, Deferred Federal and State Income Tax Benefits	-4,564,000	-1,455,000	'
Unrecognized Tax Benefits that Would Impact Effective Tax Rate	8,476,000	2,703,000	'
Other Tax Matters [Abstract]	'	'	'
Other Information Pertaining to Income Taxes	' results for fiscal 2012 were favorably impacted by a state tax benefit of $13.6 million (net of federal effects). Due to the completion of the sale of our Missouri, Iowa and Illinois service areas in the fiscal fourth quarter, the Company updated its analysis of the tax rate at which deferred taxes would reverse in the future to reflect the sale of these service areas. The updated analysis supported a reduction in the deferred tax rate which when applied to the balance of taxable income deferred to future periods resulted in a reduction of the Company’s overall deferred tax liability.	'	'
State tax benefit	'	'	$13,600,000

Income_Taxes_Rate_Reconciliati

Income Taxes Rate Reconciliation (Details) (USD $)	12 Months Ended
In Thousands, unless otherwise specified	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2012
Effective Income Tax Rate Reconciliation, Amount [Abstract]	'	'	'
Tax at statutory rate of 35%	$166,887	$130,655	$101,648
Common stock dividends deductible for tax reporting	-2,307	-2,153	-2,096
State taxes (net of federal benefit)	11,636	11,559	-4,127
Change in valuation allowance	6,969	1,085	0
Other, net	3,817	1,453	2,801
Income tax expense (benefit)	$187,002	$142,599	$98,226

Financial_Instruments_Financia

Financial Instruments Financial Instruments at Fair Value (Details) (USD $)	Sep. 30, 2014		Sep. 30, 2013
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]	'		'
Derivative Asset, Current	$45,827,000		$11,966,000
Derivative Asset, Noncurrent	13,038,000		109,354,000
Derivative Liability, Current	1,730,000		1,543,000
Derivative Liability, Noncurrent	20,126,000		0
Derivative Assets (Liabilities), at Fair Value, Net	37,009,000		119,777,000
Derivative, Cash Collateral	25,800,000		24,800,000
Derivative Liability, Collateral, Right to Reclaim Cash, Offset	3,100,000		14,700,000
Derivative, Collateral, Right to Reclaim Cash	22,700,000		10,100,000
Regulated Distribution Segment [Member]	'		'
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]	'		'
Derivative Asset, Current	23,102,000		1,837,000
Derivative Asset, Noncurrent	13,038,000		109,354,000
Derivative Liability, Current	1,730,000		1,543,000
Derivative Liability, Noncurrent	20,126,000		0
Derivative Assets (Liabilities), at Fair Value, Net	14,284,000		109,648,000
Derivative Liability, Collateral, Right to Reclaim Cash, Offset	0		0
Derivative, Collateral, Right to Reclaim Cash	0		0
Nonregulated Segment [Member]	'		'
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]	'		'
Derivative Asset, Current	22,725,000	[1]	10,129,000	[2]
Derivative Asset, Noncurrent	0		0
Derivative Liability, Current	0	[1]	0	[2]
Derivative Liability, Noncurrent	0		0
Derivative Assets (Liabilities), at Fair Value, Net	22,725,000		10,129,000
Derivative Liability, Collateral, Right to Reclaim Cash, Offset	3,033,000		14,705,000
Derivative, Collateral, Right to Reclaim Cash	$22,725,000		$10,124,000
[1]	Includes $25.8 million of cash held on deposit to collateralize certain financial instruments. Of this amount, $3.1 million was used to offset current and noncurent risk management liabilities under master netting arrangements and the remaining $22.7 million is classified as current risk management assets.
[2]	Includes $24.8 million of cash held on deposit to collateralize certain financial instruments. Of this amount, $14.7 million was used to offset current and noncurrent risk management liabilities under master netting arrangements and the remaining $10.1 million is classified as current risk management assets.

Financial_Instruments_Balance_

Financial Instruments Balance Sheet Location (Details) (USD $)	Sep. 30, 2014	Sep. 30, 2013
In Thousands, unless otherwise specified
Derivatives, Fair Value [Line Items]	'	'
Derivative, Collateral, Right to Reclaim Cash	$22,700	$10,100
Derivative Liability, Collateral, Right to Reclaim Cash, Offset	3,100	14,700
Regulated Distribution Segment [Member]	'	'
Derivatives, Fair Value [Line Items]	'	'
Derivative Asset, Fair Value, Gross Asset	36,140	111,191
Derivative Asset, Contract Netting	0	0
Derivative Asset, Net of Contract Netting	36,140	111,191
Derivative, Collateral, Right to Reclaim Cash	0	0
Derivative Asset	36,140	111,191
Derivative Liability, Fair Value, Gross Liability	-21,856	-1,543
Derivative Liability, Contract Netting	0	0
Derivative Liability, Net of Contract Netting	-21,856	-1,543
Derivative Liability, Collateral, Right to Reclaim Cash, Offset	0	0
Derivative Liability	-21,856	-1,543
Regulated Distribution Segment [Member] | Designated as Hedging Instrument [Member]	'	'
Derivatives, Fair Value [Line Items]	'	'
Derivative Asset, Fair Value, Gross Asset	34,477	107,512
Derivative Liability, Fair Value, Gross Liability	-19,835	0
Regulated Distribution Segment [Member] | Designated as Hedging Instrument [Member] | Other Current Assets [Member] | Commodity Contract [Member]	'	'
Derivatives, Fair Value [Line Items]	'	'
Derivative Asset, Fair Value, Gross Asset	0	0
Regulated Distribution Segment [Member] | Designated as Hedging Instrument [Member] | Other Current Assets [Member] | Interest Rate Contract [Member]	'	'
Derivatives, Fair Value [Line Items]	'	'
Derivative Asset, Fair Value, Gross Asset	21,869	'
Regulated Distribution Segment [Member] | Designated as Hedging Instrument [Member] | Deferred Charges And Other Assets [Member] | Commodity Contract [Member]	'	'
Derivatives, Fair Value [Line Items]	'	'
Derivative Asset, Fair Value, Gross Asset	0	0
Regulated Distribution Segment [Member] | Designated as Hedging Instrument [Member] | Deferred Charges And Other Assets [Member] | Interest Rate Contract [Member]	'	'
Derivatives, Fair Value [Line Items]	'	'
Derivative Asset, Fair Value, Gross Asset	12,608	107,512
Regulated Distribution Segment [Member] | Designated as Hedging Instrument [Member] | Other Current Liabilities [Member] | Commodity Contract [Member]	'	'
Derivatives, Fair Value [Line Items]	'	'
Derivative Liability, Fair Value, Gross Liability	0	0
Regulated Distribution Segment [Member] | Designated as Hedging Instrument [Member] | Other Current Liabilities [Member] | Interest Rate Contract [Member]	'	'
Derivatives, Fair Value [Line Items]	'	'
Derivative Liability, Fair Value, Gross Liability	0	'
Regulated Distribution Segment [Member] | Designated as Hedging Instrument [Member] | Deferred Credits And Other Liabilities [Member] | Commodity Contract [Member]	'	'
Derivatives, Fair Value [Line Items]	'	'
Derivative Liability, Fair Value, Gross Liability	0	0
Regulated Distribution Segment [Member] | Designated as Hedging Instrument [Member] | Deferred Credits And Other Liabilities [Member] | Interest Rate Contract [Member]	'	'
Derivatives, Fair Value [Line Items]	'	'
Derivative Liability, Fair Value, Gross Liability	-19,835	0
Regulated Distribution Segment [Member] | Not Designated as Hedging Instrument [Member]	'	'
Derivatives, Fair Value [Line Items]	'	'
Derivative Asset, Fair Value, Gross Asset	1,663	3,679
Derivative Liability, Fair Value, Gross Liability	-2,021	-1,543
Regulated Distribution Segment [Member] | Not Designated as Hedging Instrument [Member] | Other Current Assets [Member] | Commodity Contract [Member]	'	'
Derivatives, Fair Value [Line Items]	'	'
Derivative Asset, Fair Value, Gross Asset	1,233	1,837
Regulated Distribution Segment [Member] | Not Designated as Hedging Instrument [Member] | Deferred Charges And Other Assets [Member] | Commodity Contract [Member]	'	'
Derivatives, Fair Value [Line Items]	'	'
Derivative Asset, Fair Value, Gross Asset	430	1,842
Regulated Distribution Segment [Member] | Not Designated as Hedging Instrument [Member] | Other Current Liabilities [Member] | Commodity Contract [Member]	'	'
Derivatives, Fair Value [Line Items]	'	'
Derivative Liability, Fair Value, Gross Liability	-1,730	-1,543
Regulated Distribution Segment [Member] | Not Designated as Hedging Instrument [Member] | Deferred Credits And Other Liabilities [Member] | Commodity Contract [Member]	'	'
Derivatives, Fair Value [Line Items]	'	'
Derivative Liability, Fair Value, Gross Liability	-291	0
Nonregulated Segment [Member]	'	'
Derivatives, Fair Value [Line Items]	'	'
Derivative Asset, Fair Value, Gross Asset	69,023	115,880
Derivative Asset, Contract Netting	-69,023	-115,875
Derivative Asset, Net of Contract Netting	0	5
Derivative, Collateral, Right to Reclaim Cash	22,725	10,124
Derivative Asset	22,725	10,129
Derivative Liability, Fair Value, Gross Liability	-72,056	-130,580
Derivative Liability, Contract Netting	69,023	115,875
Derivative Liability, Net of Contract Netting	-3,033	-14,705
Derivative Liability, Collateral, Right to Reclaim Cash, Offset	3,033	14,705
Derivative Liability	0	0
Nonregulated Segment [Member] | Designated as Hedging Instrument [Member]	'	'
Derivatives, Fair Value [Line Items]	'	'
Derivative Asset, Fair Value, Gross Asset	9,669	9,510
Derivative Liability, Fair Value, Gross Liability	-9,541	-13,812
Nonregulated Segment [Member] | Designated as Hedging Instrument [Member] | Other Current Assets [Member] | Commodity Contract [Member]	'	'
Derivatives, Fair Value [Line Items]	'	'
Derivative Asset, Fair Value, Gross Asset	8,912	9,094
Nonregulated Segment [Member] | Designated as Hedging Instrument [Member] | Other Current Assets [Member] | Interest Rate Contract [Member]	'	'
Derivatives, Fair Value [Line Items]	'	'
Derivative Asset, Fair Value, Gross Asset	0	'
Nonregulated Segment [Member] | Designated as Hedging Instrument [Member] | Deferred Charges And Other Assets [Member] | Commodity Contract [Member]	'	'
Derivatives, Fair Value [Line Items]	'	'
Derivative Asset, Fair Value, Gross Asset	757	416
Nonregulated Segment [Member] | Designated as Hedging Instrument [Member] | Deferred Charges And Other Assets [Member] | Interest Rate Contract [Member]	'	'
Derivatives, Fair Value [Line Items]	'	'
Derivative Asset, Fair Value, Gross Asset	0	0
Nonregulated Segment [Member] | Designated as Hedging Instrument [Member] | Other Current Liabilities [Member] | Commodity Contract [Member]	'	'
Derivatives, Fair Value [Line Items]	'	'
Derivative Liability, Fair Value, Gross Liability	-7,082	-12,173
Nonregulated Segment [Member] | Designated as Hedging Instrument [Member] | Other Current Liabilities [Member] | Interest Rate Contract [Member]	'	'
Derivatives, Fair Value [Line Items]	'	'
Derivative Liability, Fair Value, Gross Liability	0	'
Nonregulated Segment [Member] | Designated as Hedging Instrument [Member] | Deferred Credits And Other Liabilities [Member] | Commodity Contract [Member]	'	'
Derivatives, Fair Value [Line Items]	'	'
Derivative Liability, Fair Value, Gross Liability	-2,459	-1,639
Nonregulated Segment [Member] | Designated as Hedging Instrument [Member] | Deferred Credits And Other Liabilities [Member] | Interest Rate Contract [Member]	'	'
Derivatives, Fair Value [Line Items]	'	'
Derivative Liability, Fair Value, Gross Liability	0	0
Nonregulated Segment [Member] | Not Designated as Hedging Instrument [Member]	'	'
Derivatives, Fair Value [Line Items]	'	'
Derivative Asset, Fair Value, Gross Asset	59,354	106,370
Derivative Liability, Fair Value, Gross Liability	-62,515	-116,768
Nonregulated Segment [Member] | Not Designated as Hedging Instrument [Member] | Other Current Assets [Member] | Commodity Contract [Member]	'	'
Derivatives, Fair Value [Line Items]	'	'
Derivative Asset, Fair Value, Gross Asset	43,677	65,388
Nonregulated Segment [Member] | Not Designated as Hedging Instrument [Member] | Deferred Charges And Other Assets [Member] | Commodity Contract [Member]	'	'
Derivatives, Fair Value [Line Items]	'	'
Derivative Asset, Fair Value, Gross Asset	15,677	40,982
Nonregulated Segment [Member] | Not Designated as Hedging Instrument [Member] | Other Current Liabilities [Member] | Commodity Contract [Member]	'	'
Derivatives, Fair Value [Line Items]	'	'
Derivative Liability, Fair Value, Gross Liability	-47,729	-70,876
Nonregulated Segment [Member] | Not Designated as Hedging Instrument [Member] | Deferred Credits And Other Liabilities [Member] | Commodity Contract [Member]	'	'
Derivatives, Fair Value [Line Items]	'	'
Derivative Liability, Fair Value, Gross Liability	($14,786)	($45,892)

Financial_Instruments_Descript

Financial Instruments Descriptions (Details) (USD $)	12 Months Ended
In Millions, unless otherwise specified	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Aug. 31, 2011	Sep. 30, 2012	Sep. 30, 2014	Sep. 30, 2014	Sep. 30, 2014
	MMcf			Interest Rate Hedges, Senior Notes 2013 Issuance [Member]	Interest Rate Hedges, Senior Notes 2013 Issuance [Member]	Interest Rate Hedges, Short-term Note 2012 Issuance [Member]	Interest Rate Hedges, Senior Notes 2015 Issuance [Member]	Interest Rate Hedges, Senior Notes 2017 Issuance [Member]	Interest Rate Hedges, Senior Notes 2019 Issuance [Member]
General Discussion of Derivative Instruments and Hedging Activities [Abstract]	'	'	'	'	'	'	'	'	'
Minimum Hedge Percentage Of Anticipated Heating Season Gas	25.00%	'	'	'	'	'	'	'	'
Maximum Hedge Percentage Of Anticipated Heating Season Gas	50.00%	'	'	'	'	'	'	'	'
Hedge Percentage Of Actual Heating Season Gas	32.00%	'	'	'	'	'	'	'	'
Hedge Volume Of Actual Heating Season Gas	24,800	'	'	'	'	'	'	'	'
Weighted Average Cost Of Actual Heating Season Gas	4.02	'	'	'	'	'	'	'	'
Minimum Length Of Time Hedged In Cash Flow Hedge	'0 years 1 month 0 days	'	'	'	'	'	'	'	'
Maximum Length of Time Hedged in Cash Flow Hedge	'0 years 61 months 0 days	'	'	'	'	'	'	'	'
Net Open Positions	100	'	'	'	'	'	'	'	'
Gain Loss On Hedge Ineffectiveness	$1.90	$18.20	$23.10	'	'	'	'	'	'
Regulated Segments Effective Income Tax Rate Reconciliation At Federal Statutory Income Tax Rate	37.00%	'	'	'	'	'	'	'	'
Nonregulated Segment Effective Income Tax Rate Reconciliation At Federal Statutory Income Tax Rate	39.00%	'	'	'	'	'	'	'	'
Gain Loss On Derivative Instruments Not Designated Hedges Net Pretax	-5	3	-2.5	'	'	'	'	'	'
Natural Gas Inventory [Abstract]	'	'	'	'	'	'	'	'	'
Inventory Write-down	'	'	1.7	'	'	'	'	'	'
Derivative [Line Items]	'	'	'	'	'	'	'	'	'
Derivative, Notional Amount	'	'	'	'	350	260	500	250	400
Anticipated Debt Issuance, Amount	'	'	'	'	'	'	'	'	450
Unrealized Gain (Loss) on Interest Rate Cash Flow Hedges, Pretax, Accumulated Other Comprehensive Income (Loss)	'	'	'	($66.60)	'	'	'	'	'

Financial_Instruments_Commodit

Financial Instruments Commodity Contract Volumes (Details)	Sep. 30, 2014
	MMcf
Regulated Distribution Segment [Member]	'
Commodity Contract Outstanding Volumes [Line Items]	'
Investment Contract Volume	31,812
Regulated Distribution Segment [Member] | Not Designated as Hedging Instrument [Member]	'
Commodity Contract Outstanding Volumes [Line Items]	'
Investment Contract Volume	31,812
Regulated Distribution Segment [Member] | Fair Value Hedging [Member]	'
Commodity Contract Outstanding Volumes [Line Items]	'
Investment Contract Volume	0
Regulated Distribution Segment [Member] | Cash Flow Hedging [Member]	'
Commodity Contract Outstanding Volumes [Line Items]	'
Investment Contract Volume	0
Nonregulated Segment [Member]	'
Commodity Contract Outstanding Volumes [Line Items]	'
Investment Contract Volume	135,703
Nonregulated Segment [Member] | Not Designated as Hedging Instrument [Member]	'
Commodity Contract Outstanding Volumes [Line Items]	'
Investment Contract Volume	96,711
Nonregulated Segment [Member] | Fair Value Hedging [Member]	'
Commodity Contract Outstanding Volumes [Line Items]	'
Investment Contract Volume	-10,298
Nonregulated Segment [Member] | Cash Flow Hedging [Member]	'
Commodity Contract Outstanding Volumes [Line Items]	'
Investment Contract Volume	49,290

Financial_Instruments_Fair_Val

Financial Instruments Fair Value Hedges and Cash Flow Hedges (Details) (USD $)	12 Months Ended
In Thousands, unless otherwise specified	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2012
Effect of Fair Value Hedges on Results of Operations [Abstract]	'	'	'
Commodity contracts	($792)	$2,165	$30,266
Fair value adjustment for natural gas inventory designated as the hedged item	2,486	15,938	-5,797
Total (increase) decrease in purchased gas cost	1,694	18,103	24,469
Fair Value Hedge Basis Ineffectiveness	-919	-208	1,170
Fair Value Hedge Timing Ineffectiveness	2,613	18,311	23,299
Cash Flow Hedge [Line Items]	'	'	'
Gain (loss) reclassified from AOCI into purchased gas cost for effective portion of commodity contracts	8,365	-10,778	-62,678
Gain (loss) arising from ineffective portion of commodity contracts	198	97	-1,369
Total impact on purchased gas cost	8,563	-10,681	-64,047
Net loss on settled Treasury lock agreements reclassified from AOCI into interest expense	-4,230	-3,489	-2,009
Total Impact from Cash Flow Hedges	4,333	-14,170	-66,056
Regulated Distribution Segment [Member]	'	'	'
Cash Flow Hedge [Line Items]	'	'	'
Gain (loss) reclassified from AOCI into purchased gas cost for effective portion of commodity contracts	0	0	0
Gain (loss) arising from ineffective portion of commodity contracts	0	0	0
Total impact on purchased gas cost	0	0	0
Net loss on settled Treasury lock agreements reclassified from AOCI into interest expense	-4,230	-3,489	-2,009
Total Impact from Cash Flow Hedges	-4,230	-3,489	-2,009
Nonregulated Segment [Member]	'	'	'
Cash Flow Hedge [Line Items]	'	'	'
Gain (loss) reclassified from AOCI into purchased gas cost for effective portion of commodity contracts	8,365	-10,778	-62,678
Gain (loss) arising from ineffective portion of commodity contracts	198	97	-1,369
Total impact on purchased gas cost	8,563	-10,681	-64,047
Net loss on settled Treasury lock agreements reclassified from AOCI into interest expense	0	0	0
Total Impact from Cash Flow Hedges	$8,563	($10,681)	($64,047)

Financial_Instruments_Other_Co

Financial Instruments Other Comprehensive Income (Details) (USD $)	12 Months Ended
In Thousands, unless otherwise specified	Sep. 30, 2014		Sep. 30, 2013
Other Comprehensive Income [Abstract]	'		'
Interest rate agreements fair value	($58,973)		$79,963
Forward commodity contracts fair value	7,904		-2,057
Interest rate agreements	2,686		2,216
Forward commodity contracts	-5,102		6,576
Total other comprehensive income (loss) from hedging, net of tax	-53,485	[1]	86,698	[1]
Expected Earnings [Line Items]	'		'
2015	-1,436		'
2016	-1,541		'
2017	-842		'
2018	-974		'
2019	-951		'
Thereafter	-23,609		'
Cash Flow Hedge Gain (Loss) To Be Reclassiflied, Total	-29,353	[1]	'
Interest Rate Contract [Member]	'		'
Expected Earnings [Line Items]	'		'
2015	-804		'
2016	-634		'
2017	-735		'
2018	-936		'
2019	-961		'
Thereafter	-23,609		'
Cash Flow Hedge Gain (Loss) To Be Reclassiflied, Total	-27,679	[1]	'
Commodity Contract [Member]	'		'
Expected Earnings [Line Items]	'		'
2015	-632		'
2016	-907		'
2017	-107		'
2018	-38		'
2019	10		'
Thereafter	0		'
Cash Flow Hedge Gain (Loss) To Be Reclassiflied, Total	($1,674)	[1]	'
[1]	Utilizing an income tax rate ranging from approximately 37 percent to 39 percent based on the effective rates in each taxing jurisdiction.

Accumulated_Other_Comprehensiv2

Accumulated Other Comprehensive Income Components (Details) (USD $)	12 Months Ended
In Thousands, unless otherwise specified	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2012
Accumulated Other Comprehensive Income (Loss) [Line Items]	'	'	'
Accumulated other comprehensive income (loss), beginning balance	$38,878	($47,607)	'
Other comprehensive income before reclassifications	-48,060	79,068	'
Amounts reclassified from accumulated other comprehensive income	-3,211	7,417	'
Net current-period other comprehensive income (loss)	-51,271	86,485	853
Accumulated other comprehensive income (loss), ending balance	-12,393	38,878	-47,607
Accumulated Net Unrealized Investment Gain (Loss) [Member]	'	'	'
Accumulated Other Comprehensive Income (Loss) [Line Items]	'	'	'
Accumulated other comprehensive income (loss), beginning balance	5,448	5,661	'
Other comprehensive income before reclassifications	3,009	1,162	'
Amounts reclassified from accumulated other comprehensive income	-795	-1,375	'
Net current-period other comprehensive income (loss)	2,214	-213	'
Accumulated other comprehensive income (loss), ending balance	7,662	5,448	'
Accumulated Net Gain (Loss) from Interest Rate Hedges [Member] [Member]	'	'	'
Accumulated Other Comprehensive Income (Loss) [Line Items]	'	'	'
Accumulated other comprehensive income (loss), beginning balance	37,906	-44,273	'
Other comprehensive income before reclassifications	-58,973	79,963	'
Amounts reclassified from accumulated other comprehensive income	2,686	2,216	'
Net current-period other comprehensive income (loss)	-56,287	82,179	'
Accumulated other comprehensive income (loss), ending balance	-18,381	37,906	'
Accumulated Net Gain (Loss) from Commodity Contracts Cash Flow Hedges [Member] [Member]	'	'	'
Accumulated Other Comprehensive Income (Loss) [Line Items]	'	'	'
Accumulated other comprehensive income (loss), beginning balance	-4,476	-8,995	'
Other comprehensive income before reclassifications	7,904	-2,057	'
Amounts reclassified from accumulated other comprehensive income	-5,102	6,576	'
Net current-period other comprehensive income (loss)	2,802	4,519	'
Accumulated other comprehensive income (loss), ending balance	($1,674)	($4,476)	'

Accumulated_Other_Comprehensiv3

Accumulated Other Comprehensive Income Affected Line Item in the Statement of Income (Details) (USD $)	3 Months Ended				12 Months Ended
In Thousands, unless otherwise specified	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2012	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2012
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]	'	'	'	'	'	'	'
Operation and maintenance	'	'	'	'	($505,154)	($488,020)	($453,613)
Interest charges	'	'	'	'	-129,295	-128,385	-141,174
Income (loss) before income taxes	'	'	'	'	476,819	373,297	290,422
Income Tax Expense (Benefit)	'	'	'	'	-187,002	-142,599	-98,226
Income (loss) from continuing operations	7,536	33,474	112,340	77,348	289,817	230,698	192,196
Reclassification out of Accumulated Other Comprehensive Income [Member]	'	'	'	'	'	'	'
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]	'	'	'	'	'	'	'
Income (loss) from continuing operations	'	'	'	'	3,211	-7,417	'
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	'	'	'	'	1,252	2,166	'
Income (loss) before income taxes	'	'	'	'	1,252	2,166	'
Income Tax Expense (Benefit)	'	'	'	'	-457	-791	'
Income (loss) from continuing operations	'	'	'	'	795	1,375	'
Reclassification out of Accumulated Other Comprehensive Income [Member] | Accumulated Net Gain (Loss) from Interest Rate Hedges [Member] [Member]	'	'	'	'	'	'	'
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]	'	'	'	'	'	'	'
Interest charges	'	'	'	'	-4,230	-3,489	'
Reclassification out of Accumulated Other Comprehensive Income [Member] | Accumulated Net Gain (Loss) from Commodity Contracts Cash Flow Hedges [Member] [Member]	'	'	'	'	'	'	'
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]	'	'	'	'	'	'	'
Purchased gas cost	'	'	'	'	8,365	-10,778	'
Reclassification out of Accumulated Other Comprehensive Income [Member] | Accumulated Net Gain (Loss) from Designated or Qualifying Cash Flow Hedges [Member]	'	'	'	'	'	'	'
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]	'	'	'	'	'	'	'
Income (loss) before income taxes	'	'	'	'	4,135	-14,267	'
Income Tax Expense (Benefit)	'	'	'	'	-1,719	5,475	'
Income (loss) from continuing operations	'	'	'	'	$2,416	($8,792)	'

Fair_Value_Measurements_Detail

Fair Value Measurements (Details) (USD $)	12 Months Ended
	Sep. 30, 2012	Sep. 30, 2014	Sep. 30, 2013
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]	'	'	'
Financial instruments, assets	'	$58,865,000	$121,320,000
Hedged portion of gas stored underground	'	40,492,000	44,758,000
Available-for-sale Securities	'	79,613,000	72,682,000
Total assets	'	178,970,000	238,760,000
Financial instruments, liabilities	'	21,856,000	1,543,000
Fair Value [Abstract]	'	'	'
Derivative, Cash Collateral	'	25,800,000	24,800,000
Derivative Liability, Collateral, Right to Reclaim Cash, Offset	'	3,100,000	14,700,000
Derivative, Collateral, Right to Reclaim Cash	'	22,700,000	10,100,000
Debt Instrument Carrying Amount	'	2,460,000,000	2,460,000,000
Debt Instrument Fair Value	'	2,769,541,000	'
Other Matters [Abstract]	'	'	'
Asset Impairment Charges Park City	5,300,000	'	'
Nonrecurring fair value measurement	500,000	'	'
Money Market Funds [Member]	'	'	'
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]	'	'	'
Available-for-sale Securities	'	2,185,000	4,428,000
Equity Securities [Member]	'	'	'
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]	'	'	'
Available-for-sale Securities	'	44,014,000	40,094,000
Debt Securities [Member]	'	'	'
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]	'	'	'
Available-for-sale Securities	'	33,414,000	28,160,000
Regulated Distribution Segment [Member]	'	'	'
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]	'	'	'
Financial instruments, assets	'	36,140,000	111,191,000
Financial instruments, liabilities	'	21,856,000	1,543,000
Fair Value [Abstract]	'	'	'
Derivative Liability, Collateral, Right to Reclaim Cash, Offset	'	0	0
Derivative, Collateral, Right to Reclaim Cash	'	0	0
Nonregulated Segment [Member]	'	'	'
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]	'	'	'
Financial instruments, assets	'	22,725,000	10,129,000
Financial instruments, liabilities	'	0	0
Fair Value [Abstract]	'	'	'
Derivative Liability, Collateral, Right to Reclaim Cash, Offset	'	3,033,000	14,705,000
Derivative, Collateral, Right to Reclaim Cash	'	22,725,000	10,124,000
Fair Value Inputs Level 1 [Member]	'	'	'
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]	'	'	'
Financial instruments, assets	'	25,000	745,000
Hedged portion of gas stored underground	'	40,492,000	44,758,000
Available-for-sale Securities	'	44,014,000	40,094,000
Total assets	'	84,531,000	85,597,000
Financial instruments, liabilities	'	12,000	158,000
Fair Value Inputs Level 1 [Member] | Money Market Funds [Member]	'	'	'
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]	'	'	'
Available-for-sale Securities	'	0	0
Fair Value Inputs Level 1 [Member] | Equity Securities [Member]	'	'	'
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]	'	'	'
Available-for-sale Securities	'	44,014,000	40,094,000
Fair Value Inputs Level 1 [Member] | Debt Securities [Member]	'	'	'
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]	'	'	'
Available-for-sale Securities	'	0	0
Fair Value Inputs Level 1 [Member] | Regulated Distribution Segment [Member]	'	'	'
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]	'	'	'
Financial instruments, assets	'	0	0
Financial instruments, liabilities	'	0	0
Fair Value Inputs Level 1 [Member] | Nonregulated Segment [Member]	'	'	'
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]	'	'	'
Financial instruments, assets	'	25,000	745,000
Financial instruments, liabilities	'	12,000	158,000
Fair Value Inputs Level 2 [Member]	'	'	'
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]	'	'	'
Financial instruments, assets	'	105,138,000	226,326,000
Hedged portion of gas stored underground	'	0	0
Available-for-sale Securities	'	35,599,000	32,588,000
Total assets	'	140,737,000	258,914,000
Financial instruments, liabilities	'	93,900,000	131,965,000
Fair Value Inputs Level 2 [Member] | Money Market Funds [Member]	'	'	'
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]	'	'	'
Available-for-sale Securities	'	2,185,000	4,428,000
Fair Value Inputs Level 2 [Member] | Equity Securities [Member]	'	'	'
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]	'	'	'
Available-for-sale Securities	'	0	0
Fair Value Inputs Level 2 [Member] | Debt Securities [Member]	'	'	'
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]	'	'	'
Available-for-sale Securities	'	33,414,000	28,160,000
Fair Value Inputs Level 2 [Member] | Regulated Distribution Segment [Member]	'	'	'
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]	'	'	'
Financial instruments, assets	'	36,140,000	111,191,000
Financial instruments, liabilities	'	21,856,000	1,543,000
Fair Value Inputs Level 2 [Member] | Nonregulated Segment [Member]	'	'	'
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]	'	'	'
Financial instruments, assets	'	68,998,000	115,135,000
Financial instruments, liabilities	'	72,044,000	130,422,000
Fair Value Inputs Level 3 [Member]	'	'	'
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]	'	'	'
Financial instruments, assets	'	0	0
Hedged portion of gas stored underground	'	0	0
Available-for-sale Securities	'	0	0
Total assets	'	0	0
Financial instruments, liabilities	'	0	0
Fair Value Inputs Level 3 [Member] | Money Market Funds [Member]	'	'	'
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]	'	'	'
Available-for-sale Securities	'	0	0
Fair Value Inputs Level 3 [Member] | Equity Securities [Member]	'	'	'
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]	'	'	'
Available-for-sale Securities	'	0	0
Fair Value Inputs Level 3 [Member] | Debt Securities [Member]	'	'	'
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]	'	'	'
Available-for-sale Securities	'	0	0
Fair Value Inputs Level 3 [Member] | Regulated Distribution Segment [Member]	'	'	'
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]	'	'	'
Financial instruments, assets	'	0	0
Financial instruments, liabilities	'	0	0
Fair Value Inputs Level 3 [Member] | Nonregulated Segment [Member]	'	'	'
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]	'	'	'
Financial instruments, assets	'	0	0
Financial instruments, liabilities	'	0	0
Netting And Collateral [Member]	'	'	'
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]	'	'	'
Financial instruments, assets	'	-46,298,000	-105,751,000
Hedged portion of gas stored underground	'	0	0
Available-for-sale Securities	'	0	0
Total assets	'	-46,298,000	-105,751,000
Financial instruments, liabilities	'	-72,056,000	-130,580,000
Netting And Collateral [Member] | Money Market Funds [Member]	'	'	'
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]	'	'	'
Available-for-sale Securities	'	0	0
Netting And Collateral [Member] | Equity Securities [Member]	'	'	'
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]	'	'	'
Available-for-sale Securities	'	0	0
Netting And Collateral [Member] | Debt Securities [Member]	'	'	'
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]	'	'	'
Available-for-sale Securities	'	0	0
Netting And Collateral [Member] | Regulated Distribution Segment [Member]	'	'	'
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]	'	'	'
Financial instruments, assets	'	0	0
Financial instruments, liabilities	'	0	0
Netting And Collateral [Member] | Nonregulated Segment [Member]	'	'	'
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]	'	'	'
Financial instruments, assets	'	-46,298,000	-105,751,000
Financial instruments, liabilities	'	($72,056,000)	($130,580,000)

Fair_Value_Measurements_Availa

Fair Value Measurements Available-For-Sale Securities (Details) (USD $)	12 Months Ended
	Sep. 30, 2014	Sep. 30, 2013
Schedule of Available-for-sale Securities [Line Items]	'	'
Amortized Cost	$67,466,000	$64,023,000
Available For Sale Securities Gross Unrealized Gain Accumulated In Investments	12,160,000	8,706,000
Available For Sale Securities Gross Unrealized Loss Accumulated In Investments	-13,000	-47,000
Fair value	79,613,000	72,682,000
Available-for-sale Securities, Other Disclosure Items [Abstract]	'	'
Available-for-sale Securities, Supplemental Executive Benefit Plans	46,200,000	44,500,000
Available-for-sale Securities, Gross Realized Gains	1,300,000	2,200,000
Equity Funds Domestic [Member]	'	'
Schedule of Available-for-sale Securities [Line Items]	'	'
Amortized Cost	26,633,000	27,043,000
Available For Sale Securities Gross Unrealized Gain Accumulated In Investments	10,136,000	7,476,000
Available For Sale Securities Gross Unrealized Loss Accumulated In Investments	0	-23,000
Fair value	36,769,000	34,496,000
Equity Funds Foreign [Member]	'	'
Schedule of Available-for-sale Securities [Line Items]	'	'
Amortized Cost	5,382,000	4,536,000
Available For Sale Securities Gross Unrealized Gain Accumulated In Investments	1,863,000	1,062,000
Available For Sale Securities Gross Unrealized Loss Accumulated In Investments	0	0
Fair value	7,245,000	5,598,000
Debt Securities [Member]	'	'
Schedule of Available-for-sale Securities [Line Items]	'	'
Amortized Cost	33,266,000	28,016,000
Available For Sale Securities Gross Unrealized Gain Accumulated In Investments	161,000	168,000
Available For Sale Securities Gross Unrealized Loss Accumulated In Investments	-13,000	-24,000
Fair value	33,414,000	28,160,000
Money Market Funds [Member]	'	'
Schedule of Available-for-sale Securities [Line Items]	'	'
Amortized Cost	2,185,000	4,428,000
Available For Sale Securities Gross Unrealized Gain Accumulated In Investments	0	0
Available For Sale Securities Gross Unrealized Loss Accumulated In Investments	0	0
Fair value	$2,185,000	$4,428,000

Discontinued_Operations_Detail

Discontinued Operations (Details) (USD $)	3 Months Ended				12 Months Ended
	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2012	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2012
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]	'	'	'	'	'	'	'
Discontinued Operation, Gain (Loss) from Disposal of Discontinued Operation, before Income Tax	'	'	'	'	$0	$8,203,000	$9,868,000
Discontinued Operation Income Loss From Discontinued Operation Disclosures Abstract	'	'	'	'	'	'	'
Operating revenues	'	'	'	'	'	37,962,000	114,703,000
Purchased gas cost	'	'	'	'	'	21,464,000	62,902,000
Gross profit	'	'	'	'	'	16,498,000	51,801,000
Operating expenses	'	'	'	'	'	5,858,000	24,174,000
Operating income	'	'	'	'	'	10,640,000	27,627,000
Discontinued Operations Miscellaneous Income Expense	'	'	'	'	'	548,000	611,000
Income from discontinued operations before income taxes	'	'	'	'	'	11,188,000	28,238,000
Income tax expense	'	'	'	'	0	3,986,000	10,066,000
Income (loss) from discontinued operations	0	0	4,085,000	3,117,000	0	7,202,000	18,172,000
Gain on sale of discontinued operations, net of tax	0	5,294,000	0	0	0	5,294,000	6,349,000
Net income (loss) from discontinued operations	'	'	'	'	0	12,496,000	24,521,000
Missouri, Illinois and Iowa [Member]	'	'	'	'	'	'	'
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]	'	'	'	'	'	'	'
Discontinued Operation, Cash Price Received from Disposal of Discontinued Operation	'	'	'	'	'	128,000,000	'
Discontinued Operation, Gain (Loss) from Disposal of Discontinued Operation, before Income Tax	'	'	'	'	'	9,900,000	'
Georgia [Member]	'	'	'	'	'	'	'
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]	'	'	'	'	'	'	'
Discontinued Operation, Cash Price Received from Disposal of Discontinued Operation	'	'	'	'	153,000,000	'	'
Discontinued Operation, Gain (Loss) from Disposal of Discontinued Operation, before Income Tax	'	'	'	'	$8,200,000	'	'

Selected_Quarterly_Financial_D2

Selected Quarterly Financial Data (Details) (USD $)	3 Months Ended								12 Months Ended
In Thousands, except Per Share data, unless otherwise specified	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2012	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2012
Operating Revenues by Segment [Line Items]	'	'	'	'	'	'	'	'	'	'	'
Operating revenues	$778,728	$942,718	$1,964,322	$1,255,148	$674,374	$857,935	$1,308,996	$1,034,155	$4,940,916	$3,875,460	$3,436,162
Selected Quarterly Financial Information [Abstract]	'	'	'	'	'	'	'	'	'	'	'
Gross profit	337,659	359,533	496,277	388,957	300,440	316,497	432,751	362,362	1,582,426	1,412,050	1,323,739
Operating income	83,944	106,605	250,080	170,720	50,383	86,396	210,178	154,922	611,349	501,879	446,240
Income (loss) from continuing operations	'	'	'	'	7,536	33,474	112,340	77,348	289,817	230,698	192,196
Income from discontinued operations, net of tax	'	'	'	'	0	0	4,085	3,117	0	7,202	18,172
Gain on sale of discontinued operations, net of tax	'	'	'	'	0	5,294	0	0	0	5,294	6,349
Net income	23,713	45,721	133,367	87,016	7,536	38,768	116,425	80,465	289,817	243,194	216,717
Income per share from continuing operations - basic (usd per share)	'	'	'	'	$0.08	$0.37	$1.24	$0.85	$2.96	$2.54	$2.12
Income per share from discontinued operations - basic (usd per share)	'	'	'	'	$0	$0.06	$0.04	$0.04	$0	$0.14	$0.27
Net income per share — basic (usd per share)	$0.23	$0.45	$1.38	$0.94	$0.08	$0.43	$1.28	$0.89	$2.96	$2.68	$2.39
Income per share from continuing operations - diluted (usd per share)	'	'	'	'	$0.08	$0.36	$1.23	$0.85	$2.96	$2.50	$2.10
Income per share from discontinued operations - diluted (usd per share)	'	'	'	'	$0	$0.06	$0.04	$0.03	$0	$0.14	$0.27
Net income per share — diluted (usd per share)	$0.23	$0.45	$1.38	$0.94	$0.08	$0.42	$1.27	$0.88	$2.96	$2.64	$2.37
Regulated Distribution Segment [Member]	'	'	'	'	'	'	'	'	'	'	'
Operating Revenues by Segment [Line Items]	'	'	'	'	'	'	'	'	'	'	'
Operating revenues	409,014	517,707	1,290,960	843,865	360,386	467,144	905,176	666,787	3,061,546	2,399,493	2,145,330
Selected Quarterly Financial Information [Abstract]	'	'	'	'	'	'	'	'	'	'	'
Gross profit	'	'	'	'	'	'	'	'	1,176,515	1,081,236	1,022,743
Operating income	'	'	'	'	'	'	'	'	384,568	343,093	304,461
Income (loss) from continuing operations	'	'	'	'	'	'	'	'	'	150,856	123,848
Income from discontinued operations, net of tax	'	'	'	'	'	'	'	'	'	7,202	18,172
Gain on sale of discontinued operations, net of tax	'	'	'	'	'	'	'	'	'	5,649	6,349
Net income	'	'	'	'	'	'	'	'	171,585	163,707	148,369
Regulated Pipeline Segment [Member]	'	'	'	'	'	'	'	'	'	'	'
Operating Revenues by Segment [Line Items]	'	'	'	'	'	'	'	'	'	'	'
Operating revenues	86,314	87,189	73,615	71,341	72,330	74,041	61,848	60,681	318,459	268,900	247,351
Selected Quarterly Financial Information [Abstract]	'	'	'	'	'	'	'	'	'	'	'
Gross profit	'	'	'	'	'	'	'	'	318,459	268,900	247,351
Operating income	'	'	'	'	'	'	'	'	172,819	139,853	128,824
Income (loss) from continuing operations	'	'	'	'	'	'	'	'	'	68,260	63,059
Income from discontinued operations, net of tax	'	'	'	'	'	'	'	'	'	0	0
Gain on sale of discontinued operations, net of tax	'	'	'	'	'	'	'	'	'	0	'
Net income	'	'	'	'	'	'	'	'	86,191	68,260	63,059
Nonregulated Segment [Member]	'	'	'	'	'	'	'	'	'	'	'
Operating Revenues by Segment [Line Items]	'	'	'	'	'	'	'	'	'	'	'
Operating revenues	396,855	465,033	757,683	447,721	337,264	421,808	428,948	399,894	2,067,292	1,587,914	1,348,982
Selected Quarterly Financial Information [Abstract]	'	'	'	'	'	'	'	'	'	'	'
Gross profit	'	'	'	'	'	'	'	'	87,955	63,331	55,124
Operating income	'	'	'	'	'	'	'	'	53,962	18,927	12,950
Income (loss) from continuing operations	'	'	'	'	'	'	'	'	'	11,582	5,289
Income from discontinued operations, net of tax	'	'	'	'	'	'	'	'	'	0	0
Gain on sale of discontinued operations, net of tax	'	'	'	'	'	'	'	'	'	-355	'
Net income	'	'	'	'	'	'	'	'	32,041	11,227	5,289
Intersegment Elimination [Member]	'	'	'	'	'	'	'	'	'	'	'
Operating Revenues by Segment [Line Items]	'	'	'	'	'	'	'	'	'	'	'
Operating revenues	-113,455	-127,211	-157,936	-107,779	-95,606	-105,058	-86,976	-93,207	-506,381	-380,847	-305,501
Selected Quarterly Financial Information [Abstract]	'	'	'	'	'	'	'	'	'	'	'
Gross profit	'	'	'	'	'	'	'	'	-503	-1,417	-1,479
Operating income	'	'	'	'	'	'	'	'	0	6	5
Income (loss) from continuing operations	'	'	'	'	'	'	'	'	'	0	0
Income from discontinued operations, net of tax	'	'	'	'	'	'	'	'	'	0	0
Gain on sale of discontinued operations, net of tax	'	'	'	'	'	'	'	'	'	0	'
Net income	'	'	'	'	'	'	'	'	$0	$0	$0

Valuation_and_Qualifying_Accou

Valuation and Qualifying Accounts (Details) (Allowance For Doubtful Accounts Member, USD $)	12 Months Ended
In Thousands, unless otherwise specified	Sep. 30, 2014		Sep. 30, 2013		Sep. 30, 2012		Sep. 30, 2010
Allowance For Doubtful Accounts Member	'		'		'		'
Valuation And Qualifying Accounts Disclosure [Line Items]	'		'		'		'
Balance at beginning of period	$20,624		$9,425		'		$7,440
Charged to costs & expenses	19,491		14,484		8,901		'
Charged to other accounts	0		0		0		'
Valuation Allowances And Reserves Deductions	16,123	[1]	3,285	[1]	6,916	[1]	'
Balance at end of period	$23,992		$20,624		$9,425		$7,440
[1]	Uncollectible accounts written off.